Disintegration of the genus Prosopis L. (Leguminosae, Caesalpinioideae, mimosoid clade)

Colin E. Hughes; Jens J. Ringelberg; Gwilym P. Lewis; Santiago A. Catalano

doi:10.3897/phytokeys.205.75379

Research Article

Disintegration of the genus Prosopis L. (Leguminosae, Caesalpinioideae, mimosoid clade)

Colin E. Hughes^‡, Jens J. Ringelberg^§, Gwilym P. Lewis^|, Santiago A. Catalano^¶

‡ University of Zürich, Zurich, Switzerland

§ University of Zurich, Zurich, Switzerland

| Accelerated Taxonomy Department, Royal Botanic Gardens, Richmond, United Kingdom

¶ Consejo Nacional de Investigaciones Cientificas y Tecnicas, Fundacion Miguel Lillo, S.M. de Tucuman, Argentina

Corresponding author: Colin E. Hughes ( colin.hughes@systbot.uzh.ch )

Academic editor: Luciano de Queiroz

This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Citation: Hughes CE, Ringelberg JJ, Lewis GP, Catalano SA (2022) Disintegration of the genus Prosopis L. (Leguminosae, Caesalpinioideae, mimosoid clade). In: Hughes CE, de Queiroz LP, Lewis GP (Eds) Advances in Legume Systematics 14. Classification of Caesalpinioideae Part 1: New generic delimitations. PhytoKeys 205: 147-189. https://doi.org/10.3897/phytokeys.205.75379

Abstract

Robust evidence from phylogenomic analyses of 997 nuclear genes has recently shown, beyond doubt, that the genus Prosopis is polyphyletic with three separate lineages, each with affinities to other genera of mimosoids: (i) Prosopis africana is an isolated lineage placed in the grade of Plathymenia, Newtonia and Fillaeopsis that subtends the core mimosoid clade; (ii) the remaining Old World species of Prosopis form a clade that is sister to the Indo-Nepalese monospecific genus Indopiptadenia and (iii) New World Prosopis has the Namibian / Namaqualand monospecific endemic genus Xerocladia nested within it. This means that it is now clear that maintaining the unity of the genus Prosopis sensu Burkart (1976) is no longer tenable. These three distinct lineages of Prosopis species correspond directly to Burkart’s (1976) sectional classification of the genus, to previously recognised genera and to the differences in types of armature that underpin Burkart’s sections. Here, we address this non-monophyly by resurrecting three segregate genera – Anonychium, Neltuma and Strombocarpa and provide 57 new name combinations where necessary, while maintaining the morphologically distinctive and geographically isolated genera Xerocladia and Indopiptadenia. The genus Prosopis itself is reduced to just three species and an emended description is presented. The impacts of these name changes for a genus of such high ecological and human use importance are discussed. These impacts are mitigated by clear differences in armature which facilitate identification and by potential benefits from the deeper biological understanding brought about by recognition of these divergent lineages at generic rank. We provide an identification key to genera and present a map showing the distributions of the segregate genera, as well as drawings and photos illustrating variation in armature and fruits.

Keywords

Anonychium, Fabaceae, generic delimitation, Indopiptadenia, monophyly, Neltuma, Strombocarpa, taxonomy, Xerocladia

Introduction

Burkart’s (1976) worldwide taxonomic monograph of the genus Prosopis L. recognised 44 species placed in five sections. Since then, 13 additional species have been described (Schinini 1981; Earl and Lux 1991; Palacios 2006; Vásquez Núñez et al. 2009; De Mera et al. 2019) one of which, P. bonplanda P.R. Earl & Lux, was subsequently treated as a synonym by Palacios (2006). All of these additional species belong morphologically in section Algarobia DC., such that the generic unity and infrageneric classification, proposed by Burkart (1976), remain the current framework for understanding the genus. Following Bentham (1875), Burkart (1976) justified the generic unity of a widely delimited Prosopis, based on the broad uniformity of flowers and fruits across Prosopis s.l. Perhaps the most important uniting feature was the modified indehiscent cylindrical or thickened legume, with a more or less sugary, fleshy or fibrous mesocarp and an endocarp more or less hardened and segmented into one-seeded coriaceous to bony seed chambers, these closed or sometimes opening easily. Fruits of this type are eagerly consumed by herbivores, including all kinds of livestock, the seeds benefiting from scarification as they pass through the digestive tract and as a result being widely dispersed (see below), a seed dispersal syndrome that unites all species of Prosopis s.l. Moreover, Burkart (1976) explicitly downplayed vegetative characters and notably variation in armature, as of less significance for classification, stating that “the main differences between sections Prosopis, Algarobia and Strombocarpa Benth. are vegetative spine characters and are, therefore, only of subgeneric rank” (Burkart 1976: 227), even though he acknowledged that the variation in armature probably had phylogenetic significance (see below).

This long-held generic concept of Prosopis established by Bentham (1842, 1875) and followed by Burkart in his 1976 monograph, is no longer sustainable, because molecular phylogenies have demonstrated, beyond doubt, that Prosopis is polyphyletic. This non-monophyly was first revealed by Catalano et al. (2008) and confirmed by LPWG (2017) who showed that P. africana (Guill. & Perr.) Taub. forms an isolated monospecific lineage quite separate from the rest of Prosopis and that the monospecific Namibian/S. African endemic genus Xerocladia Harv. was potentially nested within Prosopis, but these analyses lacked robust support and sampling of critical taxa. Recent phylogenomic analyses of a much larger DNA sequence dataset, based on 997 nuclear genes (Koenen et al. 2020) that now includes all but five of the 152 genera of Caesalpinioideae (Ringelberg et al. 2022), have confirmed this non-monophyly showing robust support for three separate lineages (Fig. 1): (i) a lineage comprising P. africana, which is placed in a grade made up of the genera Plathymenia Benth., Fillaeopsis Harms and Newtonia Baill., as found by Catalano et al. (2008); (ii) a lineage comprising the remaining Old World species of Prosopis which is robustly supported as sister to the monospecific genus Indopiptadenia Brenan from the Himalayan foothills of the Terai border region of Nepal and India (Bajpai et al. 2014); (iii) a lineage comprising the New World species of Prosopis plus the Namibian/South African endemic genus Xerocladia, which is nested within this clade, again confirming the preliminary results of Catalano et al. (2008). The DNA sequence dataset of Ringelberg et al. (2022), based as it is on a large number of nuclear genes, can also be used to quantify how many genes support a particular species tree topology and, thereby, how robust the phylogeny is (Fig. 1B) and also how many genes support alternative species tree topologies. These analyses show that just 69 gene trees support a sister group relationship between sections Strombocarpa (= Strombocarpa) and Algarobia + Monilicarpa Ruiz Leal & Burkart (= Neltuma Raf.), while 629 of the gene trees conflict with that topology (Fig. 1C) and none of the gene trees supports a monophyletic Prosopis s.l. (Fig. 1D), confirming that there is an overwhelming number of gene trees supporting the species tree topology in Fig. 1B. It is thus now clear that maintaining Prosopis in its current circumscription is untenable.

Figure 1.

A Phylogeny of the Caesalpinioideae showing the placement of the Prosopis grade (boxed in red) within the subfamily, based on analyses of DNA sequences of 997 nuclear genes (Ringelberg et al. 2022) B the part of the phylogeny that includes all elements of Prosopis s.l. Genera recognised in the new generic system presented here are in bold. Pie charts show the fraction of gene trees supporting that bipartition in blue, the fraction of gene trees supporting the most likely alternative configuration in green, the fraction of gene trees supporting additional conflicting configurations in red and the fraction of uninformative gene trees in grey. Numbers above pie charts are Extended Quadripartition Internode Certainty (Zhou et al. 2020) scores. Branch lengths are expressed in coalescent units and terminal branches were assigned an arbitrary uniform length for visual clarity, see Ringelberg et al. (2022); the root is not drawn to scale C, D the two most likely alternative tree topologies which would allow for a monophyletic Prosopis s.l., either without (C) or with (D) Xerocladia and Indopiptadenia. In C and D numbers above pie charts = number of gene trees supporting the species tree, numbers below pie charts = number of gene trees conflicting with the species tree C lack of gene tree support (just 69 gene trees) for the alternative species tree topology where sections Algarobia + Monilicarpa (≡ Neltuma) are sister to section Strombocarpa (≡ Strombocarpa) vs. 573 genes supporting a sister group relationship between Strombocarpa and Xerocladia (as shown in D) D lack of gene trees (zero gene trees) supporting a monophyletic Prosopis s.l.

What is immediately striking from Fig. 1 and the earlier phylogeny of Catalano et al. (2008) with its denser sampling of species across New World Prosopis, is that these three separate lineages of Prosopis species correspond to and are congruent with Burkart’s sections (apart from the inclusion of Xerocladia) and with the variation in armature upon which Burkart’s sections were based (Figs 2–4): Section Anonychium Benth. = P. africana, is unarmed in common with the rest of the grade of lineages (Plathymenia, Fillaeopsis and Newtonia) that subtend the large core mimosoid clade of Koenen et al. (2020) (Fig. 1; Ringelberg et al. 2022); Section Prosopis = the rest of Old World Prosopis, comprising P. cineraria (L.) Druce, P. farcta (Banks & Sol.) J.F. Macbr. and P. koelziana Burkart (from Iran), all have straight internodal prickles (Figs 2C, M and 3C), which are also found in the sister genus of this clade, Indopiptadenia, including in the form of large, conical, hard, sharp-pointed spines on older stems and trunk (Fig. 3B; see also Bajpai et al. 2014: figs 2B–H and 11A); species of Section Strombocarpa plus the genus Xerocladia have stipular spines (Figs 2E, H, I, O and 3A, D); and species of sections Monilicarpa + Algarobia variously have spinescent shoots or uninodal axillary solitary or geminate spines (Figs 2A, B, D, F, G, J–L, N and 3E, F and 4), but never the internodal prickles of section Prosopis, nor the stipular spines of section Strombocarpa (see also Benson 1941). These three types of armature are non-homologous, even though they have evolved to meet similar plant defence functions and can look superficially similar. To explore the evolution of armature across the Prosopis s.l. grade, we scored these different types of armature across genera of subfamily Caesalpinioideae and optimised these on to the Ringelberg et al. (2022) phylogeny. This reconstruction shows independent derivations of stipular spines, internodal prickles and axillary nodal spines (Fig. 4), each providing diagnostic synapomorphies for clades in the context of Prosopis s.l. (Fig. 4). Ironically, in his justification of the unity of Prosopis, Burkart (1976) pointed to Acacia Mill. s.l. as another group that also showed considerable diversity in types of armature and other vegetative traits, but which was considered (at that time) to comprise a single genus. Given that Acacia s.l. was later demonstrated to be polyphyletic (reviewed by Maslin et al. 2003) and has now been dismantled into seven segregate genera, several of which are distinguished primarily by differences in armature (e.g. the stipular spines that distinguish Vachellia Wight & Arn. from the cauline nodal and internodal prickles of Senegalia Raf.), Burkart’s suggestion that a wide concept of Acacia chimed with his wide concept of Prosopis can now be seen with hindsight to have been misplaced.

Figure 2.

Variation in armature of Prosopis, Strombocarpa, Neltuma and Xerocladia A Neltuma denudans (nodal spines on a zig-zag stem) B N. humilis (paired striate spine-tipped branches) C Prosopis cineraria (scattered internodal prickles) D Neltuma sericantha (spine-tipped stems) E Strombocarpa burkartii (stipular spines) F Neltuma argentina (single nodal axillary spine) G N. kuntzei (spinescent shoots) H Strombocarpa ferox (stipular spines) I S. strombulifera (stipular spines) J Neltuma elata (variation in paired nodal spines on one specimen) K N. alba (paired nodal spines) L N. velutina (paired nodal spines) M Prosopis farcta (scattered internodal prickles) N Neltuma ruscifolia (single nodal axillary spine) O Xerocladia viridiramis (recurved, deflexed stipular spines) (5 cm scale bar). All specimens at K A drawn from Seijo 1489 B Tweedie s.n. C Willcox 299 D MERL 8792 E Acosta & Rosas 748 F Guaglianone et al. 1762 G Nee & Coimbra 35556 H Atahuachi et al. MA1147 I Hunziker 2036 J Legname & Cuezzo 10396 (large and small spines from same specimen) K Hughes & Forrest 2312 L Harding & Balsinhas 140 M Guest et al. 17463 N Wood & Mamani 14063 O Kolberg & Tholkes HK2493. Drawn by Andrew Brown, July 2021.

Figure 3.

