Research Article |
Corresponding author: Tilo Henning ( henningtilo@web.de ) Academic editor: Sandy Knapp
© 2022 Claudia M. Martín, Christian A. Zanotti, Rafael Acuña-Castillo, Tilo Henning, Juan C. Catari, Maximilian Weigend.
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:
Martín CM, Zanotti CA, Acuña-Castillo R, Henning T, Catari JC, Weigend M (2022) Taxonomic revision of the peculiar genus Xylopodia (Loasaceae) with a new species from Argentina and Bolivia demonstrating an atypical trans-Andean disjunction. PhytoKeys 194: 47-62. https://doi.org/10.3897/phytokeys.194.77827
|
Loasaceae subfam. Loasoideae are a nearly exclusively American plant group with a center of diversity in Peru. Numerous new taxa have been described over the past decades; one of the most striking discoveries was that of the narrowly endemic Xylopodia with the single species Xylopodia klaprothioides in Peru, Dpto. Cajamarca in 1997. Surprisingly, field studies in the past years have resulted in the discovery of material clearly belonging to the same genus in both Bolivia and northern Argentina, approximately 1500 km SE of the next known population of Xylopodia in Contumazá, Peru. A closer examination shows that Argentinian and Bolivian material belongs to a single species, clearly different from Xylopodia klaprothioides. We here describe Xylopodia laurensis and the entire genus is revised. Both species are illustrated, all aspects of their biology and ecology are portrayed and their threat status is discussed.
Andes, Argentina, Bolivia, endemism, Loasoideae, taxonomy, Xylopodia
Loasaceae are a largely Neotropical family with a center of diversity in the Central Andes of Peru and neighboring Ecuador. This is particularly true for the most diverse subfamily Loasoideae (>200 spp.) and its most speciose genus, Nasa Weigend (>100 spp.,
Field studies were carried out in 2019 and 2021 in Chuquisaca, Bolivia and in 2021 in Jujuy, Argentina. Photographs of the plant habit and macro-morphological characters were taken in the field with a Canon EOS 7D. Morphological observations and measurements of the new species were obtained from living and dry specimens from Argentina and Bolivia. Micro-morphological characters were observed and photographed with a Leica EZ4 stereomicroscope. Argentinian and Bolivian specimens are deposited in SI and USZ respectively. The comparison with Peruvian X. klaprothioides was carried out using photographs and specimens from Bolivia, Argentina and Peru including the living type collection (Weigend et al. 97/450 – F, M, USM) of X. klaprothioides at Bonn University Botanic Gardens. Likewise, we studied previous X. klaprothioides collections, now deposited in B, F, HUT, M and USM (all made by MW, TH and their field companions since 1997). The listed herbarium acronyms follow the Index Herbariorum abbreviations (
Xylopodia klaprothioides A flower, lateral view, showing the lamellae (L) and nectar scales (NS) B flower, frontal view, showing the lamellae (L) C mature fruit with slightly opened apical valves D nectar scale in dorsal (left) and ventral (right) views E nectar scale complex with one scale removed to reveal the internal monomorphic staminodes (MS) and the inconspicuous filament flanges (FF) F sterile branches with mature leaves G xylopodium of a 2-year-old plant H seed. All from Weigend et al. 97/450.
Xylopodia klaprothioides Weigend.
Shrubs with erect branches from horizontal xylopodia; aerial vegetative organs densely hairy, with scabrid and glochidiate trichomes. Leaves simple, opposite, estipulate, petiolate; lamina with 1–3 lobes on each side, margin serrate. Inflorescences terminal dichasia, each flower with 2 bracts. Flowers tetramerous, deflexed. Sepals triangular. Petals cymbiform, greenish-white to green, aestivation valvate. Nectar scales 4, antesepalous, white and green or green and yellow, formed by 4–6 fused staminodes. Free staminodes 4–5, opposite and internal relative to the nectar scale. Fertile stamens arranged in 4 antepetalous groups. Ovary semisuperior with 4 placentae. Fruits semisuperior capsules, subglobose, straight, opening with 4 apical valves. Seeds narrowly ovoidal, testa papillose-reticulate. 2N = 24.
This name makes reference to the well-developed xylopodia (ligneous rhizomes) found in the type species of the genus.
