The Morelloid clade of Solanum L. (Solanaceae) in Argentina: nomenclatural changes, three new species and an updated key to all taxa

Abstract Since the publication of the Solanaceae treatment in “Flora Argentina” in 2013 exploration in the country and resolution of outstanding nomenclatural and circumscription issues has resulted in a number of changes to the species of the Morelloid clade of Solanum L. (Solanaceae) for Argentina. Here we describe three new species: Solanum hunzikeri Chiarini & Cantero, sp. nov., from wet high elevation areas in Argentina (Catamarca, Salta and Tucumán) and Bolivia (Chuquisaca and Tarija), S. marmoratum Barboza & S. Knapp, sp. nov., from central Argentina in Catamarca, La Pampa, La Rioja, San Juan and San Luis, and S. tiinae Barboza & S. Knapp, sp. nov., from the mountains of Jujuy, La Rioja, Salta and Tucumán. We provide descriptions, illustrations and distribution maps for all new taxa. A table of nomenclatural changes and additional taxa now known to occur in Argentina summarizes additions and changes since the “Flora Argentina”. We also provide an updated key, including all new taxa for the country, to facilitate identification and further exploration.


Introduction
Solanum L., with 1,400 species, is one of the largest genera of flowering plants (Frodin 2004). Its species occur worldwide, with highest diversity in South America, and in a wide variety of habitats, from deserts to tropical rainforests to high elevation grasslands. The genus comprises 13 major clades, one of which, the Leptostemonum clade or spiny solanums, contains approximately half the species. The non-spiny solanums are a paraphyletic grade ) within which several monophyletic groups are resolved ; one of these is the Morelloid clade (see Särkinen et al. 2015). Members of the clade are usually herbs or small short-lived subshrubs and the group is sister to the Dulcamaroid clade, a group of woody vines (See Knapp 2013). Species of the Morelloid clade are found worldwide and are being treated in a series of monographs (e.g., Old World taxa in Särkinen et al. 2018; Caribbean, North and Central American taxa in Knapp et al. 2019; South American taxa in G.E. Barboza et al., in prep); by far the highest diversity occurs in western South America (Särkinen et al. 2015). Of the 62 species of South American morelloids, 38 species are found in Argentina with 8 species occurring as country endemics (Table 1; 37 with 7 endemics excluding S. concarense Hunz., see below), making the country a hotspot for morelloid diversity. It is equalled only by Bolivia also with 38 species, 21 of which are in common with Argentina.
Solanaceae were treated in the multi-volume "Flora Argentina" in 2013 (Anton and Zuloaga 2013), and the treatment of the Morelloid clade recognised 30 species (Grupo VII. Moreloide; Barboza et al. 2013). Further exploration of the country and herbaria, coupled with taxonomic and nomenclatural work as part of the monograph, has resulted in an additional seven species for the country, and name changes for three species treated in the Flora (see Table 1). Here we document changes, describe new taxa and provide a revised key and provincial distribution (Table 2) for all morelloid species in the county.

Materials and methods
Our species circumscriptions are based on revision of herbarium material accompanied by detailed examination of living plants in the field and, where possible, in cultivation at the Instituto Multidisciplinario de Biología Vegetal (IMBIV) in Córdoba, Argentina. We have also used published and unpublished results from molecular phylogenetic study of the entire Morelloid clade (Särkinen et al. 2015;R. Hilgenhof, pers. comm.) to include or exclude taxa from the group. Descriptions for the new species are based on specimens from 14 herbaria (acronyms follow Index Herbariorum, http://sweetgum.nybg.org/science/ih/): BAA, BAB, BM, BR, CORD, CTES, E, G, K, LIL, MO, SI, US, W. Many more herbaria have been consulted during the course of monographic work on the Morelloid clade; these will be listed in full in the upcoming monograph, and details of all specimens seen to date from Argentina can be found in the Suppl. materials 1, 2: (SM 1, all morelloid species; SM 2, the three new species described here) and on the NHM Data Portal (https://doi.org/10.5519/0062836).  (Barboza et al. 2013) and the reasons for changes here. Circumscription changes and nomenclatural details will be treated in full in the upcoming monograph (G.E. Barboza et al. in prep.). Country endemics are in bold face type. NB: Solanum concarense (*) is included for consistency with Flora Argentina (Barboza et al. 2013), although it has been shown to belong to the Dulcamaroid (see text) rather than the Morelloid clade.
