Dario urops , Britz, Ralf, Ali, Anvar & Philip, Siby, 2012
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Dario urops , new species
Holotype. CRG—SAC.2012.3.1, 23.8 mm SL, male; India: Karnataka: from a small unnamed stream, off the Barapole tributary of Valapattanam river, 12 °00.310’N 75 ° 53.408 ’E; 811m asl.; R. Raghavan et al., 30 Jan 2012.
Paratypes. CRG—SAC.2012.3.2–11, 10, 17.1–23.6 mm SL, same data as holotype. BMNH 1870.5. 2.9, 28.5 mm, Wynaad, India, F. Day. BMNH 1822.214.171.12493-7, 5, 16.4–23.6 mm, Wynaad, India, F. Day.
Diagnosis. Dario urops differs from all other species of the genus Dario by the presence of a conspicuous black caudal blotch on the caudal peduncle (vs. absence), by the presence of a horizontal suborbital stripe (vs. absence), by the anterior dorsal fin lappets in males not extending beyond fin spines (vs. extending considerably beyond spines), and by its vertebral count (14 + 14–15 = 28–29 vs 11–13 + 12–14 = 24–27). It differs further from D. dario and D. hysginon by the absence in males of a dark stripe along the anterior margin of the pelvic fin, and from D. dario by the absence of bars in males.
Body elongate, moderately laterally compressed. Predorsal contour straight to slightly convex, prepelvic contour convex, giving head a pointed appearance. Eye situated in anterior half of head, snout short. Mouth terminal. Angle of jaws situated at vertical through anterior third of eye. Dorsal contour of body slightly arched, convex, less so in females, ventral contour of body straight; both contours slightly converging towards caudal peduncle. Caudal peduncle only slightly attenuated posteriorly.
Lateral-line canal pores present only on head, absent from body. Head canal pores comprise: dentary pores 3 (d 1 –d 3), anguloarticular pore 1 (aa 2), preopercular pores 5 (p 1, p 2, p 4 –p 6), nasal pores 2 (n 1 –n 2), supraorbital pores 3 (f 1 -f 3), extrascapular pores 3 (ex 1 –ex 3), posttemporal pores 2 (po 1 –po 2), coronalis pore 1 (cor), lachrymal pores 2 (l 1, l 3); no infraorbital pores.
Scales ctenoid on sides, cycloid on top of head. Predorsal scales 5 anterior to coronalis pore, 9 posteriorly. Four rows of scales on cheek. Circumpeduncular scales 16. Tubed lateral-line scales absent. Scales in a longitudinal row 28. Scales in transverse row 10.
Dorsal-fin rays XIV+ 9 (11), XV+ 8 (3), or XV+ 9 (2). Anal-fin rays III+ 8 (14) or III+ 9 (3). Pectoral-fin rays 12 (11) or 13 (6). Pelvic-fin rays I+ 5 (17). Principal caudal-fin rays 7 + 7 (14) or 7 + 6 (3), with 4–5 dorsal and ventral procurrent rays.
Interradial membranes of spinous dorsal fin projecting as short fin lappets that do not extend much beyond tips of spines. Soft dorsal and anal fins with rounded tips, extending to base of caudal fin only. Pectoral fin reaching to vertical through base of sixth or seventh dorsal-fin spine. Pelvic fin pointed in males, rounded in females, reaching posteriorly to anus or anterior base of anal fin. Caudal fin rounded to subtruncate.
Vertebrae 14 + 14 = 28 (1) or 14 + 15 = 29 (5).
Coloration. In preservative ( Fig. 1View FIGURE 1), background colour beige to light brown with several dark brownish to black marks. Preorbital stripe dark brown, well developed in males, less conspicuous in females. Dark brown horizontal suborbital stripe extending from angle of jaw to vertical through posterior margin of orbit, less developed in females. Postorbital stripe dark brown, extending from upper posterior margin of eye towards nape beginning at 12 h to 13 h and running obliquely. Large dark brown blotch present on opercle, well developed in males but fainter in females, extended posterodorsally towards supracleithral area. No cleithral spot. Series of irregular dark marks along back reaching only two scale rows down. Base of each scale on sides of body with a darker area of denser melanophores forming narrow irregular zigzag-shaped bars on caudal peduncle. Prominent caudal blotch present separated from caudal peduncle bars by much lighter anterior halo-like area. Pectoral fin mostly translucent with few melanophores along fin rays and on fin membrane, all other fins dusky. Dorsal-fin and anal-fin membranes in spinous portions with dense aggregations of melanophores, less densely developed on soft fin membranes. Caudal fin with similar densities of melanophores on both fin rays and interradial membranes.
In life ( Fig. 2View FIGURE 2), background colour yellowish beige. Supraorbital and suborbital stripes prominent. Opercle with golden green iridescense covering opercular blotch, but supracleithral extension of blotch prominent. A number of dark brown scales distributed irregularly on nape, along base of dorsal fin along and on side of body. Caudal blotch not always conspicuous. All fins except pectoral fin with a bluish-gray hue.
Distribution. Dario urops has been collected so far only from a small stream of the Barapole tributary of Valapattanam River in southern Karnataka ( Fig. 3View FIGURE 3) and from an unspecified location in Wyanad. The Valapattanam is a westward drainage that flows into the Arabian Sea, while the district of Wyanad lies within the Cauvery basin, which drains eastward into the Bay of Bengal.
Etymology. The species name urops is derived from the Greek ουρά, tail and ὄψ, eye and refers to the conspicuous eye spot on the caudal peduncle. A noun in apposition.
Remarks. The unnamed stream in southern Karnataka from which D. urops was collected is a small clear water stream, up to 10 m wide and 2 m deep, with a bottom formed of a mixture of sand and mud and larger boulders ( Fig. 4View FIGURE 4). Large stands of the aquatic plant Lagenandra were growing out of the water. Dario urops was collected mostly from among bundles of tree roots hanging into the water along the edges of the stream and from thicker layers of leaf litter that had accumulated in low current depressions of the stream.
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