Pseudolaguvia meghalayaensis, Lokeshwor & Marak, 2022

Lokeshwor, Yumnam & Marak, Pringranchi Dokgre, 2022, Pseudolaguvia meghalayaensis, a new diminutive sisorid catfish (Teleostei: Siluriformes) from Northeastern India, Zootaxa 5175 (3), pp. 367-376 : 368-372

Pseudolaguvia meghalayaensis , sp. nov.

( Fig. 1 )

Type materials. Holotype: ZSI FF 9406, 28.7 mm SL; India: Meghalaya, North Garo Hill, confluence of Rongkil and Rongdal stream at Rajasimla (Brahmaputra Basin), 25 ° 54′35″N 90 ° 55′01″E, altitude 72 m above sea level; Pringranchi D Marak, 2 October 2017.

Paratypes: ADBU-MF 1610 /2, 25.4 mm SL ; ADBU-MF 1610 /3, 26.0 mm SL; data as for holotype .

Diagnosis. Pseudolaguvia meghalayaensis differs from all congeners in having the striae in the thoracic adhesive apparatus strongly anastomosing and break up into small, rounded plaques posteromedially. It is further distinguished from them except P. assula , P. austrina , P. ferula , P. ferruginea , P. foveolata , P. inornata , P. jiyaensis , P. lapillicola , P. magna , P. nubila , P. shawi , P. spicula , P. vespa and P. viriosa in the absence (vs. presence) of serrations on the anterior edge of dorsal spine. However, it differs from the remaining fourteen species with smooth anterior edge of dorsal spine and in the absence (vs. presence with variable shape or size) of a central space in thoracic adhesive apparatus ( Fig. 2 ). It can also be distinguished from its congeners in having the following combination of characters: thoracic adhesive apparatus length 1.7 times of its width, 8 branched pectoral-fin rays, supraoccipital spine not reaching nuchal shield, pectoral-fin length 17.1–20.1% SL, predorsal length 40.4–43.8% SL, preanal length 71.1–73.1% SL, body depth at anus 15.6–18.1% SL, anal-fin base length 12.2–12.7% SL, and post adipose fin length12.3–12.6% SL.

Description. Biometric data are presented in Table 1 . Head depressed; body slender, moderately compressed. Dorsal profile rising evenly from tip of snout to dorsal-fin origin, sloping gently ventrad thereafter to end of caudal peduncle. Ventral profile flat to anal-fin base, rising gently dorsad to end of caudal peduncle. Supraoccipital spine not reaching nuchal shield, separated from it by half eye diameter. Weberian lamina well developed, approximately vertical level of nuchal shield, extending slightly beyond and 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. Thoracic region with adhesive apparatus consisting of unculiferous ridges either longitudinally, obliquely or irregular arranged in ovoid-shaped field ( Fig. 2a ), longer than broad, extending up to level of posterior distal margin of pectoral fin; shallow depression at middle of adhesive apparatus. Anus and urogenital opening located at vertical through posterior end of adpressed pelvic fin. Caudal peduncle short, moderately slender. Skin prominently tuberculate, with conical tubercles particularly prominent on dorsal third of head and body. Lateral line complete, located midlaterally, with 39–49 pores.

Mouth wide, inferior; lips papillated; upper jaw projecting beyond lower jaw, exposing most of premaxillary teeth. Teeth minute, villiform, present on both jaws, absent on palate.

Barbels in four pairs. Nasal barbel shortest, broad, reaching anterior margin of orbit. Maxillary barbel slender, with broad skin flap at base, extending to base of pectoral spine. Lateral mandibular barbel longest, with broad skin flap on dorsal margin, extending to middle of dorsal-fin base; median mandibular barbel broad, shorter, reaching to vertical through posterior margin of orbit.

Dorsal fin located about one-third along body; with 6 (3) branched rays. Dorsal-fin spine flattened, straight, robust, extending to vertical slightly anterior to base of pelvic fin when adpressed. Anterior margin of spine smooth, posterior margin with 3(1), 4*(1), or 5(1) small antrorse serrations.

Pectoral fin with stout, blade-like spine, sharply pointed at tip, with 8 (3) rays. Anterior spine margin with 11*(3) small, antrorse serrations. Posterior spine margin with 9*(3) large retrorse serrations. Anterior pectoral-fin margin slightly convex, posterior margin straight. Coracoid with moderately long posterior process, extending along proximal two-thirds of pectoral spine. Pelvic-fin origin at vertical through posterior extremity of dorsal-fin base. Pelvic fin with i,5 (3) rays, its posterior margin straight; tip of adpressed fin reaching vent but not reaching anal-fin origin. Adipose-fin base moderate, anterior origin at vertical through anal fin origin; posterior end of adipose fin deeply incised, located above anal fin base. Anal fin with ii,6,i(1)–7,i*(2) rays, its anterior and posterior margin straight. Caudal peduncle moderately deep. Caudal fin deeply forked, with i,7,7,i (3) principal rays; lobes equal in length, pointed; ventral lobe slightly broader than dorsal lobe. Procurrent rays symmetrical, extending only slightly anterior to fin base.

