Psilorhynchus piperatus , Conway, Kevin W. & Britz, Ralf, 2010

Conway, Kevin W. & Britz, Ralf, 2010, Three new species of Psilorhynchus from the Ayeyarwaddy River drainage, Myanmar (Teleostei: Psilorhynchidae), Zootaxa 2616, pp. 31-47: 39-41

publication ID 10.5281/zenodo.197944

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scientific name

Psilorhynchus piperatus

new species

Psilorhynchus piperatus  , new species

( Figure 6View FIGURE 6)

Holotype. BMNH 2010.4. 14.8, 47.7 mm SL; Myanmar: Magwe Division, Man Chaung (Ayeyarwaddy River drainage), 0.5 miles from Zinpyone village, 19 ° 55 ' 3 " N, 94 ° 30 ' 11 " E, 21 November 2009, R. Britz et al.

Paratype. BMNH 2010.4. 14.9, 1, 42.6 mm SL; same data as holotype.

Diagnosis. A species of Psilorhynchus  distinguished from all other species of the genus by its unique caudal-fin pigmentation pattern, consisting of an approximately symmetrical pattern of small black blotches on both upper and lower caudal-fin lobes (vs. caudal fin without pigmentation, with two to three irregular vertical bars across center, or with an irregular pigmentation pattern, most prominent along outer edges of upper and lower lobes). Psilorhynchus piperatus  is further distinguished by the combination of the following characters: snout length 53–55 % HL; ventral surface between paired fins with a broad rectangular scale-less patch; branched dorsal-fin rays 9; unbranched pectoral-fin rays 5; caudal-fin rays 9 + 9; lateral-line scales 32– 33; lateral sides of body marked with 6 indistinct round to squarish dark-brown blotches, arranged in a longitudinal row; dorsal saddles deep, extending 3–4 scale rows downwards from the dorsal surface, in contact with the round to squarish dark brown blotches, arranged in a longitudinal row on flank.

Description. General body shape as in Figure 6View FIGURE 6. Morphometric and meristic data are listed in Table 2. As described for P. brachyrhynchus  with the following differences. Snout long, contributing to 50 % of head length. Principal caudal-fin rays 9 + 9. Pelvic-fin rays ii. 7, pectoral-fin rays v. 11 (1). Pectoral fin reaching to one scale row anterior to pelvic-fin origin when adpressed. Scales large, 32 (1) or 33 (1) along lateral line, plus 2 on base of caudal fin. 13 predorsal scales, 9 (1) or 10 (1) scales between anus and anal-fin origin. Ventral surface with a broad, rectangular scale-less patch between paired fins. Total number of vertebrae 35, comprising 19 + 16 abdominal and caudal vertebrae.

Coloration. As described for P. brachyrhynchus  , but with the following differences. Lateral body scales irregularly pigmented, occluding round to squarish dark brown blotches, arranged in a longitudinal row on flank. Dorsal fin weakly marked with a proximal stripe running along base of rays, a more distal stripe crossing center of fin, formed by small aggregations of melanophores around first branching point of branched rays. Caudal fin densely speckled with small dark clusters of melanophores, equally distributed across both upper and lower lobes, forming an approximately symmetrical pattern ( Fig. 4View FIGURE 4 F).

Distribution and habitat. Psilorhynchus piperatus  is known at present only from the type locality ( Fig. 2View FIGURE 2). At the type locality, the Man Chaung is a swift-flowing river ( Fig. 7View FIGURE 7), with dense riparian vegetation and a substrate of sand, gravel and small boulders.

Etymology. From the Latin piperatus  , meaning peppered, in allusion to the speckling on the caudal fin. An adjective.

Remarks. Psilorhynchus piperatus  is easily distinguished from all other members of the genus by its unique caudal-fin pigmentation pattern ( Fig. 4View FIGURE 4 F), which consists of a dense speckling of small black spots, formed by clusters of melanophores, distributed evenly over both upper and lower caudal-fin lobes.

TABLE 2. Selected morphometric and meristic date for Psilorhynchus piperatus  .