Variation in armature across Prosopis s.l. and allies A stipular spines of Strombocarpa strombulifera B internodal prickles on shoots and branches of Indopiptadenia oudhensis which it shares with its sister group, Prosopis s.s. illustrated in C; C internodal prickles of Prosopis farcta D stipular spines of Xerocladia viridiramis which it shares with its sister group, the genus Strombocarpa illustrated in A; E axillary nodal spines of Neltuma juliflora F spinescent straight cylindrical shoots of the subaphyllous Neltuma kuntzei. Photos courtesy of Guillermo Debandi (A) (see https//www.inaturalist.org/taxa/78750-Prosopis-strombulifera/browse_photos), Dr. Omesh Bajpai and Dr. Lal Babu Chaudhary (B), Zeynel Cebeci (C) (see https//commons.wikimedia.org/wiki/FileProsopis_farcta_-_Syrian_mesquite_01), N. Dreber (D) (see http//www.southernafricanplants.com/), Colin Hughes (E, F).

Figure 4.

Independent evolutionary origins of stipular spines, axillary nodal spines and internodal spines across the segregate genera of the Prosopis s.l. grade. Diamonds indicate putative origins halfway along the branch subtending the clade with the character of interest. Note that, in the case of Neltuma kuntzei, a loss of axillary nodal spines, which are absent in that species, apparently coincides with an evolutionary gain of spinescent shoots (see also Fig. 3F) and with a shift to a largely aphyllous condition on the mature shoots. The reconstruction of armature characters shown here encompasses results of four independent optimisations of four types of armature, performed using the make.simmap option of R (R Core Team 2021) package phytools (Revell 2012), each with 500 simulations using the ARD model. Optimisations were performed on an ASTRAL phylogeny of the entire Caesalpinioideae, based on 821 single-copy genes (Ringelberg et al. 2022), but are here shown only for the Prosopis s.l. grade with standardised branch lengths.

The apparent phylogenetic significance of types of armature to distinguish important clades and genera across Caesalpinioideae, contrasts with the striking evolutionary lability of fruit types, as seen across Prosopis s.l. and allies (Figs 5–7). This is exemplified by the contrast between the cylindrical or sub-cylindrical thickened indehiscent fruits of Prosopis s.l. (albeit varying considerably in the degree to which they are curved or coiled (see below)) and the very different plano-compressed fruits of Indopiptadenia (Figs 5M and 7B; see also Bajpai et al. 2014: Fig. 7), which is sister to section Prosopis and which lacks a thickened mesocarp and is dehiscent along one or both sutures. Similarly, Xerocladia, which is sister to section Strombocarpa (Fig. 1), has equally distinctive small reniform to flabellate, flattened, indehiscent, 1 (–2)-seeded, winged fruits, which are unique amongst mimosoid legumes as a whole (Figs 5L and 7G) and also lack the often-thick mesocarp of Prosopis s.l. fruits (Gunn 1984). Thus, it is now clear that the thickened, sub-cylindrical fruits of P. africana (section Anonychium), which are superficially very similar (both are thick, woody, indehiscent and black when mature) to those of distantly related P. kuntzei Harms (section Algarobia) (Figs 5B, 6C, 7A, I), represent homoplasious evolutionary origins of similar endozoochorous seed dispersal syndromes, based on animal ingestion of highly palatable fruits and defecation of the seeds (Tybirk 1991; Weber et al. 2008) and, hence, are misleading as the basis for generic delimitation. In the light of phylogenetic data, it is now clear that Burkart’s (1976) reliance on fruit morphology to unite his broad concept of Prosopis and demotion of armature as only useful at sub-generic rank and not for delimiting genera were misplaced.

Figure 5.

Fruits of Prosopis, Strombocarpa, Xerocladia and Indopiptadenia A Prosopis cineraria B Anonychium africanum C Strombocarpa palmeri D Prosopis farcta E Strombocarpa ferox F S. strombulifera G S. pubescens H S. abbreviata (2 examples) I S. tamarugo J S. torquata K S. burkartii L Xerocladia viridiramis M Indopiptadenia oudhensis A-G, M (5 cm scale bar) H-L (1 cm scale bar with asterisk). All specimens at K A drawn from Gazanfar SG4332 B Dembele & Sanogo ML-146 and longitudinal section of fruit from Barter 1193 C Hughes et al. 1552 D van der Maesen 1627 E Atahuachi et al. MA1147 F Hunziker 2036 G Acocks 1788 H Tweedie s.n. (from 2 type specimens) I Aronson 7742 J Vuilleumier 1019 K Acosta & Rosas 748 L Kolberg & Tholkes HK2493 M Bajpai & Babu 264498. Drawn by Andrew Brown, July 2021.

Figure 6.

Fruits of Neltuma A Neltuma alba B N. argentina C N. kuntzei D N. denudans E N. laevigata F N. nigra G N. articulata H N. ruscifolia.(5 cm scale bar). All specimens at K A drawn from Hughes & Forrest 2312 B Guaglianone et al. 1762 C Nee & Coimbra 35556 D Seijo 1489 E Manríquez & Tenorio 6563 F Arenas 3123 G Hughes et al. 1559 H Wood & Mamani 14063. Drawn by Andrew Brown, July 2021.

Figure 7.

Variation in fruits across Prosopis s.l. and allies A indehiscent pods of Anonychium africanum with thick pulpy mesocarp collected as fodder for livestock B plano-compressed pods of Indopiptadenia oudhensis lacking a thickened mesocarp and dehiscent along both sutures C indehiscent fruits of Prosopis farcta with a thick pulpy mesocarp D tightly coiled indehiscent screwbean fruits of Strombocarpa strombulifera E indehiscent pods of Strombocarpa ferox with a thick pulpy mesocarp F indehiscent fruits of Strombocarpa palmeri G small reniform to flabellate, flattened, indehiscent, 1 (–2)-seeded, winged fruits of Xerocladia viridiramis which are unique within mimosoid legumes H indehiscent fruits of Neltuma articulata with a thick mesocarp and a hard bony segmented endocarp which remains closed I. Unripe indehiscent pods of Neltuma kuntzei with a thick pulpy mesocarp, these turning dark blackish-brown when ripe, reminiscent in colour to fruits of Anonychium. Photos courtesy of Marco Schmidt (A) (see Dressler et al. 2014), Dr. Omesh Bajpai and Dr. Lal Babu Chaudhary (B), Zeynel Cebeci (C) (https//en.wikipedia.org/wiki/Prosopis_farcta), Dick Culbert (D) (see https//eol.org/pages/640506, Colin Hughes (E, F, H, I), and Herta Kolberg (G) (see Plants of Namibia https//herbaria.plants.ox.ac.uk/bol/namibia).

It is notable that pollen exine structure also supports these groups. Pollen of the Old World species of section Prosopis is similar to that of its sister genus Indopiptadenia, showing a relatively thin (0.7–0.9 µm) tectum with irregularly areolate-verrucose raised sculpturing, whereas the New World species of Prosopis, and Xerocladia have a smooth (perforated) and even thinner (< 0.7 µm) tectum (Hernández and Guinet 1990: Fig. 5).

The type species of Prosopis, P. spicigera L. (a synonym of P. cineraria (L.) Druce), is from the Old World in section Prosopis of Burkart (1976), a clade that comprises just three of the 56 species currently recognised in the genus as a whole, implying that the remaining 53 species will require a name change to deal with the non-monophyly of Prosopis s.l. Segregation of the isolated monospecific lineage P. africana as a separate genus presents a straightforward and uncontroversial adjustment, here implemented by re-instatement of the genus Anonychium (Benth.) Schweinf. (see below). Generic re-delimitation of the New World species is less straightforward and is complicated by placement of the morphologically distinctive Namibian/Namaqualand monospecific genus Xerocladia nested within the New World Prosopis clade as sister to section Strombocarpa (Fig. 1). Despite its similar shrubby, multi-stemmed, branchy habit, green shoots, stipular spines (Fig. 3D) (shared with section Strombocarpa) and occurrence in arid succulent-rich vegetation, all of which are shared with New World Prosopis, the genus Xerocladia has been maintained as distinct from Prosopis, because it has highly distinctive reniform to flabellate, indehiscent, 1(–2)-seeded, winged fruits (Figs 5L and 7G), lacking a thickened mesocarp, which are very different from those of Prosopis s.l. and, indeed, from all other mimosoid legumes. Given this distinctive morphology, we retain Xerocladia as a separate genus. We also note that the material referred to under the name Xerocladia pampeana Speg. from Argentina, shows clear affinities to the genus Prosopidastrum Burkart, as suggested by Palacios and Hoc (2005). Even though Palacios and Hoc (2005) left X. pampeana as an excluded name in their treatment of Argentinian Prosopidastrum, examination of the material cited by them suggests that the fruits are not monospermous, but simply broken fragments of lomentiform fruits of Prosopidastrum.

Retention of the monospecific African Xerocladia at generic rank implies that the two subclades of New World Prosopis species, corresponding to Sections Strombocarpa and Monilicarpa + Algarobia of Burkart (1976) (Fig. 1), also need to be recognised as separate genera. Both of these groups have been previously ranked as genera. Bentham (1839), prior to uniting the various elements of Prosopis s.l. in a single genus in his 1875 treatment of Mimoseae, recognised section Algarobia at generic rank as the genus Algarobia Benth. (even though the name Algarobia is preceded by Neltuma Raf. published one year earlier in 1838). Similarly, section Strombocarpa was also afforded generic status as the genus Strombocarpa Englm. & A. Gray in 1845, a generic delimitation followed by Britton & Rose (1928) in their treatment for the North America Flora. The alternative to recognising these two New World clades as separate genera would be to transfer all New World species of Prosopis plus the African Xerocladia to the genus Neltuma. While it could be argued that this alternative would make generic-level identification in the New World easier, it would entail lumping Xerocladia with its highly unusual fruits which are unique within mimosoids and would detract from the overall ability to diagnose genera across mimosoids. We believe that upranking Burkart’s sections Strombocarpa and Algarobia + Monilicarpa as the genera Strombocarpa and Neltuma, respectively, distinguished by the differences in armature that provided the basis for Burkart’s sections, while retaining the African Xerocladia as a separate genus (Fig. 1), provides the best solution to render all genera monophyletic and ensure maximal ability to diagnose genera across mimosoids as a whole.

Finally, for completeness, we note that the genus Sopropis Britton & Rose, erected by Britton & Rose (1928) to accommodate the somewhat unusual species Sopropis palmeri (S. Watson) Britton & Rose (= Prosopis palmeri S. Watson) has the stipular spines of section Strombocarpa, but a straight (or only weakly falcate) fruit more typical of section Algarobia (Figs 5C and 7F), as noted by Benson (1941). In the phylogeny of Catalano et al. (2008), P. palmeri is placed in the clade corresponding to section Strombocarpa with robust support, vindicating the congruence of armature types across the phylogeny and we here treat Sopropis as a synonym of Strombocarpa. This is very much in line with Burkart’s (1976) view that too much weight had been given by Britton and Rose (1928) to the curvature and coiling of the Prosopis fruit in the recognition of three distinct genera in their Flora of North America treatment. Indeed, it is clear that curvature of the pod across New World Prosopis s.l. shows a continuum from the tightly spirally coiled ‘screwbean’ pods of, for example, P. strombulifera (Lam.) Benth. and P. pubescens Benth. (Figs 5F, G and 7D), to fruits with fewer, larger and more open coils, annular fruits and those that are only weakly curved or completely straight, variation that is discordant with sectional boundaries (Figs 5B, C, E–K, 6 and 7D–F, H–I) and with the phylogeny (Fig. 1).