Measurements were made from dried herbarium material supplemented by measurements and observations from living and cultivated material. Colours (e.g., corollas, fruits, etc.) are described from living material or from herbarium label data. Specimens with latitude and longitude data on the labels were mapped directly. Some species had few or no georeferenced collections; in these cases we retrospectively georeferenced the collections using available locality data. Maps were constructed with the points in the Table 2. Morelloid species occurring in each province of Argentina (specimens seen by the authors, see Suppl. materials 1, 2 and NHM Data Portal, https://doi.org/10.5519/0062836). No morelloid species have been collected from Tierra del Fuego or Antarctica. Solanum concarense is included for consistency with Flora Argentina (Barboza et al. 2013), although it has been shown to belong to another clade (see text). NB: Solanum concarense (*) is included for consistency with Flora Argentina (Barboza et al. 2013), although it has been shown to belong to the Dulcamaroid (see text) rather than the Morelloid clade. centres of degree squares in a 1° square grid. Conservation threat status was assessed following the IUCN Red List Categories and Criteria (IUCN 2019) using the GISbased method (Bachman et al. 2011) as implemented in the online assessment tools in GeoCat (http://geocat.kew.org). The Extent of Occurrence (EOO) measures the range of the species, and the Area of Occupancy (AOO) represents the number of occupied points within that range based on the default grid size of 2 km 2 . We have given more weight to the EOO in the threat assessments for relatively widespread species; AOO is very sensitive to georeferencing bias and collecting effort.

Name changes for Morelloid species in Argentina
Changes for inclusion and nomenclature for morelloids since the publication of "Flora Argentina" (Barboza et al. 2013) are summarised in Table 1, but some comment is necessary here. The widespread and highly variable species S. salicifolium Phil. was treated as a member of the Dulcamaroid clade by Knapp (2013) and in the Flora, but further work with DNA sequence data places S. salicifolium nested amongst the "Black nightshade" group of Särkinen et al. (2015). Further analyses have supported this position (E. Gagnon et al., pers. comm.). Solanum salicifolium is included here in the key for clarity, even though it was included in the Dulcamaroid clade earlier (Knapp 2013).
Solanum concarense was included as a member of the clade in Barboza et al. (2013), but subsequent phylogenetic analysis (R. Hilgenhof, pers. comm.) has revealed that it instead is nested within the Dulcamaroid clade. We include it here in the key for clarity, but it will not be treated as a member of the group in the upcoming monograph and a full species description is available on Solanaceae Source (http://solanaceaesource.org).
Several names have changed due to the clarification and subsequent resurrection (Särkinen et al. 2015) of older names coined by R.A. Philippi for species from high elevation areas of Chile adjacent to Argentina (Philippi 1891); S. weddellii Phil. is the older name for what was previously recognised (Barboza 2004) as S. chamaesarachidium Bitter and S. grandidentatum Phil. for the taxon previously recognised (Edmonds 1972) as S. excisirhombeum Bitter. These names have been in use since Särkinen et al. (2015). Solanum cochabambense Bitter was treated as a synonym of S. aloysiifolium Dunal in Barboza et al. (2013), but subsequent study through the entire range of S. cochabambense (north to Peru) has shown the two taxa to be distinct; we therefore recognise them as separate here.

