Diagnostic Description
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Diagnosis: Hepsetus microlepis is distinguished from H. occidentalis by a larger internasal distance, 23-31% of head length vs. 20-25%, and smaller nostril-lower jaw distance, 35-44% of head length vs. 40-48%, both positively allometric characters; it is distinguished from H. odoe by a generally higher number of lateral line scales, 47-60 vs. 43-51, and by a uniform body colour vs. a vague stripe pattern from the adipose fin to the caudal fin; it is distinguished from H. kingsleyae by a greater internasal distance, 23-31% of head length vs. 16-23%, and a greater head width, 32-46% of head length vs. 26-36%, which are both positively allometric; it is distinguished from H. lineatus by a combination of characters: a higher number of epibranchial gill rakers on the first gill arch, 4-9, exceptionally 13, vs. 0-6, and a smaller distance between dorsal and adipose fin, 9.2-12.8% of standard length vs. 12.6-16.4%; Hepsetus microlepis also has a uniform body colour, whereas H. lineatus has a prominent stripe on its flanks; Hepsetus microlepis is distinguished from H. cuvieri by a higher number of gill rakers on the first arch, 13-14 vs. 8-13, and by a greater head width, 32-46% of head length vs. 29-40%, and also a greater internasal distance, 23-31% of head length vs. 19-26%, with the latter two being positively allometric (Ref. 108775).Description: Body elongate, greatest depth at or just anterior of dorsal fin origin; dorsal profile from the vertical through first series of scales to dorsal-fin origin mostly straight or slightly convex, straight along dorsal-fin base up to adipose fin; dorsal and ventral profile of caudal peduncle slightly concave; caudal peduncle somewhat longer than deep (Ref. 108775). Head large and broad, head width 32-46% of head length, with convex to straight profile; snout large and elongated; nostrils positioned just in front of eye, anterior one close to posterior, inter-nasal distance large, 23-31% of head length; mouth terminal with upper jaw slightly prognathous; maxillary bone fully toothed and reaching posterior margin of orbit; teeth in both jaws conical; premaxillary teeth in a single row; maxillary and dentary with two teeth rows, outer row with large, sharp teeth of variable size, inner row with small teeth of uniform size lying internal to a shallow trench; a pair of triangular dermic folds on lower jaw and small and rounded folds on upper jaw, variable in size; variation does not seem to be size or sex related (Ref. 108775). Dorsal and anal fins set well back on body, insertion of dorsal fin posterior to insertion of pelvic fin; dorsal fin margin slightly convex, margin of anal fin straight; caudal fin forked, with lobes of equal size; adipose fin inserted above posterior part of anal fin (Ref. 108775). Body covered with well-developed cycloid scales; lateral line completely pored, with a large range of lateral line scales, 47-60; large number of scale rows between dorsal fin and lateral line, 9.5-10.5; scale rows between lateral line and pelvic fin origin 4-6 (Ref. 108775). Between 13-24 gill rakers on first gill arch, with 4-13 on epibranchial and 8-12 on ceratobranchial; gill rakers long and slender (Ref. 108775). Vertebrae 39-40 excluding the Weberian apparatus (Ref. 108775).Colouration: Preserved specimens: overall body colour varying from light brown to blackish in most specimens; some specimens with light coloured ventral parts; fins brown to blackish, yellowish in light brown specimens; generally translucent distally; caudal fin light greyish to yellowish, translucent in mid-centre and central parts of upper and lower-lobes; dorsal, anal and caudal fins with prominent small, rounded, dark-brown spots, more obvious in larger individuals, more than about 155 mm standard length; adipose fin creamy basally, black distally; three well-marked, dark-brown bands radiate from infraorbitals behind eye over pre-operculum to operculum; a black dorso-ventrally elongated spot behind head above lateral line; in a few specimens, a series of 6-10 small greyish elongated vertical bars on body, first one situated just behind operculum and last one just anterior to caudal-fin base (Ref. 108775).
