Paracanthocobitis triangula

Page, Lawrence M., 2017, A revision of the Paracanthocobitis zonalternans (Cypriniformes: Nemacheilidae) species complex with descriptions of three new species, Zootaxa 4324 (1), pp. 85-107: 101-103

publication ID

https://doi.org/10.11646/zootaxa.4324.1.5

publication LSID

lsid:zoobank.org:pub:101B3Cb2-7D7E-4232-A4E4-Fca46D90Fdbe

persistent identifier

http://treatment.plazi.org/id/03858783-FFFE-8E3E-58BF-FCA59699FD13

treatment provided by

Plazi

scientific name

Paracanthocobitis triangula
status

new species

Paracanthocobitis triangula  , new species

Wedged Zipper Loach

Fig. 10View FIGURE 10

Holotype. UMMZ 250272View Materials, 28.6View Materials mm SL, female, Bangladesh, Meghna drainage, 25.183N, 89.983E, 21 February 1978GoogleMaps  .

Paratypes. Bangladesh: Meghna drainage: CAS 235899View Materials, 1View Materials, 23.4View Materials mm SL, Sylhet, Nur Nody Stream, upstream from Lubha River at Nihalpur Village , 25.036N, 92.306E, 24 January 1998GoogleMaps  ; UMMZ 208784View Materials, 13View Materials (10 ex.), 25.8– 29.2 mm SL, same locality and date as holotypeGoogleMaps  ; UMMZ 208629View Materials, 1View Materials, 24.6View Materials mm SL, Sylhet, Dauki / Piyain Gang River , 25.101N, 91.753E, 19 February 1978; UF 188249View Materials, 3, 26.1–28.4 mm SL, same locality and date as holotypeGoogleMaps  .

Diagnosis. Paracanthocobitis triangula  is distinguished from all other species of Paracanthocobitis  by combination of incomplete lateral line ending near dorsal-fin insertion; 9½–10½ branched dorsal-fin rays; axillary pelvic lobe present; series of black blotches, sometimes overlain with faint dusky stripe along side of body not obscuring lateral blotches, ending just beyond dorsal-fin insertion; small black triangular  blotch in ocellus on upper margin of caudal-fin base; black pigment of the midlateral stripe not extending onto pectoral-fin base; no marmorated pattern between dorsal saddles and lateral blotches; dorsal saddles usually extending ventrally just past faint lateral stripe, usually connecting to lateral blotches; 8 branched upper caudal-fin rays.

Description. Meristic and morphometric data are in Tables 4 and 5. Body deepest just anterior to dorsal-fin origin; slightly compressed before dorsal fin, strongly compressed postdorsally. Head depressed, snout gently rounded to slightly pointed when viewed dorsally or laterally. Dorsal-fin origin far in front of pelvic-fin origin; distal margin convex. Pectoral fin not reaching pelvic fin; pelvic fin not reaching anal fin; caudal fin emarginate. Lateral line incomplete, reaching at most to just past dorsal-fin insertion with 20–37 pores. Axillary pelvic lobe present. Mouth arched with heavily papillated lips; upper lip with 3–5 rows of papillae, continuous with large pads on lower lip. Three pairs of barbels; inner rostral barbel extends to or slightly past base of maxillary barbel, maxillary barbel and outer rostral barbel extend to or slightly past eye. Body covered with scales; 9½ (1 specimens)–10½ (10 specimens) branched dorsal-fin rays; 9–10, usually 9, pectoral-fin rays; 6 pelvic-fin rays; 5½ branched anal-fin rays; 8 branched upper caudal-fin rays; 8 branched lower caudal-fin rays. Suborbital flap in male. Maximum SL 29.2 mm female.

Body yellow-brown with 10–12 dark brown to black blotches along lateral line sometimes overlain with faint dusky stripe not obscuring lateral blotches, ending just beyond dorsal-fin insertion; 12–14 small dark brown dorsal saddles uniform, equal to or wider than interspaces, usually extending ventrally just past lateral stripe and connecting to lateral blotches. Dark spots and blotches on head; uninterrupted black bar from eye to tip of snout.

Ocellus with small black triangular  blotch in center, near upper margin of caudal peduncle; 3–6 concentric rows of dark spots in dorsal fin, 2–3 rows of dark spots in anal fin, 4–6 dark bands on caudal fin. Black lateral stripe not extending onto pectoral-fin base.

Comparisons. Paracanthocobitis triangula  differs from all other species of Paracanthocobitis  except P. zonalternans  , P. phuketensis  , P. nigrolineata  , and P. marmorata  in having an incomplete lateral line ending near the dorsal-fin insertion (vs. lateral line to the end of the caudal peduncle) and 9½–10½ (vs.>10½) branched dorsal-fin rays. Paracanthocobitis triangula  differs from P. zonalternans  , P. phuketensis  , P. nigrolineata  , and P. marmorata  in having a small black triangular  (vs. circular or teardrop-shaped) blotch on the upper margin of the caudal-fin base. Paracanthocobitis triangula  further differs from P. zonalternans  in lacking black pigment extending from the lateral stripe onto the pectoral-fin base, from P. phuketensis  in having an axillary pelvic lobe (vs. usually absent, occasionally rudimentary), and from P. nigrolineata  in not having a black stripe along the side of the body with black pigment from the stripe extending onto the pectoral-fin base. Paracanthocobitis triangula  further differs from P. marmorata  in having an axillary pelvic lobe and in not having a marmorated pattern between the dorsal saddles and lateral blotches.

Distribution. Paracanthocobitis triangula  is known from the Brahmaputra (Jamuna) and Meghna drainages of Bangladesh ( Fig. 5View FIGURE 5).

Etymology. The epithet triangula  refers to the usual presence of a small black triangular  blotch in the ocellus on the upper margin of the caudal peduncle.