Re-evaluation of synonymy in two common glandular-pubescent taxa
Re-evaluation of taxon circumscription and types for the upcoming monograph has revealed that two names for species with glandular trichomes and accrescent calyces were previously incorrectly applied in "Flora Argentina" and elsewhere (Barboza et al. 2013;Särkinen and Knapp 2016). In Barboza et al. (2013), two taxa were recognised, S. "tweedianum" Hook. (a mis-spelling of S. tweedieanum, see below) and S. atriplicifolium Gillies ex Nees, both of which are glandular-pubescent with ovate, shallowly toothed leaves. Solanum physalidicalyx Bitter, the name recognised here for a distinct species with highly inflated calyces, was erroneously put into synonymy with S. tweedieanum; the type of S. tweedieanum does not match these specimens but is a better match for plants called S. atriplicifolium in 2013. The type of S. tweedieanum comes from a plant cultivated at Kew that was collected in flower only; it lacks the diagnostic calyx characters (see Fig. 1 and the key presented here) that enable easy identification in this group, but anther length can also be used to distinguish those plants not in fruit. Plants with inflated calyces have shorter anthers than do those with calyces that are merely accrescent and tightly investing the berry; the types of both S. tweedieanum and S. atriplicifolium have longer (to 6 mm) anthers and belong to the same species, for which the oldest name is S. tweedieanum. We present here a revised synonymy for the two species of glandular-pubescent morelloids with anthers more than 3 mm long that occur in Argentina to correct the error in "Flora Argentina" (Barboza et al. 2013).  (Bitter 1912) may correspond to duplicates of the type collection of the species itself, making all three names homotypic. In describing var. integrascens Bitter (1912) states "var. integrifolia quod in descriptione specie pro typo habui" [var. integrifolia I had in the description of the type of the species] suggesting this name at least is based on Lorentz & Hieronymus 364. Bitter often used duplicates with minor leaf variations as material for describing infraspecific variation (Knapp 2013 Edmonds (1972) stated that the holotype of S. tweedieanum was held at K; Barboza et al. (2013) repeated this citation but added reference to a single sheet (K000585739). This is not effective lectotypification under Art. 9.23 of the Code (Turland et al. 2018). The specimen cited as holotype by Barboza et al. (2013) and selected as lectotype here (K000585739) has open flowers and several buds and is a better match for the illustration in the protologue than the other sheet at Kew (K000585738); both specimens are annotated "S. Tweedianum Hook./B os . Ayres. Cult." in W.J. Hooker's handwriting and bear the herbarium stamp "Herbarium Hookerianum/1867" indicating they come from Hooker's own herbarium. There is no evidence on the specimens themselves that they were taken from the plants cultivated in Glasgow mentioned in the protologue, nor that they were collected prior to 1835; but the top part of the stem mounted on the sheet we have selected as the lectotype at Kew (K000585739, https://plants.jstor.org/stable/pdf/10.5555/al.ap.specimen.k000585739) is an excellent (mirror-image) match for Tab. 3385 in the protologue (Hooker 1835; see https:// www.biodiversitylibrary.org/item/14341#page/36/mode/1up) suggesting it does represent original material. The original, and all subsequent, spelling of the name was "Tweedianum" where John Tweedie's name was implicitly latinized as "Tweedius" in which the terminal vowel was eliminated. This is not acceptable under Art. 60.9(a)(1) of the Code (Turland et al. 2018) and the name should be formed as "tweedieanum" (e.g., Art. 60.9, Ex. 31, Turland et al. 2018).

New species descriptions
Solanum hunzikeri Chiarini & Cantero, sp. nov. urn:lsid:ipni.org:names:77212300-1 Figs 1A-C, 2 Diagnosis. Like Solanum tweedieanum Hook. but differing in sessile leaves with broadly winged petioles, pedicels in flower longer than 1 cm, larger flowers and anthers more than 1 mm wide.  Description. Herb or subshrub from a woody base ca. 50 cm tall; stems terete or only slightly angled, densely glandular pubescent with glandular papillae and transparent spreading simple 3-8-celled uniseriate trichomes 0.5-1 mm long, some to 1.5 mm long; bark of older stems pale brown, glabrescent; new growth densely glandular pubescent with simple uniseriate trichomes to 1 mm long. Sympodial units plurifoliate, the leaves not geminate. Leaves simple to shallowly toothed, (2-)4.5-14 cm long, (1.1-)2-7 cm wide, elliptic in outline, membranous or somewhat thick and fleshy, concolorous; adaxial surface moderately and evenly glandular pubescent with transparent spreading, simple uniseriate trichomes ca. 0.5 mm long on the lamina, ca. 1 mm long on the veins; abaxial surface moderately and evenly glandular pubescent like the adaxial surface, but the trichomes denser and longer, to 1.5 mm long; principal veins 4-7 pairs, densely glandular pubescent; base attenuate and strongly decurrent onto the petiole; margins entire or shallowly toothed, the teeth if present 1-2 mm long, 2-3 mm wide, broadly deltate with somewhat