Pseudomystus funebris, Ng, 2010

Ng, Heok Hee, 2010, Pseudomystus Funebris, A New Species Of Catfish From Borneo (Teleostei: Bagridae), Raffles Bulletin of Zoology 58 (1), pp. 87-91 : 87-90

Pseudomystus funebris new species

( Figs. 1, 2a , 4a )

Material examined. – Holotype: MZB 17181, 41.8 mm SL, Borneo : Kalimantan Tengah , Rungan River drainage in the vicinity of Tangkiling, 2°1'S 113°44'E, coll. P. Yap, 22 Oct. 2007.

Paratypes: MZB 17182, 11 ex., 30.7–37.7 mm SL ; UMMZ 248771 , 12 ex., 28.6–50.0 mm SL, locality as for holotype, P. Yap, 3 Dec. 2007 . ZRC 51845, 13 ex., 30.8–40.6 mm SL; data as for holotype ; ZRC 51846, 4 ex., mm SL; locality as for holotype, coll. P. Yap, 21 Jan. 2009 .

Diagnosis. – Pseudomystus funebris can be distinguished from congeners except for P. heokhuii (from Sumatra) in having a colour pattern consisting of a pale midlateral stripe and two pale oblique bands on the sides of the body. It differs from P. heokhuii in having a shorter adipose-fin base (14.2–17.7% SL vs. 18.2–22.8), more slender caudal peduncle (7.3–8.9% SL vs. 8.8–10.5), wider head (24.4–26.2% SL vs. 21.7–23.8) and larger eye (11.2–14.7% HL vs. 8.5–10.7) and a slightly convex (vs. evenly sloping or slightly concave) predorsal profile ( Fig. 2 ). Additional characters for distinguishing P. funebris from congeners are mentioned in the Discussion.

Description. – Biometric data as in Table 1. Head depressed; dorsal profile slightly convex and ventral profile almost straight; snout acutely rounded or truncate when viewed dorsally. Bony elements of dorsal surface of head covered with thin skin; bones visible, especially on posterior half of neurocranium, and ornamented with numerous fine, radial grooves. Midline of cranium with fontanelle extending from behind snout to just beyond level of posterior orbital margin. Supraoccipital process moderately broad, with gently converging sides and blunt tip; extending to nuchal plate. Supratemporal with short posterior process, about half as long as postcleithral process. Eye ovoid, horizontal axis longest, subcutaneous; located entirely in dorsal half of head. Gill openings wide, extending from post-temporal to beyond isthmus. Gill membranes free from isthmus, with 8 (20) branchiostegal rays. First branchial arch with 3+7 (2), 4+6 (1), 3+8 (6) or 4+7* (1) gill rakers.

Mouth subterminal. Oral teeth small and viliform, in irregular rows on all tooth-bearing surfaces. Premaxillary tooth band in a shallow arc, of equal width throughout. Dentary tooth band much narrower than premaxillary tooth band at symphysis, tapering laterally. Vomerine tooth band unpaired, continuous across midline; smoothly arched along anterior margin, of equal width throughout and wider than premaxillary band; band narrower than premaxillary band at midline, widening laterally and then tapering to a sharp point posterolaterally.

Barbels in four pairs. Maxillary barbel slender, extending to middle of pectoral-fin base. Nasal barbel slender, extending to dorsal insertion of opercle. Inner mandibular-barbel origin close to midline; barbel thicker and longer than nasal barbel and extending for two thirds of head length. Outer mandibular barbel originating posterolateral of inner mandibular barbel, extending to base of pectoral spine.

Body slightly compressed, becoming more so toward caudal peduncle. Dorsal profile rising evenly but not steeply from tip of snout to origin of dorsal fin and sloping gently ventrally from origin of dorsal fin to end of caudal peduncle. Ventral profile slightly convex to anal-fin base, then sloping slightly dorsally to end of caudal peduncle. Skin smooth; lateral line complete and midlateral in position. Vertebrae 14+21 (4), 15+20 (1), 16+19 (1), 14+22 (2), 15+21* (5), 16+20 (3), 15+22 (3) or 16+21 (1).