Taxonomic name changes are often unwelcome for many users, at least in the short term, especially for plant groups that are important ecologically and in terms of human uses. This is very much the case for Prosopis s.l. and especially so in the warm desert and dryland scrub ecosystems of the New World, where “few plant genera have received as much attention as Prosopis” (Simpson 1977: ix). Species of Prosopis are ecologically abundant in many parts of its New World range, dominating vast tracts of the Chaco in South America and the matorrales of the southern U.S.A. and parts of Mexico (Fig. 8) (Benson 1941). Trees of Prosopis s.l. also occupy a central place in silvo-pastoral systems more widely across the arid and semi-arid tropics from Rajasthan in NW India, through the Arabian Peninsula, across Sahelian Africa and throughout the arid zones of the Neotropics (Leakey and Last 1980; Fagg and Stewart 1994; Pasiecznik et al. 2001; Weber et al. 2008), because of their dependable provision of abundant protein- and sugar-rich, non-toxic, highly palatable and nutritious fruits during the dry season that are eagerly consumed by diverse livestock (cattle, sheep, goats, camelids). Furthermore, Prosopis s.l. fruits, including the mezquites in North America (Felger 1977) and the algorrobos in South America (D’Antoni and Solbrig 1977), constituted one of the most important wild food sources for pre-hispanic cultures, with P. velutina Wooton, the velvet mesquite referred to as the ‘tree of life’ (Bell and Castetter 1937) and these uses potentially prompting long distance translocation of species by humans and their livestock within the Americas in pre-Colombian times (McRostie et al. 2017). In addition to livestock fodder and human food, the wood of Prosopis is dense and durable and widely used for firewood, charcoal and parquet flooring and the flowers provide high quality, reliable and abundant forage for honey bees. Moreover, such is the ability of some Prosopis species to disperse seeds, colonise and quickly form dense spiny impenetrable thickets, that some species of Prosopis are amongst the world’s worst invasive weeds, both within and well beyond their native ranges. For example, several New World section Algarobia species are naturalised and invasive across many parts of Africa, the Middle East, the Indian subcontinent and Australia (e.g. Pasiecznik et al. 2001; Van Klinken and Campbell 2001; Ayanu et al. 2015) and have been recorded from 103 countries and considered to be invasives in 49 of those (Shackleton et al. 2014). Within their native distributions, P. ruscifolia Griseb. is a serious pest in the western Gran Chaco, referred to as a ‘plaga nacional’ and P. glandulosa Torr. has prompted the so-called ‘mesquite problem’ in Texas in the southern U.S.A. where that species is considered a serious rangeland weed (Fisher et al. 1959).

Figure 8.

The distributions of Indopiptadenia, Prosopis s.s., Anonychium, Xerocladia, Neltuma and Strombocarpa, based on 6,469 quality-controlled species occurrences from GBIF (www.gbif.org), DryFlor (www.dryflor.info), SEINet (www.swbiodiversity.org/seinet) and several other data sources (Ringelberg et al., in prep.). Map created using R packages ggplot2 (Wickham 2016), sf (Pebesma 2018) and rnaturalearth (South 2017). The eight occurrence records, mapped in Bahia Brazil, are of Neltuma ruscifolia which is considered potentially native to that region (Burkart 1976 Oliveira & Queiroz 2020), while records of N. juliflora from Bahia, which is introduced and naturalised in that region, have been eliminated.

The impacts of name changes on a group of plants of such diverse importance cannot be denied and, inevitably, we anticipate resistance, in the short term, to the nomenclatural changes we propose here. Notwithstanding, we also expect that, ultimately, there will be benefits from aligning genera with monophyletic groups that more accurately reflect their evolutionary placements and provide a deeper biological understanding of these globally-important plants. In that light, it is notable that all the serious invasive and rangeland pest species fall into Neltuma (= section Algarobia), suggesting that a propensity for invasiveness is more problematic for species in that clade. Similarly, of 29 species of bruchid beetles known to predate seeds of New World Prosopis, only two span Neltuma (sections Algarobia + Monilicarpa) and Strombocarpa, such that each of the two New World clades has largely its own exclusive bruchid fauna, including, for example, the bruchid genus Algarobius Bridwell which is largely restricted to species of section Algarobia (Kingsolver et al. 1977). More generally, biocontrol programmes to mitigate invasions of New World species of Neltuma in Africa have focused on insects, such as the bruchid seed predator Algorobius prosopis (J.L. Leconte), that do not attack native African members of Prosopis s.l. including species of Prosopis s.s., Anonychium and Xerocladia, suggesting that many insects effectively distinguish amongst the genera proposed here (Kleinjan et al. 2021).

It is also notable that, while intra-sectional interspecific hybridisation has been reported to occur in both section Strombocarpa (e.g., the hybrid origin of Prosopis burkartii Muñoz, Contreras et al. 2020) and amongst a subset of species in the ‘mesquite clade’ of Neltuma (= sections Algarobia + Monilicarpa) (Hunziker et al. 1986; Castillo et al. 2021), there are no examples of inter-sectional hybrids between species belonging to Neltuma and Strombocarpa (Solbrig et al. 1977; Hunziker et al. 1986), despite their sympatry across many areas (Fig. 8). This lack of inter-sectional crossing prompted Hunziker et al. (1986) to suggest upranking sections Algarobia (= Neltuma) and Strombocarpa “at least to the level of subgenera”, as also suggested by Saidman et al. (1996), based on genetic differences. Similarly, phylogenetic analysis of morphology and biochemical traits showed strong support for recognising Strombocarpa as a distinct clade (Burghardt and Espert 2007). These trait differences, alongside other ecological differences, are symptomatic of the deep (phylo)genetic split between these two clades which are estimated to have diverged 25 Myr (Ringelberg et al., in prep). All these differences in biology are of potential significance for genetic improvement, range management and biocontrol programmes (see Kleinjan et al. 2021), adding further justification to recognise Burkart’s sections at generic rank.

Biogeography

One of the uniting features of Prosopis s.l. is the distribution of its various lineages, first and foremost, in seasonally dry and arid tropical and subtropical climates across the New and Old Worlds (Fig. 8), a distribution that spans, in large part, the transcontinental grass-poor succulent-rich, fire-free succulent biome sensu Schrire et al. (2005) and Ringelberg et al. (2020). However, in that sense, Anonychium (P. africana) is an outlier, just as it is phylogenetically, because it grows in savannahs across Sahelian Africa. The Prosopis s.s. + Indopiptadenia clade spans an interesting dry/monsoonal west-central Asian distribution which is unique amongst mimosoids. At first sight, the sister group relationship between Strombocarpa and Xerocladia spanning the Atlantic seems a surprising disjunction, but several other Caesalpinioid legumes show similar disjunct amphi-Atlantic distributions with most of their diversity in the Neotropics and outlying endemic species in Namibia and adjacent regions of southern Africa. These include the genera Haematoxylum L., Parkinsonia L. and Pomaria Cav., with Haematoxylum dinteri Harms, Parkinsonia africana Sond. and three species of Pomaria in Namibia and S. Africa. Two things are notable about these transatlantic disjunctions. First, they often show bicentric amphitropical ranges in the New World and disjunctions in SW Africa (the Haematoxylum + Lophocarpinia Burkart clade; Pomaria (Simpson et al. 2006); Strombocarpa - Xerocladia). Second, they share similar seasonally dry tropical, grass-poor, succulent-rich, fire-free ecologies across the transcontinental Succulent Biome (Schrire et al. 2005; Gagnon et al. 2019; Ringelberg et al. 2020).

Key for the identification of the segregate genera of Prosopis and close allies (see Figs 2 and 3 for illustrations of armature characters used in the key)

1	Plants unarmed	*Anonychium*
–	Plants usually armed with stipular spines, axillary solitary or paired uninodal cauline spines, spinescent shoots or internodal prickles	2
2	Plants armed with internodal prickles on shoots and/or stems, petals glabrous	3
–	Plants armed with stipular spines, axillary solitary or paired uninodal spines or spinescent shoots, petals villous or pilose	4
3	Fruits indehiscent, cylindrical or subterete, with a pulpy or fibrous mesocarp, largest leaflets < 1.5 × 1 cm, mature stems with scattered prickles	*Prosopis*
–	Fruits dehiscent, plano-compressed, coriaceous, lacking a thick mesocarp, larger leaflets > 3 × 3 cm, mature stems with spine-tipped woody protuberances	*Indopiptadenia*
4	Fruits reniform to flabellate, indehiscent, 1–2-seeded and winged	*Xerocladia*
–	Fruits linear or oblong, always > 2-seeded	5
5	Plants armed with stipular spines	*Strombocarpa*
–	Plants armed with axillary, uninodal, solitary or paired spines or spinescent shoots	*Neltuma*

Taxonomy

We present a taxonomic synopsis of the four segregate genera, Anonychium, Prosopis, Strombocarpa and Neltuma, including 57 new nomenclatural combinations and associated synonymy. Type details are cited for accepted names, but not for heterotypic synonyms.

Anonychium (Benth.) Schweinf., Reliq. Kotschy.: 7. 1868.

Prosopis section Anonychium, Benth. Hook. J. Bot. 4: 347. 1842.

Type

Prosopis oblonga Benth. Benth., J. Bot. (Hooker) 4: 348. 1842, a synonym of Anonychium africanum.

Description

Unarmed trees 4–20 m high, branches lacking axillary brachyblasts. Stipules inconspicuous, long-lanceolate, pubescent, caducous as young leaves develop, absent from most herbarium sheets. Leaves somewhat pendulous, 1–4 pairs of pinnae, the petiole 3–5 cm long, the rachis 5–9 cm long, the pinnular rachises 6–15 cm long, with 4–13 pairs of opposite leaflets, these 1.3–3.5 × 0.4–1.5 cm, glabrous or finely pubescent, mid-vein subcentric. Inflorescences spicate, 5–9 cm long, axillary, solitary or in pairs, densely flowered; pedicels 0.5 mm. Flowers small, yellowish or greenish-white, sweetly scented; calyx ca. 1 mm long; corolla ca. 3.5 mm long, the petals linear, free, glabrous on both sides; anthers apically broadened with an unusual anther gland borne ventrally between the thecae and forming a triangular hood-shaped protrusion made up of papillate cells; pollen with costae on the pores and a smooth (perforated) tectum; ovary and style pilose or villous. Fruits indehiscent, straight or sub-falcate, dark reddish-brown to blackish, shiny, subterete, 10–20 × 1.5–3.3 cm, exocarp hard, 1–2 mm thick, mesocarp spongy, thick, dry, endocarp segments thin, longitudinal, in one row (Figs 5B and 7A). Seeds many, dark, shiny, ovate compressed, 8–10 × 4–9 mm, rattling within the pod when ripe.

Geographic distribution

Monospecific. Widespread across Sahelian Africa, from Senegal in the west to Sudan and Ethiopia in the east (Fig. 8).

Habitat and uses

Anonychium africanum is native across the whole Sahelian savannah belt. Trees are maintained and managed by farming and pastoralist communities in traditional silvo-pastoral systems throughout the African Sahel, providing essential products, including wood, fuel, food, livestock fodder and medicines and enhancing soil fertility (Weber et al. 2008). Seeds are widely dispersed by browsing animals, such as camels, cattle and goats at the end of the dry season (Tybirk 1991) and perhaps also by humans who collect the pods to feed to their animals, and cow dung (containing viable seeds) to fertilise their fields.

Etymology

Anonychium literally meaning the absence of nails or claws from the Latin or Greek ‘onych’ = ‘ónyx’ meaning nail or claw, refers to the lack of armature of this genus.

Affinities

Prosopis africana has long been considered anomalous within the genus and was placed in its own section Anonychium by Bentham (1842) and later this was upranked to its own genus, Anonychium by Schweinfurth (1868; under the name A. lanceolatum Schweinf.). Unlike almost all other species of Prosopis s.l., P. africana lacks armature, has internally glabrous petals, pollen with costae (Guinet 1969), V-shaped anthers with small stomia forming short pockets on the ventral surface of the anthers and anther glands that are apparently morphologically unique within mimosoids (Luckow and Grimes 1997). The anther glands of Anonychium africanum (as P. africana, Luckow and Grimes 1997: Figs 25–27) stand out as quite different from the typical mimosoid claviform anther glands of the remaining species of Prosopis s.l., being sessile, borne ventrally between the thecae, rather than stipitate borne apically or dorsally from the connective between the thecae as in most other mimosoids and forming triangular hood-shaped protrusions made up of papillate cells which are also unique amongst mimosoid anther glands (Luckow and Grimes 1997). Alongside the robust molecular evidence for placement of P. africana distantly related to the rest of Prosopis (Fig. 1), this suite of morphological differences amply justifies segregation of P. africana as a distinct monospecific genus.

Anonychium is a phylogenetically isolated lineage that subtends the grade of other unarmed, mainly species-poor genera, Plathymenia, Fillaeopsis and Newtonia which is paraphyletic with respect to the core mimosoid clade of Koenen et al. (2020) (Fig. 1; Ringelberg et al. 2022). This is in line with pollen of Anonychium which shows similarities to Newtonia (Guinet 1969).

Anonychium africanum (Guill. & Perr.) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303578-1

Prosopis oblonga Benth., J. Bot. (Hooker) 4: 348. 1842.

Entada durissima Baill., Adansonia 6: 208. 1866.

Anonychium lanceolatum Schweinf., Reliq. Kotschy.: 7, pl. 7. 1868.

Prosopis africana (Guill. & Perr.) Taub. in H.G.A. Engler & K.A.E. Prantl, Nat. Pflanzenfam. 3(3): 119. 1892.