rounded tips; apex acute; petioles absent and the leaves sessile or 0-0.1 mm long, the decurrent leaf bases running onto the stem, glandular pubescent like the stems and leaves. Inflorescences 2.5-4 cm long, opposite the leaves, unbranched but occasionally forked (Rodríguez 1421), with 10-20 flowers, densely glandular pubescent with transparent spreading simple uniseriate trichomes to 1.5 mm long; peduncle 1.2-2.5 cm long; pedicels 1.3-1.5 cm long, 0.5-0.7 mm in diameter at the base, ca. 1.5 mm in diameter at the apex, spreading at anthesis, densely glandular pubescent, articulated at the base; pedicel scars irregularly spaced 1-2 mm apart. Buds ellipsoid, the corolla ca. halfway exserted from the calyx before anthesis. Flowers 5-merous, perfect. Calyx tube 2-3 mm long, conical, the lobes 2.5-4 mm long, long-triangular, densely glandular pubescent with simple uniseriate trichomes like the pedicels and rest of the inflorescence, the tips acuminate and somewhat recurved at anthesis. Corolla 1.6-2.5 cm in diameter, pale lilac to violet with a yellowgreen central star, stellate, lobed ca. 1/2 way to the base, the lobes 5-5.5 mm long, 4-5.5 mm wide, deltate, reflexed or spreading at anthesis, adaxially glabrous, abaxially sparsely glandular papillate especially on the midvein, tips and margins; stamens equal; filament tube 0.35-0.5 mm; free portion of the filaments 1-1.5 mm, almost glabrous, but with a few tangled transparent eglandular simple uniseriate trichomes adaxially; anthers 4-5.5 mm long, 1.25-1.6 mm wide, ellipsoid, yellow, poricidal at the tips, the pores lengthening to slits with age. Ovary conical, glabrous; style 7-8 mm long, densely papillate with a few longer simple trichomes in the lower third; stigma large capitate to slightly bilobed, the surface minutely papillate. Fruit a globose berry, 1-1.2 cm in diameter, green (?) at maturity, opaque, the surface of the pericarp glabrous, thin, matte; fruiting pedicels 1.5-2 cm long, ca. 1.5 mm in diameter at the base, ca. 2 mm in diameter at the apex, somewhat woody, deflexed from the weight of the berry, glandular pubescent to somewhat glabrescent; fruiting calyx accrescent in young fruit tightly investing the berry, the tube 3-5 mm long, later tearing and the berry exposed, the lobes 3-5 mm long, ca. 3 mm wide, appressed to spreading. Seeds ca. 40 per berry, 1.5-2 mm long, 1-1.7 mm wide, flattened teardrop shaped with an apical hilum, reddish brown, the surfaces minutely pitted, testal morphology not clearly seen. Stone cells 10-11 per berry, 1-1.3 mm in diameter, globose, scattered throughout the berry. Chromosome number not known (but see comments on DNA content below). Distribution ( Figure 3). Solanum hunzikeri occurs in Argentina in the provinces of Catamarca and adjacent Salta and Tucumán and extends north to Bolivia in the departments of Tarija and Chuquisaca. The distribution is somewhat disjunct possibly due to loss of the wet high elevation foggy grassland habitat in the intervening areas.
Ecology and habitat. Solanum hunzikeri is confined to wet cloud forests and foggy grasslands above 1800 m elevation; it also grows in the ecotones between these vegetation types. These foggy grasslands are dominated by tall grasses (e.g., Festuca hieronymi Hack., Cinnagrostis polygama Griseb., Elionurus muticus (Spreng.) Kuntze [Poaceae]) and shrubs (e.g., Baccharis spp., Stevia spp. [Asteraceae]). Solanum hunzikeri can also be locally frequent on open grassy terraces with scattered palms, in narrow valleys with the lower slopes covered in seasonally moist forest dominated by Parajubaea torallyi (C.Mart.) Burret (Arecaceae) and with abundant Podocarpus spp. (Podocarpaceae) and can be found on steep, stony slopes in undisturbed grassland areas.
Etymology. This species is named in honour of the late Ing. Armando T. Hunziker of IMBIV in Córdoba, whose life work on the Solanaceae inspired a generation of solanologists, in both Argentina and globally.
Preliminary conservation status (IUCN 2019). AOO (80 km 2 -EN); EOO (97,627 km 2 -LC). Although the large extent of occurrence would suggest S. hunzikeri is not of conservation concern, the limited number of localities, the specialised habitat and the disjunct distribution suggest the species should be considered at risk. Solanum hunzikeri occurs in a very restricted habitat in which there are few officially protected areas. In these landscapes the main threat to the ecosystem is over-grazing; the introduction of alien forage species such as Pennisetum clandestinum Hochst. ex Chiov. (Poaceae) has severely altered the nature of the high elevation foggy grasslands and forest edges in which S. hunzikeri occurs. Although some populations are found in currently protected areas such as the Parque Nacional Aconquija, these areas are considered too small and isolated to provide long term conservation (Brown 1995). Based on the area of occupancy, the number of localities (ca. 8) in a disjunct distribution and threats to the habitat, we assign a preliminary threat status of Vulnerable (VU B2a,biii) for S. hunzikeri. The exploration of these relatively inaccessible habitats in the area between the currently known populations of S. hunzikeri is a priority.
