TAXONOMIC REVISION OF THE GENUS Calanthe R. Br. (ORCHIDACEAE) IN NEPAL

Abstract

Calanthe is the terrestrial orchid with a distinguishing character of a plicate, linear to broad leaves, 8 pollinia in 2 groups, and the genus mostly occurs in moist and humid dense forest floors. The genus was closely related to previously known genus Phaius and after the merge of these two genera in 2020 by Chase et al. the nomenclatural stability is maintained. This study is based on all the species of these taxa that are naturally distributed in Nepal. This taxonomic revisionary study is based on the herbarium specimens and fresh plant materials. The herbarium specimens are thoroughy studied from KATH and TUCH. And the examination of available images of herbarium specimens collected from Nepal are also done in international herbaria like; BM, E, K and TI. This study confirms the presence of 15 species of Calanthe in Nepal namely; C. alpina, C. arcuata, C. brevicornu, C. chloroleuca, C. davidii, C. densiflora, C. griffithii, C. mannii, C. masuca, C. plantaginea, C. puberula, C. tankervilleae, C. tricarinata, C. trulliformis and C. woodfordii. Among these 15 species, 2 species are later added from previously known genus ‘Phaius’; C. tankervilleae and C. woodfordii. The synonyms, type specimens, description, ecology, altitudinal range, flowering season, specimens examined and distribution map for all the species present in Nepal is prepared. Also, the illustration and bracketed taxonomic key is made to identify the species. The character of lip is more important in taxonomic view point for delimiting the species of this genus. Additionally, the cladistic analysis is also interpreted to find out the phylogenetic relationship between the species. The cladogram showed that C. chloroleuca and C. plantaginea are closely related species. Similarly, the study also portrayed the closest relationship between C. tankervilleae and C. woodfordii. The genus Calanthe is found to be distributed in all 3 regions of Nepal with the altitudinal range from 200 m to 3300 m in 31 districts of Nepal. The peak flowering season of this genus is May to August and more than half of species of Calanthe in Nepal have flowering time in these months.