Clarias insolitus

description

Description. Head depressed; dorsal profile slightly convex and ventral profile almost straight. Bony elements of dorsal surface of head covered with thick skin; bones not readily visible, but sutures sometimes evident. Anterior fontanel long and thin (“ knifeshaped ” of Teugels, 1986); anterior tip reaching just beyond line through anterior orbital margins. Occipital process acutely rounded. Eye ovoid, horizontal axis longest, subcutaneous; located dorsolaterally on head. Gill openings narrow, extending from dorsal-most point of pectoral-fin base to isthmus. Gill membranes free from isthmus but united to each other with 7 (n = 6) or 8 (n = 2) branchiostegal rays. First branchial arch with 2 + 10 (n = 2) or 2 + 12 (n = 6) gill rakers. Mouth subterminal, with fleshy, plicate lips. Oral teeth small and in irregular rows on all tooth-bearing surfaces. Premaxillary tooth band rectangular, with median notch on posterior edge. Dentary tooth band much narrower than premaxillary tooth band at symphysis, tapering laterally. Vomerine tooth band unpaired, continuous across midline, crescentic and smoothly arched along anterior margin, posterior margin with a median process. Premaxillary and d

Clarias insolitus, a new species of clariid catfish (Teleostei: Siluriformes) from southern Borneo.

diagnosis

Diagnosis. Clarias insolitus differs from other Southeast Asian Clarias [[ in having ]] hypertrophied sensory canal pores on the head and body easily visible to the naked eye (vs. sensory canal pores indistinct and not visible without magnification) and (except for C. batrachus) in having a long and thin (“ knife-shaped ” of Teugels, 1986) anterior fontanel [all other Asian species have a short and squat (“ sole-shaped ” of Teugels, 1986) anterior fontanel]. Clarias insolitus can be further distinguished from all other Southeast Asian Clarias (except for C. intermedius, C, meladerma, C. olivaceus, and C. planiceps) in having prominent serrations on the anterior edge of the pectoral spine (vs. anterior edge smooth or with low, indistinct asperities forming a rugose edge) and (except for C. olivaceus and C. planiceps) in lacking white spots on the body. Clarias insolitus further differs from C. intermedius and C. meladerma in having a longer distance between the tip of the occipital process and the base of the first dorsal-fin ray (10.3 - 12.4 % SL vs. 3.1 - 5.6) and a more slender body (9.9 - 11.5 % SL vs. 13.7 - 16.6), from C. olivaceus in having a more slender body (9.9 - 11.5 % S

Clarias insolitus, a new species of clariid catfish (Teleostei: Siluriformes) from southern Borneo.

discussion

Discussion Recent taxonomic studies on Southeast Asian Clarias have divided them into three species groups based on the distance between the tip of the occipital process and the base of the first dorsal ray and the relative length of the body as expressed by the number of dorsal- and anal-fin rays and vertebrae (Ng, 1999). Until a detailed phylogenetic study can be undertaken to ascertain if the species groups are indeed natural, this approach is not utilized here, largely because the characters that diagnose Clarias insolitus are highly distinctive and not seen in other Southeast Asian taxa. The color pattern of C. insolitus is also distinct in lacking white spots on the body. A color pattern consisting either of a uniform color or one with small, indistinct white spots is shared with only two other species of Southeast Asian Clarias, viz. C. batu and C. planiceps. However, C. insolitus can be distinguished from C. planiceps by the characters mentioned in the diagnosis and from C. batu by the number of vertebrae (61 - 63 vs. 67 - 71). Among other Southeast Asian Clarias, a long and thin anterior fontanel is only found in C. batrachus (Teugels et al., 1999), which can be easily dis

Clarias insolitus, a new species of clariid catfish (Teleostei: Siluriformes) from southern Borneo.

distribution

Distribution. Known from the upper Barito River drainage in southern Borneo (Fig. 3).

Clarias insolitus, a new species of clariid catfish (Teleostei: Siluriformes) from southern Borneo.