Notes. Solanum hunzikeri had been recognized as distinct from other glandularpubescent species in Argentina in the early 20 th century by the German botanist Georg Bitter as "Solanum catamarcae", a name already occupied in Solanum (S. catamarcae Bitter ex Brücher, a synonym of S. boliviense Dunal, see Spooner et al. 2019). Morton (1976) in his treatment of Solanum for Argentina, cited Sleumer 2259 as part of his concept of S. atriplicifolium and stated "This last appears to be a local form that has the petioles broadly winged nearly throughout instead of at the apex only. According to determinations by Dr. Sleumer this plant was given the unpublished name of "Solanum catamarcae" by Bitter." Morton annotated the sheet of Sleumer 2259 in US as "Solanum atriplicifolium var. sleumeri Morton HOLOTYPE" in 1971 but did not publish the infraspecific epithet; he also annotated Sleumer 2311 (US) as a paratype of the same.
The species is now known from a wider distribution, and additional specimens have clarified its differences from the widespread and highly variable S. tweedieanum. Solanum hunzikeri can be distinguished from S. tweedieanum populations in similar high elevation areas in its strongly attenuate and winged leaf bases, those of S. tweedieanum are more truncate. The single collection we have seen of S. hunzikeri with ma- ture fruit (Rodríguez 1421 from Salta) has the calyx not covering any part of the mature berry; berries of S. tweedieanum are tightly covered by the accrescent calyx for at least 50% of their length. More collections of S. hunzikeri in fruit are needed to assess these differences. Preliminary data on DNA content for S. hunzikeri and S. tweedieanum (F. Chiarini unpubl.) show differences but suggest that, like S. tweedieanum (Moscone 1992), S. hunzikeri is diploid.
Description. Watery annual herb, 10-100 cm tall, sprawling and somewhat prostrate when very large. Stems strongly winged, the wing to 1 mm side, sometimes with spinose processes (old trichome bases), sparsely to moderately pubescent with spreading to appressed eglandular simple 5-8-celled uniseriate trichomes 0.5-1 mm long, these drying white; new growth densely pubescent with eglandular, white simple uniseriate trichomes 0.5-1 mm long; older stems greenish white, not woody. Sympodial units difoliate, the leaves not geminate, axillary shoots common. Leaves simple and shallowly toothed, 2-10 cm long, 1.5-6 cm wide, much larger in older plants, ovate, widest in the lower third, membranous, watery and somewhat succulent, concolorous, very bright green on live plants; adaxial and abaxial surfaces evenly white-pubescent with eglandular simple 5-8-celled uniseriate trichomes 0.5-1 mm long, these longer and denser on the veins; principal veins 5-6 pairs; base attenuate onto the petiole; margins shallowly and irregularly toothed, the teeth 2-4 mm long, 2.4-mm wide, broadly deltate, with blunt tips; apex acute; petioles 0.5-2.5 cm long, somewhat winged from the attenuate leaf base, pubescent with simple uniseriate trichomes like the stems and leaves. Inflorescences (1)2-3 cm long, internodal and extraaxillary, unbranched, with 5-7 flowers clustered at the tip, usually only 1-2 open at a time, sparsely and evenly pubescent with antrorse simple uniseriate trichomes 0.5-1 mm long like the stems and leaves; peduncle 1.4-2.5 cm long; pedicels 0.4 cm long, ca. 0.5 mm in diameter at the base, ca. 0.6 mm in diameter at the apex, slightly tapering, spreading, eglandular pubescent like the rest of the inflorescence, articulated at the base; pedicel scars tightly packed at the tip of the in-  (Barboza et al. 5130). All photographs by S. Knapp. florescence, 0.5-1.5 mm apart. Buds broadly ellipsoid, the corolla included in the calyx tube until just before anthesis. Flowers 5-merous, perfect. Calyx tube 1.2-1.5 mm long, cup-shaped, the lobes 1-1.5 mm, narrowly deltate-triangular, fleshy and recurved in live plants, sparsely pubescent with eglandular white trichomes on both surfaces like the rest of the plant. Corolla 0.5-0.8 cm in diameter, white with a green central star, stellate, lobed ca. halfway to the base, the lobes ca. 2.5 mm long, ca. 2 mm wide, spreading to slightly reflexed at anthesis (flowers closing daily and lasting for several days), adaxially glabrous, abaxially densely pubescent with tiny simple uniseriate trichomes especially at the tips. Stamens equal or slightly unequal with one anther marginally longer than the rest; filament tube ca. 0.1 mm long; free portion of the filaments 0.5-1 mm long, elongating through anthesis, with a few tangled transparent simple uniseriate