A new species of the cyprinoid genus Psilorhynchoides Yazdani et al. (Cypriniformes: Psilorhynchidae) from Arunachal Pradesh, India

Abstract

Psilorhynchoides arunachalensis, new species is described from the Brahmaputra basin in Arunachal Pradesh of Northeastern India. It belongs to the Psilorhynchus homaloptera and P. pseudecheneis group, for which genus Psilorhynchoides was erected by Yazdani et al. (1990) because of their morphological and osteological distinctiveness from Psilorhynchus. The new species is differentiated by the following characters: eight or nine simple pectoral fin rays; more number of vertebrae 43-45 and an intermediate number of lateral line scales 42-44 between the valid species P. homaloptera and P. pseudecheneis (38-41 and 48-50 respectively).

Phylogenetic position of the enigmatic genus Psilorhynchus (Ostariophysi: Cypriniformes): Evidence from the mitochondrial genome

“…All of the species possess arched backs and flattened ventral surfaces, presumably adaptations for a benthic rheophilic lifestyle. On occasion P. homaloptera, P. pseudecheneis and P. arunachalensis are placed in a separate genus, Psilorhynchoides Yazdani, Singh and Rao (Yazdani et al, 1990;Nebeshwar et al, 2007) but this is not generally accepted and for the purpose of this investigation all species will be retained within Psilorhynchus.…”

“…Psilorhynchus was created by McClelland (1839) and currently contains eight described species, P. sucatio (Hamilton, 1822), P. balitora (Hamilton 1822), P. homaloptera Mukerji, 1935, P. pseudecheneis Menon andDatta, 1964, P. gracilis Rainboth, 1983, P. micropthalmus Vishwanath and Manojkumar, 1995, P. arunachalensis (Nebeshwar et al, 2007) and P. amplicephalus Arunachalam, Muralidharan and Sivakumar, 2007. The genus is restricted to the fast flowing streams of the Ganga-Brahmaputra Drainage of India, Nepal and Bangladesh and the Ayeyarwady River of Northern Myanmar and adjacent China (Rainboth, 1983).…”

Molecular systematics of the Asian torrent minnows (Ostariophysi: Psilorhynchidae) inferred from nuclear and mitochondrial DNA sequence data

“…This taxonomic change appears to have been followed only by Nebeshwar et al. () and was criticized by Conway and Kottelat (), who placed Psilorhynchoides in the synonymy of Psilorhynchus . Based predominantly on osteological characters, Conway and Kottelat () identified two putative monophyletic groups of ‘deep‐bodied’ Psilorhynchus , including a group composed of Psilorhynchus gracilis Rainboth, ; Psilorhynchus melissa Conway and Kottelat, and Psilorhynchus robustus Conway and Kottelat, ; and a larger group, including Psilorhynchus sucatio (Hamilton, ), Psilorhynchus balitora (Hamilton, ), Psilorhynchus breviminor Conway and Mayden (), Psilorhynchus pavimentatus Conway and Kottelat, and Psilorhynchus rahmani Conway and Mayden, 2008.…”

“…Based on the phylogenetic hypotheses obtained (Fig. a), Conway () assigned or tentatively assigned all species of Psilorhynchus described at that time (except for P. sucatio ) into one of three species groups based on morphological characters, including: the P. balitora species group (comprising Psilorhynchus amplicephalus Arunachalam, Muralidharan and Sivakumar, 2007, P. balitora , Psilorhynchus nepalensis Conway and Mayden, 2008, P. rahmani , P. breviminor , P. pavimentatus and Psilorhynchus brachyrhynchus Conway and Britz, ), the Psilorhynchus nudithoracicus species group, referred to as the P. gracilis species group in Conway () (comprising P. melissa , P. gracilis and P. robustus ) and the P. homaloptera species group (comprising Psilorhynchus arunachalensis (Nebeshwar, Bagra and Das, ), P. homaloptera , Psilorhynchus microphthalmus Vishwanath and Manojkumar, 1995 and P. pseudecheneis ). The relationships within each of these species groups were poorly resolved, as was the position of Psilorhynchus tenura Arunachalam and Muralidharan (), a species only recently described from the Western Ghats of Peninsular India.…”

“…Based mostly on external characteristics, Yazdani et al (1991) proposed a close relationship between the dorso-ventrally compressed Psilorhynchus pseudecheneis Menon and Datta, 1964 and Psilorhynchus homaloptera Hora and Mukerji, 1935, for which they erected the genus Psilorhynchoides (designating P. homaloptera as the type species). This taxonomic change appears to have been followed only by Nebeshwar et al (2007) and was criticized by Conway and Kottelat (2007), who placed Psilorhynchoides in the synonymy of Psilorhynchus. Based predominantly on osteological characters, Conway and Kottelat (2010) identified two putative monophyletic groups of 'deep-bodied' Psilorhynchus, including a group composed of Psilorhynchus gracilis Rainboth, 1983; Psilorhynchus melissa Conway and Kottelat, 2010 and Psilorhynchus robustus Conway and Kottelat, 2007; and a larger group, including Psilorhynchus sucatio (Hamilton, 1822), Psilorhynchus balitora (Hamilton, 1822), Psilorhynchus breviminor Conway and Mayden (2008a), Psilorhynchus pavimentatus Conway and Kottelat, 2010 and Psilorhynchus rahmani Conway and Mayden, 2008.…”