Ompok brevirictus

description

Description. Biometric data in Table 1. Body laterally compressed; maximum body depth located below dorsal-fin origin; head as broad as body and slightly depressed. Dorsal profile of head very gently convex. Anterior profile of snout rounded. Anterior pair of nostrils tubular and anteromedial to maxillary barbel base. Posterior pair of nostrils bordered by fleshy dorsal and ventral membranes and posteromedial to maxillary barbel base. Mouth terminal; gape almost horizontal, large and extending between anterior orbital margins. Welldeveloped rictal lobes present, subtended by deep submandibular groove; upper rictal lobe without skin fold. Thin, broad supralabial fold extending from below orbit to maxillary barbel base. Mouth rictus separated from anterior orbital margin by more than one-third eye diameter. Jaw teeth depressible, villiform. Premaxillary teeth in narrow, gently curved rectangular bands. Dentary teeth in similar, slightly narrower bands narrowing posterolaterally, reaching from symphysis almost to mouth corners. First row of dentary teeth slightly visible with mouth closed. Palatal teeth in two gently curved arcshaped patches on either side of midline. Two pairs of bar

Ompok brevirictus, a new catfish (Teleostei: Siluridae) from Sumatra

diagnosis

Diagnosis. Ompok brevirictus can be distinguished from all Southeast Asian congeners, except for O. siluroides and O. miostomus, in having melanophores on the tympanic region forming a prominent black spot (vs. tympanic region dark, but without any melanophores forming a distinct spot). It differs from O. siluroides and O. miostomus in having an evenly convex predorsal profile (vs. with a concavity posterior to orbit) and a more prominent lower jaw that is more broadly curving. Ompok brevirictus additionally differs from O. siluroides in having the mouth rictus separated from the anterior orbital margin by a distance of more than one-third (vs. less than one-third) eye diameter (4.2 – 5.2 % HL vs. 3.2 – 3.7) and lacking (vs. possessing) a distinct dark wedge-shaped spot on base of the caudal fin.

Ompok brevirictus, a new catfish (Teleostei: Siluridae) from Sumatra

distribution

Distribution. Known from the short coastal rivers that drain the western face of the Leuser Mountain Range in northern Sumatra, including the Kreung Kluet (Kluet River) drainage (Fig. 2).

Ompok brevirictus, a new catfish (Teleostei: Siluridae) from Sumatra

etymology

Etymology. From the Latin brevis meaning short, and rictus meaning an open mouth. The name is used in reference to the relatively short mouth of this species (correspondingly causing the mouth rictus to be separated from the anterior orbital margin by a distance of more than one-third eye diameter).

Ompok brevirictus, a new catfish (Teleostei: Siluridae) from Sumatra