Didymoplexis recurvata P.J.Cribb , Nusb. & L.Gaut. Candollea 68(1): 44. 2013 [12 Jul 2013]
Description:
Holomycotrophic herb up to 10 cm tall, growing from a subterranean elongated blackish tuberous rhizome. Leaves scale like, very small. Inflorescence erect, racemose, laxly up to 6-flowered, the flowers opening one at a time and successively; peduncle slender, erect, bearing a small ovate bract below inflorescence, white; rachis terete, slender; pedicel with longitudinal ridges; bracts ovate, acute, 1.5-2 mm long. Flowers with white sepals and petals and a white to rose-pink lip with a yellow callus, the column buff flushed. Dorsal sepal erect, lanceolate, subacute, 7-8 x 4-5 mm; lateral sepals adnate in basal third, ovate, rounded to subacute, 7-8 x 4-5 mm. Petals oblanceolate, acute, 7-8 x 5-7.5 mm, adnate in basal third to the sepals. Lip shortly narrowly clawed at base, very broadly obovate-spatulate, emarginate, 3.5-4 x 5-6 mm, slightly decurved at apex; callus on claw erect, dilated and 3-lobed at tip. Column 3.5-5 mm long, slender at base, strongly winged at apex, the wings dependent, recurved, rounded at tip, 1 mm long. Fruit unknown.
Etymology:
The specific epithet refers to the column with recurved apical arms bilobed at the tips.
Habitat and ecology:
Didymoplexis recurvata was recorded in evergreen montane forest on metamorphic rock; at 985 m. This terrestrial herb occurs in forests with canopies reaching 11 to 15 m, emergent trees reaching 21 to 24 m and with a second aborescent stratum at 8 to 10 m, with two woody strata at 5 to 7m and at 1 to 2 m high, and with a no herbaceous strata, the soil densely covered with dry leaves of trees. recurvata in Loky-Manambato vegetation surveys include, in decreasing abundance: Marojejya insignis Humbert, Ravenea sambiranensis Jum. & H. Perrier, Dypsis nodifera Mart., Wein-mannia decora Tul., Syzygium condensatum (Baker) Labat & G. E. Schatz, Plagioscyphus aff. louvelii Danguy & Choux and Blechnum attenuatum (Sw.) Mett. var. attenuatum.
Flowering time:
December.
Notes:
Didymoplexis recurvata is clearly distinguished from the other African and Malagasy species of Didymoplexis known in flower by its column which has short recurved apical arms that are bilobed at the tips, as well as by its lip which lacks rows of warts but has at the base a tall apically trilobed entire callus and by its sepals and petals that are adnate in the basal third.
Distribution:
The species is only known from the Binara forests in the Loky-Manambato (Daraina) region, in Antsiranana Province in North-East Madagascar. Only 1520 individuals were observed in one population in the Loky-Manambato region among the 54,000 plant occurrences recorded during the Loky-Manambato vegetation study.