Pankaj Kumar

Preponderance of clonality triggers loss of sex in Bulbophyllum bicolor, an obligately outcrossing epiphytic orchid

Vegetative propagation (clonal growth) conveys several evolutionary advantages that positively affect life history fitness and is a widespread phenomenon among angiosperms that also reproduce sexually. However, a bias towards clonality can interfere with sexual reproduction and lead to sexual extinction, although a dearth of effective genetic tools and mathematical models for clonal plants has hampered assessment of these impacts. Using the endangered tropical epiphytic or lithophytic orchid Bulbophyllum bicolor as a model, we integrated an examination of breeding system with 12 microsatellite loci and models valid for clonal species to test for the “loss of sex” and infer likely consequences for long‐term reproductive dynamics. Bagging experiments and field observations revealed B. bicolor to be self‐incompatible and pollinator‐dependent, with an absence of fruit‐set over 4 years. Challenging the assumptions that clonal populations can be as genotypically diverse as sexually reproducing ones and that clonality does not greatly influence genetic structure, just 22 multilocus genotypes were confirmed among all 15 extant natural populations, 12 of the populations were found to be monoclonal, and all three multiclonal ones exhibited a distinct phalanx clonal architecture. Our results suggest that all B. bicolor populations depend overwhelmingly on clonal growth for persistence, with a concomitant loss of sex due to an absence of pollinators and a lack of mating opportunities at virtually all sites, both of which are further entrenched by habitat fragmentation. Such cryptic life history impacts, potentially contributing to extinction debt, could be widespread among similarly fragmented, outcrossing tropical epiphytes, demanding urgent conservation attention.

Cheirostylis pusilla (Orchidaceae), a new record for Hong Kong

SummaryThe jewel orchid Cheirostylis pusilla Lindl. is newly recorded from Hong Kong, a significant distance from Yunnan Province, the only other confirmed locality for the species in China. A full description, photos and line drawings are presented for this hitherto poorly known species, and its conservation status is assessed. Cheirostylis malleifera C. S. P. Parish & Rchb. f. is shown to be a later synonym.

Eulophia obtusa (Orchidaceae: Epidendroideae: Cymbideae) an addition to the flora of Bangladesh, with notes on its ecology and conservation status

SummaryLittle published information exists about Eulophia obtusa, a showy and distinctive species previously recorded from North India and Nepal. It is here reported from Bangladesh for the first time. The population occurring in Bangladesh may represent a distinct colour form, with pure white instead of bright yellow sepals and petals as in previous records. A species growing in seasonally waterlogged grassland, its only known site in Bangladesh has already been destroyed for agricultural development. No reliable data on its present day occurrence in India and Nepal could be obtained. However, the most recent of only three collections in the Kew Herbarium dates from 1902, which suggests that it is quite a rare species. It must be assessed as critically endangered (CR) in Bangladesh, according to the IUCN Red Listing criteria.

Taxonomic Notes on Didymoplexiella siamensis and Gastrodia peichatieniana, Two Fully Mycoheterotrophic Orchids New to the Flora of Hong Kong

The ephemeral, leafless orchids Didymoplexiella siamensis and Gastrodia peichatieniana are newly recorded from Hong Kong. A lectotype is selected for the former, and the recently described D. denticulata from southern Vietnam is reduced to its synonymy. Full descriptions and global conservation assessments are presented for these hitherto poorly known species.

Neotypification of Zeuxine agyokuana (Goodyerinae, Orchidoideae, Orchidaceae) with a New Synonym

Based on examination of protologues and herbarium material, combined with field observations, we suggest that Zeuxine bidupensis Averyanov should be considered a heterotypic synonym of Z. agyokuana Fukuyama. Thus, the known distribution of Z. agyokuana includes China, India, Japan, Thailand and Vietnam. A neotype is designated for Z. agyokuana, since all original material underlying Fukuyamas description seems to be lost. An improved morphological description, based on all available herbarium material from the entire geographic range of the species, is provided together with illustrations.