Glyptothorax malabarensis, Gopi, 2010

Gopi, K. C., 2010, Glyptothorax malabarensis, a new catfish (Teleostei: Sisoridae) from the Western Ghats of Kerala, India, Zootaxa 2528, pp. 53-60 : 54-57

Glyptothorax malabarensis , sp. nov.

( Figs. 1 & 2a)

Type material. Holotype. ZSI– WGRC 18343 , 55.2 mm SL; India: Western Ghats, Kerala, Kannur District: Pottichapara (11°58'12.4"N, 75°49'38.7"E) in Aralam Wildlife Sanctuary (Urutty Stream (210 mtrs amsl), Valapattanam River drainage); K. C. Gopi; 22 Feb 2007.

Paratypes: ZSI-WGRC 18344 (2), 42.0– 42.1 mm SL; same data as holotype .

Diagnosis. Glyptothorax malabarensis is distinguished from its congeners in peninsular India by the following combination of characters: body depth 19.6–19.9% SL (at dorsal-fin origin); caudal-peduncle length 14.3–14.7% SL; caudal-peduncle depth 12.4–12.7 % SL, 86.4–88.1% its length; thoracic adhesive apparatus approximately pentagonal, as long as broad, without a median depression; skin of head and body minutely granulated; and a coloration in life consisting of a black background with three flesh-red or orange transverse bands on the body; in preservative, changing to dark-grey with black mottling and three whitish transverse bands.

The new species differs from G. anamalaiensis , the congener it most closely resembles in the Indian peninsula, by having a deeper body (19.6–19.9% vs. 12.9–16.8% SL), a deeper caudal peduncle (86.4–88.1 % vs. 34.1–37.8% its length), longer nasal barbels (reaching the anterior margin of the orbit vs. reaching only half the distance to the orbit), and the thoracic adhesive apparatus as long as broad and pentagonal in shape vs. adhesive apparatus broader than long and inverted V-shaped with short unculiferous ridges.

Description. Biometric data are given in Table 1. Head depressed, broad; body moderately compressed, deep, (19.6–19.9% SL). Dorsal profile rising evenly from tip of snout to origin of dorsal fin, thereafter sloping gently ventrally to end of caudal peduncle. Ventral profile horizontal to anal-fin origin, thence sloping gently dorsally to end of caudal peduncle. Caudal peduncle short, deep (14.3–14.7, 12.4–12.7 % SL, respectively), its depth 86.4–88.1 % its length. Anus and urogenital openings located at vertical through just behind middle of adpressed pelvic fin. Skin finely granulated on head and body; rounded, minute, sparsely distributed tubercles present on dorsal and lateral surface of head and on body anterior to dorsal-fin origin. Lateral line complete, midlateral, extending onto fleshy base of caudal fin, displaced a little dorsally on caudal-fin base.

Head depressed, broad; snout acutely triangular in lateral aspect ( Fig.1C), obtusely triangular in dorsal aspect. Anterior and posterior nares large, subequal (81.8-84.6%) to eye diameter, separated only by membranous base of nasal barbel. Gill openings broad, extending from immediately ventral to posttemporal, reaching isthmus. Length of occipital process 2.1 times its width at base, its lateral margins tapering, tip not reaching basal bone of dorsal fin, separated by a gap of approximately half eye diameter. Eyes small, round, located entirely in dorsal half of head; middle of eye located in posterior half of head. Orbit without free margin. Eye diameter 21.5–22.0% snout length, 36.4–37.2% inter-orbital distance. Gill rakers 7 (1) or 8 (2); branchiostegal rays 8 (3).

Barbels in four pairs. Maxillary barbel long, broad at base, slender, extending to middle of pectoral-fin base. Nasal barbel slender, extending to anterior orbital margin. Origin of inner mandibular barbel just posterior to margin of lower lip, slightly closer to outer mandibular-barbel origin than to midline, extending to midway between its base and that of pectoral spine. Origin of outer mandibular barbel posterolateral to that of inner mandibular-barbel, extending to origin of pectoral-fin spine.

Mouth inferior, gape extending to level of outer mandibular-barbel origin. Lips covered with closely packed conical papillae. Premaxillary tooth-band partly exposed with mouth closed. Oral teeth small, villiform, densely packed in irregular rows. Premaxillary teeth in a single, broad, crescentic band. Dentary teeth in two narrow crescentic bands, slightly separated at midline. Palate edentulous.

Dorsal-fin base located entirely in anterior half-part of body, with 1,6 (3) rays; anterior insertion of fin at level just posterior to middle of pectoral fin, posterior insertion slightly anterior to vertical through pelvic-fin origin; posterior fin margin convex; spine short, slender, gently curved, without serrae. Anterior margin of adipose fin straight or slightly concave, posterior margin slightly convex, angular; adipose-fin base slightly longer than dorsal-fin base. Caudal fin strongly forked, with 1,7,8,1 (3) principal rays, its lower lobe slightly longer and broader than upper one. Procurrent rays 5 + 5 (3), symmetrical, extending slightly anterior to fin base. Anal-fin base at level of or slightly posterior to adipose-fin origin. Anal-fin anterior margin straight, posterior margin slightly convex, with iii,8 (3) rays. Pelvic-fin origin immediately posterior to vertical through posterior end of dorsal-fin base. Pelvic fin with slightly convex margin and i,5 (3) rays; tip of adpressed fin barely reaching anal-fin origin. Pectoral fin with 1,8 (3) rays; posterior margin of fin slightly concave; anterior margin of spine smooth, posterior margin with 3–5 feeble serrae. Outer rays of paired fins ventrally devoid of adhesive skin pleats.

Thoracic adhesive apparatus present, approximately pentagonal in shape, with posterior face medially open ( Fig. 1D). Adhesive apparatus as long as broad, without a median depression, located on belly, consisting of moderately elongate pleats of skin, set in symmetrical pattern, extending from just behind gill opening to vertical through posterior extremity of pectoral-fin base.

Coloration. In life, dorsal and lateral surfaces of head and body black with three flesh-red or orange transverse bands: a broad one just anterior to adipose-fin origin, another just posterior to adipose-fin base, a third at caudal-fin base; ventral surface orange or pinkish-red ( Fig.1, A & B). Fins black with orange or yellow distal margins. In preservative, overall color rapidly fading to dark-grey with black mottling on head and body, red or orange color of belly and body bands becoming yellowish-white; orange-yellow band on caudal-fin base and all distal margins of fins turning white.

Distribution. The new species is presently known only from the type locality in the Aralam Wildlife Sanctuary (Urutty Stream, Valapattanam River drainage), Kannur District, Kerala, India.

Habitat. The type series was obtained from submerged crevices formed by large boulders in an upland stream (210 m a.s.l.), about 6 m wide and 0.5–1.5 m deep, flowing through a forest patch on the western slopes of the Western Ghats in Kerala ( Fig. 3). The streambed in this area comprises pebble and sand in which are embedded large boulders. Our survey took place in February, a relatively dry month, when the stream was in a depleted phase with clear— but not fast flowing—water. Riparian forest vegetation in the vicinity of the stream provided ample shade. Other fishes from the collection site included Barilius bakeri Day , Garra mullya (Sykes) (Cyprinidae) ; Bhavania australis (Jerdon) and Schistura denisoni denisoni (Day) (Balitoridae) , from the pebble-bottomed area of the stream.

Etymology. The specific name malabarensis is derived from ‘Malabar’, an older name for the region of northern Kerala, in which this species occurs.