Erethistes Mueller & Troschel, 1849

Alfred W. Thomson & Lawrence M. Page, 2006, Genera of the Asian Catfish Families Sisoridae and Erethistidae (Teleostei: Siluriformes)., Zootaxa 1345, pp. 1-96 : 13-15

Erethistes Mueller & Troschel, 1849

Fig. 5

Erethistes Mueller & Troschel, 1849 : 12. (Type species: Erethistes pusillus Mueller & Troschel, 1849 , by monotypy. Originally proposed as a subgenus of Bagrus . Date may be 1845 as given by Kottelat, 1983). Gender masculine.

Hara Blyth, 1860 : 152. (Type species: “ Hara buchanani nobis; Pimelodus hara , B. H.” [= Pimelodus hara Hamilton, 1822 ], by original designation). Gender feminine.

Laguvia Hora, 1921b : 739. (Type species: Pimelodus asperus McClelland, 1844 , by subsequent designation. Type designated by Jordan, 1923). Gender feminine.

Diagnosis: No thoracic adhesive apparatus; robust (vs. slender) body; 8-12 anal rays; anterior margin of pectoral spine with serrations all pointing toward tip of spine, or arranged in divergent pairs, or outwardly directed and not divergent; smooth to granulate anterior margin on dorsal spine; papillate upper lip; 8-12 anal rays.

Erethistes is distinguished from Erethistoides by its more robust body (Fig. 5), and by the direction of the serrations on the anterior margin of the pectoral spine: all serrations point toward the tip, are arranged in divergent pairs, or are outwardly directed and not divergent (Fig. 6a & b); in Erethistoides , the serrations point toward the base of the spine in the proximal half and toward the tip in the distal half (Fig. 6c). Erethistes is distinguished from Ayarnangra by having 8-12 (vs. 13-16) anal-fin rays, a serrated (vs. granulate) anterior margin on the pectoral spine, and a more robust body (Fig. 5). Erethistes is distinguished from Conta , Caelatoglanis and Pseudolaguvia by the absence of a thoracic adhesive apparatus and by having moderate gill openings (vs. narrow and restricted to pectoral-fin base in Conta , and wide and nearly meeting on the venter in Caelatoglanis and Pseudolaguvia ). It is further distinguished from Conta by having a smooth to granulate (vs. serrated) anterior margin on the dorsal spine, and from Caelatoglanis by having a papillate (vs. plicate) upper lip.

Description: Dorsal fin with strong spine, 5-6 rays; pectoral fin with strong spine, 5 rays; 6 pelvic-fin rays; 8-12 anal-fin rays. Head large, broad; snout conical. Body moderately short, flattened (Fig. 5). Skin tuberculate or smooth. Eyes small to moderate, dorsolaterally situated slightly posterior to middle of head. Teeth in upper jaw villiform, arranged in three to four series; outer series more elongated. Teeth in lower jaw minute, scattered, arranged in crescent-shaped patch; palatal teeth absent. Maxillary barbel with well-developed membrane, soft base. All barbels annulated with black rings. Gill moderate extend onto venter; branchiostegal membranes broadly fused to isthmus. Pectoral girdle with long coracoid process. Pectoral spine serrated anteriorly and posteriorly. Dorsal spine smooth to granulated anteriorly, serrated posteriorly. No thoracic adhesive apparatus. Paired fins non-plaited.

Remarks: Hora (1950) restricted Erethistes to “forms in which the denticles on the outer edge of the pectoral spine are divergent” and recognized Hara for species in which the denticles on the outer edge of the pectoral spine “are pointed in one direction (backwards)”. Kottelat (1983) described Erethistes maesotensis with denticles on the anterior edge of the pectoral spine “being outwardly directed and not divergent,” placing it in Erethistes because “none of the differences between E. maestotensis and E. pusillus justify separating them at the generic level.” We agree with the view that the direction of the denticles on the anterior edge of the pectoral spine is an insufficient characteristic on which to separate genera. We have found no other differences to justify recognizing Hara and place it in the synonymy of Erethistes .

Ng & Kottelat (2005) synonymized Laguvia with Hara ; both herein become synonyms of Erethistes . Generic assignments of species described in Laguvia are discussed by Ng & Kottelat (2005).

Distribution: Ganges and Brahmaputra drainages in northern India and Nepal, east and south to the Salween drainage on the border of Myanmar and Thailand (Kottelat, 1983; Jayaram, 1999).