Entada coulteri Roberty, Bull. Inst. Fondam. Afrique Noire, Sér. A, Sci. Nat. 16: 346. 1954.

Basionym

Coulteria africana Guill. & Perr., Fl. Seneg. Tent.: 256, 1832.

Type material

Senegal. Kounoun, Presqu’île du Cap-Vert, G.S. Perrottet 20 (holotype: P [P00418356]).

Prosopis L., Mantissa Pl. 68: 10. 1767. emend. C.E. Hughes & G.P. Lewis.

Lagonychium M. Bieb., Fl. Taur.-Caucas. 3: 288. 1819.

Prosopis section Adenopis DC., Prodr. 2: 446. 1825.

Pleuromenes Raf., Sylva Tellur.: 144. 1838.

Type

Prosopis spicigera L., a synonym of P. cineraria (L.) Druce.

Description

Prickly subshrubs, shrubs, small trees or occasionally lianescent (P. farcta), 0.3–6.5 (–10) m high, deep-rooted and sometimes invading via root suckers, prickles internodal, scattered, straight, somewhat acroscopic, conical with broad bases, 3–5 mm long (Figs 2C, M and 3C), stipular or axillary spines absent. Stipules foliaceous, ovate-acute, caducous. Leaves with 1–6 (–7) pairs of pinnae, the petiole and rachis 0.5–4 cm, sometimes a prickle at the base of the petiole, the pinnular rachises 2–7 cm long, with 7–15 pairs of leaflets, these ovate or lanceolate, straight to sub-falcate or auriculate, mucronate, 2–15 × 2–4.5 mm, glabrous, puberulous or pubescent, mid-vein excentric. Inflorescences spicate, 4–13 cm long, axillary, solitary or in fascicles, peduncle sometimes with an amplexicaul bract, this caducous and leaving an oblique scar; pedicels 0.5–1.5 mm. Flowers small, yellow, yellowish-white, green or cream-green; calyx truncate, 0.8–1.2 mm long; corolla 3.5–4 mm long, the petals linear, nearly free, reflexed, glabrous on both sides; anthers with a minute caducous incurved claviform gland arising from the connective; pollen lacking costae on the pores, tectum irregularly areolate-verrucose. Fruits indehiscent, slender, elongate straight or sub-falcate, dark reddish-brown to blackish, shiny, cylindrical to sub-cylindrical, torulose, 1.5–19 × 0.4–2.5 cm, exocarp thin, brittle, shiny and smooth, orange-red becoming brown, red or black when ripe (Fig. 7C), mesocarp spongy, endocarp segments thin, little developed, seed chambers longitudinal or transverse. Seeds well separated, longitudinal, ovate to ovoid, compressed, 6–8.5 × 5–6 × 2.5–3 mm.

Geographic distribution

Reduced now to just three Old World species, these distributed across arid parts of North Africa (but apparently the genus rare at its western limits in Algeria and Tunisia), the Middle East and NW India (especially Punjab and Rajasthan) and reaching its northern limits in Afghanistan and Azerbaijan (Fig. 8).

Habitat and uses

Abundant in dry and arid parts of NW India, where it is sometimes the most common tree in parts of Punjab and Rajasthan and abundant in arid thorn scrub in parts of the Near East (where P. farcta, which can spread via root suckers, is sometimes considered weedy), tolerating saline soils. Highly valued as a source of high quality durable wood, pods for livestock feed and bee forage.

Etymology

Pasiecznick et al. (2001) suggested the name to be derived from pros- (Gk.: towards) and Opis (wife of Saturn, the Greek goddess of abundance and agriculture), hence ‘towards agriculture’ referring to the widespread utility of the genus.

Affinities

Prosopis s.s. is here reduced to three species and is sister to the monospecific genus Indopiptadenia (Fig. 1). These two genera share stem/internodal prickles and a W-C Asian distribution that is unique within mimosoids.

Prosopis cineraria (L.) Druce, Rep. Bot. Exch. Club Soc. Brit. Isles 3: 422. 1913. (publ. 1914).

Mimosa cinerea L., pro parte, Sp. Pl.: 517. 1753 (see note below).

Prosopis spicigera L., Mant. Pl.: 68. 1767.

Prosopis spicata Burm.f., Fl. Indica: 102. 1768.

Prosopis aculeata J. Koenig ex Roxb., Asiat. Res. 4: 405. 1795.

Adenanthera aculeata (J. Koenig ex Roxb.) W. Hunter, Asiat. Res. 6: 66. 1799.

Acacia cineraria (L.) Willd., Sp. Pl., ed. 4, 4: 1057. 1806.

Note

The name Mimosa cineraria L. (Syst. Nat., ed. 10: 1311. 1759), based on M. cinerea L. (Sp. Pl.: 517 [non 520]. 1753; see Art. 53 Ex. 19), was transferred to Prosopis L. by Druce (in Bot. Exch. Club Brit. Isles Rep. 3: 422. 1914) as P. cineraria (L.) Druce. However, the correct name in Prosopis would have been a combination based on M. cinerea (l.c.) had not that name been successfully proposed for rejection (see App. V). in ICN Art. 53.5, Note 4.

Type material

India.

Prosopis farcta (Banks & Sol.) J.F. Macbr., Contr. Gray Herb. 59: 17. 1919.

Mimosa farcta Banks & Sol. in A. Russell, Nat. Hist. Aleppo, ed. 2, 2: 266. 1794.

Mimosa stephaniana M. Bieb., Tabl. Prov. Mer Casp.: 120. 1798.

Acacia stephaniana (M. Bieb.) Willd., Sp. Pl., ed. 4, 4: 1088. 1806.

Acacia heterocarpa Delile, Descr. Egypte, Hist. Nat.: 79. 1813.

Lagonychium stephanianum (M. Bieb.) M. Bieb., Fl. Taur.-Caucas. 3: 288. 1819.

Mimosa arvensis Sieber ex Steud., Nomencl. Bot. 1: 533. 1821, nom invalid.

Prosopis stephaniana (M. Bieb.) Kunth ex Spreng., Syst. Veg. 2: 326. 1825.

Mimosa agrestis Sieber ex Spreng., Syst. Veg. 2: 206. 1825.

Pleuromenes heterocarpa Raf., Sylva Tellur.: 145. 1838.

Acacia persica Sterler ex Steud., Nomencl. Bot., ed. 2, 1: 7. 1840.

Mimosa micrantha Vahl ex Walp., Repert. Bot. Syst. 5: 582. 1846.

Lagonychium farctum (Banks & Sol.) Bobrov in V.L. Komarov (ed.), Fl. URSS 11: 14. 1941.

Prosopis farcta var. glabra Burkart, J. Arnold Arbor. 57: 454. 1976.

Type material

Syria. Aleppo, without collector; no additional information in protologue.

Prosopis koelziana Burkart, J. Arnold Arbor. 57: 455. 1976.

Prosopis koelziana var. puberula J. Léonard, Bull. Jard. Bot. Natl. Belg. 56: 485. 1986.

Type material

Iran. Madenu, Kirman, Koelz 14246 (holotype: US [US00000985]).

Strombocarpa (Benth.) Engelm. & A. Gray, Boston J. Nat. Hist. 5: 243. 1845.

Spirolobium A.D. Orb., Voy. Amér. Mér. 8 (Atlas, Bot): t. 13. 1839, nom. rej., non Spirolobium Baill. 1889. (Apocynaceae).

Prosopis sect. Strombocarpa Benth., J. Bot. (Hooker) 4: 351. 1841.

Sopropis Britton & Rose in N.L. Britton & al. (eds.), N. Amer. Fl. 23: 182. 1928.

Type

Prosopis strombulifera (Lam.) Benth. [= Strombocarpa strombulifera (Lam.) A. Gray].

Description

Low spiny, sometimes creeping, shrubs or small trees, 0.15–3 (–18) m high, multi-stemmed from the base or sometimes with a short trunk to 10–30 (–45) cm diameter, usually densely and intricately much-branched, some species forming long underground, spreading, horizontal runners (gemmiferous roots or rhizomes), armed with strongly decurrent, straight, cinereous spiny stipules (Figs 2E, H, I and 3A), 0.1–3.5 (–5.5) cm long, brachyblasts congested, blackish. Leaves always unijugate, the petiole (0.5–) 2–15 mm, the pinnular rachises 1–4 cm long, with 3–30 pairs of well separated, alternate to opposite leaflets, these oblong or elliptic-oblong, obtuse to subacute, veins lacking or weakly 1–3-veined, 2–12 × 0.6–4 mm, glaucous, puberulous or glabrescent. Inflorescences axillary, solitary, globose, ovoid-elliptic heads to 1.5 cm diameter at anthesis or shortly cylindrical-spicate, 3–8 cm long. Flowers small, bright or lemon yellow, young filaments red; calyx, 1.5–2.3 mm long; corolla 3–4 (–6) mm long, the petals linear, partially united, villous within; stamens and style exserted, anthers with a minute, caducous, incurved claviform gland arising from the connective. Fruits densely clustered with 1–21 per flower head, indehiscent, lemon-yellow, straw-yellow or reddish-brown when ripe, slender, elongate, straight or falcate (in S. palmeri and S. ferox; Figs 5C, E and 7E–F), but usually more or less tightly spirally coiled (like corkscrews) with (1–) 8–19 (–24) regular coils, forming a cylindrical body 1.8–5.5 × 0.6–1.5 cm (Figs 5F, G and 7D) or irregularly and more openly coiled; exocarp crustaceous, mesocarp thin or more usually thick and pulpy, tannic, reddish, endocarp delicately segmented in longitudinal or transverse seed chambers which are easy to open or hard and closed. Seeds ovate or reniform ovoid, grey-green, 3–6 (–7) × 3–4 mm.

Geographic distribution

Ten species. Restricted to the New World and there occupying a markedly bicentric amphitropical distribution in arid and semi-arid regions of N. America (southern U.S.A., especially in the Sonoran Desert, Baja California and northern Mexico (Coahuila)) and S. America (south-central Peru to Argentina and Chile) (Fig. 8).

Habitat and uses

In cactus-rich semi-desert Monte vegetation, deserts and arid mesetas, dry river beds and washes and in the hyper-arid Pampa del Tamarugal in northern Chile (S. tamarugo), where it is the only tree present and dependent on moisture absorbed from fog. Fruits browsed by cattle and sheep and much valued in arid deserts for that purpose. Wood valued for fuel, and occasionally cultivated (S. tamarugo).

Etymology

Strombo- (Italian. = conch) and -carpa (Gk. = fruit), referring to the resemblance of the fruits to the spiral shells of tropical marine molluscs (see Figs 5F, G and 7D).

Affinities

Strombocarpa is robustly supported in recent molecular phylogenies as sister to the African monospecific genus Xerocladia (Fig. 1; Ringelberg et al. 2022). These two genera share the diagnostic synapomorphy of stipular spines which are not found elsewhere in Prosopis s.l.

Strombocarpa abbreviata (Benth.) Hutch., Gen. Fl. Pl. 1: 287. 1964.

Prosopis abbreviata Benth., J. Bot. (Hooker) 4: 352. 1842.

Type material

?Argentina. “San Jago”, Tweedie 168 (holotype: K [K000504799]).

Strombocarpa burkartii (Muñoz) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303579-1

Basionym

Prosopis burkartii Muñoz, Bol. Mus. Nac. Hist. Nat., Santiago de Chile 32: 364. 1971.

Type material

Chile. Prov. Tarapacá, Pampa del Tamarugal, El Gobierno, sector La Huaica, C. Muñoz Pizarro 7370 (holotype: SGO [SGO000002436]).

Strombocarpa cinerascens A. Gray, Smithsonian Contr. Knowl. 3(5): 61. 1852.

Prosopis cinerascens (A. Gray) Benth., Trans. Linn. Soc. London 30: 381. 1875.

Prosopis reptans var. cinerascens (A. Gray) Burkart, Darwiniana 4: 75. 1940.

Prosopis reptans subsp. cinerascens (A. Gray) A.E. Murray, Kalmia 13: 24. 1983.

Mimosa calcarea Buckley, Proc. Acad. Nat. Sci. Philadelphia 1861: 453. 1862.

Type material

Mexico. Nuevo León (“New Leon”), valley near Azufrosa, Gregg 492 (holotype: GH [GH00003469]; isotypes: K [K000791013], MO [MO356342]).

Strombocarpa ferox (Griseb.) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303580-1

Basionym

Prosopis ferox Griseb., Abh. Königl. Ges. Wiss. Göttingen 24: 118. 1879.

