Pseudolaguvia magna, Tamang, Lakpa & Sinha, Bikramjit, 2014

Tamang, Lakpa & Sinha, Bikramjit, 2014, Two new species of the South Asian catfish genus Pseudolaguvia from northeastern India (Teleostei: Sisoridae), Zootaxa 3887 (1), pp. 37-54 : 38-45

Pseudolaguvia magna , sp. nov.

( Fig. 1 )

Type material. Holotype: ZSI/ V/ APRC /P-947, 46.1 mm SL; India: Arunachal Pradesh, Lower Dibang Valley District, Jiya stream, near Bolik village, approximately 14 km from Roing towards Shantipur, Assam, 28°00.377'N 95°45.562'E; 149 m asl., B. Sinha & L. Tamang, 18 March 2014.

Paratypes: ZSI/ V/ APRC /P-948 (8) 31.9–46.7 mm SL, (2) 40.5–42.3 mm SL (skeleton; bigger individual (female) that contained eggs); collection data as for holotype.

Diagnosis. Pseudolaguvia magna is distinguished from all its congeners by the following unique characters: a larger body (up to 47 mm SL vs. a maximum of 35.6 mm SL); two pale-brown to cream patches straddling the middorsal region: one rectangular to elliptical patch on mid-interdorsal region, and another indistinct elliptical patch in between the adipose and caudal fins; a broader rhomboidal thoracic adhesive apparatus; a small pale-brown to cream round spot on the ventrolateral side of the head, almost perpendicular to the eye; and no pale-brown to cream-coloured cross-bands on the body (which character it also shares, however, with P. inornata , P. austrina , P. virgulata and P. assula ).

So far, seven species of Pseudolaguvia are known from the Brahmaputra River drainages (Ng & Tamang, 2012): P. foveolata Ng, 2005 a, P. ferula Ng, 2006 a, P. ri beiroi ( Hora, 1921), P. s h aw i ( Hora, 1921), P. ferruginea Ng, 2009 , P. viriosa Ng & Tamang, 2012 and P. muricata Ng, 2005 b. The first six species are known from northeastern India, and the last from the Rangapani Khal, Bangladesh. The first two species are known from the Tista River and third from one of its tributaries, the fourth from the Mahanadi River below Darjeeling, the fifth from the Raidak River in the state of West Bengal, and sixth from the Sille River in Arunachal Pradesh.

Besides a larger body size, P. magna can be further distinguished from all its congeners in the Brahmaputra drainage in lacking (vs. having) pale-brown to cream bands on the body, having (vs. lacking) a roughly rectangular to ovoid pale to cream patch on the mid-dorsal region of the body, and a considerably broader (vs. narrower) thoracic adhesive apparatus. Pseudolaguvia magna is further distinguished from P. foveolata , P. ferula , P. v i r i os a and P. m uri cat a by having a shorter pectoral-fin spine (15.7–19.9% SL vs. 20.2–35.7) and pectoral fin (20.7–25.5% SL vs. 27.3–38.1, except in P. ferula ), and in addition to P. ferruginea , a narrower interorbital width (24–27% HL vs. 27–38, except P. ferula ). Pseudolaguvia magna is further distinguished from, P. v i r i os a and P. m u r i c a t a by having a shorter dorsal-spine (13.7–18.4% SL vs. 21.2–29.0) and longer caudal peduncle (18.0–21.0% SL vs. 12.6–17.7); further: from P. ferula , P. ferruginea and P. m u r i ca t a by having a shorter anal-fin base (9.1–11.8% SL vs. 13.2–17.7), and a longer snout (51–60% HL vs. 44–51, except in P. m u r i ca t a), from P. m u r i c a t a by having a shallower head (12.3–16.5 % SL vs. 16.7–19.5), caudal fin with a narrower and incomplete (vs. broader and complete) hyaline band in the middle of each lobe (compare Fig. 1 here and fig. 3 in Ng, 2005b) and lacking (vs.

having) prominent black rings on the maxillary and mandibular barbels; from P. ferula by having a longer dorsalfin base (13.0–17.8% SL vs. 7.9–11.9); from P. foveolata and P. ferruginea by having a longer predorsal (41.3–44.8% SL vs. 35.3–40.8), and fewer vertebrae (27–29 vs. 31–33); from P. foveolata by having a shorter pelvic fin (13.4–15.8% SL vs. 19.0), adipose-fin base (10.7–14.2% SL vs. 24.0), and nasal barbel (11–20% HL vs. 24), a longer head (28.0–31.0% SL vs. 26.7), greater prepectoral length (23.6–27.7% SL vs. 22.7), and deeper caudal peduncle (7.5–9.2% SL vs. 5.0), and from P. v i r i o s a by having a greater interdorsal distance (16.2–20.3% SL vs. 11.7–15.4), and shorter caudal fin (19.9–23.7% SL vs. 26.5–32.4). Pseudolaguvia magna is distinguished from P. ribeiroi by having a smooth (vs. serrated) anterior margin of the dorsal spine, narrower interorbital width (24–27% HL vs. 31–40), deeper caudal peduncle (7.5–9.2% SL vs. 6.6–7.2), and caudal fin with a continuous (vs. discontinuous) dark-brown band extending from the base up to the tip of the median rays, with (vs. without) a narrow hyaline band in the middle of the upper and lower lobes, and the upper lobe with a small and indistinct (vs. broad and distinct) hyaline tip (see Fig.1 here and fig. 5b in Ng, 2005a); from P. shawi by having a shorter adiposefin base (10.7–14.2% SL vs. 15.9–20.3) and anterolateral margin of the thoracic adhesive apparatus widely (vs. moderately) extended (see Fig. 1 here and fig. 4b in Ng, 2005a). The holotype of P. shawi (ZSI F 10085/1) was not in good condition to record most of the morphometric landmarks except for parts of the head. P. magna can be distinguished from P. shawi by having a narrower (24–27% HL vs. 35) interorbital width; and from P. jiyaensis by having a shorter anal-fin base (9.1–11.8% SL. vs. 11.3–15.2) and caudal fin (19.9–23.7% SL vs. 22.3–29.7), a shorter adipose-fin base (10.7–14.2% SL vs. 13.8–18.0), lesser interdorsal distance (16.2–20.3% SL vs. 14.4–17.0), and a shorter head (28.0–31.0% SL vs. 30.3–33.3).

