Thismia (Thismiaceae): the first record of the mycoheterotrophic genus to the Flora of India with a new species revealing the phytogeographical significance of Western Ghats

Thismia, a genus of mycoheterotrophic plants, is reported for the first time from mainland India, from Neryamangalam forests in Idukki district of Kerala, along with a new species, T. sahyadrica. Thismia sahyadrica, described and illustrated here, is unique within Thismia in having a mitre with a single opening; five perianth lobes are fused into a mitre-like structure, while the sixth one is free, forming a lateral single opening of the flower. Due to its unique morphological characteristics, the taxonomic placement of the new species remains obscure, although some root and flower characters suggest an affinity with species from the sections Glaziocharis, Sarcosiphon, Geomitra, and Scaphiophora. Ecological specificity and phytogeographical peculiarities of the new species are also discussed.