A Synopsis of Corybas (Orchidaceae) in West Malesia and Asia

Abstract

Corybas is a remarkable genus of largely terrestrial orchids comprising about 100 species found from South China and India to New Zealand and the Subantarctic and Western Pacific Islands. All species are small and inconspicuous from a distance; plants consist of a single underground tuber and a single leaf subtending a single flower. Although inconspicuous from afar, plants are often extraordinarily beautiful when examined closely and have a special jewel-like quality. Structurally the flower is remarkable for the elaboration of the dorsal sepal and lip which together form a tube with an expanded mouth; the lateral sepals and petals vary between long tentacle-like structures and almost invisible threads; the lip usually bears two spurs. Everyone who has written about Corybas has waxed poetic over the charm of these 'botanical jewels' (van Steenis 1972). Unfortunately differences between taxa of Corybas which are strongly manifest in the field, tend to disappear in spirit material and dried pressed specimens are very difficult to interpret. Add to this the facts that some taxa are very widespread (e.g. C. carinatus) whereas others are known from one collection only (e.g. C. vinosus) and that two or three taxa may be found growing together, and there arises a great potential for confusion. This paper arises from the frustration experienced in trying to identify species of Corybas from Peninsular Malaya, followed by the realization that names used in Malaya were applied to taxa quite different from the taxa in the type country. Further, during the last ten years we have been able to accumulate a series of colour transparencies which, more successfully than any other method, have recorded the habit and colours of the flowers and shown distinctions, where none were originally thought to exist. Finally during fieldwork in West Malesia in 1977 during our spare time, we found an extraordinary abundance of Corybas and so it was possible to study variation between populations. Originally it was our intention to prepare a paper giving fieldnotes and illustrations of the species of Corybas known to us in the Malay Peninsula and Java, and to describe the species thought by us to be new. However, as might be expected, it has not been possible to prepare such an account in isolationwe have thus considered all species in the West Malesian and Asian region as well as those we know in the field in Sumatra, Java, Borneo and Malaya. Obviously no satisfactory account of the genus can be prepared without monographic treatment; a monograph of the species east of Wallace's Line has