Dorsal fin with spinelet, spine, and 7 (20) rays. Origin of dorsal fin anterior to mid-body, about two-fifths of body. Dorsal fin margin convex, usually with anterior branch of fin rays longer than other branches. Dorsal fin spine short, straight and slender, posterior edge without serrations. Nuchal shield moderately broad, with rounded tip anteriorly.

Pectoral fin with stout spine, sharply pointed at tip, and 6,i (11) or 7* (9) rays. Anterior spine margin smooth; posterior spine margin with 9–15 large serrations along entire length (number of serrations is ontogenetically related; 9 serrations in specimens ca. 30 mm SL and 15 serrations in specimens ca. 50 mm SL). Pectoral fin margin straight anteriorly, convex posteriorly. Postcleithral process of moderately broad, with slightly convex dorsal margin and extending for half of pectoral-spine length.

Pelvic fin origin posterior to vertical through posterior end of dorsal-fin base, with i,5 (20) rays and slightly convex margin; tip of adpressed fin reaching base of second or third anal-fin ray. Anus and urogenital openings located at vertical through middle of adpressed pelvic fin. Males with an elongate conical genital papilla reaching to base of first anal-fin ray.

Adipose fin with convex margin for entire length, with deeply-incised posterior portion and origin at or immediately anterior to vertical through base of first anal-fin ray; fin-base moderate, spanning about one-third of postdorsal distance. Anal fin base at or just posterior to vertical through origin of adipose fin, with iv,8,i (3); iv,9 (13); v,8* (1) or iv,10 (3) rays and curved posterior margin.

Caudal peduncle moderately deep. Caudal fin deeply forked, with i,7,8,i (20) principal rays; upper and lower lobes slender and lanceolate. Procurrent rays extend anterior to fin base.

Colouration. – In 70% ethanol: Body dark brownish-gray above, dusky below. Sides with pale stripe over the lateral line from middle of body below dorsal fin origin to base of caudal peduncle. Ventral surfaces of head and body dark yellow. Caudal fin hyaline with dark brownish gray submarginal bar on each caudal lobe, and two separate spots in middle of upper and lower caudal lobes; spots faintly coalescent to form irregular bar in some individuals. Three irregular yellowish bars: first (indistinct in some individuals) over nape, second from immediately posterior to dorsal fin base to immediately posterior to pelvic origin, third on anterior part of caudal peduncle from immediately posterior to adipose fin base to immediately posterior to anal-fin base. Small yellowish blotches also present on anterior part of upper and lower procurrent caudal rays, adipose fin origin, and along anal fin base. Dorsal, anal and pelvic fins hyaline with dark basal and submarginal bars; dark markings nearly absent in anal and pelvic fins of some individuals. Posterior edge of adipose fin hyaline.

Live colour similar, with more pronounced yellow colouration.

Distribution. – Known currently only from the Rungan River in southern Borneo ( Fig. 3 ). The Rungan River is part of the Kahayan River drainage.

Etymology. – The specific epithet comes from the Latin funebris , meaning “of a funeral”. Being clothed in black is traditionally associated with funerals, and the name alludes to the blackwater habitat of this species.

Figures

Fig. 2. Predorsal profiles of:a, Pseudomystus funebris, ZRC 51845, paratype, 36.3 mm SL; b, P. heokhuii, ZRC 39069, paratype, 42.6 mm SL. Images not to scale.

Fig. 4. Postdorsal views of: a, Pseudomystus funebris, ZRC 51845, paratype, 36.3 mm SL; b, P. heokhuii, ZRC 39069, paratype, 36.1 mm SL, showing differences in shapes of adipose fin. Images not to scale.

Fig.3. Map showing collectionlocalities of blackwater Pseudomystus species (P. funebris and P. heokhuii).