trichomes adaxially; anthers 1-1.5 mm long 0.6-1 mm wide, ellipsoid, yellow, poricidal at the tips, the pores elongating with age. Ovary conical, glabrous; style 2-2.5 mm, included within the anther cone or the stigma just beyond, densely papillate in the lower 3/4; stigma large capitate, held at the level of the anthers when flowers first open, later included within the anther cone, bright green in life plants, the surfaces minutely papillate. Fruit a globose berry, 0.8-1.5 cm in diameter, dark green marbled with white at maturity, glabrous, translucent, the pericarp surface thin, shiny; fruiting pedicels 1.2-1.5 cm long, ca. 1 mm in diameter at the base, ca. 1.5 mm in diameter at the apex, fleshy and watery, tapering to the spreading calyx, strongly deflexed at maturity, with a distinct bend at the pedicel base; fruiting calyx somewhat expanded, the tube 3-4 mm long, the lobes 4-5 mm long, ca. 3 mm wide, spreading and fleshy, the tips rounded. Seeds 50-70 per berry, ca. 2 mm long, ca. 1.7 mm wide, flattened teardrop shape with an apical hilum, pale tan to reddish brown, the surfaces minutely pitted, the testal cells mostly rectangular to pentagonal in outline, more sinuate towards the seed centre. Stone cells 1-2, 1-1.1 mm in diameter, found randomly positioned in the berry. Chromosome number: not known.
Distribution (Figure 6). Solanum marmoratum is endemic to Argentina and occurs in the provinces of Catamarca, La Pampa, La Rioja, San Juan and San Luis; we expect it also to be found in Mendoza, because several collections are known from Desaguadero (San Luis) a locality very close to the provincial border that crosses through uniform habitat.
Ecology and habitat. Solanum marmoratum is found in shady areas in Prosopis woodlands (Fig. 4A) and at the edges of arable fields; it usually grows under trees and shrubs with a number of other herbaceous plants such as S. tweedieanum, various species of Asteraceae and grasses. Specimens have been collected from 200 to 1400 m elevation.
Etymology. The species is named for its distinctive marbled berries (Fig. 4F, G) that easily distinguish it from the similar tiny-flowered eglandular species S. americanum.
Preliminary conservation status (IUCN 2019). AOO (84 km 2 -EN); EOO (239,336 km 2 -LC). Solanum marmoratum is a relatively widespread species, the extent of occurrence suggests is should be given a status of least concern. The small area of occupancy perhaps reflects a lack of collecting in the dry forest and partially degraded habitats where S. marmoratum occurs. The number of localities (ca. 9) is probably an underestimate due to the widespread perception that these habitats are not interesting; most collections are quite old and the species has not be collected recently (except by us). The large-scale conversion of land in the range of S. marmoratum to intensive monoculture of commercial crops such as maize, peanuts and sunflowers poses a risk for this and other species in these habitats; use of herbicides and elimination of patches of forest leave little room for even weedy species to persist. We suggest a preliminary threat status of Least Concern (LC) to S. marmoratum, but the widespread habitat conversion in central Argentina warrants further studies as to population status across the species' historical range.
Notes. Solanum marmoratum has long confused botanists working with Argentinian solanums. In the herbarium at CORD specimens of S. marmoratum collected by P. Steibel in the province of San Luis were the subject of correspondence with A.T. Hunziker over their identification; they were tentatively identified as S. adventitium Polg., a synonym of S. americanum described from adventive material in Hungary (Särkinen et al. 2018). None of the pre-1970s specimens we have seen were cited in Morton (1976), but Semper s.n. at US (barcode 02837698) was annotated "Solanum dolichopteryx Morton, paratype" by C.V. Morton in 1971. We have not found specimens annotated as other types at US or elsewhere. A.T. Hunziker had kept specimens  Barboza & S.Knapp. of this species aside with the herbarium name "Solanum alatocaule", a reference to the strongly winged stems (Fig. 4B, C) on the folder, but never described it. We collected S. marmoratum in 2013 (Barboza et al. 3668) along with S. tweedieanum, and mistakenly noted the leaves of S. marmoratum as sticky (see Fig. 5); it was only examination of the dried specimens that alerted us to our error. Careful examination of all morelloid collections at CORD in early 2020 showed the distinctness of S. marmoratum, and its relatively widespread distribution.