Type material

Argentina. “in regione Puna pr. Humaguaca, pr S José de Tilcara”, Jujuy, Humahuaca, P.G. Lorentz & G.H.E.W. Hieronymus 776 (lectotype: GOET [GOET009646]; isolectotypes: CORD [CORD00004889], F [F0BN001461], SI [SI002480]).

Strombocarpa palmeri (S. Watson) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303581-1

Basionym

Prosopis palmeri S. Watson, Proc. Amer. Acad. Arts 24: 48. 1889.

Sopropis palmeri (S. Watson) Britton & Rose in N.L. Britton & al. (eds.), N. Amer. Fl. 23: 183. 1928.

Type material

Mexico. Eastern Baja California, Mulegé, E. Palmer 2 (isotypes: BM [BM000952298], GH [GH00003471], K [K000478262], NDG [NDG24111], NY [NY00005123], US [US00930830]).

Strombocarpa pubescens (Benth.) A. Gray, Smithsonian Contr. Knowl. 3(5): 60. 1852.

Prosopis pubescens Benth., London J. Bot. 5: 82. 1846.

Prosopis emoryi Torr. In W.H. Emory, Not. Milit. Reconn. 2: 189. 1848.

Strombocarpa brevifolia Nutt. ex A. Gray, Smithsonian Contr. Knowl. 3(5): 60. 1852.

Type material

U.S.A. California: between San Miguel and Monterey, Coulter s.n.

Strombocarpa reptans (Benth.) A. Gray, U.S. Expl. Exped., Phan. 1: 475. 1854.

Prosopis reptans Benth., J. Bot. (Hooker) 4: 352. 1842.

Prosopis abbreviata var. argentina Griseb., Abh. Königl. Ges. Wiss. Göttingen 19: 133. 1874.

Type material

South America. with the label “Mortworta of Cordova, used as a cure for Dysentery” , Tweedie s.n. (K [K000504784]).

Strombocarpa strombulifera (Lam.) A. Gray, U.S. Expl. Exped., Phan. 1: 475. 1854.

Mimosa strombulifera (“strumbulifera”) Lam., Encycl. 1: 15. 1783.

Acacia strombulifera (Lam.) Willd., Sp. Pl., ed. 4, 4: 1055. 1806.

Prosopis strombulifera (Lam.) Benth., J. Bot. (Hooker) 4: 352. 1842.

Type material

Peru. no further details in protologue of Mimosa strombulifera.

Strombocarpa strombulifera var. ruiziana (Burkart) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303582-1

Basionym

Prosopis strombulifera var. ruiziana Burkart, J. Arnold Arbor. 57: 459. 1976.

Type material

Argentina. Mendoza: Dept. Junín, in aridis salsis inter Barrancas et Rodríguez Peña, A. Ruiz Leal 3787 (holotype: SI [SI002507]).

Strombocarpa strombulifera var. strombulifera

Mimosa retortunium Lam., Encycl. 1: 15. 1783, nom. invalid pro syn.

Mimosa circinalis Cav., Icon. 6: 41. 1801, nom. illeg.

Spirolobium australe A.D. Orb., Voy. Amér. Mér. 8 (Atlas, Bot): t. 13. 1839.

Strombocarpa tamarugo (Phil.) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303583-1

Basionym

Prosopis tamarugo Phil., Anales Mus. Nac. Santiago de Chile 1891: 21. 1891.

Type material

Chile. Prov. Tarapacá, Valle de Tamarugal, F. Philippi 1840 (holotype: SGO [SGO000002445]; isotype: SI [SI002508]).

Strombocarpa torquata (Lag.) Hutch., Gen. Fl. Pl. 1: 287. 1964.

Acacia torquata Lag., Gen. Sp. Pl.: 16, 206. 1816.

Prosopis torquata (Lag.) DC., Prodr. 2: 448. 1825.

Prosopis adesmioides Griseb., Abh. Königl. Ges. Wiss. Göttingen 19: 132. 1874.

Type material

probably t.36, ined., del Hortus de Cavanilles (fide Burkart in Darwiniana 4: 66. 1940).

Neltuma Raf., Sylva Tellur.: 119. 1838.

Prosopis sect. Algarobia DC. Prodr. 2: 446. 1825.

Mitostax Raf., Sylva Tellur.: 120. 1838.

Algarobia (DC.) Benth., Pl. Hartw.: 13. 1839.

Prosopis sect. Monilicarpa Ruiz Leal ex Burkart, J. Arnold Arbor. 57(3): 230. 1976.

Type

Neltuma juliflora (Sw.) Raf. [= Mimosa juliflora Sw.].

Description

Spiny, erect to prostrate subshrubs, shrubs and small trees, (0.1–) 4–10 (–20) m high, usually with a short trunk to 40–60 (–>100) cm diameter, branching lax with a spreading rounded or flat-topped crown, twigs cylindrical, flexuous, often arched downwards, glabrous, green or reddish, often with rather long internodes, armed with uninodal axillary, solitary or paired, straight, strong, cylindrical, subulate spines (Figs 2 and 3E), these not necessarily at all nodes, 0.2–15 (–33) cm long × 0.2–1.4 cm in diameter and sometimes thicker than the subtending twig, or with spinescent rigid straight cylindrical branchlets 8–50 cm, brachyblasts congested, blackish. Stipules small, triangular and dry. Leaves with 1–3 (–8) pairs of pinnae, the petiole (0.2–) 2–7.5 cm long, the pinnular rachises (0.2–) 4–19 (–24.5) cm long, with (1–) 2–30 (–50) pairs of opposite leaflets, these linear, ovate-oblong, oblong-linear or lance-ovate, more or less acute, palmately pinnativeined or almost without veins, (0.15–) 2.5–10 × 0.05–3.5 cm, puberulous to scarcely ciliolate or glabrous, or sometimes aphyllous or subaphyllous (N. sericantha, N. kuntzei), the leaves small and soon falling off the young developing shoots which become spinescent. Inflorescences axillary, solitary or fascicled, spicate, (1.5–) 3–15 cm long with 20–250 flowers on short 1.6 mm pedicels. Flowers white, yellow, greenish-yellow or occasionally red, often perfumed, sometimes some functionally male flowers; calyx 1–2 mm long; corolla 3–5 mm long, the petals almost free, pubescent, usually villous within; stamens and style exserted, anthers with a minute caducous incurved claviform gland arising from the connective. Fruits linear moniliform or compressed turgid (Figs 6 and 7H–I), straw yellow, sometimes tinged reddish-maroon or black, 1–several per infructescence, indehiscent, glabrous, mostly straight to subfalcate, S- or C-shaped or annular with 1–3 very lax open spirals, acuminate, (2–) 5–29 cm in length × 0.5–2.6 cm diameter, margins often thickened and undulate, valves striate corrugate or smooth, exocarp crustaceous, mesocarp thin or more usually thick and pulpy, mealy or spongy, dry, usually sweet, endocarp hard and bony or coriaceous, with convex faces and acute extremities, segmented in longitudinal or transverse subquadrate closed seed chambers. Seeds brown, compressed ovate, 5–10 × 3–6 mm. See also Johnston (1962).

Geographic distribution

Potentially up to 43 species, but probably somewhat fewer (see below). Widespread across seasonally dry tropical and arid regions of the Americas with a pseudo-amphitropical bicentric pattern of greatest species diversity in the Mexican-Texan and Argentinian-Chilean-Paraguayan regions, especially diverse and abundant in the Chaco, with an outlying disjunct occurrence of Neltuma ruscifolia of questionable nativity in the Caatinga in north-east Brazil (Burkart 1976; Oliveira & Queiroz 2020) and extending into warm and some colder temperate areas in Texas and Nevada in the north and Patagonia in the south, where N. denudans Benth. reaches 48 °S (Fig. 8).

Habitat and uses

Dominant across large tracts of the Gran Chaco in mixed sub-xerophyllous woodland, also in Monte vegetation, open desert forests in quebradas along seasonal rivers, in Stipa-dominated pampas and semi-desert shrub steppe with hot summers and cold winters in Patagonia as far as 48 °S, some species capable of surviving extreme drought; spanning a wide range of substrates and edaphic conditions including stony and sandy mesas, coastal and inland sand dunes and deep black seasonally inundated, sometimes saline, clay vertisols. Some species weedy and invasive, both within their native ranges and where introduced (see Introduction). The wood generally hard, dense, durable and flexible and widely used for fence posts, parquet flooring, barrels, firewood and charcoal and the fruits are eagerly consumed by all forms of livestock (see Introduction).

Etymology

Possibly derived from the common name Mulla Thumma in the Dravidian language Teluga in the Indian states of Andhra Pradesh and Telangana, where Neltuma juliflora is introduced.

Affinities

Neltuma is sister to, but deeply divergent from, the combined Strombocarpa + Xerocladia clade (Fig. 1).

Thirteen species of Prosopis have been described since the publication of Burkart’s (1976) monograph. One of these, Prosopis bonplanda P.R. Earl & Lux, was already placed in synonymy under P. glandulosa by Palacios (2006). All of the rest can be confidently placed in Neltuma (= Prosopis sect. Algarobia + Prosopis sect. Monilicarpa), based on morphological descriptions and illustrations from their respective protologues. We provide new combinations in Neltuma for all these names, listing potentially up to 43 species for the genus, but we suspect that some of these new species may be no more than regional variants of the widespread and taxonomically difficult N. pallida / N. juliflora species complex. Given the difficulties of species delimitation across parts of Neltuma, we suggest that a detailed molecular study with complete sampling of species and dense sampling of multiple accessions, representing intraspecific diversity, is needed to properly re-assess species boundaries and possible hybridisation. The Mimobaits gene set of Koenen et al. (2020) would be an ideal tool for such a study.

Neltuma affinis (Spreng.) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303584-1

Prosopis algarobilla Griseb., Abh. Königl. Ges. Wiss. Göttingen 19: 131. 1874.

Prosopis nandubey Lorentz ex Griseb., Abh. Königl. Ges. Wiss. Göttingen 24: 117. 1879.

Prosopis algarobilla var. nandubay (Lorentz ex Griseb.) Hassl., Repert. Spec. Nov. Regni Veg. 16: 154. 1919.

Basionym

Prosopis affinis Spreng., Syst. Veg. 2: 326. 1825.

Type material

Uruguay. Montevideo, F. Sello s.n. (lectotype (designated by Burkart 1976: 491): MO [MO-954306]).

Neltuma alba (Griseb.) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303585-1

Basionym

Prosopis alba Griseb., Abh. Königl. Ges. Wiss. Göttingen 19: 131. 1874.

Type material

Argentina. Córdoba, Estancia Germania, Lorentz 5 (isotypes: F [F0BN001457], M [M0218675], MPU [MPU016115], SI [SI002458]).

Neltuma alba var. alba

Prosopis siliquastrum var. longisiliqua Phil., Anales Mus. Nac. Santiago de Chile 1: 20. 1891.

Prosopis atacamensis Phil., Anales Univ. Chile 84: 444. 1893.

Neltuma alba var. panta (Griseb.) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303586-1

Prosopis panta (Griseb.) Hieron., Bol. Acad. Nac. Ci. Republ. Argent. 4: 284. 1881.

Basionym

Prosopis alba var. panta Griseb., Abh. Königl. Ges. Wiss. Göttingen 24: 118. 1879.

Type material

Argentina. Córdoba, Lorentz s.n.

Neltuma alpataco (Phil.) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303587-1

Basionym

Prosopis alpataco Phil., Anales Univ. Chile 21(2): 394. 1862.

Type material

Argentina. nr Mendoza, W. Diaz s.n. (probable isotypes: SGO [SGO000002428], SI [SI002464]).

Neltuma alpataco var. alpataco

Prosopis stenoloba Phil., Anales Mus. Nac. Santiago de Chile 1: 20. 1891.

Neltuma alpataco var. lamaro (F.A. Roig) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303588-1

Basionym

Prosopis alpataco var. lamaro F.A. Roig, Parodiana 5: 56. 1987. (publ. 1988).

Type material

Argentina. Roig 8946 (holotype: MERL).

Neltuma alpataco f. rubra (F.A. Roig) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303589-1

Basionym

Prosopis alpataco f. rubra F.A. Roig, Parodiana 5: 56. 1987. (publ. 1988).

Type material

Argentina. Roig et al. 223 (holotype: MERL).

Neltuma andicola (Burkart) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303590-1

Prosopis andicola (Burkart) A. Galán, E. Linares, J. Montoya & Vicente Orell., Phytotaxa 414: 49. 2019.

Basionym

Prosopis laevigata var. andicola Burkart, J. Arnold Arbor. 57: 510. 1976.

Type material

Peru. Cuzco, Prov. Calca, Hacienda Urco, J.C. Vargas-Calderón 709 (holotype: SI [SI002483]).

