Olyra saginata, Ng, Heok Hee & Lalthanzara, Hmar, 2014

Ng, Heok Hee & Lalthanzara, Hmar, 2014, Olyra saginata, a new species of bagrid catfish (Actinopterygii: Siluriformes) from northeastern India, Zootaxa 3821 (2), pp. 265-272 : 266-269

Olyra saginata , new species

( Figs. 1–3 )

Type material. Holotype: PUCMF 13015, 76.2 mm SL; India: Mizoram, Saiha District, Palak River in the vicinity of Phurra Village, 22°14'15"N; 92°54'04"E; Lalramliana & H. Lalthanzara, 7 December 2011.

Paratypes: PUCMF 13016 (3), 64.7–85.8 mm SL; India: Mizoram, Saiha District, Sala River in the vicinity of Lungpuk Village, 22°03'36"N 92°55'15"E; Lalramliana et al., 14 November 2012; PUCMF 13017 (1), 62.1 mm SL; India: Mizoram, Saiha District, Tuisi River in the vicinity of Khopai Village, 22°10'38"N, 93°02'45"E; Lalramliana et al., 16 November 2012; PUCMF 13018 (7), 55.9–85.1 mm SL; UMMZ 249919 (2), 64.9–72.9 mm SL; ZRC 54437 (1), 70.5 mm SL; PUCMF 13019 (4), 45.2–80.1 mm SL (cleared and stained); data as for holotype.

Diagnosis. Olyra saginata is distinguished from congeners in having the following unique combination of characters: interorbital distance 27.9–35.9% HL; 54–66 lateral-line pores; body depth at anus 10.5–12.0% SL; length of adipose-fin base 17.3–22.4% SL; adipose fin separate from upper principal caudal-fin rays; post-adipose distance 11.8–14.3% SL; caudal peduncle length 14.8–17.7% SL; and caudal peduncle depth 7.8–8.9% SL.

Description. Morphometric data in Table 1 . General appearance as in Figs. 1 and 2 . Body anguilliform, depressed anterior to dorsal fin, ellipsoidal at level of dorsal-fin origin, subquadrangular immediately anterior to pelvic-fin origin, gradually more compressed caudally. Dorsal profile from snout margin to base of dorsal-fin spine slightly convex, slightly concave along dorsal-fin base and relatively straight 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 hypurals; with 54-66 pores. Anus located at one fifth distance from base of posteriormost pelvic-fin ray to anal-fin origin. Urogenital papilla elongate and separate from anus, located three-quarters of distance between center of anus and anal-fin origin. Vertebrae 20+26=46 (3), 21+26=47* (4), 21+27=48 (1), 22+26=48 (3) or 22+27=49 (1).

Head depressed, 1.5–1.6 times longer than wide; neurocranial roof covered with thick skin. Adductor mandibulae muscles prominent on cheeks. 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. Nostrils widely separated. Anterior nares tubular, immediately above margin of upper lip. Anterior margin of posterior nostril confluent with posterior base of nasal barbel. Branchiostegal membranes free, joined to isthmus only at gular apex and not overlapping medially, with six (4) branchiostegal rays. Gill rakers 1+10 (3) or 1+11 (1). Eye small, subcutaneous, ovoid; closer to snout tip than to opercle margin; skin covering eye thin and translucent. Interorbital area markedly concave.

Mouth subterminal, jaws subequal, lips thickened. 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 pectoral-fin origin. Maxillary barbel long, reaching beyond posterior base of pectoral fin. Outer mandibular barbel just reaching posterior base of pectoral fin. Inner mandibular barbel short, about two-thirds length of outer mandibular barbel.

Cephalic laterosensory canals simple ( Fig. 3 ). Preoperculomandibular canal with 10 pores, the last pore fused with first postotic canal pore. Supraorbital canal with five pores: SO1 adjacent to anterior naris; SO2 posteromedial to anterior naris, fused with second infraorbital canal pore (IO2); SO3 at posteromedial corner of posterior naris; SO4 (epiphyseal) approximately halfway between midline of head and midline of orbit, located at level just beyond posterior ocular border; SO5 posterior to SO4, approximately at midway of head length. Infraorbital canal with seven pores: IO1 at posterolateral corner of anterior naris; IO2 posteromedial to anterior naris, fused with second supraorbital canal pore (SO2); IO3 medial to base of maxillary barbel and posterior naris; IO4 at level of anterior ocular border; IO5 slightly posterolateral to orbit; IO6 behind orbit; IO7 posteromedial to IO6. Postotic canal with four pores: POT1, POT2 and POT3 above opercle and gill opening; POT4 at posteromedial corner of opercle.

Dorsal-fin margin convex, with i,7 (15) rays; first two fin rays unossified. Base of first fin element very slightly in advance of 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 and last basal radial above vertebra 17. Pectoral fin with strong, sharp spine and 6 (1) or 7* (18) fin rays. Spine short, with 8–9 erect serrae along anterior margin and 8–11 retrorse serrae on posterior margin. Pelvic fin with i,5 (19) rays; pelvic-fin origin slightly posterior to vertical through base of first dorsal-fin element. Anal fin elongate, with viii,9 (3), v,13 (1),vi,12 (2), ix,9 (3), vii,12 (3), viii,11* (5) or ix,10 (2) rays; ventral margin straight. Adipose fin elongate and low, originating at about 60% of SL and at about level of fifth or sixth anal-fin ray. Adipose fin with distinct posterior margin, separate from dorsal procurrent fin rays of caudal fin; dorsal margin slightly convex. Caudal fin strongly forked, with i,6,6,i (19) rays; upper lobe 1.8–3.1 times longer than lower.

