Description of Pareuchiloglanis sp. (Siluriformes: Sisoridae) in the Da River basin belonging to Phong Tho district, Lai Chau province

The genus Pareuchiloglanis (Siluriformes: Sisoridae) consists of 26 species in the world. In Vietnam, this genus has eight species, including five that are in uncertain taxonomy status. In the present study, we described one species of Pareuchiloglanis based on collections from the Da River basin in Phong Tho district, Lai Chau province. Pareuchiloglanis sp. can be distinguished from congeners by the following unique combination of characters: D. i,6; A. i,4; P1. i,14-16 (primarily i,16); C. i,6-8,6-8,i (primarily i,8,8,i); interorbital distance\eye diameter 2.4-3.4; caudal peduncle length 17.1-21.5; caudal pedunle depth 6.0-7.0% SL; length of adipose base\dorsal to adipose distance averaged 1.8; head length 19.2-24.3; anal-fin origin closer to the anus than to the caudal-fin base; adipose-fin base posterior to the tip of pelvic-fin rays; the pelvic-fin insertion located opposite to the fourth dorsal fin-ray element; maxillary barbel extending just beyond base of first pectoral-fin element; and yellow patches on dorsal surface (a broader pair on the last doral-fin ray, as large as two thirds length of pelvic-fin). Morphological analysis showed that Pareuchiloglanis sp. are closed to two species in the same surveyed area, P. tamduongensis and P. songdaensis. This paper also indicated morphological differences between Pareuchiloglanis sp. and other species that have yellow patches on dorsal surface. This species record implied the potential of biodiversity of Pareuchiloglanis in the headwaters of the Red River. These findings provide worthy data for further studies on taxonomy of this genus in northern Vietnam.