Silurichthys ligneolus

description

Description. Biometric data are given in Table 1. Body laterally compressed. Head somewhat depressed. Dorsal profile straight, descending gradually from dorsal-fin origin to snout tip. 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, situated posteromedial to maxillary-barbel base. Eyes small, subcutaneous; located in anterior half of head; visible dorsally, not visible ventrally. Mouth subterminal; gape horizontal or very slightly oblique. Well-developed rictal fold present, consisting of large and fleshy upper lobe joined at corner of mouth with lower lobe; lower lobe subtended by short submandibular groove. Teeth villiform. Dentary teeth in slightly curved, elongate bands narrowing posteriorly, reaching from symphysis almost to mouth corners; premaxillary teeth in broader, slightly curved rectangular bands; vomerine teeth in a single crescent-shaped band. Maxillary barbels slightly flattened, reaching to anterior third of anal fin. One pair of mandibular barbels present; located slightly anterolateral to gular fold; barbels flattened for most

Silurichthys ligneolus, a new catfish (Teleostei: Siluridae) from southern Borneo, Indonesia

diagnosis

Diagnosis. Silurichthys ligneolus can be distinguished from all congeners except for S. sanguineus in having 3 – 4 (vs. 5 – 7) principal rays on the lower caudal-fin lobe. It differs from S. sanguineus in having (vs. lacking) pelvic fins, fewer anal-fin rays (44 – 45 vs. 60) and vertebrae (46 – 48 vs. 57). The following combination of characters additionally distinguishes it from congeners: body depth at anus 9.1 – 11.0 % SL, caudal peduncle depth 4.7 – 5.5 % SL, eye diameter 6.7 – 9.8 % HL, lower lobe of caudal fin indistinct, one gill raker on first branchial arch, and uniformly brown body.

Silurichthys ligneolus, a new catfish (Teleostei: Siluridae) from southern Borneo, Indonesia

distribution

Distribution. This species is known only from blackwater habitats in the Kahayan and Sebangau river drainages in southern Borneo (Fig. 2).

Silurichthys ligneolus, a new catfish (Teleostei: Siluridae) from southern Borneo, Indonesia

etymology

Etymology. The specific epithet comes from the Latin ligneolus, the diminutive form of the Latin noun ligneus, meaning wood. This name is used in allusion to the slender, uniformly brown body of this species (resembling a small piece of wood).

Silurichthys ligneolus, a new catfish (Teleostei: Siluridae) from southern Borneo, Indonesia