Pseudolaguvia nubila, Ng, Heok Hee & Lalronunga, Samuel, 2013

Ng, Heok Hee & Lalronunga, Samuel, 2013, Pseudolaguvia nubila, a new sisorid catfish (Teleostei: Sisoridae) from northeastern India, Zootaxa 3647 (4), pp. 518-526 : 519-523

Pseudolaguvia nubila sp. nov.

( Figs. 1–3 )

Type material. Holotype: ZSI FF 4861, 29.3 mm SL; India: Mizoram, Saiha District, Sala River (a tributary of the Kaladan River) in the vicinity of Lungpuk Village, 22°03'36.11"N 92°55'15.37"E; S. Lalronunga & Lalramliana, 14 November 2012.

Paratypes: ZSI FF 4862 (3), 25.9–28.6 mm SL; PUCMF 13004 (9), 24.8–32.5 mm SL; data as for holotype.

Diagnosis. Pseudolaguvia nubila differs from congeners except for P. austrina , P. kapuri , P. s p i c u l a, P. virgulata and P. v ir i os a in having a deeper caudal peduncle (9.1–11.1% SL vs. 5.0–9.0) and a combination of the following characters: head width 19.7–21.0% SL, dorsal-spine length 16.4–19.3% SL, pectoral-spine length 18.1– 22.0% SL, pelvic-fin length 15.8–18.5% SL, and body depth at anus 13.9–17.1% SL. It is distinguished from P. austrina in having a mottled brown body with yellowish bands (vs. uniform pale brown body), a weakly projecting snout in which the premaxillary teeth are barely exposed (vs. a strongly projecting snout in which the premaxillary teeth are almost entirely exposed) when the mouth is closed, a larger eye (10.8–14.0% HL vs. 4.4–8.1), fewer serrations on the anterior edge of the pectoral spine (7–8 vs. 17–19), a shorter dorsal to adipose distance (13.1– 16.8% SL vs. 29.5–32.7) and longer caudal peduncle (15.7–20.2% SL vs. 8.8–14.7); and from P. kapuri in having a smooth (vs. serrated) anterior edge of the dorsal spine, a shorter adipose-fin base (14.2–15.9% SL vs. 17.1–18.9), and narrower head (19.7–21.7% SL vs. 23.4–24.0), and from P. s p ic u la in having longer dorsal- (16.4–19.3% SL vs. 11.6–14.3) and pectoral-fin (18.1–22.0% SL vs. 15.7–17.4) spines and fewer serrations (7–8 vs. 9–15) on the anterior edge of the pectoral spine. Pseudolaguvia nubila differs from P. v i rg u l a t a in having shorter dorsal- (16.4– 19.3% SL vs. 21.5–24.0) and pectoral-fin (18.1–22.0% SL vs. 28.5–29.1) spines, a smooth (vs. serrated) anterior edge of the dorsal-fin spine, the presence of pale vertical bands (vs. pale longitudinal stripes) on the flanks and the absence (vs. presence) of a pale Y-shaped marking on the dorsal surface of the head and supraoccipital process, and from P. v i r i o s a in having shorter dorsal- (16.4–19.3% SL vs. 23.4–29.0) and pectoral-fin (18.1–22.0% SL vs. 26.9– 32.9) spines.

Description. Biometric data as in Table 1 . Head depressed, body moderately compressed. Dorsal profile rising evenly from tip of snout to origin of dorsal fin, then sloping gently ventrally to end of caudal peduncle. Ventral profile flat to anal-fin base, then sloping gently dorsally to end of caudal peduncle. Supraoccipital spine nearly reaching nuchal shield. Weberian lamina well developed, slightly longer than supraoccipital spine, extending parallel to either side of spine. Eye ovoid, horizontal axis longest; located entirely in dorsal half of head. Orbit with free margin. Gill openings narrow, extending from posttemporal to isthmus. Branchiostegal membranes united at isthmus. Caudal peduncle of moderate length and depth. Anus and urogenital openings located at vertical through middle of adpressed pelvic fin. Skin prominently tuberculate, with conical tubercles particularly prominent on dorsal third of head and body. Lateral line complete and midlateral. Vertebrae 15+16=31* (5), 16+15=31 (6) or 17+15=32 (2). Thoracic adhesive apparatus consisting of longitudinal, unculiferous ridges arranged in elliptical field and with prominent central median depression. Adhesive apparatus extending to midway of distance between base of last pectoral-fin ray and pelvic-fin origin.

Mouth small, inferior and with papillate lips; upper jaw projecting beyond lower jaw. Oral teeth small and in irregular rows on all tooth-bearing surfaces. Premaxillary tooth band consisting of single broad lunate patch across midline; with conical teeth and very slightly exposed when mouth is closed. Dentary tooth band narrow, with conical teeth.

Barbels in four pairs. Nasal barbel very short, broad, extending to midway between its base and anterior orbital margin. Maxillary barbel slender, with broad skin flap at base, extending to base of pectoral-fin spine. Lateral mandibular barbel with broad skin flap on dorsal margin, extending to base of pectoral-fin spine; medial mandibular barbel broad and shorter, reaching to vertical through middle of orbit.

Dorsal fin located about two-fifths along body; with 5 (13) rays. Dorsal-fin spine flattened, straight, robust; spine extending to vertical slightly posterior to base of pelvic fin. Anterior margin of spine smooth; posterior margin with low asperities.

