A new species of Acanthopotamon Kemp, 1918 (Decapoda: Brachyura: Potamidae: Potaminae) from northeastern India, with a key to the species of the genus and notes on their distribution in relation to freshwater ecoregions

Abstract

The potamid genus AcanthopotamonKemp, 1918 is known from three species, A. fungosum (Alcock, 1909), A. martensi (Wood-Mason, 1875) (type species), and A. panningi (Bott, 1966), and is found in Bangladesh, India, Nepal, and Pakistan. Within this range, the genus is found in the ‘Ganges Delta and Plain,’ ‘Lower and Middle Indus,’ and ‘Namuda-Tapi’ freshwater ecoregions. Here we describe a fourth species, A. horaisp. nov., from northeastern India (Arunachal Pradesh, Assam, and Mizoram) in the ‘Middle Brahmaputra’ and ‘Ganges Delta and Plain’ freshwater ecoregions. The new species possesses a unique suite of external and gonopod morphological characters, with the slender and narrowly conical terminal segment of the first male gonopod being particularly diagnostic. A key to the species of Acanthopotamon is provided.

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

“…Lobothelphusa is often confused with Acanthopotamon. However, the smooth and glabrous carapace and short sternopleonal cavity that reaches only up to the level of the imaginary line that connects the median part of the cheliped coxae are the main morphological characteristics of Lobothelphusa (absent in Acanthopotamon) (Pati et al, 2019). Apart from the generic differences, the following are the most noticeable differences between L. woodmasoni and A. horai: the anterolateral margin of the carapace was with four epibranchial teeth in L. woodmasoni, but three epibranchial teeth in A. horai; a convex carapace with a deep cervical groove was found in L. woodmasoni, but a comparatively less convex carapace with a superficial cervical groove in A. horai.…”

“…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.…”

Abormon, a new genus of freshwater crab (Crustacea: Brachyura: Potamidae) from northeastern India, with descriptions of two new species

“…Nauplius, 29: e2021014 introduction The diversity of potamid freshwater crabs in the northeastern region of India (Arunachal Pradesh, Assam, Manipur, Meghalaya, Mizoram, Nagaland, Sikkim, and Tripura states) is very high and includes all known potamid genera (12 genera) and 29 of the 38 species now known from the country (Wood-Mason, 1871;1875;1876;Henderson, 1893;Rathbun, 1904;1905;Alcock, 1909;1910;Kemp, 1913;Bott, 1966;1970;Dutta, 1983;Ghosh and Ghatak, 1999;2000;Brandis, 2000;Roy et al, 2003;Ghosh et al, 2006;Yeo and Ng, 2007;Takeda et al, 2012;Absar et al, 2017;Mitra, 2017;Mitra et al, 2018;2020;Pati and Thackeray, 2018;Shaw et al, 2018;Mitra and Waikhom, 2019;Pati et al, 2019;2020a;2020b). Of these, three genera and 23 species (nearly 61 % of India's potamid fauna) are endemic to this area (Absar et al, 2017;Mitra, 2017;Mitra et al, 2018;2020;Pati and Thackeray, 2018;Mitra and Waikhom, 2019;Pati et al, 2019;2020a;2020b).…”

“…Many areas of northeastern India, however, remain poorly explored for freshwater crabs, and recent studies have substantially increased the number of known taxa (Absar et al, 2017;Mitra, 2017;2020;Mitra et al, 2018;Mitra and Waikhom, 2019;Pati et al, 2019;2020a;2020b). Despite this, more new taxa await description as many remote localities remain unsurveyed.…”

“…With the present descriptions of the new genus and two new species, Arunachal Pradesh now has 13 species in 10 genera of potamid crabs, and four species and four genera of gecarcinucid crabs (cf. Mitra et al, 2018;Pati and Thackeray, 2018;Pati et al, 2019;Mitra, 2020).…”