Pycnocraspedum squamipinne Alcock, 1889

Teena, Jayakumar T. K., Murugan, A., Kumar, Ajith T. T. & Lal, Kuldeep K., 2021, Redescription of a rare cusk eel, Pycnocraspedum squamipinne (Actinopterygii, Ophidiiformes, Ophidiidae), from Bay of Bengal, Acta Ichthyologica et Piscatoria 51 (1), pp. 77-83 : 77

Pycnocraspedum squamipinne Alcock, 1889

Figs 1 , 2 , 3 , 4

Pycnocraspedum squamipinne Alcock, 1889 (Type locality: Bay of Bengal, 20°17'30"N, 88°50'E)

Materials examined.

INDIA 1; Syntype of P. squamipinne (TL = 291 mm); Bay of Bengal ; 20°17'30"N, 88°50'E R.I. M.S. Investigator coll. leg.; ZSI F11700 1 ; Syntype of P. squamipinne (TL = 299 mm) same collection data as preceding; ZSI F 11703 (1, 299 mm TL) .

INDIA 5; Chennai coast, Tamil Nadu; March 2018; Teena Jayakumar T.K and T.T Ajith Kumar leg.; NBFGR / OPHPSQU1 to 5 • 10; same collection data as for preceding; NBFGR / CE1 to 10 .

Diagnosis.

Deep bodied cusk eel with head 3.0-3.9 times in SL; eye diameter 5.5-6.8 in HL; interorbital 4.8-6.3 in HL; snout 3.8-5.2 in HL; depth 4.3-6.8 in SL; predorsal length 3.3-4.7 in SL, distance between pelvic origin to anal origin 2.5-4.4 in SL; no pseudobranchiae and 12-13 pyloric caeca. Two median basibranchial tooth patches. Single opercular spine and 3 short blunt spines at lower angle of preopercle. Pycnocraspedum squamipinne differs from its congeners in origin of dorsal fin above preopercle, absence of pseudobranchial filaments, pectoral fins and pelvic fins short and not reaching anus.

Description.

Body compressed, moderately deep and tapers caudally, its depth 4.3-6.8 in SL (Fig. 1 ). Body covered by small cycloid scales. Head large, compressed, fully scaled except lips, head length 3.0-3.9 in SL. Eye diameter 15.2%-18.4% HL; preorbital length 19.2%-23.6% HL and postorbital length 61.9%-72.7% HL. Head length in preanal distance 1.6-1.9. Anterior nostril tubular, behind snout rim with small skin flap, smaller than posterior nostril being simple pore in front of eye. Eyes moderately large, elliptical, snout length greater than diameter of eye, interorbital space wide equal to or slightly greater than eye diameter. Mouth large and oblique, snout blunt, maxilla extending beyond posterior margin of eye, wide posteriorly. Granular teeth in bands in jaws, vomer and palatines, vomerine tooth-patch narrow, v-shaped, tongue pointed, reaching below vomer. Median basibranchial with elongate tooth patch from first gill arch to third and second small tooth patch near fourth gill arch followed by pair of teardrop-shaped (rounded anteriorly and pointed posteriorly) lower pharyngeal tooth patches (Fig. 2 ). Sagittal otolith long and oval (Fig. 3A, B ). Ratio of length to height ranging from 2.4 to 2.9 times; length to thickness from 5.9 to 7.4 times. Pseudobranchial filaments absent. Developed gill rakers 4 on first gill arch, having small granular teeth (Fig. 3C ). Branchiostegal rays 8; 6 in ceratohyal and 2 on epihyal. Opercle thin, soft with weak posterodorsal spine, three broad and blunt spines at lower angle of preopercle. Origin of dorsal fin above hind margin of preopercle. Pectoral fins elongate with prominent skin flap above its base but not reaching anus. Pelvic fins united basally and separated distally. Caudal distinguishable from dorsal and anal by closer grouping of last 10 rays. Lateral line well developed, terminating at point about length of postorbit from caudal fin base. Stomach black with 13 long and finger-like pyloric caeca. Total of 12 precaudal vertebrae and 47-49 total vertebrae number (Fig. 4 ). Meristic and morphometric characters of the specimen are presented in Tables 1 , 2 .

Color.

Body greyish brown but on ventral side dull silvery brown. Body without markings or spots. Distal margins of dorsal and anal fins dark black, ground color of dorsal and anal fin pale brown. Pectoral fins thick black but base of the pectoral light grey. Pelvic fin rays white with blackish tinge. Lateral line with blackish tinge. Orobranchial cavity greyish white, peritoneum black.

Figures

Figure 1. (A) Pycnocraspedum squamipinne, 40.3 cm TL, off Chennai coast, Bay of Bengal; (B) Pycnocraspedum squamipinne syntype 29.9 cm TL, ZSI F 11703, Bay of Bengal.

Figure 2. (A) Basibranchial tooth patches of Pycnocraspedum squamipinne, 29.8 cm SL, scale bar = 1 cm; (B) Dentition in jaws premaxillary, vomerine, palatine, dentary, and basibranchial tooth patches, scale bar = 1 cm.

Figure 3. Pycnocraspedum squamipinne, 20 cm SL (A) left sagitta, (B) right sagitta; (C) First gill raker of Pycnocraspedum squamipinne, 29.8 cm SL, scale bar = 1 cm.

Figure 4. Radiograph of Pycnocraspedum squamipinne, 38 cm SL.