Didymoplexiella, Garay, 1954

Nuraliev, Maxim S., Averyanov, Leonid V., Nguyen, Khang Sinh, Nguyen, Cuong Huu, Le, Tuan Anh, Maisak, Tatiana V., Lyskov, Dmitry F., Kuznetsov, Andrey N. & Kuznetsova, Svetlana P., 2023, The mycoheterotrophic genus Didymoplexiella (Orchidaceae) in Cambodia, Laos and Vietnam, Phytotaxa 620 (1), pp. 18-32 : 19

Key to the species of Didymoplexiella in Cambodia, Laos and Vietnam

The key is partly based on Rojchana-umpawan et al. (2014) and Suddee (2014).

Didymoplexiella trichechus (J.J. Smith 1920: 19) Garay (1954: 34) is included provisionally, given its occurrence in the neighboring Thailand, and the high probability of confusion of this species with some of the species inhabiting Eastern Indochina. Morphological characters of D. trichechus are taken from Smith (1920), Rojchana-umpawan et al. (2014), Suddee (2014), Tsukaya et al. (2014) and Kumar et al. (2020). This species was described from Sumatra and is also known from Borneo and Peninsular Thailand.

1. Labellum unlobed or with indistinct side lobes that are much wider than long........................................ Didymoplexiella siamensis

- Labellum with distinct side lobes.......................................................................................................................................................2

2. Side lobes of labellum usually longer than wide (oblong rectangular), forward directed (at sharp angle with median lobe in a flattened labellum) and distinctly projecting beyond median lobe (i.e. exceeding median lobe along the main flower axis); apical margin of side lobes of labellum denticulate.............................................................................................. Didymoplexiella laosensis

- Side lobes of labellum usually ± as long as wide (often roundish to subquadrate), forward directed or spreading aside (at sharp or right angle with median lobe in a flattened labellum), projecting or not projecting beyond median lobe; apical margin of side lobes of labellum entire or denticulate.........................................................................................................................................................3

3. Sepals and petals usually olive to brown with red stripes; side lobes of labellum forward directed (and projecting beyond median lobe) or spreading aside; apical margin of side lobes of labellum entire ....................................................... Didymoplexiella ornata

- Sepals and petals usually dark brownish (often without red markings or tint); side lobes of labellum spreading aside (thus never projecting beyond median lobe); apical margin of side lobes of labellum denticulate ............................ Didymoplexiella trichechus