Disperis latigaleata H. Perrier

Croix, Isobyl la, Bosser, Jean & Cribb, Phillip J., 2002, The genus Disperis (Orchidaceae) in Madagascar, the Comores, the Mascarenes and the Seychelles, Adansonia (3) 24 (1), pp. 55-87 : 62-64

5. Disperis latigaleata H. Perrier

Not. Syst. (Paris) 8: 36 (1939); in Humbert H. (ed.), Fl. Madag., 49 e fam., Orchidées 1: 183 (1939); Du Puy et al., Orch. Madag.: 135 (1999). — Type: Humbert 13440, Madagascar, Mt. Itrafanaomby (Ankazondrano) (lecto-, P, chosen here, photo K!) .

Slender terrestrial or epiphytic herb (10-) 14- 21 cm tall. Leaves 2, opposite, borne on the upper half of the stem, 1.6-6 × 1-2 cm, lanceolate or ovate, acute, rounded at the base, pale green, one of the pair much larger than the other. Inflorescence 1-4-flowered; bracts 6-12 × 2-7 mm. Flowers violet or white tinged with pink; pedicel and ovary 8-13 mm long. Dorsal sepal 6-8 × 1 mm, linear; lateral sepals free to base or a little united, 6-10 × 5-7 mm, semiorbicular, apparently lacking a spur or pouch. Petals 5-7 × 4.5-5 mm, very concave, adnate to the dorsal sepal and forming a broad hood with it. Lip with a claw c. 4 mm long, the basal half joined to the column, bearing a 3-lobed appendage in front; mid-lobe pendent, pubescent on top except for the subspathulate apex which is glabrous, glabrous below; side lobes slightly shorter than the mid-lobe, cylindrical, slightly thickened and rounded at the tips, slightly curved, pubescent on both surfaces. Rostellum arms c. 1.3 mm long, spathulate. — Fig. 4.

DISTRIBUTION. — Madagascar; endemic.

HABITAT. — Growing in shade, terrestrial or on moss-covered boulders, on river sides, in forest on laterite and gneiss; epiphytic; 600-1950 m.

MATERIAL STUDIED. — MADAGASCAR: Humbert 13440, Mt. Itrafanaomby (Ankazondrano) and its SW flanks (High Mandrare), 1600-1950 m, Dec. 1933 ( P!) ; Kotozafy & Randriamanantena 252, Ranomafana National Park, Parcelle 2, Maranony, S of Ambomiera , 880-1100 m, 18-20 Sep. 1993 ( K!, MO!, P!) ; Rakoto, Randriamantena & Rafamontanantsoa in S. Malcomber et al. 1565, Fianarantsoa Prov., Ranomafana National Park , Parcelle 1, SW of Miazanomy, 600 m, 22-23 Sep. 1992 ( K!, MO!, P!) .

This species resembles D. oppositifolia , but differs in having a wider hood, in the lateral sepals being free to the base and lacking a spur, in the mid-lobe of the lip appendage being as long as or slightly longer than the side lobes, and in the spathulate lobes of the rostellum. The markedly uneven size of the leaves also seems to be characteristic (all species with opposite leaves tend to have one slightly larger than the other) but with so few specimens available, it is not possible to be sure that this is consistent.

Figures

Fig. 4. — Disperis latigaleata: A, flowering plant; B, dorsal sepal; C, lateral sepal; D, petal; E, column and lip, front view; F, column and lip, back view; G, lip. (Humbert 13440, P).