Pseudolaguvia fucosa, Ng, Heok Hee & Lalronunga, Samuel, 2016

Ng, Heok Hee & Lalronunga, Samuel, 2016, A new diminutive sisorid catfish (Actinopterygii: Siluriformes) from northeastern India, Zootaxa 4105 (6), pp. 546-556 : 547-551

Pseudolaguvia fucosa sp. nov.

( Figs. 1 , 2 a, 3)

Type material. Holotype: PUCMF 16001 , 27.3 mm SL; India: Mizoram, Lawngtlai District , Tuichawng River in the vicinity of Bandukbanga village, Karnaphuli drainage, 22°3’11”N 92°38’56”E; S. Lalronunga & Lalramliana, 6 March 2013.

Paratypes: PUCMF 16002 (19), 23.7–27.4 mm SL; data as for holotype .

Diagnosis. Pseudolaguvia fucosa differs from congeners except for P. virgulata in having (vs. lacking) a pale, y-shaped marking on the dorsal surface of the head; it also differs from congeners except for P. flavida , P. kapuri , P. muricata , P. nepalensis , P. ribeiroi and P. virgulata in having (vs. lacking) serrations on the anterior edge of the dorsal spine. It is distinguished from the remaining six species in having a combination of the following characters: length of dorsal-fin spine 18.0–21.6% SL; 4–10 serrations on the anterior edge of the dorsal spine; length of pectoral-fin spine 20.7–26.1% SL; length of adipose-fin base 21.5–26.3% SL; body depth at anus 12.3–15.9% SL; caudal peduncle depth 7.5–9.8% SL; caudal peduncle length 17.0–20.5% SL; sides of body with pale yellowish patches and irregular bands.

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 in contact with 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 14+15=29 (5), 14+16=30* (1), 15+15=30 (10), 15+16=31 (3) or 16+15=31 (1). Thoracic adhesive apparatus consisting of longitudinal, unculiferous ridges arranged in elliptical field and with prominent central median depression. Adhesive apparatus extending to level of tips of postcoracoid processes ( Fig. 2 a).

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 anteriormost portion of pectoral-fin spine base. Lateral mandibular barbel with broad skin flap on dorsal margin, extending to middle of pectoral-fin spine base; medial mandibular barbel broad and shorter, reaching to vertical through posterior orbital margin.

Dorsal fin located about two-fifths along body; with 5 (20) rays. Dorsal-fin spine flattened, straight, robust; spine extending to vertical slightly posterior to base of pelvic fin. Anterior margin of spine with 4 (1), 5 (3), 6 (7), 7 (3), 8* (4), 9 (1) or 10 (1) small, antrorse serrations; posterior margin with 2 (1), 3 (6), 4* (10), or 5 (3) small, antrorse serrations.

Pectoral fin with stout, blade-like spine, sharply pointed at tip, with 6,i (20) rays. Anterior spine margin with 9 (5), 10 (4), 11 (3), 12 (4), 13 (2), 14 (1) or 15 (1) small, antrorse serrations. Posterior spine margin with 6 (7), 7 (12) or 8* (1) large, retrorse serrations. 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 (20) rays, its margin straight; tip of adpressed fin not reaching anal-fin origin. Adipose-fin base moderate, anterior origin very near base of last dorsal-fin ray. Fin with posterior end deeply incised and located above anal-fin base. Anal fin with iv,5,i (18), iv,6, i (1) or iv,7* (1) rays, its anterior and posterior margins straight. Caudal peduncle moderately deep. Caudal fin deeply forked, with i,7,6,i (4) or i,7,7,i* (16) 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 medium brown, fading to light brown on belly, chest and ventral surfaces of head and body. Two short, pale (light brown) lines on dorsal surface of neurocranium running from posterior margin of posterior nares to above orbits (through lateral ethmoids and anterior half of frontals), coalescing at posterior end of frontals, extending throughout supraoccipital to tip of process and continuing along nuchal shield to form a y-shaped marking. Nuchal shield with pale (light brown) elongate, irregular kidney-shaped spot delineating its lateral edges. Body with two irregular light brown bands: first band on sides of body between dorsal and adipose fins, second band on caudal peduncle. Dorsal fin medium brown, with very thin, irregular hyaline distal margin. Anal fin with medium brown base and irregular sub-distal band; latter band incomplete in some individuals. Pelvic fin hyaline with irregular medium brown spot at base and irregular bands or spots along middle third of fin. Pectoral fin with medium brown base, spine and faint transverse medium brown sub-distal band. Caudal fin hyaline, with subdistal brown stripe running along length of each lobe. Adipose fin brown at base, paler along dorsal and posterior parts. Nasal barbel brown dorsally, light-brown ventrally; maxillary and lateral mandibular barbels light brown, annulated with brown bands; medial mandibular barbel light brown.

