Scyphostelma gracile H. A. Keller, Meve & Liede, 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 : 91-94

3. Scyphostelma gracile H. A. Keller, Meve & Liede , sp. nov. – Fig. 1 , 3 , 6 , 7 .

Holotype: Bolivia, Cochabamba, Chapare , 6 km below Sehuencas, roadsides/gullies , 17°29'S, 65°15'W, 2200 m, 26 Dec 1995, J. R. I. Wood 10297 ( K 62678! ; isotype: UBT!).

Diagnosis — Similar to Scyphostelma harlingii (Morillo) Liede & Meve but with gynostegium sessile (vs seated on barrel-shaped filament tube [stipe] in S. harlingii ); corona basally fused to form a cup-like structure (vs basally connected only by a basal fringe in S. harlingii ), corona lobes suberect with a vertical wave (vs spreading and bent together in S. harlingii ) and anthers nearly as long as wide (vs c. 1/2 as long as wide in S. harlingii ).

Morphological description — Twining plants, 1.5–6 m tall; stems reddish, with uniseriate, scattered, retrorse adpressed trichomes; internodes of long shoots 60–76 × 1–1.2 mm, internodes of short shoots 15–58 × c. 0.7 mm. Leaves: petiole 4–10 mm long, reddish, with pubescence similar to that of shoots; lamina ovate-lanceolate, 16–42 × 5–12 mm, base rounded, truncate to subcordate, apex acute to acuminate; abaxial surface with short trichomes on veins only, adaxial surface with sparse appressed trichomes, with 2 conic colleters at base; venation brochidodromous with 4–8 pairs of secondary veins. Inflorescences extra-axillary, alternate, with 3–9 flowers per cyme, 2 or 3 in simultaneous anthesis; peduncle filiform, 25–40 mm long, with pubescence like that of stems; bracts 2–3 × 0.8–1 mm. Flowers: pedicel filiform, 12–16 × 0.2–0.35 mm, with scattered, appressed trichomes; calyx lobes ovate, 1.5–2 × 0.9–1.1 mm, abaxially with scattered trichomes, margin ciliate, apex acute; corolla pale purple, rotate, tube c. 1.8 mm in diam., free lobes triangular-lanceolate, 4.5–5 × c. 2 mm, spreading, abaxially glabrous, adaxially densely covered with short, verrucose trichomes (becoming longer toward tip). Gynostegial corona green in vivo to yellowish in sicco, bowl-shaped, c. 1 × 3 mm, fused for basal 1/3, free staminal corona lobes rectangular with rounded shoulders, 0.2–0.8 × 1.5–1.8 mm, suberect, membranous, with a vertical wave, closely and firmly attached just to gynostegium base; gynostegium sessile, 1.7–1.9 × 1.2–1.3 mm; anthers subrectangular, c. 1.2 × 1 mm, anther appendages suborbicular, c. 0.5 × 1 mm, translucent, adpressed to style head, guide rails broadly protruding, 0.9–1.1 mm long; style head umbonate c. 1.2 mm in diam. Pollinarium: corpusculum ovoid, 0.22–0.28 × 0.11–0.12 mm; caudicles sigmoid, 0.2–0.23 mm long; pollinia oblong-subreniform, 0.45–0.5 × 0.20–0.24 mm, subapically attached to caudicles, apex rounded. Follicles and seeds not seen.

Phenology — Found with flowers from November to December. Flowers are visited by small diptera ( Fig. 7E ).

Distribution and ecology — Scyphostelma gracile is known at present from two Andean localities, both in Cochabamba, Bolivia ( Fig. 3 ). The species inhabits moist cloud forests in deep valleys with steep slopes and high rainfall. Scattered plants on the edge of the forest and scrubland at altitudes between 2200–2500 m.

Etymology — The specific epithet refers to its graceful inflorescences with filiform peduncles and pedicels.

Additional specimens (paratypes) — BOLIVIA: Cochabamba, Prov. Chapare, Parque Nacional Carrasco , 17°27'43.76''S, 65°16'26.67''W, 2325 m, 16 Jan 2021, M. H. Porcel & al. 302 ( BOLV, CTES) .

Figures

Fig. 1. Phylogenetic reconstruction of Orthosiinae based on six cpDNA markers (see text), highlighting the position of the Scyphostelma harlingii clade. The remaining genera of Orthosiinae, Jobinia, Monsanima and Orthosia, with a sampling identical to Liede- Schumann & Meve (2013), are summarized by triangles, and so is the remainder of Scyphostelma. Numbers on branches indicate Bootstrap percentages / posterior probabilities. The root of the tree is that of Liede-Schumann & Meve (2013).

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. 6. Scyphostelma gracile – A: stem node with two leaves and inflorescence; B: flower, two petals removed; C: gynostegium with corona; D: details of guide rails (one in frontal, one in lateral view), with area of attachment of the corona (cross-hatched); E: pollinarium. – A–E from the isotype, J. R. I. Wood 10297 (UBT). – Drawn by U. Meve.

Fig. 7. Scyphostelma gracile – A: floriferous branches; B: inflorescences; C: leaves; D: venation; E: flower with diptera. F: flower detail showing the gynostegium. – A–F from M. H. Porcel & al. 302 (CTES). – Scale bars: A = 5 cm; B = 1 cm; C, D, E = 5 mm; F = 1 mm. – Photographs by J. A. Balderrama-Torrico & M. H. Porcel.