Hemibagrus divaricatus, Ng & Kottelat, 2013

Ng, Heok Hee & Kottelat, Maurice, 2013, Revision Of The Asian Catfish Genus Hemibagrus Bleeker, 1862 (Teleostei: Siluriformes: Bagridae), Raffles Bulletin of Zoology 61 (1), pp. 205-291 : 254-256

Hemibagrus divaricatus new species

( Fig. 34 )

Hemibagrus planiceps (non Valenciennes, in Cuvier & Valenciennes, 1840) - Sauvage, 1884: 219.

Mystus planiceps (non Valenciennes, in Cuvier & Valenciennes, 1840) - Herre & Myers, 1937: 68.

Mystus aff. planiceps – Zakaria-Ismail & Lim, 1995: 322, Pl. 4c.

Holotype. — ZRC 41151, 308.0 mm SL, Malaysia: Perak, Sungai Perak at Kampung Kenderong, 3 km from Gerik (5°24'52.5"N 101°9'5.1"E), coll. H. H. Ng et al., 21 Feb.1997.

Paratypes. — CAS 114179 , 1 ex., 277.7 mm SL, Peninsular Malaysia: Perak, Chenderoh Dam , coll. A. W. Herre, 18–23 Mar.1937 ; CAS 114252 , 1 ex., 262.0 mm SL, Peninsular Malaysia: Perak, Chenderoh Dam , coll. A. W. Herre, 19 Mar.1937 ; CAS 131002 , 1 ex., 164.3 mm SL, Peninsular Malaysia: Perak, Plus River near Kuala Legap , coll. M. W. F. Tweedie, Mar.1933 . MNHN 1884-96 , 2 ex., 134.2, 205.0 mm SL, Peninsular Malaysia: Perak, Kinta River at Pengkalan Pegoh, coll. J. Errington de la Croix , date unknown.

Diagnosis. — Hemibagrus divaricatus differs from all congeners in this species group except H. gracilis and H. velox in having a shorter adipose-fin base (11.1–15.5% SL vs. 15.1–21.1); the adipose fin is also relatively deeper compared to al species except H. planiceps (maximum height 1.9–3.2 times in length of base vs. 2.9–6.0). It is distinguished from H. gracilis in having a deeper caudal peduncle (7.3–8.0% SL vs. 6.2–7.5) and a smaller eye (11–17% HL vs. 17–21), and from H. velox in having a deeper caudal peduncle (7.3–8.0% SL vs. 6.2–7.6) and shorter inner mandibular barbels (37–44% HL vs. 42–57). Hemibagrus divaricatus further differs from H. bongan in having a smaller eye (11–17% HL vs. 16–20), from H. lacustrinus in having a shorter adipose-fin base (11.1–15.5% SL vs. 18.8–20.4), a longer dorsal to adipose distance (15.4–17.6% SL vs. 7.6–10.9; adpressed dorsal fin not reaching vs. reaching origin of adipose fin), and smaller eye (11–17% HL vs. 17–19), and from H. planiceps in having a smaller interorbital distance (28–32% HL vs. 32–37), longer dorsal spine (12.3–12.9% SL vs. 8.3–11.7) and maxillary barbels (214–250% HL vs. 148–220).

Description. — Biometric and meristic data as in Table 20. General description as for genus. Head depressed and broad,

body moderately compressed. Snout length 33–37% SL. Interorbital distance 28–32% HL. Eye diameter 11–17% HL. Dorsal profile rising evenly but not steeply from tip of snout to origin of dorsal fin, then sloping gently ventrally from there to end of caudal peduncle. Ventral profile horizontal to origin of anal fin, then sloping dorsally to end of caudal peduncle. Body depth at anus 11.7–13.9% SL. Adipose-fin base short, approximately as long as anal-fin base (11.1–15.5% SL); maximum height 1.9–3.2 times in length of base; separated from base of last dorsal-fin ray by distance of 4.0–17.6% SL. Dorsal spine stout, with 6–8 serrations on posterior edge; length 12.3–12.9% SL. Adpressed dorsal fin not reaching adipose-fin origin. Pectoral spine stout, with 22–23 large serrations on posterior edge; length 16.9–17.0% SL. Analfin origin slightly posterior to adipose-fin origin. Caudalpeduncle depth 7.3–8.0% SL. Caudal fin forked; upper lobe tapering with principal ray produced into a filament, lower lobe rounded posteriorly. Maxillary-barbel length 214–250% HL. Inner mandibular-barbel length 37–44% HL. Vertebrae 51. Branchiostegal rays 10–12. Maximum recorded size 308 mm SL.

Males with elongate genital papilla not reaching to origin of anal fin. Anus separated from genital appendages of both sexes by 5.2–7.6% SL.

Colour. — Dorsal surface of head and body uniform light grey to grey (live or freshly-dead specimens with yellowish hue, fading in preserved specimens); lateral line cream to yellow; ventral surface of head and body dirty white; adipose fin and fin rays of all fins grey; inter-radial membranes of all fins dirty yellow.

Etymology. — From the Latin divaricatus , meaning spread apart, in reference to the relatively large distance between the dorsal and adipose fins of this species.

Distribution. — Known from the Perak River drainage in western Peninsular Malaysia ( Fig. 32 ).

Figures

Fig. 34. Hemibagrus divaricatus, ZRC 41151, holotype, 308.0 mm SL, Peninsular Malaysia: Sungai Perak.

Fig.32. Map showing collection localities ofHemibagrus planiceps, H. bongan, H. divaricatus, H. gracilis, H. lacustrinus, and H. velox specimens examined in this study.