Coloration. In 10% buffered formalin: dorsal and side of head and body light to dark brown, darker on occipital region. Belly, chest and ventral surfaces of head and body cream. A single pair of creamy spots on body just below dorsal-fin origin present. Body with two irregular cream bands: first band on sides of the body between dorsal and adipose fins, second band on caudal peduncle. Both side of first band confluent at dorsum, forming cream saddle. Bands vary widely in some individuals, covering most of area between dorsal and adipose fins and caudal peduncle respectively, with irregular dark brown spots scattered within. Bands with indistinct margins. Entire body scattered with light to dark-brown spots.

Dorsal fin brown, with very thin, irregular hyaline distal margin. Anal fin hyaline with dark-brown base and irregular sub-distal band. Pelvic fin hyaline with transverse dark-brown bands at base and middle third of fin. Pectoral fin hyaline with dark brown base and transverse brown sub-distal band. Caudal fin hyaline with irregular dark brown blotch at base of each lobe and irregular broad sub-distal brown blotch on each lobe. Adipose fin dark-brown at base, creamy-white along dorsal and posterior margin.

Nasal barbel hyaline with brown sub-distal portion, base dark brown blended with background; maxillary and lateral mandibular barbells cream, annulated with brown bands; medial mandibular barbel cream.

Distribution and habitat. This species is known from the confluence of Rongkil and the Rongdal streams at Rajasimla village, small tributaries of the Brahmaputra River ( Fig. 3 ). The Rongkil and the Rongdal streams originate from the Imsambal and the Tokkol villages in the North Garo Hill, Meghalaya respectively, draining north and converging at Wari, Rajasimla Meghalaya before entering Rangjuli in Assam. It then debouches to the Brahmaputra River in Goalpara District, Assam. The type locality was a shallow stream with a moderate to strong current and a substrate of sand and pebbles ( Fig. 4 ). One or more species each of Pethia, Puntius, Badis, Channa, Paracanthocobitis, Barilius , and Opsarius were collected with the new species.

Etymology. The species epithet comes from Meghalaya. An adjective.

Figures

FIGURE 1. Pseudolaguvia meghalayaensis, ZSI FF 9406, holotype, 28.7 mm SL; A. lateral, B. dorsal, and C. ventral. ADBU- MF 1610/2, paratype, 25.4 mm SL; D. lateral.

FIGURE 2. Schematic illustrations of thoracic adhesive apparatus of: a. Pseudolaguvia meghalayaensis, ZSI FF 9406, holotype, 28.7 mm SL; b. P. assula, CAS 23552, holotype, 22.8 mm SL (Ng & Conway, 2013); c. P. austrina, CUSAT F/212, 32.2 mm SL, illustrated (Radhakrishnan et al., 2010); d. P. ferula, UMMZ 245986, 30.0 mm SL, illustrated (Ng, 2006); e. P. ferruginea, UMMZ 248800, 28.9 mm SL, illustrated (Ng, 2009); f. P. foveolata, UMMZ 244867, 30.0 mm SL, illustrated (Ng, 2005); g. P. inornata, UMMZ 245580, holotype, 25.8 mm SL (Ng, 2005); h. P. jiyaensis, ZSI/V/APRC/P 1035, 29.6 mm SL (Tamang & Sinha, 2014); i. P. magna, ZSI/V/APRC/P 948, 45.4 mm SL (Tamang & Sinha, 2014); j. P. lipillicola, CRG-SAC 2012.4.1, holotype, 27.2 mm SL (Britz et al., 2013); k. P. nubila, ZSI FF 4861, holotype, 29.3 mm SL (Ng et al., 2013); l. P. shawi, UMMZ 343652, 27.0 mm SL, illustrated (Ng, 2006); m. P. spicula, PUCMF 1032, holotype, 31.1 mm SL (Ng & Lalramliana, 2010); n. P. vespa, ZSI/APRC/P 1882, holotype, 30.6 mm SL (Praveenray et al., 2021); and o. P. viriosa, RGUMF 006, holotype, 26.0 mm SL (Ng & Tamang, 2012). Dotted line indicates posteriormost extent of thoracic adhesive apparatus; arrow indicates tip of postcoracoid process. Images not to scale.

FIGURE 3. Map showing collection locality of Pseudolaguvia meghalayaensis. Solid star represents the collection site.

FIGURE 4. Type locality of Pseudolaguvia meghalayaensis (Rongkil and Rongdal stream at Rajasimla, North Garo Hill, Meghalaya, India).