Dario neela

Britz, Ralf, Anoop, V. K. & Dahanukar, Neelesh, 2018, Dario neela, a new species of badid fish from the Western Ghats of India (Teleostei: Percomorpha: Badidae), Zootaxa 4429 (1), pp. 141-148: 142-146

publication ID

https://doi.org/10.11646/zootaxa.4429.1.6

publication LSID

lsid:zoobank.org:pub:7D49A6EE-B758-441D-9D0A-8A8A6F6FC19F

persistent identifier

http://treatment.plazi.org/id/1D70614D-CC1F-FFAC-E986-D145882F8DAF

treatment provided by

Plazi

scientific name

Dario neela
status

new species

Dario neela  , new species

Figures 1–2View FIGURE 1View FIGURE 2

Holotype. BNHSAbout BNHS FWF 612, 31.2 mm SL; India: Kerala: from a small unnamed stream between Periya and Boys Town, a tributary of the Kabini river , 11°49’27"N 75°51’45"E, 738 m asl; V.K. Anoop and Liju Thomas, 20 June 2016.GoogleMaps 

Paratypes. BNHSAbout BNHS FWF 613–623, 11, 16.6–28.5 mm SL, same data as holotypeGoogleMaps  . BNHS 624–625, 2, 21.5–21.7 mm SL, same data as holotype, but preserved in ethanolGoogleMaps  . BNHSAbout BNHS FWF 626–627, 2, 16.7– 7.8 mm SL, c&s, same data as holotypeGoogleMaps  .

Diagnosis. Dario neela  differs from all other species of the genus Dario  by the male colour pattern, which shows wide rims of iridescent blue in all median fins and the pelvic fin. It is further distinguished from all Dario  spp. except D. urops  by the number of abdominal vertebrae (14 vs. 11–13), and from all species of Dario  except D. urops  and D. huli  by the presence of a conspicuous black blotch on the caudal-fin base. It is distinguished from D. urops  by lacking the horizontal suborbital stripe (vs. having the suborbital stripe), and possessing a series of up to 8 black bars on the body (vs. 2–3 black bars restricted to the caudal peduncle). It differs from D. huli  by having more vertebrae (14+13–14=27–28 vs 13+13=26), 27 scales in a lateral row (vs. 25), absence of tubed lateral-line scales (vs. 3–5 tubed lateral-line scales) and by absence of teeth on hypobranchial 3 (vs. presence of teeth).

Description. For general appearance see Figs. 1–2View FIGURE 1View FIGURE 2; morphometric data are provided in Table 1.

Body elongate, moderately laterally compressed in males, nearly round in cross section in females. Predorsal contour convex, giving head a rounded appearance. Eye situated in anterior half of head. Snout short. Mouth terminal. Rictus situated at vertical through anterior third of eye. Dorsal contour of body almost straight; prepelvic contour slightly convex, continuing almost straight up to pelvic-fin origin, slightly concave in males between pelvic fin and anal fin, but straight to slightly convex in females; dorsal and ventral contours converging towards caudal peduncle. Caudal peduncle with parallel sides, tapering slightly posteriorly.

Lateral-line canal pores on head: dentary pores 3 (d2–d4), anguloarticular pores 2 (aa1–aa2), preopercular pores 5 (p1, p3–p5, p7), nasal pores 2 (n1–n2), supraorbital pores 3 (f1–f4), extrascapular pores 3 (ex1–ex3), posttemporal pores 2 (po1–po2), coronalis pore 1 (cor), lachrymal pores 2 (l1, l3); no infraorbital pores.

Scales ctenoid on sides, cycloid on top of head. Predorsal scales 4–5 anterior to coronalis pore, 9–10 posteriorly. Three to four rows of scales on cheek. Circumpeduncular scales 16. Tubed lateral-line scales entirely absent; instead lateral line represented by superficial neuromasts located in shallow central depression on 16–21 scales; however, one large male with a single tubed scale in second scale row behind posterior posttemporal canal opening (po2). Scales in lateral row 27. Scales in transverse row 1–2 small scales at anal-fin base plus 8 large scales on sides plus 2 small scales at dorsal-fin base.