Live coloration similar, but with faint dark midlateral stripe present in some individuals ( Fig. 3 a) and absent in others ( Fig. 3 b).

Distribution and habitat. This species is known from the headwaters of the Karnaphuli River drainage in southern Mizoram ( Fig. 4 ). The type locality was a river with a moderate current and a substrate of sand and pebble ( Fig. 5 ). Amblyceps cf. mangois , Mystus bleekeri , and one or more species each of Psilorhynchus , Schistura , Physoschistura and Badis were collected together with the new species.

Etymology. The specific epithet comes from the Latin adjective fucosus, meaning painted or colored. This name is used in reference to the color pattern of this species, which includes more pale spots and stripes than most congeners.

Figures

FIGURE 1. Pseudolaguvia fucosa, PUCMF 16001, holotype, 27.3 mm SL; dorsal, lateral and ventral views.

FIGURE 2. Ventral view showing details of thoracic adhesive apparatus in: a. Pseudolaguvia fucosa, PUCMF 16002, paratype, 24.6 mm SL; b. P. virgulata, PUCMF 1026, paratype, 24.2 mm SL. Dotted line indicates tip of postcoracoid process; arrows indicate posteriormost extent of thoracic adhesive apparatus. Images not to scale.

FIGURE 3. Pseudolaguvia fucosa, PUCMF 16002, paratypes: a. 22.2 mm SL, b. 22.7 mm SL, showing live coloration.

FIGURE 4. Map showing collection locality of Pseudolaguvia fucosa.

FIGURE 5. Type locality of Pseudolaguvia fucosa (Tuichawng River, Mizoram, India).

Tables

TABLE 1. Biometric data for Pseudolaguvia fucosa (n = 20)

	Holotype	Range	Mean±SD
%SL
Predorsal length	39.2	37.3–42.0	40.0±1.62
Preanal length	65.2	63.8–68.9	66.4±1.77
Prepelvic length	50.0	48.7–52.2	50.7±1.39
Prepectoral length	23.1	19.0–25.9	22.3±2.19
Dorsal-fin base length	16.8	14.5–18.6	16.6±1.22
Dorsal-fin spine length	21.6	18.0–21.6	20.0±1.06
Anal-fin base length	19.8	16.0–19.8	18.0±1.35
Pelvic-fin length	14.3	14.3–19.2	16.4±1.54
Pectoral-fin length	27.1	24.6–29.5	27.0±1.59
Pectoral-fin spine length	23.8	20.7–26.1	23.2±1.66
Caudal-fin length	29.7	27.3–33.5	29.5±2.10
Adipose-fin base length	24.2	21.5–26.3	23.4±1.63
Dorsal to adipose distance	4.4	3.9–8.0	5.2±1.43
Post-adipose distance	16.5	14.6–18.7	16.9±1.50
Caudal-peduncle length	20.5	17.0–20.5	18.7±1.12
Caudal-peduncle depth	8.8	7.5–9.8	8.5±0.75
Body depth at anus	13.2	12.3–15.9	13.8±1.12
Head length	28.6	26.3–31.5	29.6±1.41
Head width	23.8	20.0–23.8	21.8±1.31
Head depth	18.6	15.0–18.6	16.7±1.05
%HL
Snout length	55.1	50.7–55.1	53.0±1.67
Interorbital distance	35.9	31.9–35.9	34.0±1.54
Eye diameter	12.8	9.1–14.5	11.1±1.78
Nasal-barbel length	16.7	13.0–19.2	16.0±2.13
Maxillary-barbel length	66.7	54.5–69.6	64.1±4.79
Medial mandibular-barbel length	33.3	27.5–39.2	34.3±4.32
Lateral mandibular-barbel length	42.5	39.1–57.1	49.9±6.99