So far, Xylopodia is known in a few widely separated, disjunct localities in strongly seasonal habitats of the tropical Andes in NW Peru, NW and S Bolivia and NW Argentina, from low (850–900 m) to moderate (2,900 m) elevations.
Plants of this genus can be recognized from all other Loasaceae by the diagnostic combination of the presence of underground xylopodia, opposite, lobed leaves, tetramerous flowers, petals with longitudinal lamellae and well developed nectar scales.
Peru. Cajamarca: Prov. Contumazá: Road from Contumazá to Chilete, first roadbend after highest point pass, 2900 m, (07°19'48"S, 078°48'38.5"W) 5. Feb. - 2. Abr. 1997, M. Weigend, N. Dostert & K. Drießle 97/450 (holotype: M! mounted on two sheets, barcodes: M-0274954 & M-0274955; isotypes: F!, USM!).
Shrub with erect or leaning shoots up to ca. 300 cm tall from a horizontal xylopodium (= ligneous rhizome), up to 30 × 5 cm, with several aerial branches arising from it; aerial vegetative organs densely hairy, with white scabrid and glochidiate trichomes, ca. 1 mm long. Leaves opposite, 8–20 × 65–15 cm, lamina with 1–3 lobes on each side, margin serrate, apices acute to rounded, base cuneate, petiole 1–3 cm long. Inflorescences terminal dichasia; peduncle ca. 7–20 cm long; basal bracts 1.5 × 0.5 cm, 3-lobed, margin denticulate, base cuneate; distal bracts 0.5 × 0.1 cm, lanceolate, subentire. Flowers tetramerous, pedicels 2–4 mm long, deflexed. Sepals broadly triangular, ca. 3 × 2 mm, margins entire, erect in bud, spreading during anthesis, and pubescent on both sides, pubescence similar to that of vegetative organs. Petals 10–15 × 3–5 mm, pale to deep green, unguiculate, with a short claw (< 1/4 of petal length), cucullate in the distal half, with two membranous longitudinal lamellae with densely ciliate margin, aestivation valvate, margin with a tooth on each side near the base where the limb starts, with scabrid-glochidiate trichomes abaxially, adaxially glabrous. Nectar scales 4, antesepalous, 3.5–4 × 2.5–3 mm, cucullate, formed by 5–6 fused staminodes, mostly green, pubescent in lower half, virtually uniform in color, apex yellowish green, slightly recurved. Free staminodes 4–5 per scale, opposite and internal to it, monomorphic, lower halves densely pubescent, green, ca. 4 mm long, with an inconspicuous, pubescent, knee-like filament flange below the middle, apex filiform, twisted randomly or reflexed. Fertile stamens arranged in 4 antepetalous groups of ca. 7–15 per petal, free, filament ca. 6–8 mm long, anthers white, with two ovate thecae. Ovary half-superior, broadly ovate to conical, placentae 4; style to 7 mm long, lower half pubescent, stigma with four ribs tapering towards the apex. Fruits subglobose capsules, with a conical apex, opening with 4 apical valves. Seeds numerous, narrowly ovoidal, testa papillose-reticulate up to ca. 2 × 0.4 mm.
Xylopodia laurensis. A flower, lateral view, showing the nectar scales (NS) B flower, showing the lamellae (L) C mature fruit, showing the four apical valves D details of the central staminode (left), showing the well-developed filament flange (FF), lateral staminode (right) E staminodes within the nectar scale, showing the lateral staminodes (LS) and the central ones (CS) F plant G xylopodium. All from Martín 2887, except C (Catari 2510).
The species name refers to the clear affinity of this taxon to the genus Klaprothia Kunth.
Xylopodia klaprothioides is restricted to a small area of the Pacific slope of the Cordillera Occidental in Andean NW Peru. It is a very narrowly endemic species, known from only two localities some 8 km apart (in a direct line) in Dpto. Cajamarca Prov. Contumazá, at elevations from ca. 2,500–3,000 m (Fig.
Xylopodia klaprothioides occurs in seasonally dry Andean scrub habitats, mostly around hedges and gullies, often on rocky soil dominated by xeric adapted shrubs, small trees and other vegetation including Cylindropuntia (Engelm.) F.M. Knuth and terrestrial bromeliads (Fig.