Neltuma argentina (Burkart) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303591-1

Basionym

Prosopis argentina Burkart, Revista Argent. Agron. 4: 39. 1937.

Type material

Argentina. Catamarca: Fiambalá, A. Castellanos s.n. (holotype: CTES [CTES0000667]; isotype: SI [SI002606]).

Neltuma articulata (S. Watson) Britton & Rose, in N.L. Britton & al. (eds.), N. Amer. Fl. 23: 187. 1928.

Prosopis articulata S. Watson, Proc. Amer. Acad. Arts 24: 48. 1889.

Prosopis juliflora var. articulata (S. Watson) Wiggins, Contr. Dudley Herb. 4: 17. 1950.

Neltuma pazensis Britton & Rose, in N.L. Britton & al. (eds.), N. Amer. Fl. 23: 187. 1928.

Prosopis pazensis (Britton & Rose) Wiggins, Contr. Dudley Herb. 4: 18. 1950.

Type material

Mexico. Sonora, Guaymas, E. Palmer 197 (lectotype designated by Palacios (2006): GH [GH00003478]; isolectotypes: BM [BM000952297, BM000952297], K [K000478261], NY [NY00005127], US [US00000983, US00930831], YU [YU001419]).

Neltuma caldenia (Burkart) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303592-1

Prosopis dulcis Gillies ex Hook., Bot. Misc. 3: 203. 1833, nom. illeg.

Prosopis calden Monticelli, Lilloa 3: 348. 1939, nom. nud.

Basionym

Prosopis caldenia Burkart, Darwiniana 3: 111. 1939.

Type material

Argentina. San Luis: Sierra, El Volcán (cerca de la capital), A.L. Pastore s.n., Herb Burkart 6629 (holotype: SI [SI002466]).

Neltuma calderensis (A. Galán, E. Linares, J. Montoya & Vicente Orell.) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303593-1

Basionym

Prosopis calderensis A. Galán, E. Linares, J. Montoya & Vicente Orell., Phytotaxa 414: 50. 2019.

Type material

Peru. Arequipa: Mollebaya, A. Galán et al. AG4633 (holotype: CPUN, isotypes: HUSA, MA, MO, USP).

Neltuma calingastana (Burkart) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303594-1

Basionym

Prosopis calingastana Burkart, Bol. Soc. Argent. Bot. 6: 223. 1957.

Type material

Argentina. San Juan, Calingasta, Quebrada Las Leñas y Est. Las Hornillas, Valle de Los Patos, Moreau & Perrone s.n. (BA55032) (holotype: SI [SI002468]).

Neltuma campestris (Griseb.) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303595-1

Basionym

Prosopis campestris Griseb., Abh. Königl. Ges. Wiss. Göttingen 19: 132. 1874.

Type material

Argentina. Córdoba, pr. Chañar, P.G. Lorentz 2 (holotype: GOET [GOET009644]; isotypes: CORD [CORD00005674], F [F0BN001459], SI [SI002469]).

Neltuma castellanosii (Burkart) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303728-1

Basionym

Prosopis castellanosii Burkart, Darwiniana 5: 66. 1941.

Type material

Argentina. Mendoza: Payún-Matrú, A. Castellanos 14253 (BA 36732) (holotype: SI [SI002471]; isotypes: LIL [LIL000715], GH [GH00063863]).

Neltuma chilensis (Molina) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303729-1

Prosopis chilensis (Molina) Stuntz, U.S.D.A. Bur. Pl. Industr. Invent. Seeds 31: 85. 1914.

Basionym

Ceratonia chilensis Molina, Sag. Stor. Nat. Chili: 172. 1782.

Type material

Chile. (no type details given in protologue to Ceratonia chilensis).

Neltuma chilensis var. catamarcana (Burkart) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303730-1

Basionym

Prosopis chilensis var. catamarcana Burkart, J. Arnold Arbor. 57: 497. 1976.

Type material

Argentina. Prov. Catamarca, Dept. Belén, Ulibarri 581 (holotype: SI [SI002472, SI002473]).

Neltuma chilensis var. chilensis

Acacia siliquastrum Cav. ex Lag., Gen. Sp. Pl.: 16. 1816.

Prosopis siliquastrum (Cav. ex Lag.) DC., Prodr. 2: 447. 1825.

Prosopis siliquosa St.-Lag., Ann. Soc. Bot. Lyon 7: 132. 1880, orth. var.

Prosopis schinopoma Stuck., Bull. Acad. Int. Géogr. Bot. 13: 87. 1904.

Neltuma chilensis var. riojana (Burkart) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303731-1

Basionym

Prosopis chilensis var. riojana Burkart, Darwiniana 9: 75. 1949.

Type material

Argentina. Prov. de La Rioja: Quebrada de lka Troya, cerca de Jagüel, A. Burkart 12355 (holotype: SI [SI002474]).

Neltuma denudans (Benth.) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303732-1

Basionym

Prosopis denudans Benth., J. Bot. (Hooker) 4: 351. 1842.

Type material

Argentina. Patagonia, Santa Cruz, near Puerto Deseado (“Port Desire”), Middleton s.n. (holotype: K [K000504789]).

Neltuma denudans var. denudans

Neltuma denudans var. patagonica (Speg.) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303733-1

Prosopis denudans var. patagonica (Speg.) Burkart, J. Arnold Arbor. 57: 480. 1976.

Basionym

Prosopis patagonica Speg., Revista Fac. Agron. Univ. Nac. La Plata 3: 510. 1897.

Type material

Argentina. Patagonia, “Golfo de San Jorge ”, C. Spegazzini s.n.

Neltuma denudans var. stenocarpa (Burkart) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303734-1

Basionym

Prosopis denudans var. stenocarpa Burkart, Darwiniana 9: 75. 1949.

Type material

Argentina. Gob. del Chubut: Dept. Rawson, south of Trelew, A. Krapovickas 4367 (isotypes: SI [SI002475, SI002476], BAB [BAB00000476]).

Neltuma elata (Burkart) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303735-1

Prosopis elata (Burkart) Burkart, Legum. Argent., ed. 2: 544. 1952.

Basionym

Prosopis campestris var. elata Burkart, Darwiniana 4: 112. 1940.

Type material

Paraguay. Chaco, Puesto Buenos Aires, en el sector Pilcomayo, T. Rojas 8323 (holotype: SI [SI002477]).

Neltuma fiebrigii (Harms) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303736-1

Basionym

Prosopis fiebrigii Harms, Repert. Spec. Nov. Regni Veg. 13: 524. 1915.

Type material

Paraguay. Chaco, Fiebrig 1254 (isotypes: F [F0BN001462, F0058760F, F0360901F], G [G00400139], K [K000504802], M [M0218669]).

Neltuma flexuosa (DC.) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303737-1

Acacia flexuosa Lag., Gen. Sp. Pl.: 16 (1816), nom. illeg.

Basionym

Prosopis flexuosa DC., Prodr. 2: 447. 1825.

Type material

Chile.

Neltuma flexuosa var. depressa (F.A. Roig) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303738-1

Prosopis juliflora f. fruticosa Hauman, Anales Mus. Nac. Hist. Nat. Buenos Aires 24: 391. 1913.

Prosopis alba f. fruticosa (Hauman) Monticelli, Lilloa 3: 347. 1938.

Basionym

Prosopis flexuosa var. depressa F.A. Roig, Parodiana 5: 53. 1987 (publ. 1988).

Type material

Argentina. Mendoza, Depto. Malargüe, Matancilla, Roig et al. “coleción Sierra de Chachahuén 32” (neotype: MERL).

Neltuma flexuosa var. flexuosa

Prosopis juliflora f. arborea Hauman, Anales Mus. Nac. Hist. Nat. Buenos Aires 24: 391. 1913.

Neltuma flexuosa var. fruticosa (Meyen) C.E. Hughes & G.P. Lewis

Prosopis flexuosa var. fruticosa (Meyen) F.A. Roig, Parodiana 5: 53. 1987. (publ. 1988).

Basionym

Prosopis fruticosa Meyen, Observ. Bot. 1: 376. 1834.

Type material

Chile. Prov. de Copiapó, Roig 12536 (holotype: MERL).

Neltuma flexuosa f. subinermis (Burkart) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303739-1

Basionym

Prosopis flexuosa f. subinermis Burkart, J. Arnold Arbor. 57: 513. 1976.

Type material

Argentina. San Juan: Calingasta a Barreal, entre La Isla y Sorocayense, J.H. Hunziker 6451 (holotype: SI).

Neltuma glandulosa (Torr.) Britton & Rose, in N.L. Britton & al. (eds.), N. Amer. Fl. 23: 186 (1928).

Prosopis glandulosa Torr., Ann. Lyceum Nat. Hist. New York 2: 192. 1827.

Dasiogyna glandulosa (Torr.) Raf., Atlantic J. 1: 146. 1832.

Algarobia glandulosa (Torr.) Torr. & A. Gray, Fl. N. Amer. 1: 399. 1840.

Prosopis juliflora var. glandulosa (Torr.) Cockerell, Bull. New Mexico Agric. Exp. Sta. 15: 58. 1895.

Prosopis chilensis var. glandulosa (Torr.) Standl., Contr. U.S. Natl. Herb. 23: 1658. 1926.

Type material

U.S.A. New Mexico, Union County, Major Long`s Creek (a tributary of the Canadian River (“on the Canadian”), James s.n. (holotype: NY [NY00005945]).

Neltuma glandulosa var. glandulosa

Prosopis juliflora var. constricta Sarg., Trees & Shrubs 2: 249. 1913.

Neltuma constricta (Sarg.) Britton & Rose, in N.L. Britton & al. (eds.), N. Amer. Fl. 23: 186. 1928.

Neltuma neomexicana Britton, in N.L. Britton & al. (eds.), N. Amer. Fl. 23: 186. 1928.

Prosopis bonplanda P.R. Earl & Lux. Publ. Biol. FCB/UANL. Mex. 5 (2): 38. 1991.

Neltuma glandulosa var. prostrata (Burkart) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303740-1

Basionym

Prosopis glandulosa var. prostrata Burkart, J. Arnold Arbor. 57: 516. 1976.

Type material

U.S.A. Texas: Kleberg County, western part of Laureles Division of King Ranch, M.C. Johnston 54359 (holotype: COLO; isotype SI [SI015053]).

Neltuma hassleri (Harms) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303741-1

Basionym

Prosopis hassleri Harms, Repert. Spec. Nov. Regni Veg.13: 523. 1915.

Type material

Paraguay. river Pilcomayo, Puerto Tolderia, T. Rojas 329 (isotypes: A [A00063864], BM [BM000545192], F [F0BN001463, F0360902F], GH, P).

Neltuma hassleri var. hassleri

Neltuma hassleri var. nigroides (Burkart) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303742-1

Basionym

Prosopis hassleri var. nigroides Burkart, J. Arnold Arbor. 57: 479. 1976.

Type material

Argentina. Prov. Santa Fe: Dept. General Obligado, Estancia Las Camelias, A.E. Ragonese 2423 (holotype: SI [SI002481]).

Neltuma humilis (Gillies ex Hook.) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303743-1

Basionym

Prosopis humilis Gillies ex Hook., Bot. Misc. 3: 204. 1833.

Type material

Argentina. in the Pampas of Buenos Aires (“Ayres”), J. Gilles s.n. (holotype: K [K000504787]; isotypes: E [E00158975, E00158976]).

Neltuma juliflora (Sw.) Raf., Sylva Tellur.: 119. 1838.

Mimosa juliflora Sw., Prodr. Veg. Ind. Occ.: 85. 1788.

Acacia juliflora (Sw.) Willd., Sp. Pl., ed. 4, 4: 1076. 1806.

Prosopis juliflora (Sw.) DC., Prodr. 2: 447. 1825.

Algarobia juliflora (Sw.) Heynh., Alph. Aufz. Gew.: 18. 1846.

Entada juliflora (Sw.) Roberty, Bull. Inst. Fondam. Afrique Noire, Sér. A, Sci. Nat. 16: 346. 1954.

Type material

Jamaica. O.P. Swartz s.n. (S [S-R-3632, S06-5737]).

Neltuma juliflora var. horrida (Kunth) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303744-1

Prosopis juliflora var. horrida (Kunth) Burkart, J. Arnold Arbor. 57: 502. 1976.

Basionym

Prosopis horrida Kunth, Mimoses: 106. 1822.

Type material

Peru. “crescit ad radices Andium orientalium, juxta ripam fluminis Amazonum, inter Tomependa(m) et confluentem Chamaya; item prope litus Oceani Pacifici, in arenosis, inter Piura(m) et Lambayeque”, Humboldt & Bonpland 3603 (isotypes: P [P00679172, P02734496]).

