Olyra praestigiosa, Ng & Ferraris Jr, 2016

Ng, Heok Hee & Ferraris Jr, Carl J., 2016, A new species of anguilliform catfish (Actinopterygii: Siluriformes: Bagridae) from Bangladesh and northeastern India, Zootaxa 4079 (3), pp. 381-387 : 382-384

Olyra praestigiosa , new species

( Fig. 1 )

Olyra kempi (non Chaudhuri)— Ataur Rahman, 2005: 191, Fig. 139; Vishwanath et al., 2007: 144. Olyra longicaudata (non M’Clelland)— Biswas et al., 2007: 84; Patra, 2011: 1612, Image 3; Arunachalam et al., 2013a: 55, Figs. 5, 6; 2013b: 7.

Olyra horae (non Prashad & Mukherji)— Pathak et al., 2013: 504, Fig. 1A .

Type material. Holotype: UMMZ 250262 , 74.1 mm SL; India: West Bengal, Darjeeling District, Kalimpong Subdivision, Chel River , approximately 1.25 km N of Gorubathan, 26°58’19.6”N 88°41’56.3”E; A. Rao (donated), 21 February 2014 .

Paratypes: ZRC 54729 (1), 48.6 mm SL; data as for holotype . UMMZ 243661 (2): 56.3–66.8 mm SL; India: West Bengal, Tista River at Tista Barrage , 26°45’10”N 88°34’11”E; H. H. Ng et al., 15 April 2004 . UMMZ 243660 (1), 87.7 mm SL; India: West Bengal, Karotowa River at Ambari Barrage , 26°35’40”N 88°29’48”E; H. H. Ng et al., 14 April 2004 . UMMZ 208790 (3), 59.8–71.1 mm SL; Bangladesh: Sylhet, Piyain Gang River at Sangram Punji, 2.4 km downstream from Indian border, 25°11’N 89°59’E; W. J. Rainboth & A. K. Ataur Rahman, 21 February 1978 . UMMZ 208635 (9), 60.1–101.7 mm SL; Bangladesh: Sylhet, Piyain Gang River at Sangram Punji, 400 m downstream from Indian border, 25°11’N 92°1’E; W. J. Rainboth & A. K. Ataur Rahman, 19 February 1978 . UMMZ 208811 (5), 54.0– 117.9 mm SL; data as for UMMZ 208635; W. J. Rainboth & A. K. Ataur Rahman, 21 February 1978 .

Diagnosis. Olyra praestigiosa is distinguished from congeners in having the following unique combination of characters: interorbital distance 30–37% HL; body depth at anus 6–9% SL; length of adipose-fin base 9–16% SL; adipose fin separate from upper principal caudal-fin rays; post-adipose distance 15–18% SL; 17–22 anal-fin rays; caudal peduncle length 14–19% SL; and caudal peduncle depth 6–8% SL.

Description. Morphometric data in Table 1. General appearance as in Fig. 1 . Body anguilliform, depressed anterior to dorsal fin, becoming more terete posteriorly and more compressed caudally. Dorsal profile from snout margin to base of dorsal-fin spine slightly convex, relatively straight from dorsal-fin base posteriorly to end of adipose-fin base, sloping dorsally from end of adipose-fin base to caudal-fin base. Ventral profile of head slightly convex, nearly straight from posterior margin of branchiostegal membranes to end of anal-fin base, and sloping ventrally along caudal peduncle. Lateral line complete, reaching compound caudal complex. Anus located at one third distance from base of posteriormost pelvic-fin ray to anal-fin origin. Urogenital papilla elongate (in males) and separate from anus, located one sixth of distance between center of anus and anal-fin origin. Vertebrae 21+25=46 (1); 21+26=47 (5); 22+25=47 (3); 23+24=47 (1); 22+26=48 (5); 23+25=48 (4) or 23+28=51* (1).

Head depressed, neurocranial roof covered with thick skin. Snout spatulate, rounded when viewed dorsally; with dorsolateral groove accommodating maxillary barbel immediately posterior to its insertion and extending posteriorly to anterior orbital margin. Upper and lower jaws almost equal, with upper jaw projecting very slightly beyond lower jaw. Lips thickened. Nostrils widely separated. Anterior nares tubular, immediately above margin of upper lip. Posterior nares closer to eye than to snout tip; anterior margin confluent with posterior base of nasal barbel. Branchiostegal membranes free, joined to isthmus only at gular apex and not overlapping medially, with six (2) branchiostegal rays. Gill rakers 1+10 (2). Eye small, subcutaneous, ovoid; closer to snout tip than to opercle margin; skin covering eye thin and translucent. Interorbital area markedly concave. Premaxillary teeth short, conical, arranged in crescentic band. Mandibular teeth small, conical, pointed, arranged in crescentic band interrupted at middle. Four pairs of barbels. Nasal barbel short, reaching midway between posterior margin of eye and base of pectoral-fin spine. Maxillary barbel long, reaching beyond base of last pectoral-fin ray. Outer mandibular barbel just reaching base of last pectoral-fin ray. Inner mandibular barbel short, about two-thirds length of outer mandibular barbel.