Pectoral fin with stout, blade-like spine, sharply pointed at tip, with 6,i (2), 7*(9), 7,i (1) or 8 (1) rays. Anterior spine margin with 7–8 distinct serrae. Posterior spine margin with 6–7 large, very distinct serrae. Anterior and posterior pectoral-fin margin straight. Coracoid with moderately long posterior process, extending along proximal two-thirds of pectoral spine. Pelvic-fin origin at vertical through middle of dorsal-fin base. Pelvic fin with i,5 (13) rays, its margin straight; tip of adpressed fin not reaching anal-fin origin. Adipose fin short, posterior end deeply incised. Fin located above anal-fin base. Anal fin with iv,5,i* (5), iv,6 (2) or iv,6,i (6) rays, its anterior and posterior margins straight. Caudal peduncle moderately deep. Caudal fin deeply forked, with i,7,7,i (13) principal rays; upper and lower lobes pointed, with lobes of equal length but ventral lobe slightly broader than dorsal lobe. Procurrent rays symmetrical, extending only slightly anterior to fin base.

Coloration. In 70% alcohol: dorsal surface and sides of head and body brown. Belly, chest and ventral surfaces of head and body cream. Body with two irregular cream bands: first band on sides of body between dorsal and adipose fins, second band on caudal peduncle. Bands very wide in some individuals, covering most of area between dorsal and adipose fins and caudal peduncle respectively and with irregular dark markings within ( Fig. 2 ). Bands with indistinct margins. Dorsal fin brown, with very thin, irregular hyaline distal margin. Anal fin with brown base and irregular sub-distal band. Pelvic fin hyaline with transverse brown bands at base and along middle third of fin. Pectoral fin with brown base and transverse brown sub-distal band. Caudal fin with irregular brown blotch at base of each lobe and irregular sub-distal brown band parallel to posterior edge of fin. Adipose fin brown at base, paler along dorsal and posterior parts. Nasal barbel brown dorsally, cream-colored ventrally; maxillary and lateral mandibular barbels cream, annulated with brown bands; medial mandibular barbel cream. Coloration in life similar, with slightly more yellowish hue ( Fig. 3 ).

Distribution and habitat. This species is known from the Kaladan River drainage in southern Mizoram ( Fig. 4 ). The type locality was a shallow stream with a moderate to strong current and a substrate of sand, pebble and rocks ( Fig. 5 ). One or more species each of Garra , Schistura and Glyptothorax were collected together with the new species.

Etymology. The specific epithet comes from the Latin adjective nubila , meaning cloudy. This name is used in reference to the relatively mottled appearance in some individuals of this species.

Figures

FIGURE 1. Pseudolaguvia nubila, ZSI FF 4861, holotype, 29.3 mm SL; dorsal, lateral and ventral views.

FIGURE 2. Pseudolaguvia nubila, PUCMF 13004, paratype, 29.8 mm SL.

FIGURE 3. Pseudolaguvia nubila, PUCMF 13004, paratype, 29.6 mm SL, showing coloration in life.

FIGURE 4. Map showing collection locality of Pseudolaguvia nubila.

FIGURE 5. Type locality of Pseudolaguvia nubila (Sala River, Mizoram, India).

Tables

TABLE 1. Biometric data for Pseudolaguvia nubila (n = 13).

	Holotype	Range	Mean±SD
%SL
Predorsal length	39.6	36.6–40.6	39.4±1.42
Preanal length	68.9	65.8–69.6	68.5±1.40
Prepelvic length	49.5	49.5–52.3	50.9±0.95
Prepectoral length	24.2	22.0–24.9	23.5±1.09
Dorsal-fin base length	16.7	15.1–17.3	16.3±0.72
Dorsal-fin spine length	16.4	16.4–19.3	17.6±1.03
Anal-fin base length	18.4	15.6–19.7	17.5±1.40
Pelvic-fin length	18.1	15.8–18.5	16.9±1.15
Pectoral-fin length	24.9	24.1–26.4	25.4±0.96
Pectoral-fin spine length	21.5	18.1–22.0	20.6±1.59
Caudal-fin length	22.5	20.3–25.3	22.9±1.75
Adipose-fin base length	15.7	14.2–15.9	15.5±0.65
Dorsal to adipose distance	14.7	13.1–16.8	14.4±1.40
Post-adipose distance	16.7	13.9–16.7	15.7±1.09
Caudal-peduncle length	15.7	15.7–20.2	17.3±1.57
Caudal-peduncle depth	9.2	9.1–11.1	9.7±0.76
Body depth at anus	16.7	13.9–17.1	16.0±1.12
Head length	29.0	29.0–32.4	30.3±1.37
Head width	20.1	19.7–21.7	20.5±0.80
Head depth	17.1	15.3–18.9	17.3±1.38
%HL
Snout length	52.9	44.0–53.1	50.3±3.36
Interorbital distance	31.8	25.6–31.8	27.9±2.45
Eye diameter	12.9	10.8–14.0	12.0±1.28
Nasal-barbel length	17.6	8.6–20.9	16.1±4.45
Maxillary-barbel length	81.2	60.4–84.4	75.6±9.21
Medial mandibular-barbel length	30.6	24.2–42.0	31.4±5.89
Lateral mandibular-barbel length	54.1	44.0–63.0	56.1±7.04