Neltuma juliflora var. juliflora

Mimosa piliflora Sw., Fl. Ind. Occid. 2: 986. 1800.

Mimosa furcata Desf., Tabl. École Bot.: 180. 1804.

Acacia cumanensis Humb. & Bonpl. ex Willd., Sp. Pl., ed. 4, 4: 1058. 1806.

Mimosa salinarum Vahl, Eclog. Amer. 3: 35. 1807.

Acacia diptera Humb. & Bonpl. ex Willd., Enum. Pl.: 1051. 1809.

Mimosa algarrobo Azara, Voy. Amér. Mér. 2: 483. 1809.

Mimosa cumana Poir., in J.B.A.M. de Lamarck, Encycl., Suppl. 1: 65. 1810.

Mimosa levigata Poir., in J.B.A.M. de Lamarck, Encycl., Suppl. 1: 65. 1810.

Mimosa pallida Poir., in J.B.A.M. de Lamarck, Encycl., Suppl. 1: 65. 1810.

Acacia furcata (Desf.) Desv., J. Bot. Agric. 3: 67. 1814.

Acacia falcata Desf., Tabl. École Bot., ed. 2: 207. 1815, nom. illeg.

Mimosa diptera Poir., in J.B.A.M. de Lamarck, Encycl., Suppl. 5: 529. 1817.

Desmanthus salinarum (Vahl) Steud., Nomencl. Bot. 1: 269. 1821.

Prosopis cumanensis Kunth, in F.W.H. von Humboldt, A.J.A. Bonpland & C.S. Kunth, Nov. Gen. Sp. 6: 310. 1824.

Prosopis inermis Kunth, in F.W.H. von Humboldt, A.J.A. Bonpland & C.S. Kunth, Nov. Gen. Sp. 6: 307. 1824.

Acacia salinarum (Vahl) DC., Prodr. 2: 456. 1825.

Prosopis bracteolata DC., Prodr. 2: 447. 1825.

Prosopis domingensis DC., Prodr. 2: 447. 1825.

Mimosa pseudoschinus Terán & Berland., Mem. Comis. Limites: 11. 1832.

Algarobia dulcis Benth., Pl. Hartw.: 13. 1839.

Prosopis dulcis var. domingensis (DC.) Benth., J. Bot. (Hooker) 4: 350. 1842.

Mimosa laevigata Benth., Linnaea 22: 530. 1849, orth. var.

Prosopis vidaliana Náves, Descr. Prosopsis vidaliana: 15. 1877.

Neltuma bakeri Britton & Rose, in N.L. Britton & al. (eds.), N. Amer. Fl. 23: 185. 1928.

Neltuma occidentalis Britton & Rose, in N.L. Britton & al. (eds.), N. Amer. Fl. 23: 185. 1928.

Neltuma pallescens Britton & Rose, in N.L. Britton & al. (eds.), N. Amer. Fl. 23: 185. 1928.

Prosopis juliflora var. inermis (Kunth) Burkart, J. Arnold Arbor. 57: 502. 1976.

Neltuma kuntzei (Harms ex C.E.O. Kuntze) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303745-1

Prosopis barba-tigridis Stuck., Comun. Mus. Nac. Buenos Aires 1: 66. 1899.

Prosopis casadensis Penz., Malpighia 12: 408. 1899.

Basionym

Prosopis kuntzei Harms ex C.E.O. Kuntze, Revis. Gen. Pl. 3(2): 71. 1898.

Type material

Bolivia. Sierra de Santa Cruz, O. Kuntze s.n. (isotypes: F [F0BN001465], NY [NY00003276] , US [US00000986]).

Neltuma laevigata (Humb. & Bonpl. ex Willd.) Britton & Rose, in N.L. Britton & al. (eds.), N. Amer. Fl. 23: 187. 1928.

Acacia laevigata Humb. & Bonpl. ex Willd., Sp. Pl., ed. 4, 4: 1059. 1806.

Prosopis laevigata (Humb. & Bonpl. ex Willd.) M.C. Johnst., Brittonia 14: 78. 1962.

Prosopis dulcis Kunth, Mimoses: 110. 1822.

Acacia tortuosa Billb. ex Beurl., Kongl. Svenska Vetensk. Acad. Handl., n.s., 2: 24. 1856, nom. illeg.

Mimosa rotundata Sessé & Moc., Pl. Nov. Hisp.: 178. 1890.

Neltuma michoacana Britton & Rose, in N.L. Britton & al. (eds.), N. Amer. Fl. 23: 187. 1928.

Type material

Mexico. “in America meridionali”, Morelos, between Huajintlán (“Guasintlan ”) and Puente de Istla, fide Johnston (1962), Humboldt & Bonpland (holotype B, microfiche reproduction Herbarium Willdenow Cat. N. 19132 (MO), fide Palacios (2006).

Neltuma limensis (Benth.) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303746-1

Basionym

Prosopis limensis Benth., J. Bot. (Hooker) 4: 350. 1842.

Type material

Peru. Lima, H. Cuming 974 (lectotype designated by Perry 1998. Fl. Australia 12: 193; isolectotypes: BM [BM000952294], E [E00319916, E00319926], GH [GH00063865], K [K000821140], US).

Neltuma mantaroensis (L. Vásquez, Escurra & Huamán) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303747-1

Basionym

Prosopis mantaroensis L. Vásquez, Escurra & Huamán, Sciéndo 12(1): 70. 2009.

Type material

Peru. Ayacucho, Prov. Huanta, Distr. Huanta, L. Vásquez Núñez et al. 12845 (holotype: PRG; isotype: PRG).

Neltuma mayana (R.A. Palacios) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303748-1

Basionym

Prosopis mayana R.A. Palacios, Bol. Soc. Argent. Bot. 41: 115. 2006.

Type material

Mexico. Yucatán, entre Dzilam de Bravo y El Tajo, R. Palacios 2362 (holotype: MEXU [MEXU01241933]; isotypes: BAFC, TEX [TEX00202236]).

Neltuma mezcalana (R.A. Palacios) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303749-1

Basionym

Prosopis mezcalana R.A. Palacios, Bol. Soc. Argent. Bot. 41: 105. 2006.

Type material

Mexico. Guerrero, entrada a Chacamerito y Tanganhuato, R. Palacios 2402 (holotype: MEXU; isotypes: BAFC, TEX [TEX00202211]).

Neltuma nigra (Griseb.) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303750-1

Prosopis nigra (Griseb.) Hieron., Bol. Acad. Nac. Ci. Republ. Argent. 4: 283. 1881.

Basionym

Prosopis algarobilla var. nigra Griseb., Abh. Königl. Ges. Wiss. Göttingen 24: 118. 1879.

Type material

Argentina. Córdoba, prope urban Chacra de la Merced, C. Galander s.n. (?holotype: HBG [HBG519250].

Neltuma nigra var. longispina (Burkart) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303751-1

Basionym

Prosopis nigra var. longispina Burkart, J. Arnold Arbor. 57: 507. 1976.

Type material

Argentina. Prov. Corrientes, Dept. Capital, 2 km S of Paso Pessoa, T.M. Pedersen 2808 (holotype: SI [SI002485]; isotypes: C [C10012323], CTES [CTES0000668], L [L0019214], MO [MO-954304], WAG [WAG0132133]).

Neltuma nigra var. nigra

Prosopis dulcis var. australis Benth., J. Bot. (Hooker) 4: 350. 1842.

Neltuma nigra var. ragonesei (Burkart) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303752-1

Basionym

Prosopis nigra var. ragonesei Burkart, Darwiniana 7: 518. 1947.

Type material

Argentina. Santa Fe: Videla, A.E. Ragonese 2078 (holotype: SI [SI002490]).

Neltuma nuda (Schinini) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303753-1

Basionym

Prosopis nuda Schinini, Bonplandia (Corrientes) 5: 105. 1981.

Type material

Paraguay. Dep. Boquerón. Mariscal Estigarribia, A. Schinini & E.E. Bordas 15222 (holotype: CTES [CTES0000670]; isotype: SI [SI002493]).

Neltuma odorata (Torr. & Frém.) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303754-1

Strombocarpa odorata (Torr. & Frém.) A. Gray, U.S. Expl. Exped., Phan. 1: 475. 1854.

Prosopis juliflora var. torreyana L.D. Benson, Amer. J. Bot. 28: 751. 1941.

Prosopis glandulosa var. torreyana (L.D. Benson) M.C. Johnst., Brittonia 14: 82. 1962.

Prosopis glandulosa subsp. torreyana (L.D. Benson) A.E. Murray, Kalmia 12: 23. 1982.

Basionym

Prosopis odorata Torr. & Frém., in J.C. Frémont, Rep. Exped. Rocky Mts.: 313. Pl. 1. 1845. Pro parte, excluding the fruits, fide L. D. Benson Madroño 15: 53. 1959.

Type material

U.S.A. California, along Mohave and Virgin River, Fremont s.n. (lectotype designated Benson (1959): NY), excluding the fruits.

Neltuma pallida (Humb. & Bonpl. ex Willd.) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303755-1

Prosopis pallida (Humb. & Bonpl. ex Willd.) Kunth, in F.W.H. von Humboldt, A.J.A. Bonpland & C.S. Kunth, Nov. Gen. Sp. 6: 309. 1824.

Mitostax pallida (Humb. & Bonpl. ex Willd.) Raf., Sylva Tellur.: 120. 1838.

Basionym

Acacia pallida Humb. & Bonpl. ex Willd., Sp. Pl., ed. 4, 4: 1059. 1806.

Type material

Peru. Prov. Jaén de Bracamoros, Passo de Matara, “in America meridionali”, ?Bonpland.

Neltuma palmeri Britton & Rose, in N.L. Britton & al. (eds.), N. Amer. Fl. 23: 185. 1928.

Prosopis tamaulipana Burkart, J. Arnold Arbor. 57: 494. 1976.

Type material

Mexico. Tamaulipas: vicinity of Victoria, E. Palmer 400 (holotype: NY [NY00005077]; isotypes: CM [CM1060], GH, MO [MO-356247], US [US00000993]).

Although the nom. nov. P. tamaulipana Burkart was required when Neltuma palmeri Britton & Rose was transferred to Prosopis because the name Prosopis palmeri S. Watson (= Strombocarpa palmeri (S.Watson) C.E. Hughes & G.P. Lewis) was already occupied, the original N. palmeri provides a valid accepted name.

Neltuma peruviana (L. Vásquez, Escurra & Huamán) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303756-1

Basionym

Prosopis peruviana L. Vásquez, Escurra & Huamán, Sciéndo 12(1): 74. 2009.

Type material

Peru. Apurímac, Prov. Andahuaylas, Distr. Sapichaca, L. Vásquez Núñez et al. 12849 (holotype: PRG; isotype: PRG).

Neltuma piurensis (L. Vásquez, Escurra & Huamán) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303757-1

Basionym

Prosopis piurensis L. Vásquez, Escurra & Huamán, Sciéndo 12(1): 76. 2009.

Type material

Peru. Piura, Prov. Sullana, borde de carretera panamericana cerca al Puente del rio Chira, L. Vásquez Núñez et al. 13258 (holotype: PRG).

Neltuma pugionata (Burkart) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303758-1

Basionym

Prosopis pugionata Burkart, Darwiniana 9: 70. 1949.

Type material

Argentina. Prov. de Córdoba, extremo noroeste, bosques xerófilos a las Salinas Grandes, km 907, A.E. Ragonese & B. Piccinini 6097 (holotype: BAB [BAB00000478]; isotype: SI [SI002497]).

Neltuma purpurea (L. Vásquez, Escurra & Huamán) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303759-1

Basionym

Prosopis purpurea L. Vásquez, Escurra & Huamán, Sciéndo 12(1): 79. 2009.

Type material

Peru. Tumbes, Distr. Puerto Pizarro, L. Vásquez Núñez et al. 12941 (holotype: PRG; isotype: PRG).

Neltuma rojasiana (Burkart) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303760-1

Basionym

Prosopis rojasiana Burkart, Darwiniana 5: 70. 1941.

Type material

Paraguay. Chaco paraguayo, Sector López de Filippis, Rojas 8310 (holotype: SI [SI002500]).

Neltuma rubriflora (Hassl.) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303761-1

Basionym

Prosopis rubriflora Hassl., Repert. Spec. Nov. Regni Veg. 8: 552. 1910.

Type material

Paraguay. Centurión, zwischen Apa und Aquidaban, K. Fiebrig 5348 (isotypes: F [F0BN001468], GH [GH00063869], HBG [HBG519244], M [M0218666], P [P02436145], fragment SI [SI002502]).

