Pseudecheneis serracula, Heok Hee Ng & David R. Edds, 2005

Heok Hee Ng & David R. Edds, 2005, Two new species of Pseudecheneis, rheophilic catfishes (Teleostei: Sisoridae) from Nepal., Zootaxa 1047, pp. 1-19 : 6-12

Pseudecheneis serracula sp. nov.

(Fig. 3)

Pseudecheneis sulcatus (non M’Clelland, 1842) Edds, 1986a: 6; 1986b: 18; 1987: 11; 1993: 59; Shrestha, 1981: 197, Fig. 91 (in part); 1994: 62, Fig. 97 (in part).

Type material. Holotype: KU 29554, 153.2 mm SL; Nepal: Mugu/Bajura, Jhugala, Karnali River, purchased at Jhugala, 29°31'18.0"N 81°46'48.0"E; D. Edds, 25 September 1996.

Paratypes: BMNH 1985.9.16.50-51 (2), 48.0-48.2 mm SL; Nepal: Narayani River, Chitawan National Park; Edinburgh University, November 1984 - February 1985. KU 28669 (5), 41.5-56.5 mm SL; Nepal: Kanchanpur, Brahamadev, Mahakali River at Brahamadev, 29°4'54.1"N 80°8'30.1"E; D. Edds, 24 February 1996. KU 29038 (1), 58.0 mm SL; Nepal: Gulmi/Syangja, Kali Gandaki River at Ridi Bazar; 27°56'6.0"N 83°26'30.1"E; D. Edds, 21 May 1996. KU 35545 (2), 48.0-95.3 mm SL; Nepal: Tanahun, Khairenitar, Seti River at Khairenitar, 28°2'0.0"N 84°4'0.0"E; D. Edds, 15 June 1996.

OSUS 15703 (4), 31.6-59.3 mm SL; Nepal: Syangja, Kali Gandaki River at Nimaa; D. Edds, 4 May 1985. OSUS 15718 (9), 34.1-75.5 mm SL; Nepal: Gulmi/Syangja, Kali Gandaki River at Ridi Bazar; 27°56'6.0"N 83°26'30.1"E; D. Edds, 22 May 1984. OSUS 15729 (3), 53.5-59.6 mm SL; Nepal: Baglung, Kali Gandaki River at Sumsaa Ghat (Binamaare); D. Edds, 25 May 1984. OSUS 15736 (6), 19.8-54.4 mm SL; Nepal: Myagdi, Kali Gandaki River at Simaa; D. Edds, 27 May 1984. OSUS 16340 (1), 79.5 mm SL; Nepal: Chitawan, Narayani River at Narayanagarh, upstream from irrigation office; D. Edds, 10 February 1985. OSUS 16609 (1), 22.2 mm SL; Nepal: Chitawan, Narayani River at Amaltaari Ghat; D. Edds, 5 April 1985. OSUS 16637 (15), 63.0-130.5 mm SL; Nepal: Chitawan, Narayani River at Narayangarh, upstream from irrigation office; D. Edds, 19 April 1985. OSUS 16695 (1), 62.3 mm SL; Nepal: Syangja, Kali Gandaki River at Nimaa; D. Edds, 2 May 1985. OSUS 17179 (1), 80.0 mm SL; Nepal: Syangja, Kali Gandaki River at Nimaa; D. Edds, 6 January 1986.

Diagnosis. Pseudecheneis serracula is distinguished from P. paviei and P. sympelvica in having an elongate body with 36-38 vertebrae (vs. short body with 33-35 vertebrae) and from P. sympelvica in having separate (vs. fused) pelvic fins. It differs from other congeners in having strongly elevated neural spines of the last 2-3 preanal and first 6-7 postanal vertebrae (vs. neural spines of corresponding pre- and postanal vertebrae gradually increasing in height; Fig. 4) and, except for P. immaculata , in having a longer adipose-fin base (at least 2.0 times length of anal-fin base vs. 1.5-2.0 times; 26.8-30.4% SL vs. 17.8-24.3). Pseudecheneis serracula is further distinguished from P. immaculata in the presence (vs. absence) of pale spots on the body, and from P. sulcata in having pelvic fins that reach (vs. do not reach) the base of the first anal-fin ray.

Description. Morphometric data as in Table 2. Head and abdominal region narrow and strongly depressed. Dorsal profile rising gently from tip of snout to origin of dorsal fin, then almost horizontal or sloping very gently ventrally to end of caudal peduncle. Ventral profile horizontal to anal-fin base, then sloping very gently dorsally to end of caudal peduncle. Caudal peduncle long and moderately compressed. Anus and urogenital openings located at posteriormost extent of pelvic fin. Skin smooth, tuberculate in some areas. Lateral line complete and midlateral. Vertebrae 18+18=36 (14), 19+17=36 (1), 18+19=37 (14), 19+18=37* (19), 19+19=38 (3) or 20+18=38 (1).

Head acutely rounded when viewed from above. Gill openings moderate, extending from posttemporal region to base of first pectoral-fin element. Head covered with thick, tuberculate skin. Ventral surface of head with unculiferous collar on distal margin of branchiostegal membrane immediately anterior to thoracic adhesive apparatus.

Thoracic adhesive apparatus consisting of 13-18 transverse ridges (laminae) separated by grooves (sulcae); ridges frequently not meeting at midline of adhesive apparatus. Adhesive apparatus extending from immediately posterior to collar on distal margin of branchiostegal membrane to level of last pectoral-fin ray.

