Devario browni ( Regan, 1907 )

Kullander, Sven & Norén, Michael, 2022, The real Devario browni from the Irrawaddy River basin, and the new Devario ahlanderi from the Salween River basin in Myanmar (Teleostei: Cyprinidae: Danioninae), Zootaxa 5100 (1), pp. 54-72 : 58-61

Devario browni ( Regan, 1907)

Lectotype BMNH 19071907.10 .22.1, Adult male. 57.0 mm SL ( Fig. 2A ); paralectotypes BMNH 1907.10.22.2–4, ZSI F1872/1. The lectotype designation here is motivated by the uncertainty about which specimens belong in the type series, and the taxonomic uncertainty resulting from previous misidentifications. Data in this description and lectotype designation fulfil paragraph74.7 and as far as relevant Recommendations A, C, D, E, and F of the International Code of Zoological nomenclature (International Commission for Zoological Nomenclature, 1999).

Revised definition. Distinguished from all other species of Devario by the shape of the P stripe: gradually expanding posteroanteriorly, either forming a uniform brown blotch anteriorly, or P stripe diverging anteriorly, forming a brown blotch enclosing a small light spot or two contiguous small light spots.

Description based on referred specimens and type series. Representative specimens are shown in Figures 2–3 . Morphometric and meristic data are given in Appendix 2.

Body laterally compressed, elongate; sexes significantly different in body depth (ANCOVA, p>0.05, but only eight adult specimens were available. Predorsal contour ascending in straight line, sloping posteriorly from anterior dorsal-fin insertion. Prepelvic contour strongly curved; chest conspicuously compressed below pectoral fin, but not keeled. Snout short, rounded in dorsal aspect, subtriangular in lateral aspect, about as long as eye diameter. Infraorbital process broader than high, with truncate distal margin which may be slightly irregular. Danionine notch caudally margined by well-developed anteromediad projecting laminar dentary process. Skin thin or absent from distal part of infraorbital process, dentary process, and anterior margin of supraorbital. Mouth terminal, obliquely directed upwards. Bony knob at dentary symphysis minor, fitting in shallow depression in upper jaw. Blunt tubercles present in adults in 1–2 (males) or 1 row (females) on lateral adoral surface of dentary, and additional scattered tubercles anteriorly on dentary. Maxilla reaching to below anterior margin of orbit. Jaws equal in anterior extension; lower jaw ending anteriorly at horizontal through middle of eye. In large males, bands of strong, densely arranged sharp-tipped conical tubercles on anterior seven rays of pectoral fin; pectoral-fin tubercles absent in females, but one specimen, 59.8 mm SL potentially female with spaced tubercles on three anterior pectoral fin rays and relatively deep body. Rostral barbel short, reaching slightly beyond junction of lacrimal and first infraorbital; maxillary barbel much shorter. Pharyngeal teeth in three rows: 5,4,2,2,4,5 (one specimen dissected).

Lateral line complete, comprising one tubed scale followed by a canal running steeply caudoventrad under five unperforated scales to slightly posterior to pectoral-fin base where canal curved caudad and represented by scales with indistinct or absent perforation anteriorly, but distinctly perforated posterior to adpressed pectoral fin; running in a curve parallel to the ventral body outline and ending low on caudal peduncle and caudal-fin base. About of caudal-fin length scaled basally.

Dorsal fin inserted at highest point of dorsum, slightly posterior to middle of body.Anal fin inserted below anterior rays of dorsal fin. Pectoral-fin insertion at about vertical through posterior margin of osseous opercle; extending to pelvic-fin insertion. Pectoral axial lobe present. Pelvic fin inserted slightly anterior to midbody, not reaching to anal-fin insertion. Pelvic axillary scale present. Caudal fin forked, lobes of about equal length, tips rounded.

Colouration in preservative. Dorsum pale brown; dark brown mid-dorsal stripe from occiput to base of upper caudal-fin rays; lower sides, chest and abdomen pale yellowish white. Caudal peduncle ventrally yellowish white. Opercle silvery, powdered with brown; a brown patch dorsally. Vertically oriented brown cleithral spot covering part of first lateral-line scale and scale above.

Flank colour pattern varying with specimen size, and slightly on each side. Adults with dark brown P stripe along middle of side, narrow at end of caudal peduncle, irregular, gradually widening cephalad to about doubled width or more at abrupt anterior termination. Light spot anteriorly in P stripe present or absent. P+1 narrower than P stripe, light brown, paralleling P stripe, running from caudal peduncle to anterior termination of P stripe.

P+2 stripe absent. P-1 stripe narrower than P stripe; irregular, greyish brown, well demarcated against I-1 stripe, fading ventrally; extending from end of caudal peduncle cephalad to about level of anterior termination of P stripe. Two or three brown vertical bars or ovoid blotches anterior to P stripe. Interstripes I+1 and I-1 joined anterior to termination of P stripe, or light interspace of vertical bar anterior to P stripe bridging ends of interstripes I+1 and I-1.

Dorsal fin proximally pale grey, translucent; distal half diaphanous. Middle rays of caudal fin light grey, translucent, fading posteriorly on fin. Pectoral and pelvic fins white, translucent.

Juveniles about 25 mm similar to adults but interstripes not connected anteriorly; P stripe brown, distinct, relatively narrower than in adults. In specimens about 18 mm, SL and shorter, horizontal stripes indistinct; P stripe represented by light brown pigmentation suffused on abdominal side.

Devario sp. cf. browni from Yunnan. Yunnan specimens inadequately preserved, overall brownish and most specimens with indistinct colour pattern ( Fig. 5 ). Body proportions and meristic data similar to D. browni and D. ahlanderi , but specimens not in a good state of preservation.

Most specimens from the Nangun River with relatively narrow P stripe, only slightly widened anteriorly and terminating in a short vertical bar. Specimens from the Qingshui River (in the Nangun River basin) with large or small dark blotch terminating P stripe at level of pelvic fin insertion.

Geographical distribution and habitat. The type locality of Devario browni is not known, but was probably near Lashio in the upper Irrawaddy River basin. Specimens from streams near Lashio were identified as D. browni (Appendix 1). Presence of D. browni in the upper Salween River basin in Yunnan was not confirmed. Devario shanensis was syntopic with D. browni near Lashio (Appendix 1).Other syntopic fish species were identified as Opsarius barnoides , Pethia stoliczkana , and Danio roseus .

Figures

FIGURE 2. Devario browni. BMNH 1907.10.22:1–4; A, Lectotype, male 57.0 mm SL; B, Paralectotype, female, 52.5 mm SL; Northern Shan States.

FIGURE 3. Devario browni. A, NRM 36393, adult male, 62.1 mm SL, reversed; B, adult female, 58.3 mm SL, reversed; C, young male, 44.9 mm SL, reversed; D, young male, 49.5 mm SL; E, NRM 36361, young male 49.7 mm SL. All from Myanmar, Shan State, Irrawaddy River basin, Lawe Pyat stream, on Road Lashio–Tigyaing.

FIGURE 5. Devario cf. browni, all from P.R. China,Yunnan, Salween River basin. A, ZMUYU 874064, adult male, 60.5 mm SL: Canguyan County: Nangun River. B. ZMYU 80650, young female 42.1 mm SL; Gengma County: Qingshui River. C, ZMYU 80650, young female, 49.9 mm SL, right side, reversed: Gengma County: Qingshui River. D, ZMYU, young female, 50.0 mm SL; Canguyan County: Nangun River; E, ZMYU 80650, young female, 42.7 mm SL; Gengma County: Qingshui River.