Clarias batrachus, (LINNAEUS, 1758)

Ng, Heok Hee & Kottelat, Maurice, 2008, The identity of Clarias batrachus (Linnaeus, 1758), with the designation of a neotype (Teleostei: Clariidae), Zoological Journal of the Linnean Society 153 (4), pp. 725-732 : 726-728

CLARIAS BATRACHUS ( LINNAEUS, 1758)

FIG. 1

Silurus batrachus Linnaeus, 1758: 305 (type locality: Asia, Africa).

Neotype: NRM 54718, 174.1 mm SL; Java: vicinity of Bandung; C. L. Hubbs, 22.v.1929.

Other material examined: UMMZ 155807 (3), 168.0– 215.0 mm SL; data as for neotype. UMMZ 70684 (1), 101.2 mm SL; Java: Kali Mandiku Jember. UMMZ 155704 (3), 193.1–206.2 mm SL; Java: vicinity of Bogor. UMMZ 155708 (3), 136.8–153.0 mm SL; UMMZ 155710 (5), 55.3–139.0 mm SL; UMMZ 155711 (5), 162.0–209.0 mm SL; Java: Ranu Lamongan, lake at Klakah. UMMZ 155709 (1), 172.2 mm SL; Java: Ranu Klidungan. UMMZ 155801 (1), 116.6 mm SL; Java: Cikedang, tributary to Citanduy, 1.5 km N of Ciawi. UMMZ 155802 (2), 128.7–131.9 mm SL; Java: Ciwalen, tributary of Citanduy at Godebak between Panaunbangan and Panjalu. UMMZ 155803 (5), 128.0–152.0 mm SL; Java: vicinity of Singaparna. UMMZ 155805 (3), 81.8–159.7 mm SL; Java: Citi’is (creek), just below road near mouth in Cimanuk, 3 km N of Garut. UMMZ 155806 (3), 153.6–183.9 mm SL; Diagnosis: Clarias batrachus is distinguished from all Asian congeners in having a narrow snout, in dorsal view with straight lateral outline and convex anteriorly ( Fig. 1 ). It can be further distinguished from all Asian congeners in having a unique combination of the following characters: 63–74 dorsal-fin rays (vs. 82–108 in C. nigricans , C. nieuhofii and C. pseudonieuhofii ; 56–63 in C. fuscus ), 47–58 anal-fin rays (vs. 56–96 in C. anfractus , C. nigricans , C. nieuhofii , C. pseudonieuhofii and C. sulcatus ), 54–60 vertebrae (vs. 61–71 in C. anfractus , C. batu , C. insolitus , C. leiacanthus , C. microstomus and C. planiceps ), distance between occipital process and dorsal fin 5.5– 8.9% SL (vs. 1.2–5.6% in C. intermedius , C. macrocephalus , C. meladerma and C. pseudoleiacanthus ; 9.9–13.1% in C. batu , C. insolitus and C. microstomus ), frontal fontanelle long and thin (vs. short and squat in C. anfractus , C. brachysoma , C. dussumieri , C. kapuasensis , C. leiacanthus , C. olivaceus , C. planiceps and C. pseudoleiacanthus ), anterior margin of pectoral spine rugose and with irregular bumps (vs. smooth in C. anfractus , C. kapuasensis and C. pseudoleiacanthus and with distinct serrations in C. brachysoma , C. dussumieri , C. fuscus , C. insolitus , C. intermedius , C. magur , C. meladerma , C. olivaceus and C. planiceps ).

Description: Biometric data as in Table 1 . Head depressed; dorsal profile slightly convex and ventral profile almost straight. Snout narrow, lateral outline straight and anterior outline convex when viewed dorsally. Bony elements of dorsal surface of head covered with thick skin; bones not readily visible, but sutures sometimes evident. Frontal fontanelle long and thin (‘knife-shaped’ of Teugels, 1986: 6); anterior tip reaching just posterior to line through posterior orbital margin. Occipital process rounded. Eye ovoid, horizontal axis longest, subcutaneous; located dorsolaterally on head. Gill openings narrow, extending from dorsalmost point of pectoral-fin base to isthmus. Gill membranes free from but united to each other across isthmus.

Mouth narrow and 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 posteriorly directed process. Premaxillary and dentary teeth viliform, vomerine teeth subgranular.

Barbels in four pairs; long and slender with thick fleshy bases. Maxillary barbel extending nearly to base of first dorsal-fin ray. Nasal barbel extending nearly to tip of occipital process. Inner mandibularbarbel origin close to midline; barbel thicker and longer than nasal barbel and extending to base of pectoral spine. Outer mandibular barbel originating posterolateral of inner mandibular barbel, extending to tip of pectoral fin.

Body cylindrical, becoming compressed towards caudal peduncle. Dorsal profile rising gently from tip of snout to origin of dorsal fin and thereafter almost horizontal to end of caudal peduncle. Ventral profile slightly convex to middle of head and thereafter almost horizontal to end of caudal peduncle.

Skin smooth. Lateral line complete and midlateral in position. Vertebrae 17 + 37 = 54 (1), 19 + 39 = 58 (2), 20 + 38 = 58 (2), 19 + 40 = 59 (1), 20 + 39 = 59 (5), 21 + 38 = 59 (2), 19 + 41 = 60 (1), 20 + 40 = 60* (3) or 21 + 39 = 60 (3).

Dorsal fin with long base, spanning posterior threequarters of body; with 63 (1), 64 (2), 65 (1), 66 (3), 67 (1), 68 (4), 69* (2), 70 (1), 71 (3) or 74 (2) rays covered by thick layer of skin and without spine. Dorsal-fin margin straight, parallel to dorsal edge of body. Anal fin with long base and 47 (1), 50 (1), 51* (6), 53 (4), 54 (2), 55 (2), 56 (1), 57 (2) or 58 (1) rays covered by thick layer of skin; margin straight and parallel to ventral edge of body. Dorsal and anal fins separate from caudal fin. Caudal fin rounded, with i,7,7,i* (16) or i,8,7,i* (4) principal rays.

Pectoral fin with small spine, sharply pointed at tip, and 8,i (20) rays. Anterior margin of spine rugose, with a series of low, irregular bumps. Pectoral fin margin straight anteriorly, convex posteriorly. Pelvic fin origin at anterior third of body, with i,5 (20) rays and convex margin; tip of fin reaching base of first few anal-fin rays. Anus and urogenital openings located at vertical through middle of pelvic fin.

Coloration: Dorsal and lateral surfaces of head and body grey to dark grey, fading to pale grey on ventral surfaces. Eleven to 15 vertical rows of two to five minute white spots present, subtended ventrally with an irregular row of minute white spots running just below lateral line. An additional irregular row or two of white spots sometimes present on body dorsal to anal-fin base. Dorsal and caudal fins grey to dark grey with very thin hyaline distal margin. Anal fin light grey, with thin hyaline distal margin. Pectoral-fin rays grey to dark grey, with hyaline interradial membranes. Pelvic fin hyaline. Barbels and pectoral spine grey to dark grey dorsally and light grey ventrally.

Distribution: Clarias batrachus is definitively known only from river drainages in Java. Records of C. batrachus from mainland Southeast Asia and the rest of Sundaic Southeast Asia are likely to refer to two separate, undescribed species (see Discussion). The species has been recorded from the Philippines, but we were unable to examine material to ascertain the identity of this population.

Figures

Figure 1. Clarias batrachus, neotype, NRM 54718, 174.1 mm SL. Dorsal, lateral and ventral views.