Comprehensive DescriptionRead full entry
Glyptothorax botius (Hamilton, 1822)
(Figs. 1 & 8)
Pimelodus botius Hamilton, 1822 ZBK : 192 (type locality: Pargong, fluviis Kamrupa borealis) .
Glyptosternum telchitta (non Hamilton) Day, 1877: 498, Pl. CXVI Figs. 2 & 2a; 1889: 199.
Glyptothorax telchitta (non Hamilton) Hora, 1923: 28; (?) Shaw & Shebbeare, 1938: 103, Fig. 105; Hora & Menon, 1949: 57 (in part); Menon, 1954: 42 (in part).
Material examined. ZRC 50223, neotype (herein designated), 74.6 mm SL ; ZRC 49129 (29), 25.6-71.0 mm SL ; UMMZ 244940 (2), 27.6-28.5 mm SL; India : west Bengal : Hooghly River at Kalna, 23°13'30.0"N88°22'39.0"E .
Diagnosis. Glyptothorax botius and G. telchitta can be distinguished from congeners in northeast India in having a combination of large, prominent tubercles on the head and body, a thoracic adhesive apparatus without a median depression, and a very slender body and caudal peduncle (sometimes described as “spindle shaped”). Glyptothorax botius differs from G. telchitta in having a more rounded snout when viewed laterally (Fig. 2), the presence (vs. absence) of dark saddles on the body, a thoracic adhesive apparatus with broader folds of skin (Fig. 3), a longer adipose-fin base (12.0-16.4% SL vs. 9.5-11.5) and a more slender caudal peduncle (3.1-4.2% SL vs. 4.7-5.9).
Description. Morphometric data in Table 1. Head depressed, body moderately compressed. Dorsal profile rising evenly from tip of snout to origin of dorsal fin, then sloping gently ventrally from there to end of caudal peduncle. Ventral profile flat to anal-fin base, then sloping gently dorsally from there to end of caudal peduncle. Caudal peduncle long and very slender. Anus and urogenital openings located at vertical through middle of adpressed pelvic fin. Skin prominently tuberculate, with ovoid tubercles particularly visible on sides of body. Lateral line complete and midlateral, delineated by series of closely spaced, conical tubercles. Vertebrae 13+21 (4), 14+20 (5), 15+19 (1), 14+21 (13), 14+22 (1), 15+20 (6) or 15+21 (2).
Head depressed and narrow, with rounded snout margin when viewed laterally (Fig. 2a). Snout prominent. Anterior and posterior nares large and separated only by base of nasal barbel. Gill openings broad, extending from immediately ventral to posttemporal to isthmus. Bony elements of dorsal surface of head covered with thick, tuberculate skin. Eye ovoid, horizontal axis longest; located entirely in dorsal half of head. Orbit with free margin.
Barbels in four pairs. Maxillary barbel long and slender, extending almost to base of pectoral spine. Nasal barbel slender, extending to one-third of distance between its base and anterior orbital margin. Inner mandibular-barbel origin close to midline, extending to midway between its base and that of pectoral spine. Outer mandibular barbel originates posterolateral of inner mandibular barbel, extending to two-thirds of distance between its base and that of pectoral spine.
Mouth inferior, premaxillary tooth band not exposed when mouth is closed. Oral teeth small and villiform, in irregular rows on all tooth-bearing surfaces. Premaxillary teeth in single broad semilunate band. Dentary teeth in two narrow crescentic bands separated at midline.
Dorsal fin located above anterior two-fifths of body, with I,5 (2), I,5,i (4) or I,6 (26) rays; posterior fin margin straight or slightly concave; spine moderately long, slender and gently curved, without serrations on anterior or posterior edges. Adipose fin with anterior margin slightly concave and posterior margin angular. Caudal fin strongly forked, with i,6,5,i (1), i,7,7,i (9), i,7,8,i (11) or i,8,7,i (11) principal rays, and subequal upper and lower lobes; lower lobe slightly longer and broader than upper lobe. Procurrent rays symmetrical and extending only slightly anterior to fin base. Anal-fin base slightly anterior to adipose-fin origin. Anal fin with straight anterior margin and slightly concave posterior margin; with iv,8 (1), iv,9 (12), iv,9,i (4), iii,10 (3) or iv,10 (12) rays. Pelvic-fin origin immediately posterior to vertical through posterior end of dorsal-fin base. Pelvic fin with slightly convex margin and i,5 (32) rays; tip of adpressed fin not reaching anal-fin origin. Pectoral fin with I,8 (5), I,8,i (21), I,9 (5) or I,9,i (1) rays; posterior fin margin slightly concave; anterior spine margin smooth, posterior margin with 5-12 serrations. Thoracic adhesive apparatus present, located on belly and consisting of broad longitudinal pleats of skin in narrow elliptical field. Adhesive apparatus without median depression and extending from just behind gill opening to immediately posterior to base of last pectoral-fin ray.
Coloration. In 70% ethanol: Dorsal and lateral surfaces of head, and dorsal surface of body very pale brown, fading to a lighter color ventrally. Occipital and opercular region with large darker brown patches. Ventral surface of head and belly yellowish. A series of narrow darker brown saddles along dorsal surfaces of body; saddles extending only to lateral line: 1) immediately posterior to base of last dorsal-fin ray; 2) immediately in front of and below anterior quarter of adipose-fin base; and 3) anterior half of caudal peduncle, immediately posterior to adipose-fin base. Faint darker brown spot at base of caudal peduncle. Dorsal-fin rays with evenly-distributed brown chromatophores along middle third of fin rays, imparting appearance of faint band across fin; all other parts of dorsal fin hyaline. Pectoral, pelvic and anal fins hyaline. Pectoral spine with slightly darker coloration on dorsal surface throughout most of its length. Adipose fin light very pale brown, with hyaline distal margin. Caudal fin hyaline, with brown chromatophores on median fin rays of each caudal lobe, imparting appearance of a broad brown band along each lobe. Other parts of caudal fin hyaline. Barbels yellowish.
Distribution. Known from the Ganges River drainage. Only material from the Hooghly River was examined for this study (Fig. 4).