Badis rhabdotus

Kullander, Sven, Norén, Michael, Rahman, Md. Mizanur & Mollah, Abdur Rob, 2019, Chameleonfishes in Bangladesh: hipshot taxonomy, sibling species, elusive species, and limits of species delimitation (Teleostei: Badidae), Zootaxa 4586 (2), pp. 301-337: 322-325

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Badis rhabdotus

new species

Badis rhabdotus  , new species

( Fig. 11View FIGURE 11)

Holotype. DU 9035, male, 46.9 mm SL; Bangladesh, Sylhet Division: Sylhet District: Meghna River drainage, Pyain River at Jaflong , 25°11′4″N 92°0′59″E. M.M Rahman et al., 24 March, 2016.GoogleMaps 

Paratypes. DU 9036, 1, 34.6 mm SL  ; DU 9037 [ex NRMAbout NRM 69035View Materials (11525], 1, 27.5 mm SL; NRMAbout NRM 68599View Materials, 4View Materials, 37.2View Materials.– 39.6 mm SL; NRMAbout NRM 69034View Materials, 1View Materials, 39.7View Materials mm SL; collected with the holotype. NRMAbout NRM 51432View Materials, 1View Materials, 51.2View Materials mm SL; NRMAbout NRM 70335View Materials, 2View Materials, 37.5View Materials 38.4View Materials mm SL; India: Meghalaya: Wanapha River at Ummulong; H. Bleher, Sep 2009. 

Diagnosis. Similar to B. badis  , B. chittagongis  , B. ferrarisi  , B. kanabos  , B. khwae  , B. pallidus  , B. ruber  , B. siamensis  , B. soraya  , tuivaiei  , and different from all other species of Badis  in the presence of a dark blotch on the exposed cleithrum. Distinguished from B. khwae  , B. ruber  , and B. siamensis  , in the absence of dark blotch dorsolaterally on the caudal peduncle. Distinguished from B. ferrarisi  by the absence of short black bars along the middle of the side, and absence of a dark blotch on the gill cover. Distinguished from B. tuivaiei  in the absence of a black blotch anteriorly on the dorsal fin, curved vs. straight vertical bars, and lower meristic values (28–29 vertebrae vs. 30–31; lateral scale row 27–29 vs. 26–32, modally 30; dorsal-fin rays XVI.8½ or XVII.7½–8½ vs. XVI.9-10, XVII.8, XVIII.8 and modally XVIII.9); from B. kanabos  by the absence of black spot anteriorly on the dorsal fin, and from B. Badis  by narrower interorbital space (4.8–5.5% SL vs. 6.5–8.3%, and more slender body (25.7–32.0% SL vs. 30.7–38.9%; not corrected for allometry). Similar only to Badis soraya  in the presence of intense black narrow vertical bars on the sides in males, vs. indistinct or absent vertical bars on the sides, or vertical bars present but wide, not contrasting; vertical bars narrow, unpaired in both sexes, distinguishing from juvenile bar pattern in Badis  , which consists of pairs of narrow bars. Distinguished from B. chittagongis  and B. pallidus  , particularly by the colour pattern of prominent narrow vertical stripes, vs. wide vertical bars or uniform sides. Distinguished from B. soraya  by meristic values (vertebrae 28–29 vs. 27; lateral scales 28–29, exceptionally 27 vs. 25–27; dorsal-fin rays XVII.9–10, exceptionally XVI.9, vs. XIV.9–XVI.11,modally XV.10), and proportional measurements (narrower interorbital width, 4.8–5.5% SL vs. 6.3–8.8% SL; averaging lesser body depth, 25.7– 32.0%SL vs. 29.6–35.5%; not corrected for allometry).

Description. Based on Bangladeshi specimens. Proportional measurements are given in Table 5; selected meristics in Tables 6–7). Moderately elongate, strongly compressed laterally. Predorsal contour straight or slightly curved, sloping at same angle as slightly curved prepelvic contour, or steeper. Orbit situated in anterior half of head and level of midaxis of body. Jaws about equal anteriorly, lower jaw only slightly projecting before upper; maxilla reaching slightly posterior of vertical through anterior margin of orbit. Lower jaw articulation below middle of orbit. Well-developed tooth-patches on parasphenoid, basibranchial 3, basihyal, palatine and vomer. Dentary pores 3; anguloarticular pores 2; preopercular pores 7; nasal pores 2; supraorbital pores 3; extrascapular pores 2; supracleithral pores 2; posttemporal pores 2; coronalis pore; lachrymal pores 3; a row of free neuromasts across gap between lachrymal and anteriormost infraorbital; infraorbital pores 4.