Flowering and fruiting of this species have been recorded at the very end of the rainy season and the start of the dry season in May and June; thus most plants are leafless during the peak of the flowering period.
Perú: Dpto. Cajamarca, Prov. Contumazá, Road from Contumazá to Chilete. First road bend after highest point of pass, 2900 m, (07°19'48"S, 078°48'38.5"W) 17. Jun. 1998, M. Weigend et al. 98/536 (F, HUT, M, USM); same locality, 09. May 2003, M. Weigend et al. 7601 (B, F, HUT, M, USM); Dpto Cajamarca, Prov. Contumazá, road Contumazá to Cascas, after tunnel, ca. 2400–2600 m, (07°24'14"S, 078°47'53"W) 10. May 2003, M. Weigend et al. 7617 (B, F, HUT, M, USM).
See Xylopodia laurensis.
Xylopodia klaprothioides seems to be restricted to only a few populations near Contumazá in northern Peru and has been considered as globally endangered (
Xylopodia laurensis is closely related to Xylopodia klaprothioides Weigend, but the former is readily distinguishable by the sepals reflexed in anthesis, petals greenish white with a long claw (ca. 1/3 of petal length); back of nectar scale white, apically striped green and yellowish; free staminodes are dimorphic, ligulate, the central pair with a conspicuous, papillose, scale-like filament flange below the middle.
Argentina: Prov. Jujuy, Dpto. San Pedro, San Juan de Dios, Estancia Las Lauras, camino al “Chorro”, a tres metros del arroyo Chico, 24°33'49.8"S, 64°39'05.8"W, 925 m, 22 Aug 2021, C. M. Martín 2887 (holotype SI)
Shrub with erect shoots up to 130 cm tall from a short horizontal xylopodium (= ligneous rhizome), ca. 5 × 3 cm, sometimes divided into 3–4 branches distally; aerial vegetative organs densely hairy, with white scabrid and glochidiate trichomes, ca. 0.5 mm long. Leaves opposite, 14–22 × 13–9 cm, lamina with 1–2 lobes in each side, margin serrate, apices acute to rounded, base cuneate, petiole 1.5–3 cm long. Inflorescences terminal dichasia; peduncle ca. 6 cm long; basal bracts 3 × 2 cm, 3-lobed, margin denticulate, base cuneate; distal bracts 0.8–1.8 × 0.3–0.5 cm, lanceolate, margin entire. Flowers tetramerous, pedicels 4–6 mm long, deflexed. Sepals broadly triangular, ca. 5 × 3 mm, margins entire, erect in bud, reflexed during anthesis, and pubescent on both sides, pubescence similar to that of vegetative organ. Petals 7 ×3 mm, greenish white, unguiculate, with a long claw (ca. 1/3 of petal length), cucullate in the distal half, with two membranous longitudinal lamellae with densely ciliate margin, aestivation valvate, margin with a tooth on each side near the middle, where the limb starts, dorsal veins three, with scabrid-glochidiate trichomes abaxially, mostly glabrous adaxially. Nectar scales 4, antesepalous, 4 × 3 mm, cucullate, formed apparently by 6 fused staminodes, mostly white, pubescent in lower half, striped green and yellowish in distal third, apex green, slightly recurved. Free staminodes 4 per scale, opposite and internal to it, dimorphic, their lower halves partly fused, densely pubescent, with laciniate margins, central staminodes green, 4 mm long, with a conspicuous, papillose, scale-like filament flange below the middle, apex reflexed, spathulate the lateral ones yellowish-white, 5.3 mm long, with a filiform apex. Fertile stamens arranged in 4 antepetalous groups of ca. 7 per petal, free, filament ca. 6 mm long, base pubescent, anthers white, with two obovate thecae. Ovary half-superior, broadly ovate to conical; style to 5 mm long, lower half pubescent, stigma with four ribs tapering towards the apex. Fruits subglobose capsules, with a conical, slightly asymmetrical apex, opening with 4 apical valves.
The name of the species refers to the locality of the type collection in Argentina (Estancia Las Lauras, Jujuy, Argentina).
