Scyphostelma solomonii Meve & Y. M. Pineda, 2023

Pineda, Yam M., Keller, Héctor A., Balderrama-Torrico, José A., Meve, Ulrich, Nürk, Nicolai M. & Liede-Schumann, Sigrid, 2023, Phylogenetics in Scyphostelma (Apocynaceae: Orthosiinae) and description of new species, Willdenowia 53, pp. 83-112 : 96

6. Scyphostelma solomonii Meve & Y. M. Pineda , sp. nov. – Fig. 3 , 10 .

Holotype: Bolivia, La Paz , Prov. Murillo, 20.8 km al norte de La Cumbre del valle del Río Zongo, 16°09'S, 68°07'W, 3200 m, 28 Feb 1987, J. C. Solomon 16120 ( MO- 3147137! ; isotype: K!).

Diagnosis — Similar to Scyphostelma bolivianum Y. M. Pineda, Liede & Meve (this paper) but with leaves linear-lanceolate, to 1 cm long (vs ovate-lanceolate, to 4 cm long in S. bolivianum ), corolla lobes adaxially pubescent (vs glabrous in S. bolivianum ), gynostegium as long as wide (vs wider than long in S. bolivianum ), corona lobes deltate, channelled above (vs rounded rectangular and plain in S. bolivianum ) and nectarial orifices present below each guide rail (vs no such orifices present in S. bolivianum ).

Morphological description — Twining plants; stems bright green, glabrous or nearly so, internodes of long shoots 100–120 × c. 1.5 mm, internodes of short shoots 15–43 × c. 1 mm. Leaves reduced to scales, shortly petiolate; lamina linear-lanceolate, 4–10 × c. 1 mm, glabrous. Inflorescences subaxillary, with 2–5 flowers per cyme, most in simultaneous anthesis; peduncle (1.5–)10–13 × c. 0.5 mm; bracts ovate, c. 0.8 × 0.2–0.4 mm, glabrous. Flowers: pedicel filiform, 10–15 × c. 0.3 mm, glabrous; calyx purplish, lobes narrowly deltate, c. 2.5 × 1 mm, abaxially with scattered trichomes, margin ciliate; corolla rotate, creamish reddish, 10–14 mm in diam., tube c. 0.2 mm long, free lobes oblong-elliptic, 4.2–5 × 1.8–2.2 mm, spreading, abaxially glabrous, adaxially pubescent, more so apically, trichomes 0.05–0.1 mm long, left side margin and base glabrous. Gynostegial corona creamish, c. 4 mm in diam., shallowly cup-shaped, only very basally fused, free corona lobes suberect (in sicco), deltate, adaxially channelled and apically pointed and notched (retuse), 2–2.3 × 1.5–2 mm; gynostegium stipitate, 2.8–3.7 × 3–4 mm, stipe c. 0.7 mm long; anthers narrowly trapezoidal, c. 2.5 × 1.75 mm, fertile part of anthers c. 1/2 as long as guide rails, abaxially almost flat, anther appendages broadly deltate, c. 0.7 × 0.8 mm, suberect, translucent, guide rails straight, slightly protruding, to 2.7 mm long; style head flattened, c. 1.5 mm in diam., constricted below a salver-shaped apex c. 0.5 mm in diam. Pollinarium: corpusculum broadly obovoid, 0.33–0.4 × 0.24–0.25 mm; caudicles flattened bone-shaped, 0.11–0.17 mm long, spreading; pollinia flattened ellipsoid, 0.40–0.5 × 0.20–0.26 mm, subapically attached to caudicles. Follicles solitary, drooping, reddish brown, straight fusiform, long beaked, 110–120 × 0.7–0.8 mm, glabrous; seeds not seen.

Phenology — The single gathering documented was found flowering and fruiting in February.

Distribution and ecology — Scyphostelma solomonii is known from only one locality in the Bolivian Andes at around 3200 m altitude. It was recorded in dense, lowgrowing (3–5 m tall) cloud forest, together with species of Barnadesia Mutis ex L. f., Chusquea Kunth , Myrsine L. and Solanum L.

Etymology — The specific epithet refers to the collector of the type specimen, James C. Solomon, MO senior botanist, collector and collaborator (for Cactaceae and Vitaceae ) in the “Flora of Bolivia ” project.

Remarks — Only three narrow leaves, better described as leaf scales, were found to be present in the holotype. In contrast to Orthosia , where reduced foliage is regularly observed, the new species represents the first Scyphostelma with foliage so strongly reduced in size and number. The large, rotate flowers seated on filiform pedicels and the large and solid pollinaria immediately mark S. solomonii as a member of the S. harlingii group. These features are particularly reminiscent of S. bolivianum . However, the flowers are larger and the corolla pubescent in S. solomonii (vs glabrous in S. bolivianum ); above all, gynostegial and coronal structures are so different in the two taxa that a treatment within a single species is impossible. The staminal corona is deltate, adaxially channelled and apically pointed and notched (retuse) in S. solomonii , whereas those of S. bolivianum are rounded rectangular, flat and plain. Moreover, the gynostegium is as long as wide in S. solomonii , the anther wings (guide rails) c. 2 mm long, straight and slightly protruding, whereas in S. bolivianum the gynostegium is wider than long, with guide rails c. 1.3 mm long, slightly convex and curved inward. Below each guide rail, deeply sunken in the filament tube, S. solomonii has a distinct nectarial orifice, which is absent in S. bolivianum . The massive and stout pollinaria of S. solomonii are remarkable ( Fig. 10E ); no other species in Scyphostelma has larger pollinaria. Ripe follicles are rarely documented on herbarium specimens, especially within the S. harlingii group. The holotype of S. solomonii represents a lucky exception, because it possesses solitary follicles that are drooping, fusiform and exceptionally large (to 12 cm long). These fruits are more than twice as long as those typically found in Scyphostelma (cf. Fig. 14A ).

Figures

Fig. 3. Distribution map of Scyphostelma bolivianum (diamonds), S. erikseniae (circles), S. gra- cile (stars), S. harlingii (upright triangles), S. rotorum (square) and S. solomonii (inverted trian- gle). – Map created in QGIS (QGIS Development Team 2009).

Fig. 10. Scyphostelma solomonii – A: flowering branch; B: leaf; C: flower; D: gynostegium; E: pollinarium; F: follicle. – A, C–E from the isotype, J. C. Solomon 16120 (K); B, F from the holotype, J. C. Solomon 16120 (MO). – Drawn by U. Meve.

Fig. 14. Scyphostelma unguiculatum – A: branch with inflorescences and twin follicles; B: flower, two corolla lobes removed; C: gynostegium and corona; D 1: pollinarium, one pollinium removed; D 2: pollinarium; E: style head. – A, B, E from S. Liede & J. Conrad 3140 (UBT); C, D1 from H. Ruiz & J. A. Pavón 5/80 (MA814543); D2 from J. R. I.Wood 10086 (LPB). – A, B, E drawn by J. Conrad; C, D drawn by U. Meve.