Neltuma ruizlealii (Burkart) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303762-1

Basionym

Prosopis ruizlealii Burkart, Darwiniana 4: 328. 1942.

Type material

Argentina. Prov. Mendoza, Dep. San Rafael: Agua del Sapo, Ruiz Leal 7358 (holotype: SI).

Neltuma ruscifolia (Griseb.) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303763-1

Basionym

Prosopis ruscifolia Griseb., Abh. Königl. Ges. Wiss. Göttingen 19: 130. 1874.

Type material

Argentina. Santiago del Estero, P.G. Lorentz 21 (holotype: GOET [GOET009549]; isotypes: CORD [CORD00005670], SI [SI002504]).

Neltuma sericantha (Gillies ex Hook.) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303764-1

Basionym

Prosopis sericantha Gillies ex Hook., Bot. Misc. 3: 204. 1833.

Type material

Argentina. Prov. San Luis, J. Gilles s.n. (holotype: K [K000504780]; isotypes: E [E00180081, E00180082], GH [GH00063870]).

Neltuma tupayachensis (L. Vásquez, Escurra & Huamán) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303765-1

Basionym

Prosopis tupayachensis L. Vásquez, Escurra & Huamán, Sciéndo 12(1): 82. 2009.

Type material

Peru. Prov. Cuzco, Distr. Lucre, L. Vásquez Núñez et al. 12846 (holotype: PRG; isotype: PRG).

Neltuma velutina (Wooton) Britton & Rose, in N.L. Britton & al. (eds.), N. Amer. Fl. 23: 186. 1928.

Prosopis velutina Wooton, Bull. Torrey Bot. Club 25: 456. 1898.

Prosopis juliflora var. velutina (Wooton) Sarg., Silva N. Amer. 13: 15. 1902.

Prosopis chilensis var. velutina (Wooton) Standl., Contr. U.S. Natl. Herb. 23: 1658. 1926.

Type material

U.S.A. Arizona, without further locality, Pringle 13665 (lectotype NY [NY00003272] designated by Britton & Rose in N. Am. Fl. 23(3): 186. 1928; isolectotypes: A [A00003470], CM [CM1091], MO [MO-954307]).

Neltuma × vinalillo (Stuck.) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303766-1

N. alba var. panta (as P. panta)× N. ruscifolia.

Basionym

Prosopis × vinalillo Stuck., Anales Mus. Nac. Buenos Aires 7 (ser. 2, t. 4): 73. 1902.

Type material

Argentina. Prov. Tucumán: Depto. De Burruyaco, ? Cañada Alegre.

Neltuma yaquiana (R.A. Palacios) C.E. Hughes & G.P. Lewis, comb. nov.

urn:lsid:ipni.org:names:77303767-1

Basionym

Prosopis yaquiana R.A. Palacios, Bol. Soc. Argent. Bot. 41: 117. 2006.

Type material

Mexico. Sinaloa, alrededores del Cementerio de Topolobampo, R. Palacios 2417 (holotype: MEXU; isotypes: BAFC, TEX [TEX00202225]).

Acknowledgements

We thank Erik Koenen for contributions to constructing the phylogeny and valuable discussions about generic delimitation of Prosopis s.l., Andrew Brown for the elegant botanical drawings in Figs 2, 5 and 6, Eduardo Estrada Castillón for searching for the protologue of P. bonplanda, Guillermo Debandi, Omesh Bajpai, Lal Babu Chaudhary, Zeynel Cebeci, N. Dreber, Marco Schmidt, Dick Culbert and Herta Kolberg for photos used in Figs 3 and 7, David Mabberley for information about the possible etymology of the name Neltuma, Marcelo Simon and Luciano de Queiroz for constructive and very helpful comments on an earlier version of the manuscript and the Swiss National Science Foundation for funding (through grants 310003A_156140 and 31003A_182453/1 to C.E.H.).

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﻿Abstract

Keywords

﻿Introduction

﻿Biogeography

﻿Key for the identification of the segregate genera of Prosopis and close allies (see Figs 2 and 3 for illustrations of armature characters used in the key)

﻿Taxonomy

﻿ Anonychium (Benth.) Schweinf., Reliq. Kotschy.: 7. 1868.

Type

Description

Geographic distribution

Habitat and uses

Etymology

Affinities

﻿ Anonychium africanum (Guill. & Perr.) C.E. Hughes & G.P. Lewis, comb. nov.

Basionym

Type material

﻿ Prosopis L., Mantissa Pl. 68: 10. 1767. emend. C.E. Hughes & G.P. Lewis.

Type

Description

Geographic distribution

Habitat and uses

Etymology

Affinities

﻿ Prosopis cineraria (L.) Druce, Rep. Bot. Exch. Club Soc. Brit. Isles 3: 422. 1913. (publ. 1914).

Note

Type material

﻿ Prosopis farcta (Banks & Sol.) J.F. Macbr., Contr. Gray Herb. 59: 17. 1919.

Type material

﻿ Prosopis koelziana Burkart, J. Arnold Arbor. 57: 455. 1976.

Type material

﻿ Strombocarpa (Benth.) Engelm. & A. Gray, Boston J. Nat. Hist. 5: 243. 1845.

Type

Description

Geographic distribution

Habitat and uses

Etymology

Affinities

﻿ Strombocarpa abbreviata (Benth.) Hutch., Gen. Fl. Pl. 1: 287. 1964.

Type material

﻿ Strombocarpa burkartii (Muñoz) C.E. Hughes & G.P. Lewis, comb. nov.

Basionym

Type material

﻿ Strombocarpa cinerascens A. Gray, Smithsonian Contr. Knowl. 3(5): 61. 1852.

Type material

﻿ Strombocarpa ferox (Griseb.) C.E. Hughes & G.P. Lewis, comb. nov.

Basionym

Type material

﻿ Strombocarpa palmeri (S. Watson) C.E. Hughes & G.P. Lewis, comb. nov.

Basionym

Type material

﻿ Strombocarpa pubescens (Benth.) A. Gray, Smithsonian Contr. Knowl. 3(5): 60. 1852.

Type material

﻿ Strombocarpa reptans (Benth.) A. Gray, U.S. Expl. Exped., Phan. 1: 475. 1854.

Type material

﻿ Strombocarpa strombulifera (Lam.) A. Gray, U.S. Expl. Exped., Phan. 1: 475. 1854.

Type material

﻿ Strombocarpa strombulifera var. ruiziana (Burkart) C.E. Hughes & G.P. Lewis, comb. nov.

Basionym

Type material

﻿ Strombocarpa strombulifera var. strombulifera

﻿ Strombocarpa tamarugo (Phil.) C.E. Hughes & G.P. Lewis, comb. nov.

Basionym

Type material

﻿ Strombocarpa torquata (Lag.) Hutch., Gen. Fl. Pl. 1: 287. 1964.

Type material

﻿ Neltuma Raf., Sylva Tellur.: 119. 1838.

Type

Description

Geographic distribution

Habitat and uses

Etymology

Affinities

﻿ Neltuma affinis (Spreng.) C.E. Hughes & G.P. Lewis, comb. nov.

Basionym

Type material

﻿ Neltuma alba (Griseb.) C.E. Hughes & G.P. Lewis, comb. nov.

Basionym

Type material

﻿ Neltuma alba var. alba

﻿ Neltuma alba var. panta (Griseb.) C.E. Hughes & G.P. Lewis, comb. nov.

Abstract

Introduction

Biogeography

Key for the identification of the segregate genera of Prosopis and close allies (see Figs 2 and 3 for illustrations of armature characters used in the key)

Taxonomy

Anonychium (Benth.) Schweinf., Reliq. Kotschy.: 7. 1868.

Anonychium africanum (Guill. & Perr.) C.E. Hughes & G.P. Lewis, comb. nov.

Prosopis L., Mantissa Pl. 68: 10. 1767. emend. C.E. Hughes & G.P. Lewis.

Prosopis cineraria (L.) Druce, Rep. Bot. Exch. Club Soc. Brit. Isles 3: 422. 1913. (publ. 1914).

Prosopis farcta (Banks & Sol.) J.F. Macbr., Contr. Gray Herb. 59: 17. 1919.

Prosopis koelziana Burkart, J. Arnold Arbor. 57: 455. 1976.

Strombocarpa (Benth.) Engelm. & A. Gray, Boston J. Nat. Hist. 5: 243. 1845.

Strombocarpa abbreviata (Benth.) Hutch., Gen. Fl. Pl. 1: 287. 1964.

Strombocarpa burkartii (Muñoz) C.E. Hughes & G.P. Lewis, comb. nov.

Strombocarpa cinerascens A. Gray, Smithsonian Contr. Knowl. 3(5): 61. 1852.

Strombocarpa ferox (Griseb.) C.E. Hughes & G.P. Lewis, comb. nov.

Strombocarpa palmeri (S. Watson) C.E. Hughes & G.P. Lewis, comb. nov.

Strombocarpa pubescens (Benth.) A. Gray, Smithsonian Contr. Knowl. 3(5): 60. 1852.

Strombocarpa reptans (Benth.) A. Gray, U.S. Expl. Exped., Phan. 1: 475. 1854.

Strombocarpa strombulifera (Lam.) A. Gray, U.S. Expl. Exped., Phan. 1: 475. 1854.

Strombocarpa strombulifera var. ruiziana (Burkart) C.E. Hughes & G.P. Lewis, comb. nov.

Strombocarpa strombulifera var. strombulifera

Strombocarpa tamarugo (Phil.) C.E. Hughes & G.P. Lewis, comb. nov.

Strombocarpa torquata (Lag.) Hutch., Gen. Fl. Pl. 1: 287. 1964.

Neltuma Raf., Sylva Tellur.: 119. 1838.

Neltuma affinis (Spreng.) C.E. Hughes & G.P. Lewis, comb. nov.

Neltuma alba (Griseb.) C.E. Hughes & G.P. Lewis, comb. nov.

Neltuma alba var. alba

Neltuma alba var. panta (Griseb.) C.E. Hughes & G.P. Lewis, comb. nov.

Neltuma alpataco (Phil.) C.E. Hughes & G.P. Lewis, comb. nov.

Neltuma alpataco var. alpataco

Neltuma alpataco var. lamaro (F.A. Roig) C.E. Hughes & G.P. Lewis, comb. nov.

Neltuma alpataco f. rubra (F.A. Roig) C.E. Hughes & G.P. Lewis, comb. nov.

Neltuma andicola (Burkart) C.E. Hughes & G.P. Lewis, comb. nov.

Neltuma argentina (Burkart) C.E. Hughes & G.P. Lewis, comb. nov.

Neltuma articulata (S. Watson) Britton & Rose, in N.L. Britton & al. (eds.), N. Amer. Fl. 23: 187. 1928.

Neltuma caldenia (Burkart) C.E. Hughes & G.P. Lewis, comb. nov.

Neltuma calderensis (A. Galán, E. Linares, J. Montoya & Vicente Orell.) C.E. Hughes & G.P. Lewis, comb. nov.

Neltuma calingastana (Burkart) C.E. Hughes & G.P. Lewis, comb. nov.

Neltuma campestris (Griseb.) C.E. Hughes & G.P. Lewis, comb. nov.

Neltuma castellanosii (Burkart) C.E. Hughes & G.P. Lewis, comb. nov.

Neltuma chilensis (Molina) C.E. Hughes & G.P. Lewis, comb. nov.

Neltuma chilensis var. catamarcana (Burkart) C.E. Hughes & G.P. Lewis, comb. nov.

Neltuma chilensis var. chilensis

Neltuma chilensis var. riojana (Burkart) C.E. Hughes & G.P. Lewis, comb. nov.

Neltuma denudans (Benth.) C.E. Hughes & G.P. Lewis, comb. nov.

Neltuma denudans var. patagonica (Speg.) C.E. Hughes & G.P. Lewis, comb. nov.

Neltuma denudans var. stenocarpa (Burkart) C.E. Hughes & G.P. Lewis, comb. nov.

Neltuma elata (Burkart) C.E. Hughes & G.P. Lewis, comb. nov.

Neltuma fiebrigii (Harms) C.E. Hughes & G.P. Lewis, comb. nov.

Neltuma flexuosa (DC.) C.E. Hughes & G.P. Lewis, comb. nov.

Neltuma flexuosa var. depressa (F.A. Roig) C.E. Hughes & G.P. Lewis, comb. nov.

Neltuma flexuosa var. flexuosa

Neltuma flexuosa var. fruticosa (Meyen) C.E. Hughes & G.P. Lewis