 |
| Abormon praecalvum Mitra, Pati & Ng, 2021 |
Abstract
A new genus and two new species of potamiscine freshwater crabs (Potamidae) are described from the Abor Hills in the Upper Siang District of Arunachal Pradesh State, northeastern India. Abormon gen. nov. is morphologically most similar to Pararanguna Dai and Chen, 1985, from Yunnan Province in China but can be differentiated by the setose dorsal surface and the medially concave posterolateral margins of the carapace, the concave lateral margins of the male telson, the relatively low dorsal flap on the terminal segment of the male first gonopod, and the anteriorly open and transversely ovate vulvae. Abormon capillosum sp. nov. can be distinguished from A. praecalvum sp. nov. by characters of the carapace, pereiopods, male pleonal somite 6, male gonopods, and vulvae.
Keywords: Abor Hills; Arunachal Pradesh; Decapoda; Potamiscinae; taxonomy
 |
| Coloration and habitat of Abormon praecalvum sp. nov. A, coloration of freshly preserved holotype male (10.2 × 8.5 mm) (ZSIK C.8610/2); B, dried stream at type locality, Tutting. |
SYSTEMATICS
Superfamily Potamoidea Ortmann, 1896
Family Potamidae Ortmann, 1896
Subfamily Potamiscinae Bott, 1970 (sensu Yeo and Ng, 2004)
Abormon gen. nov.
Type species. Abormon praecalvum sp. nov., by present designation.
Diagnosis. Small adult size (adult CW < 15 mm); carapace transversely ovate, low to moderately deep (CH/CW = 0.4-0.5); dorsal surface gently convex in frontal view, rugose, punctate, sparsely to densely setose; anterolateral margins gently convex, cristate with low granules; posterolateral margins concave medially; front sloping downwards; frontal margin concave medially, broad (FW/CW = 0.35); epigastric cristae very low, visible as 2 broad protuberances; postorbital cristae indiscernible; external orbital angle triangular, with long outer margin, approximately 2.0-2.5 times length of inner margin; epibranchial tooth very low, with very small cleft; cervical grooves barely visible; supraorbital margin gently concave medially; suborbital margin concave, confluent with supraorbital margin ....
Geographical distribution. Abormon gen. nov. is only known from the Abor Hills in the Upper Siang District of Arunachal Pradesh State, northeastern India.
Etymology. The genus name is derived from the Abor Hills, a region of Arunachal Pradesh in the northeast India where the crabs reside, in arbitrary combination with the ending of “Potamon”. The gender is neuter.
Abormon praecalvum sp. nov.
Etymology. The species name is derived from the Latin ‘praecalvus’ for ‘becoming bald’, referring to the presence of only a few scattered setae on the carapace and pereiopods of the crab.
Geographical distribution. Abormon praecalvum sp. nov. is currently known only from the Mouling National Park in the Upper Siang District of Arunachal Pradesh State, northeastern India.
Abormon capillosum sp. nov.
Etymology. The species name is derived from the Latin ‘capillosus’ for very hairy, alluding to the dense setae covering the carapace and pereiopods of the crab.
Geographical distribution. Abormon capillosum sp. nov. is currently known only from the type locality, i.e., Tutting in the Upper Siang District of Arunachal Pradesh State, northeastern India.
Santanu Mitra, Sameer K. Pati and Peter K.L. Ng. 2021. Abormon, A New Genus of Freshwater Crab (Crustacea: Brachyura: Potamidae) from northeastern India, with Descriptions of Two New Species. Nauplius. 29; DOI: 10.1590/2358-2936e2021014