Coloration in alcohol: dorsal and lateral surfaces of head and body dark grayish brown, fading to cream on ventral surfaces. Three dark, moderately broad longitudinal stripes present on flanks, extending from immediately posterior to opercle to base of caudal fin: dorsal, medial and ventral stripes above, along and below lateral myoseptum, respectively. Adipose fin, and fin rays and membranes of median fins dark brownish gray. Paired fins dark brownish gray dorsally, cream ventrally. Nasal and maxillary barbels dark brownish gray dorsally, cream ventrally. Mandibular barbels cream.

Etymology. The specific name saginata comes from the Latin verb sagino, meaning to fatten, cram or to feast, in allusion to the relatively deep body of this species compared to all other congeners from the northeastern part of the Indian subcontinent.

Habitat. Olyra saginata was collected from a shallow stream with a moderate to strong current and a substrate of sand, pebble and rocks. Other fish species associated with it include Badis spp. ( Badidae ), Rasbora rasbora (Cyprinidae) , Garra spp, ( Cyprinidae ) Glyptothorax chimtuipuiensis (Sisoridae) , G. caudimaculatus (Sisoridae) and Pseudolaguvia nubila (Sisoridae) .

Distribution. Known from the Palak, Sala and Tuisi rivers (all tributaries of the Kaladan River) in Mizoram, northeastern India ( Fig. 4 ).

Figures

FIGURE 1. Olyra saginata, PUCMF 13015, holotype, 76.2 mm SL; dorsal, lateral and ventral views.

FIGURE 2. Olyra saginata, PUCMF 13018, paratype, 55.9 mm SL; lasteral view of freshly-preserved specimen. Scale bar represents 10 mm. Drawing by Kelvin Lim.

FIGURE 3. A, ventral and B, dorsal views of head of Olyra saginata, paratype, PUCMF 13018, 65.8 mm SL, showing arrangement of cephalic laterosensory pores (pores not drawn at scale). Abbreviations: A. POM 1 – 8, preoperculomandibular pores 1 – 8; B. IO 1 – 7, infraorbital pores 1 – 7; LL 1 – 3, lateral line pores 1 – 3; POM 10; preoperculomandibular pore 10; POT 1 – 3 postotic pores 1 – 3 and SO 1 – 3, supraorbital pores 1 – 3. Scale bar indicates 5 mm.

FIGURE 4. Map showing collecting localities of Olyra saginata. Single circle represents three localities (Khopai Village, 22 ° 10 ' 38 " N, 93 ° 02 ' 45 " E; Lungpuk Village, 22 ° 03 ' 36 " N 92 ° 55 ' 15 " E; Phurra Village, 22 ° 14 ' 15 " N; 92 ° 54 ' 04 " E).

Tables

TABLE 1. Morphometric data for Olyra saginata (n = 19).

Standard length (mm)	holotype PUCMF 13015 76.2	range 45.2–85.8	mean±SD
Percent of standard length Predorsal length Preanal length	35.4 54.9	35.4–39.7 54.5–60.3	37.8±1.3 56.6±1.9
Prepelvic length Prepectoral length Length of dorsal-fin base	36.4 16.5 10.1	36.4–40.6 16.1–17.9 8.6–10.6	38.3±1.5 17.0±0.7 9.7±0.6
Length of anal-fin base Pelvic-fin length Pectoral-fin length	26.7 10.7 10.3	26.7–29.9 10.6–13.2 10.3–12.5	28.1±0.9 12.0±0.9 11.4±0.7
Pectoral-spine length Length of upper caudal-fin lobe Length of lower caudal-fin lobe	4.8 44.0 14. 4	3.7–6.5 32.7–44.0 14.4–18.1	5.3±0.8 36.3±4.3 17.0±1.3
Length of adipose-fin base Dorsal to adipose distance Post-adipose distance	22.4 17.1 13.8	17.3–22.4 17.0–21.8 11.8–14.3	20.4±1.4 19.6±1.7 13.2±0.8
Caudal-peduncle length Caudal-peduncle depth Body width	17.1 8.5 10.8	14.8–17.7 7.8–8.9 10.8–12.7	16.4±1.1 8.4±0.4 11.5±0.6
Body depth at dorsal origin Body depth at anus Head length	12.2 11.1 19.2	11.9–13.5 10.5–12.0 18.3–20.9	12.4±0.6 11.4±0.5 19.5±0.9
Percent of head length Head width Head depth	74.4 45.5	69.1–74.4 42.4–50.8	71.7±1.8 47.2±2.7
Snout length Interorbital distance Eye diameter	30.1 33.3 13.5	26.6–32.8 27.9–35.9 12.2–15.4	29.5±1.9 32.2±2.9 13.5±1.0
Nasal barbel length Maxillary barbel length Inner mandibular barbel length	33.3 145.5 46.8	33.3–52. 8 123.0–166.0 46.8–53.5	42.9±5.4 147.6±11.9 50.7±2.3
Outer mandibular barbel length	81.4	69.1–96.8	80.9±9.5