Accepted by R. Pethiyagoda: 8 Sept. 2017; published: 19 Oct. 2017 ZOOTAXA ISSN 1175-5326 (print edition) ISSN 1175-5334 (online edition) Copyright © 2017 Magnolia Press Zootaxa 4337 (3): 403–412 http://www.mapress.com/j/zt/ Article 403 https://doi.org/10.11646/zootaxa.4337.3.5 http://zoobank.org/urn:lsid:zoobank.org:pub:4A839CF4-EDF3-4E9C-A899-7F76F01D4E06 Physoschistura harkishorei, a new species of loach from Arunachal Pradesh, north-eastern India (Teleostei: Nemacheilidae) DEBANGSHU NARAYAN DAS 1,2 & ACHOM DARSHAN 2,3 1 Fishery and Aquatic Biology Laboratory, Department of Zoology, Rajiv Gandhi University, Rono Hills, Doimukh:791112, Arunachal Pradesh, India 2 Center with Potential for Excellence in Biodiversity, Rajiv Gandhi University, Rono Hills, Doimukh:791112, Arunachal Pradesh, India 3 Corresponding author. E-mail: achom_darshan@yahoo.com Abstract Physoschistura harkishorei, a new species of nemacheilid loach, is described from the Dibang and Lohit Rivers of Ar- unachal Pradesh, north-eastern India. The new species can be distinguished from all known congeners by the combination of the following characters: the second branched ray of pectoral fin with a distal filamentous extension; body colour pat- tern consisting of 9–10 vertically-elongated brownish spots or blotches along the flank, and 8–10 brownish saddles on back, the saddles not contiguous with the lateral blotches; lateral line complete; prominent, well-developed pelvic-fin lobe; a well-developed free posterior chamber of the air-bladder; and caudal fin with 7+8 branched rays. The new species occurs sympatrically with Physoschistura dikrongensis and P. elongata in the Brahmaputra basin. Key words: New nemacheilid, Dibang River, Lohit River, Brahmaputra basin Introduction The genus Physoschistura was established by Bănărescu & Nalbant (in Singh et al. 1982), with Nemacheilus brunneanus (= Physoschistura brunneana) (Annandale 1918) as the type species. The genus is diagnosed in having a conical free posterior air-chamber immediately behind the air-bladder capsule (Singh et al. 1982); mouth strongly arched, its width 1.5–2.0 times its length; lower lip medially interrupted, forming two broadly triangular lateral pads with a deep furrow; and irregularly-shaped bars on the body (Kottelat 1990, Lokeshwor & Vishwanath 2012a). The largest known specimen reaches 73.6 mm standard length (Lokeshwor & Vishwanath 2012b). Members of the genus occur in eastern India, Myanmar, and northern Thailand (see Suvarnaraksha 2013). Presently, fifteen species of Physoschistura are considered valid (Endruweit 2017), viz. P. dikrongensis Lokeshwor & Vishwanath and P. elongata Sen & Nalbant from the Brahmaputra basin; P. tuivaiensis Lokeshwor et al. from the Barak basin; P. chhimtuipuiensis Lalramliana et al. from the Kaladan basin; P. chindwinensis Lokeshwor & Vishwanath, P. tigrina Lokeshwor & Vishwanath, and P. prashadi (Hora), from the Chindwin basin; P. pseudobrunneana Kottelat and P. shuangjiangensis (Zhu & Wang) from the Mekong basin; P. chulabhornae Suvarnaraksha from the Chao Phraya basin; P. rivulicola (Hora), P. raoi (Hora) and P. absumbra Endruweit from the Salween basin; and P. brunneana (Annandale) and P. shanensis (Hora) from the Inlé Lake of Myanmar. During our examination of various ichthyological collections from the Dibang and Lohit Rivers (Brahmaputra basin) of Arunachal Pradesh in north-eastern India, we encountered an undescribed species of Physoschistura, which is herein described as Physoschistura harkishorei, new species. Materials and methods Fin counts and measurements of body parts were made on the left side of the specimens wherever possible with a