The flowers of S. marmoratum are among the tiniest in the morelloid solanums (Fig. 4D, E) rivalled only by the globally distributed S. americanum and S. nitidibaccatum Bitter and the North American S. emulans Raf. (see Knapp et al. 2019). Solanum nitidibaccatum also has somewhat marbled berries but is always extremely sticky and covered with glandular trichomes, in contrast to the eglandular pubescence of S. marmoratum. Solanum americanum and S. emulans both have eglandular pubescence but have purplish black rather than green marbled berries. The fleshy spreading calyx lobes of S. marmoratum (Fig. 4G) are distinct from those of all of these taxa with tiny flowers.
Solanum marmoratum appears to be highly autogamous and is perhaps entirely self-fertilising. The style is completely included within the anther cone (Fig. 4D, E) and the filaments appear to elongate through anthesis (see. Fig. 4E) bringing the style further into the cone as the flower ages. Flowers stay open for several days (closing at night) and in cultivation the plant goes from bud to flower to fruit in 15-18 days with all flowers setting fruit. Over the course of anthesis the style becomes enclosed in the anther cone (Fig. 4E), with the anthers as they dehisce leaving pollen directly on the stigma. Ripe berries last more than two weeks after being gathered from desiccated plants, remaining unchanged as to colour or odour.
Description. Perennial herbs or subshrubs sprawling from a woody base, to 50 cm tall. Stems narrowly winged, the wing to 0.5 mm wide, often invested with spinose processes (enlarged trichome bases), sparsely pubescent with antrorse eglandular, simple uniseriate trichomes, 6-10-celled, ca. 0.5 mm long, these white when dry; new growth densely to moderately pubescent with antrorse eglandular, simple 2-8-celled uniseriate trichomes, ca. 0.5 mm long; bark of older stems pale greenish brown, glabrescent. Sympodial units plurifoliate, the leaves not geminate. Leaves simple, 2-5 cm long, 0.6-2 cm wide, narrowly elliptic to almost lanceolate in some individuals, membranous, concolorous; adaxial surfaces sparsely and evenly pubescent with antrorse eglandular simple 2-4-celled uniseriate trichomes to 0.5 mm long, the trichomes slightly longer on the veins, white when dry; abaxial surfaces with similar, but denser eglandular antrorse pubescence; principal veins 4-6 pairs, drying yellow, especially abaxially;  (Barboza et al. 3491) E flowers at anthesis, note the changing colour and size (Barboza et al. 3491) F mature fruits (Barboza et al. 3491). All photographs by S. Knapp. base attenuate and decurrent onto the winged stem and the leaves sessile or nearly so; margins entire or with a few teeth ca. 2 mm long, ca. 2 mm wide with blunt tips in the lower third to half; apex acute to slightly blunt-tipped; petiole absent to 0.2 mm long, eglandular pubescent like the stems and leaves. Inflorescences 2.5-5 cm long, opposite the leaves or internodal, forked with 2 short branches, with 10-20 flowers clustered at the tips of the inflorescence branches, sparsely pubescent with antrorse eglandular simple uniseriate trichomes like those of the stems; peduncle 1.2-2.5 cm long; pedicels 0.8-1 cm long, ca. 0.5 mm in diameter at the base, ca. 1 mm in diameter at the apex, strongly tapering, spreading to somewhat deflexed at anthesis, sparsely to moderately sparsely pubescent with antrorse eglandular simple uniseriate trichomes like the rest of the inflorescence, articulated at the base; pedicel scars clustered at the tips of the inflorescence branches, ca. 0.5 mm apart. Buds ellipsoid to somewhat turbinate (widest in lower third), the corolla strongly exserted from the calyx tube before anthesis, the style sometimes exserted from the bud before anthesis. Flowers 5-merous, perfect. Calyx tube 1.5-2 mm long, conical, the lobes (0.5)1-2 mm long, deltate with lanceolate tips, the sinuses rounded, sparsely pubescent with antrorse eglandular trichomes like the pedicels. Corolla 1.2-2.2 cm in diameter, white, pale violet or white tinged with violet, sometimes changing colour through anthesis, with a brownish yellow to yellow-green central star edged with brownish purple, stellate, lobed halfway to the base, the lobes 5-8 mm long, 4-5 mm wide, deltate to triangular, spreading or slightly reflexed at anthesis, adaxially glabrous, abaxially densely pubescent with eglandular papillae and simple uniseriate