Two new species of freshwater crabs of the genus Potamiscus Alcock, 1909 (Brachyura: Potamidae) from Nagaland, northeastern India

Abstract

Two new species of freshwater crabs of the potamid genus Potamiscus Alcock, 1909 are described from Nagaland State of northeastern India. Potamiscus chizami sp. nov. and Potamiscus mima sp. nov. most resemble two Indian congeners [Potamiscus palelensis Mitra and Waikhom, 2019 and Potamiscus tumidulus (Alcock, 1909)] and a species from Myanmar (Potamiscus whitteni Ng, Hla Htoo and Win Mar, 2020) due to the similar terminal segment of the male first gonopod. Both new species can be distinguished from Po. palelensis by their stouter ambulatory legs, from Po. tumidulus by their more-slender male first gonopod, and from Po. whitteni by their strongly concave lateral margins of the male telson and the straight tip of the male first gonopod. Characters of the carapace, male pleon, male gonopods, and female vulvae are employed to differentiate Po. chizami sp. nov. from Po. mima sp. nov.

Gurumon gurumayum, a new genus and new species of freshwater crab (Decapoda: Brachyura: Potamidae) from Arunachal Pradesh, northeastern India

“…The terminologies for female vulvae are adopted from Guinot et al (2013). The measurement methods of the carapace follow Pati et al (2022), whereas the measurements of the female sternum and vulvae follow Pati (2021). The techniques recommended by Montesanto (2015Montesanto ( , 2016 and Coleman (2018) were followed for the digital illustrations.…”

“…The potamiscine freshwater crab genus, Potamiscus Alcock, 1909 (type species Potamiscus annandalii Alcock, 1909, from Nemotha, Cachar, Assam State, India) currently includes 20 species from northeastern India, Myanmar, and China (Ng et al 2008(Ng et al , 2020Naruse et al 2018;Mitra & Waikhom 2019;Pati 2021). Potamiscus, however, is not monophyletic (Shih et al 2009;Chu et al 2017;Zhang et al 2020).…”

“…While the taxonomy of Potamiscus needs an urgent revision, Pati (2021) separated the members of the genus into different informal groups based on the structure of the terminal segment of the male first gonopod. One such group of Potamiscus included species with the terminal segment of the male first gonopod being stout, cylindrical, relatively long, and lacking a dorsal flap, viz., Potamiscus loshingensis (Wu, 1934) and P. rongjingensis Dai & Chen in Dai, Chen, Liu, Luo, Yi, Liu, Gu & Liu, 1990(cf.…”

Description of a new species of Spiralothelphusa Bott, 1968, and redescription of Spiralothelphusa wuellerstorfi (Heller, 1862) (Decapoda: Brachyura: Gecarcinucidae)

“…The terminologies for male second gonopod (or pleopod) are essentially after Ng & Tay (2001). The terminologies and measurement of female sternum/vulvae are after Guinot et al (2013) and Pati (2021), respectively. The width of the carapace was measured across the widest part of the carapace.…”

Diversity of freshwater crabs (Crustacea: Decapoda: Brachyura) in the Subansiri River basin of Arunachal Pradesh and Assam, northeast India

“…In northeast India, freshwater crabs are the most extensively consumed aquatic species by the various tribal communities, second only to fish, due to their distinct taste, medicinal properties, and aboriginal faith in crab meat. Despite the fact that 44 species of freshwater crabs have been reported in northeast India (Ghosh et al, 2006;Takeda et al, 2012;Mitra, 2017Mitra, , 2020; Pati and Thackeray, 2018; Pati et al, 2019;Mitra et al, 2021;Pati, 2021), there is currently no systematic and evidence-based record of freshwater crab diversity in this region. As a result, the current survey was carried out to contribute to the documentation of freshwater crabs in Arunachal Pradesh and Assam, India's far northeast.…”