Dorsal-fin rays XIII+8 (1), XIII+9 (2), XIV+8 (7), XIV+9 (2) or XIV+10(2). Anal-fin rays III+7 (3) or III+8 (11). Pectoral-fin rays 12 (10) or 13 (4). Pelvic-fin rays I+5. Principal caudal-fin rays 7+7 (14), 4 dorsal and 5 ventral procurrent rays (2). Vertebrae: 14+13=27 (1) or 14+14=28 (1). Caudal-fin skeleton consisting of one epural and two hypural plates, suggesting fusion of hypurals 1+2 and 3+4+5. Three slender supraneurals in front of dorsal-fin pterygiophores. Teeth present on vomer and palatine, on circular patch on posterior parasphenoid and on upper and lower pharyngeal jaws, but absent from hypobranchial 3 and basihyal. Seven elongate and pointed gill rakers on lateral face of lower limb of first branchial arch. Jaws with multiple rows of minute conical slightly recurved teeth.

Interradial fin membranes of spinous dorsal fin projecting as short fin lappets, which in males extend beyond tips of spines. Soft dorsal and anal fins with rounded (females) or slightly pointed tips (males), extending beyond base of caudal fin in males. Pectoral fin reaching to vertical through base of seventh dorsal-fin spine. Pelvic fin not reaching anus in juveniles and females, but reaching posteriorly to anus (in male holotype and 28.5 mm SL male paratype with apparently damaged fin tips) or beyond anterior base of anal fin (25.8 mm SL male paratype with undamaged fin). Caudal fin rounded to truncate. One female paratype (21.0 mm SL) with about 20 large ripe eggs in ovaries.

Colouration in alcohol. Colour pattern sexually dimorphic. Overall colouration in males dusky greyish black with up to seven black bars in posterior third of body starting at about vertical through anal-fin base ( Fig. 1 View Figure ). Preorbital stripe faint. Horizontal suborbital stripe absent. Dorsal part of head, black, much more darkly pigmented than cheeks. Opercular bones also with denser covering of melanophores appearing darker. All fin rays and fin membranes densely covered with melanophores appearing dusky greyish to blackish, including pectoral fin. Caudal-fin base with black blotch. Caudal fin with indistinct caudal fin band separated from caudal fin blotch by lighter area in front of it. Preorbital stripe present but faint; horizontal suborbital stripe absent. Dorsal part of head with dense aggregations of melanophores between eyes appearing darker than rest.

In females, background colour light beige. Body peppered with numerous scattered melanophores. Three to four darkly pigmented scales above pectoral fin separated from each other by lightly pigmented scale appearing as short midlateral bars or blotches. Posterior third of body with up to eight narrow bars expressed as zig-zagging black lines. Caudal-fin base blotch distinct and separated from posteriormost zigzagging bar by crescentic light area forming an anterior halo around caudal-fin blotch. All fin rays and membranes with peppering of melanophores, but pectoral fin only with rows of melanophores following margins of fin rays otherwise transparent.

Coloration in life. Males upon capture with blackish blue body and intensely light blue iridescent fins, faded when photographed in photo tank to greyish blue body colour and light bluish grey but still iridescent dorsal, anal, pelvic and caudal fins ( Fig. 2A View Figure ). Females with an overall light beige colour on body and transparent fins, with no striking markings compared to preserved specimens ( Fig. 2B View Figure ).

Geographical distribution. Dario neela  has been collected so far only from a small tributary of the headwaters of the Kabini River (part of the larger Cauvery river system) in northern Kerala ( Fig. 3 View Figure ). At the time of capture, the unnamed stream from which Dario neela  was collected was a small, clear-water stream, up to 1.5 m wide and 0.5 m deep, with a sandy bottom ( Fig. 4 View Figure ). The fish were collected along the edges of the stream from algal mats, in between stems and roots of Colocasia  ( Arecaceae  ) and from among bamboo branches hanging into the water. Associated species comprised: Schistura semiarmata  , S. denisoni  , and Devario malabaricus  .

Etymology. The species name neela  is derived from the Malayalam word mnoe, ‘Nīla’, for blue and alludes to the striking iridescent blue colour of males. A noun in apposition.

Molecular data. In the mitochondrial CO1 gene, the uncorrected p-distance between Dario neela  and its Western Ghats congeners D. urops  and D. huli  was 5.9% and 13.1%, respectively ( Table 2), and 19.6% between D. neela  and the Gangetic congener D. dario  .

BNHS

Bombay Natural History Society