trichomes to 0.2 mm long. Stamens equal; filament tube minute; free portion of the filaments 0.5-1 mm long, adaxially densely pubescent with tangled transparent simple uniseriate trichomes; anthers 4-5 mm long, 1-1.25 mm wide, ellipsoid, yellow, the abaxial surfaces occasionally papillate, poricidal at the tips, the pores lengthening to slits with age. Ovary conical, glabrous; style 7-10 mm long, pubescent along almost the entire length, more densely in the lower half with tangled transparent simple trichomes to 0.5 mm long; stigma capitate to clavate, bright green in live plants, the surface minutely papillose. Fruit a globose berry, 0.8-0.9 cm in diameter, green with tiny white spots (immature?), opaque, the pericarp surface thin, matte, glabrous; fruiting pedicels 0.8-1 cm long, ca. 0.75 mm in diameter at the base, ca. 1.5 mm in diameter at the apex, thickened but not woody, strongly deflexed with a distinct bend at the pedicel base; fruiting calyx not enlarged or accrescent, the lobes appressed to the surface of the berry. Seeds 10-30 per berry, 1.7-2 mm long, 1-1.5 mm wide, not markedly flattened, teardrop shaped with an apical hilum, pale tan, the surfaces minutely pitted, the testal cells sinuate in outline. Stone cells 4-9 per berry, 0.7-1.5 mm in diameter, 2 usually larger than the rest. Chromosome number: n=12 (Moscone 1992, as S. lorentzii Bitter var. montigenum C.V.Morton).
Distribution (Figure 9). Solanum tiinae is endemic to Argentina; it has been collected from the provinces of Jujuy, La Rioja, Salta and Tucumán, with most collections from the area around the type locality at El Infiernillo.
Ecology and habitat. Solanum tiinae grows among rocks and in open areas in prepuna habitats in the Andes (Fig. 7A), from 2400 to 4000 m elevation.
Etymology. Solanum tiinae is named in honour of our long-term collaborator and colleague Dr. Tiina Särkinen of the Royal Botanic Garden Edinburgh; she was the first to notice the uniqueness of these plants, giving them the field name "Solanum misterioso" while in the field in 2012.
Preliminary conservation status (IUCN 2019). AOO (76 km 2 -EN); EOO (41,143 km 2 -NT). Most collections of S. tiinae are from a very few commonly vis- Figure 9. Distribution of Solanum tiinae Barboza & S.Knapp. ited localities and the main road between Tafí del Valle and Amaicha del Valle in the province of Tucumán. Solanum tiinae is not found in protected areas, and based on the number of localities (ca. 5), the area of occupancy and the extent of occurrence, we assign a preliminary threat status of Vulnerable (VU B2a,biii). Where it occurs S. tiinae is not common or weedy, although it does grow in open areas.
Notes. It is surprising that S. tiinae has not been described previously, as the area from which the type and many other collections come is one of the most intensively collected Andean areas in Argentina. None of the collections we cite here were cited in Morton (1976). We have encountered specimens of S. tiinae identified as S. aloysiifolium (and its synonyms, see Barboza et al. 2013) and S. cochabambense. It is similar to those taxa in its forked inflorescence with a long peduncle, but differs from S. aloysiifolium in its larger, less deeply stellate purple or purplish cream (rather than white) corollas, and from S. cochabambense in its smaller habit and winged stems. The strongly antrorse pubescence of S. tiinae is distinctive and not found in either S. aloysiifolium or S. cochabambense. Solanum tiinae also resembles the highly variable species S. salicifolium, from which it can be distinguished by its shorter (1-2 mm versus 2.5-3 mm long) calyx lobes, the strongly antrorse pubescence (Fig. 7B), the strictly furcate (versus only occasionally once branched) inflorescences with more flowers (10-20 versus 4-10) (Fig. 7B, C) and the calyx lobes (Fig. 7F) that are tightly appressed to the berry (versus spreading and slightly recurved). These two taxa have been collected in the same habitat (e.g., Barboza et al. 3491,S. tiinae and Barboza et al. 3494,S. salicifolium from km 92 on the Amaicha del Valle to Tafí del Valle road) and can be easily distinguished in the field using corolla shape -those of S. salicifolium are deeply stellate with relatively narrow lobes, while those of S. tiinae are less deeply and more broadly lobed (Fig. 7E).
Additional specimens examined ( Artificial key to morelloid species occurring in Argentina *