Devario ahlanderi, Kullander & Norén, 2022

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 : 61-64

Devario ahlanderi , new species

Type series. Holotype, NRM 57999 ( Fig. 4 A ), adult female, 65.2 mm SL; Myanmar: Shan State: stream close to Naung Al Village, about 6 miles (9 km) east of Kak-ku, 2026’5’N, 9713’2’’E; Thein Win and Thein Tan , 13 March 2008 . Paratypes listed in Appendix 1.

Definition. Distinguished from all other species of Devario by the modification in adults of the anterior half of the P stripe into a series of short irregular bars or spots.

Description of type series. Morphometric and meristic data are given in Appendix 2.

Body laterally compressed, elongate, sexes not significantly different in body depth, but sample small. Predorsal contour straight ascending or with minor indentation above orbit, dorsal contour sloping posterior to posterior dorsal-fin insertion. Prepelvic contour strongly curved, more so in females; chest conspicuously more 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 usually slightly irregular, not projecting from skin. Danionine notch caudally margined by well-developed anteromediad projecting laminar dentary process. Skin cover absent from distal part of dentary process. Mouth terminal, directed obliquely upwards. Bony knob at dentary symphysis minor, fitting in shallow depression in upper jaw. Maxilla reaching to below anterior margin of orbit. Jaws equal anteriorly; lower jaw ending anteriorly at horizontal through middle of eye. Three specimens, 42.2–56.9 mm SL identified as adult males by presence of irregular band or two distinct rows of short tubercles along orad margin of dentary and presence of dense bands of sharp tubercles on pectoral-fin rays. Tubercles absent from lower jaw in holotype and remaining paratypes. Rostral barbel short, reaching to junction of lacrimal and first infraorbital; maxillary barbel much shorter.

Pharyngeal teeth in three rows: 5,42,2,4,5 (one specimen dissected).

Lateral line complete, along 31–34 scales; comprising one tubed scale followed by a canal running steeply caudoventrad under unperforated scales to slightly posterior to pectoral-fin base, where curved caudad and represented by scales with indistinct or absent perforation anteriorly, becoming 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; vertical section represented by about six scales. A row of scales covering anal-fin base. About ¼ of caudal-fin length scaled basally.

Dorsal fin inserted at highest point of dorsum, distinctly 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 well developed. Pelvic fin inserted slightly anterior to midbody, not reaching to anterior insertion of anal fin. Pelvic axillary scale present. Caudal fin forked, lobes of about equal length, tips rounded.

Colouration in preservative. Dorsum pale grey, dark grey line from occiput to base of upper caudal fin rays; sides off-white, chest and abdomen off-white or yellowish white depending on conservation. Opercle silvery, powdered with scattered melanophores; a brown patch dorsally. Dark brown vertically oriented cleithral spot covering part of first lateral-line scale and scale above.

Adult flank colour pattern ( Fig. 4 ) varying with specimen size, and slightly on each side. Adults with black P stripe along middle of side from slight widening at end of caudal peduncle, running cephalad with irregular margins and increasing slightly in width anteroposteriorly; from about level of dorsal-fin anterior insertion replaced by black, irregularly shaped spots (rounded or as short vertical bars); anterior two spots much lighter and smaller than remainder. P-1 stripe narrower than P stripe; irregular, brown, extending from end of caudal peduncle cephalad to about vertical from anterior insertion of dorsal fin, where broken up in irregular spots paralleling or interdigitating with P stripe spots. P-2 stripe indistinct, grading into light abdomen. P+1 stripe extending from end of caudal peduncle, narrower than P stripe but wide medially and tapering in width at ends; consisting of brown blotches paralleling or interdigitating with P stripe blotches. Dorsal fin distally without pigment, basally light grey, translucent. Anal fin not pigmented. Middle rays of caudal fin light grey, fading posteriorly on fin. Pelvic fin white, translucent.

Juveniles similar to adults, but spotted pattern absent ( Fig. 6 ). Smallest juveniles available 20 mm, with pale brown mid-dorsal stripe, black line along middle of side, and suffused brown or grey pigmentation on lower flank. At about 30 m SL, wide brown P stripe, slightly increasing in width anteriorly, with contrasting marginal interstripes. At about 40 mm SL each specimen with unique colour pattern with irregular bars or small spots anteriorly in the P stripe, and the marginal stripes continuous or not in front of the P stripe.

Geographical distribution and habitat. Devario ahlanderi is known only from two small streams near Taunggyi ( Figs 1 ). The type locality was a small shaded stream 100% shaded by bamboo trees. Devario jayarami was collected together with D. ahlanderi , and Devario sondhii was available in the Taunggyi market together with D. ahlanderi (Appendix 1). Other syntopic species were identified as Lepidocephalichthys berdmorei , Pethia stoliczkana , Danio margaritatus , and Trichogaster trichopterus .

Explanation of the specific name: The specific name is a noun in the genitive case. The species is dedicated to Erik Åhlander, long time Senior Assistant in the ichthtyology and herpetology collection of the Swedish Museum of Natural History, and a key person in the successful development and operation of ichthyology at the NRM.

Figures

FIGURE 1. Map of sampling sites of Devario ahlanderi, D. browni, Devario cf. browni, and D. kysonensis.

FIGURE 4. Devario ahlanderi. All from Myanmar, Shan State, Salween River basin. A, holotype, NRM 57999, adult female, 65.2 mm SL; stream close to Naung Al Village, about 6 miles (9 km) east of Kak-ku. B, paratype, NRM 58062, adult male, 56.9 mm SL, same locality as holotype; C, paratype, NRM 58061, adult female, 55.6 mm SL; small stream running under Naung Pic bridge near Naung Pic Village, on the way from Kak-ku to Taunggyi.

FIGURE 6. Devario ahlanderi, subadult paratypes. A, 42.0 mm SL; B, 36.9 mm SL; both from Myanmar, Shan State, small stream running under Naung Pic bridge near Naung Pic Village, on the way from Kak-ku to Taunggyi.