Dorsal-fin margin convex, with i,7 (22) rays; first and second dorsal-fin elements unossified. Base of first fin element almost at vertical through pelvic fin insertion. Base of dorsal fin, including basal parts of rays, covered by thick skin. Seven basal radials supporting dorsal fin, first basal radial associated with neural spine of vertebra 11 or 12 and last basal radial above vertebra 16 or 17. Pectoral fin with strong, sharp spine and 4,i (1), 5,i* (2), 6 (11), 6,i (4) or 7 (4) fin rays. Spine short, with 7–12 erect serrae along anterior margin and 8–15 retrorse serrae on posterior margin. Pelvic fin with i,5 (22) rays. Anal fin elongate, with vi,10,i (4), vi,11,i (1), vii,10,i (4), vii,11,i (4), viii,10,i (2), x,8,i (1), viii,11,i (3), ix,10,1 (1), x,10,i* (1) or vii,14,i (1) rays; ventral margin straight. Adipose fin low, with short base; originating at about level of ninth or tenth anal-fin ray. Adipose fin terminating as small oar-like projection, posterior margin separate from dorsal procurrent fin rays of caudal fin. Caudal fin strongly forked, with i,6,6,i (22) rays; upper lobe 1.5–1.7 times as long as lower.

Coloration in alcohol: dorsal and lateral surfaces of head and body brown, fading to cream on ventral surfaces. Three darker brown, moderately broad longitudinal stripes present on flanks, extending from immediately posterior to opercle to base of caudal fin, becoming very indistinct posterior to middle of anal-fin base: dorsal, medial and ventral stripes above, along and below lateral myoseptum, respectively. Longitudinal stripes, adipose fin, and fin rays and membranes of median fins darker brown. Paired fins dark brown dorsally, cream ventrally. Nasal and maxillary barbels brown dorsally, cream ventrally. Mandibular barbels cream. Live coloration similar, but considerably darker ( Fig. 2 ).

Etymology. The specific name comes from the Latin adjective meaning “full of deceitful tricks”, in allusion to the confusion surrounding the identity of this species (see Chresonymy and Discussion).

Habitat. Olyra praestigiosa was collected from a small river with a substrate of sand, mud and rocks (UMMZ 243660). The current was moderate and the water was turbid. Other fish species collected at this habitat were: Barilius bendelisis (Hamilton 1807) (Cyprinidae) , Danio dangila (Hamilton 1822) (Cyprinidae) , Devario devario (Hamilton 1822) ( Cyprinidae ), Pethia conchonius (Hamilton 1822) (Cyprinidae) , Salmostoma phulo (Hamilton 1822) (Cyprinidae) , Botia almorhae Gray 1831 ( Botiidae ), Canthophrys gongota (Hamilton 1822) (Cobitidae) , Lepidocephalichthys guntea (Hamilton 1822) (Cobitidae) , Paracanthocobitis botia (Hamilton 1822) (Nemacheilidae) , Psilorhynchus balitora (Hamilton 1822) (Psilorhynchidae) , Mystus vittatus (Bloch 1794) (Bagridae) , Parambassis baculis (Hamilton 1822) (Ambassidae) , P. ranga (Hamilton 1822) (Ambassidae) , Badis kanabos Kullander and Britz 2002 (Badidae) , Channa punctata (Bloch 1793) (Channidae) , Glossogobius giuris (Hamilton 1822) (Gobiidae) and Macrognathus pancalus Hamilton 1822 (Mastacembelidae) .

Distribution. Known from the Brahmaputra River drainage in Bangladesh and northeastern India ( Fig. 3 ).

Figures

FIGURE 1. Olyra praestigiosa, UMMZ 250262, holotype, 74.1 mm SL; dorsal, lateral and ventral views.

FIGURE 2. Olyra praestigiosa, India: Assam, Chel River, 102 mm SL; showing live coloration (specimen not preserved). Photograph courtesy of Benjamin Lee.

FIGURE 3. Map showing collecting localities of Olyra praestigiosa. Open circle indicates type locality.