Barbels flattened, and in four pairs. Maxillary barbel with ventral surface densely covered with papillae, and pointed tip; barbel extending about two-thirds of distance between its base and base of first pectoral-fin element. Distal half of barbel attached to snout via large, thin flap of skin. Nasal barbel with small flap of thin skin fringing posterior margin and extending midway to distance between posterior nares and anterior orbital margin. Inner mandibular-barbel densely covered with papillae; origin close to midline, extending to collar on distal margin of branchiostegal membrane. Outer mandibular barbel originates posterolateral of inner mandibular barbel, extending to level of anterior orbital margin. Eye small and almost rounded, subcutaneous and located on dorsal surface of head.

Mouth inferior, with moderately broad, thin papillate lips. Rictal lobe large and papillate. Premaxillary tooth band not exposed when mouth is closed. Premaxillary teeth short and conical, arranged in irregular rows on a moderately large quadrangular patch. Dentary teeth long, thin and somewhat rounded at tip; arranged in irregular rows on two separated, roughly triangular patches.

Dorsal-fin origin located at point through anterior third of body. First and second dorsal fin-ray elements not ossified, bearing i,5 (1), i,5,i (4) or i,6* (47) rays, and fin margin straight. Adipose fin with moderately long base, at least 2.0 times anal-fin base length; located in middle third of postdorsal region. Adipose fin margin gently convex; posterior end deeply incised. Caudal fin forked, with i,7,7,i (1), i,7,8,i* (47), i,8,7,i (1) or i,8,8,i (3) principal rays; procurrent rays symmetrical and extend only slightly anterior to fin base. Anal fin with short base extending less than half of adipose fin-base length and iv,7 (15), iv,8 (22), v,6 (1), v,6,i (7) or v,7* (7) rays. Anal fin margin almost straight.

Pelvic-fin origin at vertical through second or third dorsal fin-ray base. Pelvic fin greatly enlarged, extending to base of first anal-fin ray. Anterior fin margin strongly convex, first element broadened and with regular striae on ventral surface; with i,5 (52) rays. Pectoral fin greatly enlarged and with convex anterior margin, reaching to just beyond pelvic-fin base. First element not ossified, broadened and with regular striae on ventral surface; fin with i,12 (2), i, 13* (40) or i, 14 (10) rays.

Coloration. In 70% ethanol and 45% isopropanol: chestnut brown on dorsal and lateral surfaces of head and body, fading to very light brown on ventral region. Dorsal surfaces of head and body with distinctive series of small very light brown spots and bands: one ovate spot on base of first dorsal-fin ray, and another pair on each side of body immediately posterior to last dorsal-fin ray; one band on each side of body at adipose-fin origin, and another on caudal peduncle at base of caudal fin. Dorsal and anal fins hyaline, with brown base and brown subdistal band; brown coloration of base and subdistal band connected to each other at anterior third of fin. Adipose fin light brown, with lighter color around distal edge, especially at posterior end of fin. Caudal fin brown, with hyaline distal margin. Dorsal surfaces of pectoral and pelvic fins brown, ventral surfaces light yellow. Maxillary and nasal barbels brown dorsally and light yellow ventrally.

Distribution. Presently known only from rivers of the Middle Hills and Tarai (lowlands) of western (Karnali drainage) and central (Gandaki drainage) Nepal, in and at the base of foothills of the Himalayas (Fig. 2). The Karnali (= Ghaghara or Gogra in India) is a major tributary of the Ganges River in India. The Mahakali (= Sarda in India) forms the western border of Nepal with India, and is a tributary to the Ghaghara in India. The Seti and Kali Gandaki are tributaries to the Trisuli, which becomes the Narayani (= Sapta Gandaki) in Nepal. The Narayani (= Gandak in India) is a major tributary of the Ganges River in India.

Habitat and ecology. This species was captured exclusively in riffles, which were typically broad and shallow, well-oxygenated, and had swift water velocities over rocky substrate (Fig. 4). Habitat assessment for seven of these areas showed mean water depths of 10 cm (SE = 0.3), mean water velocities of 0.7 m/s (SE = 0.08), minimum dissolved oxygen of 8 mg/L, and pH from 8.0 to 8.75. Substrate was primarily cobble (ca. 64-256 mm) (68%, SE = 12.0) and pebble (ca. 32-64 mm) (17%, SE = 6.8).

Pseudecheneis serracula feeds on aquatic insects, including caddisflies (Edds, 1987). Species associates in our collections included Crossocheilus latius (Cyprinidae), Garra annandalei (Cyprinidae), G. gotyla (Cyprinidae), Schizothoraichthys progastus (Cyprinidae), Schizothorax richardsonii (Cyprinidae), Botia almorhae (Cobitidae), and Glyptothorax cf. pectinopterus (Sisoridae). In the Seti River, P. serracula was found syntopically with P. sulcata . Local fishermen report that P. serracula (local name = kabre) ascends the Kali Gandaki River to ca. 1000 m asl during monsoon (Edds, 1986b), suggesting these fish may breed in upper reaches of the river, then migrate downstream following spawning season.

Etymology. From the Latin serraculum, meaning rudder, in allusion to the large adipose fin of this species. Used as a noun.