Xylopodia laurensis grows on the eastern slope of the Andes from Bolivia (Dptos. La Paz and Chuquisaca) to northern Argentina (Prov. Jujuy) at elevations from 850–900 m asl (Jujuy and Chuquisaca) to 2360 m asl (La Paz) (Fig.
Xylopodia laurensis occurs in the understory of seasonally dry (scrub) forest in shallow rocky soil and in soil pockets on rock-outcrops across its range (Fig.
The flowering and fruiting of this species have been recorded in the dry season, from late August to mid-September in Jujuy and from April to August in Chuquisaca. In Chuquisaca, plants lose their foliage by August and produce new leaves when the rainy season starts in October to November.
Bolivia: Dpto. Chuquisaca. Prov. Luis Calvo, Municipio Villa Vaca Guzmán, A 5.5 km al Norte de la Comunidad Ivoca y 3 km al Este de la Quebrada Angoba. Estancia del Sr. Jhony Labras. 850 m, 11. Sep. 2019, J.C. Catari & Z. Pérez 2501 (USZ); same locality, 17. Oct. 2021, J.C. Catari 2510 (USZ). Photographs examined: Bolivia: Dpto. La Paz, Prov. Larecaja, Municipio Sorata, Cueva de San Pedro, s.d., autor: A.F. Fuentes (available in http://legacy.tropicos.org/Image/100494035)
Xylopodia laurensis is a close ally of Xylopodia klaprothioides. Vegetatively, it mainly differs in the much smaller woody rhizome, which easily reaches 30 cm and more in length in mature X. klaprothioides. Aerial stem and leaf morphology appear to be similar, although the leaves of X. klaprothioides are usually smaller and not as deeply lobed (Figs
There is a disjunction of ca. 1500 km between the populations of X. klaprothioides in northern Peru and X. laurensis in Bolivia (Fig.
False-color BSE-image of the trichome cover of the leaves of X. klaprothioides. Mineralized areas are highlighted in red, non-mineralized areas in green A abaxial surface densely covered with unicellular, glochidiate and a few scabrid trichomes B adaxial surface densely set with scabrid hairs. (Credit: H.J. Ensikat, Bonn).
As mentioned above, the actual abundance of Xylopodia is very difficult to assess, both globally and locally. Both species share a very nondescript appearance, even during flowering and especially after the shedding of leaves during the dry season. Hence, there are only very few collections. However, unlike the type species, X. laurensis is evidently more widespread and likely present in suitable habitats in between the known populations (Fig.
1 | Sepals reflexed at anthesis, petals greenish white, claw long (ca. 1/3 of length of petals); back of nectar scale white, apically striped green and yellowish, apex green; free staminodes dimorphic, with their lower halves partly fused, the central pair abruptly expanded basally into unusually large, scale-like,abaxial filament flanges ca. ½ from base | X. laurensis |
– | Sepals spreading at anthesis, petals pale to deep green, claw short (< 1/4 of length of petals); back of nectar scale uniformly green, apex yellowish-green; free staminodes monomorphic, free, with small and inconspicuous “knee shaped” abaxial filament flanges ca. ¼ from base | X. klaprothioides |
We would like to thank the staff of the herbaria listed above, in particular Eric F. Rodríguez-Rodríguez (HUT) and Sarah Bollendorf (B) for helping us with locating additional collections of Xylopodia. CM thanks Laura and Ole Mustad, great friends, owners of Estancia Las Lauras, who hosted her at their home during field expeditions and collaborated with the logistics. Thanks are due to Alfredo F. Fuentes and Peter Jørgensen for making photos of the first X. laurensis sighting publicly available via tropicos (www.tropicos.org) and giving permission to use them. The efforts to collect the new species at this locality by Belén Escobari Vargas (La Paz & Berlin) are, although unfortunately unsuccessful, gratefully acknowledged. CM and CZ thank Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina (CONICET) for the provided financial support. RA thanks Diego Bogarín (JBL) for his feedback regarding plate layout and appearance. JC thanks to the staff of REPSOL E&P Bolivia S.A. for their support in the field stage in Bolivia. TH tanks Julian Ahlborn for help with the preparation of the distribution map. Thanks are due to Rainer W. Bussmann, Daniel Montesinos-Tubée, Lucas Majure and Sandra Knapp whose valuable comments helped to improve an earlier version of the manuscript.