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Rediscovery of Brachystelma attenuatum after 188 years

Published online by Cambridge University Press:  28 June 2022

Amber Srivastava
Affiliation:
Botanical Survey of India, Dehradun, India; current address: Council of Scientific and Industrial Research-National Botanical Research Institute, Lucknow, India.
Nishant Chauhan
Affiliation:
Department of Geography, Himachal Pradesh University, Shimla, Indianishant287037@gmail.com

Abstract

Type
Conservation News
Creative Commons
Creative Common License - CCCreative Common License - BY
This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence CC BY 4.0.
Copyright
Copyright © The Author(s), 2022. Published by Cambridge University Press on behalf of Fauna & Flora International

The genus Brachystelma includes more than 100 species, occurring mainly in tropical and subtropical regions of Africa, Asia and Australia. In India the genus is represented by c. 40 species, primarily distributed in the Western Ghats, with only four species reported from northern India. Of these, only two species, B. parviflorum (Wight) Hook f. and B. attenuatum (Wight) Hook f. are reported from the Indian Western Himalayas. Both these species were reported from a single locality by Robert Wight in 1835 and were believed to be extinct (Venu & Prasad, 2015, Current Science, 109, 680–682; Pullaiah et al., 2019, Monograph on Brachystelma and Ceropegia in India, CRC Press, Boca Raton, USA).

The rediscovery of B. parviflorum in 2021 (Srivastava & Chauhan, 2021, Oryx, 55, 329) attracted our attention, and NC surveyed extensively for the species in various regions of Hamirpur and adjoining areas during March–August 2021. While studying the collected specimens, we noticed that specimens from Thana Darogan and Jhandwin village resembled B. parviflorum in the vegetative state but had different flower characteristics. With the commencement of the flowering season, we revisited the localities on 26 March 2022 and were able to identify the plants as B. attenuatum. Brachystelma attenuatum is characterized by larger flowers than B. parviflorum, with long and narrow corolla lobes.

Flowers of Brachystelma attenuatum Hook. f. Photo: Amber Srivastava.

This species was described by Robert Wight under the genus Eriopetalum Wight in 1835 on the basis of J.F. Royle's collection from Doongie (Dungi, Hamirpur, Himachal Pradesh). The two localities where we recollected the species are 4–10 km from this type locality. Along with this, one more locality was discovered on 3 April 2022 in Jodhan village, Sarkaghat, in Mandi district of Himachal Pradesh. During regular field surveys we observed that the species appears to be declining as a result of local exploitation for its edible tubers. We estimate that the species has an area of occupancy and extent of occurrence of 8.2 and 91.3 km2, respectively, which suggests it should be categorized as Critically Endangered on the basis of IUCN Red List criteria B1ab(iv,v)+2ab(iv,v). The rediscovery within a short period of two species presumed extinct indicates the need for further botanical exploration of this region of the Himalayas.