Otostylis alba (Ridl.) Summerhayes (1951: 293)

Thiago E. C. Meneguzzo, José F. A. Baumgratz & Cássio Van Den Berg, 2015, Taxonomic studies in the Aganisia complex (Orchidaceae, Zygopetalinae), Phytotaxa 238 (1), pp. 1-39 : 22-24

4.1. Otostylis alba (Ridl.) Summerhayes (1951: 293) .

Aganisia alba Ridl. in im Thurn (1886: 204). Zygopetalum venustum Ridl. in Oliver (1887: 283), nom. illeg. Aganisia venusta (Ridl.) Rolfe ex Hook. f. in Hooker (1892: sub t. 7270), nom. illeg. Warreella venusta (Ridl.) Schlechter (1914: 425) , nom. illeg. Koellensteinia alba (Ridl.) Schlechter (1915: 32) . Otostylis venusta (Ridl.) Schlechter (1918b: 41) , nom. illeg. Type: — VENEZUELA. Bolívar: Roraima Mount, River Kukenán [“Kookenaam”], August 1884, im Thurn 360 (lectotype, designated by Romero-González & Meneguzzo (2012: 236), K 589020!, isolectotypes BR 13052539 fragment!, K 588991!). Fig. 7 A, 8A–C

Etymology:— From Latin, albus, whitish, in relation to flower colour.

Terrestrial herb with pseudobulbs 1.5–2.0 × 1.0–1.5 cm, fusiform. Leaves 2–3; petiole 7.0–13.5 cm long; blade (15.0–)17.0–52.0 × (1.2–)3.5–4.5 cm, lanceolate, rarely linear. Inflorescences 61–77 cm long, (7–)12–18 flowered, racemose; peduncle 56–65 cm long; rachis 5.5–13 cm long. Pedicellate ovary 0.8–1.5 cm long; sepals and petals white, lip white with yellow disc. Sepals 1.1–1.5 × 0.6–0.8 cm, elliptic, base cuneate, dorsal with acute apex, the laterals oblique with an obtuse apex. Petals 1.0–1.4 × 0.5–0.8 cm, slightly oblique, elliptic to narrowly elliptic, base cuneate, apex obtuse-apiculate. Lip with lateral lobes 0.1–0.2 × 0.1–0.2 cm, deltoid; midlobe 0.8–1.0 × 0.8–1.1 cm, elliptic, apex truncate to rounded, proximal part constricted, callus hippocrepiform with an emarginate apex composed of digiform processes. Column 0.6 × 0.3 cm, ½ lip length, semi-clavate. Capsules not seen.

Material examined:— GUYANA. S.loc., s.d., im Thurn 126 (K). Barima-Waini: Waini River, s.d., Hohenkerk 619 (K). Cuyuni-Mazaruni: Maipuri Falls, Karowrieng River, 16 December 1989, Gillespie & Smart 2702 (U). Upper Mazaruni, 11 January 1985, Renz 14076 (RENZ). Potaro-Siparuni: Mount Ayanganna, 5 February 1955, Maguire et al. 40569 (K). VENEZUELA. Amazonas: Antures, Morichal, 30 June 1988, Carnevali F.C. et al. 2663 (VEN).

Distribution:— Guiana and Venezuela. TDWG code: 82 GUY-OO VEN-OO.

Diagnostic characters:— Differs from O. brachystalix by its lanceolate leaves with a rarely linear lip callus composed of digiform processes and the apex emarginate, and column with half lip length.

Note:— An extensive account for Otostylis alba was included in Romero-González & Meneguzzo (2012).

Figures

FIGURE 7. Distribution of Otostylis. A. Otostylis alba. B. Otostylis brachystalix.

FIGURE 8. Otostylis alba. A. Habit. B. Flower. C. Dissected perianth. Otostylis brachystalix. D. Flower. E. Dissected perianth. A–C. Hohenkerk 619 (K). D–E. Jansen-Jacobs 1875 (K). By Maria Alice Rezende.