Scales in lateral row 27 (1), 28 (5). Lateral-line scales 19/4, 21/5, 22/6, 23/6, 24/5, 25/5 (one of each). Predorsal scales 11 (2), 12 (3), 14 (1). Circumpeduncular scale rows 18 (6). Scales between first dorsal fin-spine and upper lateral line 3, posteriorly 1½ scales between dorsal-fin base and upper lateral line; full-size scales between first anal-fin spine and upper lateral line 6 (1), (7 (5). Scale rows on cheek 4, on opercle 5, on subopercle 1 (8 scales), on preopercle 1 (4 scales), on interopercle 1 (6 scales). From about fifth dorsal-fin spine, dense layer of small rounded scales, 3 on each interradial space, covering spinous dorsal-fin base up to at most middle of fin height; on base of soft dorsal fin, scales smaller, up to 7 scales in an interradial space. Anal fin from behind third spine to anterior soft rays with narrow layer of small, rounded scales, one to five in each interradial space. Caudalfin base densely scaled, up to about 10 scales on middle rays.

Dorsal-fin rays XVI.8.5 (1), XVII.7½ (1), XVII.8½ (6), XVII.9½ (1). Soft anal-fin rays 6½ (3), 7½ (5). Soft dorsal and anal fins with rounded or subacuminate tip, reaching to or slightly beyond base of caudal fin; dorsal fin slightly longer in largest male, not quite reaching to middle of caudal fin. Caudal fin rounded; principal caudal-fin rays 14 (6). Pectoral-fin rays (11 (1), 12 (2), 13 (5). Pectoral fin rounded, not reaching posteriorly to tip of pelvic fin. Pelvic fin with point formed by second soft ray, reaching more than halfway to vent.

Ceratobranchial gill-rakers 6 (6). Supraneurals 3 (6), vertebrae 15+13=28 (2), 15+14=29 (4).

Colouration in preservative. Ground colour pale beige or brown. Three scales in oblique row posterodorsally from orbit at about 1400h position black in preserved specimens, iridescent dark green in living specimens. Suborbital and preorbital stripes dark grey or brown. Tip of maxilla pale grey or white. Top of head and occipital region medially dark brown. Spot covering exposed part of cleithrum black in preserved specimens, iridescent dark green in living specimens. Cheek pale brown, gill cover dorsoposteriorly darker brown than cheek. Seven or eight distinct narrow, deep black vertical bars from about level of tip of pectoral fin to middle of caudal peduncle, each bar 1–2 scales in width, formed by dark scale margins. Posterior bars distinctly curved, concave caudad. Posteriormost bar encircling caudal peduncle; three bars anterior to that extending between dorsal vertical fin bases, remaining bars reaching to dorsal-fin base but ventrally only to level of pectoral fin base. Anteriorly on side, scattered scales with dark margins not forming bars, or only partial bars. Bars more intensely pigmented and distinctly undulating in males. Dorsal fin basally black, rest of spinous dorsal fin brown, soft fin brownish grey; each dorsal-fin lappet with white margin and narrow black submarginal streak. Anal and caudal fins pale grey. Pectoral fin hyaline. Pelvic fin grey with white leading edge. Black square or slightly elongate blotch at base of caudal fin. Dorsally and ventrally on side of caudal fin base a dark brown blotch varying in shape from round to elongate. Genital papilla black in females; black proximally in males. Ethanol-fixed specimens retain traces of red or maroon pigmentation on sides, between bars ( Fig. 11CView FIGURE 11).

Specimens from Meghalaya. Four specimens from Ummolong in Meghalaya agree with B. rhabdotus  from Bangladesh in meristics, colour pattern and mitochondrial DNA sequences, but are in a poor state of preservation, and data could not be obtained for all characters. They have 28 (2) or 29 (1) lateral row scales. Two radiographed specimens have 14+13 (1) or 15+14 (1) vertebrae.

Etymology. Named rhabdotus  , from the Greek ῥαβδωτóς, meaning striped, with reference to the prominent vertical bars characterizing this species. An adjective with alternative endings, -a, -um.

Geographical distribution and habitat. In Bangladesh, specimens were sampled from a shallow sandy beach in a heavily converted area on the right bank of the Pyain River at Jaflong ( Figs 3View FIGURE 3, 12View FIGURE 12). The site had some aquatic vegetation, but was otherwise bare. Seining in the main river, with a rocky bottom and current, did not yield any specimens of Badis  . The sampling was made at the extreme low water season and may not have been characteristic of the biotope of the species. Georeferenced GenBank sequences ( Fig. 1View FIGURE 1) show that B. rhabdotus  has a wide distribution in the Meghna River basin, including the lower Barak River, tributaries in southern Meghalaya, distant Karnafuli headwaters, and possibly the Madopkundo Falls in Bangladesh.


Swedish Museum of Natural History - Zoological Collections