Sisor torosus, Ng, 2003

Ng, H. H., 2003, A revision of the south Asian sisorid catfish genus Sisor (Teleostei: Siluriformes), Journal of Natural History 37 (23), pp. 2871-2883 : 2878-2880

Sisor torosus n. sp.

(figures 2d, 4d, 7)

Sisor rhabdophorus (non Hamilton, 1822): Day, 1877: 491, pl. 115, figure 1 (in part); 1889: 105, figure 43 (in part); Misra, 1976: 312, figure 54 (in part); Menon, 1977: 83 (in part);

Talwar and Jhingran, 1991: 681, figure 217 (in part); Jayaram, 1999: 301 (in part); Menon, 1999: 234 (in part); Karmakar, 2000: 34 (in part).

Material examined

H  . CAS 96629 , 94.9 mm SL; India: Bihar State, Ganges River at Patna ; T. R. Roberts, April to May 1996 .

P    . CAS 211744 , nine specimens, 57.4–94.9 mm SL; data as for holotype. AMS B7821, 89.1 mm SL; India: Delhi; F. Day collection . RMNH 8806 , 77.0 mm SL; India: Delhi; collector and date unknown .

Diagnosis

Sisor torosus can be distinguished from its congeners in having a relatively deep body (body depth at anus 6.0–7.8% SL vs 4.2–5.8), 29–34 and 12–18 serrations on the anterior and posterior edges of the pectoral spine, respectively. It can be further distinguished from S. rheophilus in having a wider nuchal plate (width 1.2–1.3 times length vs width equal to length; figure 2d).

Description

General appearance as for genus. In % SL: body depth at anus 6.0–7.8, predorsal length 30.5–32.3, preanal length 64.7–69.0, prepelvic length 33.8–36.6, prepectoral length 17.1–17.9, length of dorsal-fin base 11.4–14.3, length of dorsal spine 7.5–8.9, length of anal-fin base 7.3–9.0, length of pelvic fin 12.8–14.8, length of pectoral fin 19.9–21.2, length of pectoral spine 15.7–17.5, depth of caudal peduncle 1.4–1.8, length of caudal peduncle 22.6–27.5, length of caudal fin 11.1–12.9, head length 20.2–21.3, head width 14.1–15.7, head depth 7.7–8.2; in % HL: snout length 53.4–57.3, interorbital distance 19.0–23.4, eye diameter 6.9–10.9, length of maxillary barbel 52.6–70.3, length of inner mandibular barbel 25.3–43.1, length of outer mandibular barbel 50.3–58.9. Branchiostegal rays five (5) or six (1). Vertebrae 19 + 14 = 33 (1), 20 + 13 = 33 (3), 21 + 13 = 34 (1) or 21 + 14 = 35 (1). Lateral line ossicles 74–79. Nuchal plate with long and narrow central process, width 1.2–1.3 times length, (figure 2d).

Fin-ray counts: dorsal I, 5 (1) or I, 6 (5); pectoral I, 10 (2) or I, 10, i (4); pelvic i, 6 (6); anal ii, 4 (6); caudal 5/7 (6). Anterior edge of pectoral spine with 29–34 long and narrow serrations on anterior edge, and 12–18 smaller, more recurved serrations on posterior edge (figure 4d).

Etymology

From the Latin torosus , meaning stout, in reference to the relatively deep body of this species. Used as an adjective.

Distribution

Known from the middle part of the Ganges River basin in Bihar and Delhi States, India .