Only two species of Pseudolaguvia have been reported from Myanmar: P. tenebricosa Britz & Ferraris, 2003 and P. tuberculata ( Prashad & Mukerji, 1929) known from the Sittang and Irrawaddy river drainages respectively. Pseudolaguvia magna is distinguished from P. tenebricosa by having a longer caudal peduncle (18.0–21.0% SL vs. 15.4–17.5) and snout (51–60% HL vs. 45–51), a narrower head (19.7–23.0% SL vs. 23.2–25.1), shorter caudal fin (19.9–23.7% SL vs. 25.4–30.4) and adipose-fin base (see Fig. 1 here and fig.1a in Britz & Ferraris, 2003; they mistakenly inserted the caption of P. tuberculata of figure 2 in figure 1, but should be the caption of P. tenebricosa as per Fig. 1 a-e, given in page 2); and from P. tuberculata by having the adipose fin not contiguous (vs. contiguous) with the dorsal-fin base, a shorter caudal fin (19.9–23.7% SL vs. 26.7), and a narrower head (19.7–23.0% SL vs. 26.7). Further, P. magna can be distinguished from both the foregoing species in lacking (vs. having) black rings on the maxillary and mandibular barbels.

Pseudolaguvia spicula Ng & Lalramliana, 2010 is the only species of Pseudolaguvia so far known from the Surma-Meghna River system of the Barak River drainage in Mizoram, northeastern India and Meghna River drainage in northeastern Bangladesh. Pseudolaguvia magna is distinguished from P. s p i c ul a by having a shorter caudal fin (19.9–23.7% SL vs. 24.2–27.5) and adipose-fin base (10.7–14.2% SL vs. 14.7–17.1), a longer caudal peduncle (18.0–21.0% SL vs. 15.4–17.9), a narrower interorbital width (24–27% HL vs. 28–32), and fewer vertebrae (27–29 vs. 30–32). Further it can be distinguished by having the caudal fin with a dark-brown (vs. hyaline) patch on median rays.

Pseudolaguvia nubila Ng et al., 2013 was discovered from a tributary of Kaladan River in Mizoram, northeastern India. Pseudolaguvia magna is distinguished from it by the following characteristics: a greater predorsal (41.3–44.8% SL vs. 36.6–40.6) and interdorsal distance (16.2–20.3% SL vs. 13.1–16.8), a shorter analfin base (9.1–11.8% SL vs.15.6–19.7), a shallower caudal peduncle (7.5–9.2% SL vs. 9.1–11.1), and fewer vertebrae (27–29 vs. 31–32).

The other members of Pseudolaguvia known from the Ganges drainage are: P. kapuri (Tilak & Husain, 1975) from the Padhoi River near Kalsia Ghat, Uttar Pradesh, northern India; P. flavida Ng, 2009 from the Hooghly (Bhagirathi) River, West Bengal; P. virgulata Ng & Lalramliana, 2010 a from the Barak River drainage, and P. inornata Ng, 2005 b from the Feni River drainage, Bangladesh in the east and P. as s ul a Ng & Conway, 2013 from the Reu River, Chitwan Valley near confluence with Rapti River in Nepal.

Pseudolaguvia magna is distinguished from P. virgulata , P. inornata and P. assula by having a shorter pectoral-fin spine (15.7–19.9% SL vs. 20.4–28.3); and further from P. virgulata in having a narrower interorbital width (24–27 % HL vs. 29–35), a shorter dorsal-fin spine (13.7–18.4% SL vs. 21.5–24.0), a shorter pectoral fin (20.7–25.5% SL vs. 28.1–28.8), a shorter caudal fin (19.9–23.7% SL vs. 28.8–30.0), and a shallower head (head depth 12.3–16.5% SL vs. 16.6–19.4); and from P. flavida by having a longer snout (51–60% HL vs. 43), a greater: prepelvic length (47.7–56.0% SL vs. 45.9), preanal length (66.7–73.7% SL vs. 63.8), prepectoral length (23.6–27.7% SL vs. 19.5), pelvic-fin length (13.4–15.8% SL vs. 10.2), maxillary barbel length (56–73% HL vs.

43), and outer mandibular barbel length (41–56% HL vs. 34), a shallower body (depth at anus 13.7–17.5% SL vs. 27.6), deeper caudal peduncle (7.5–9.2% SL vs. 6.5), and fewer vertebrae (27–29 vs. 32); from P. inornata by having a shorter dorsal-fin spine (13.7–18.4% SL vs. 18.6–21.7) and caudal fin (19.9–23.7% SL vs. 27.8–29.8); from P. assula by having a shorter pectoral fin (20.7–25.5% SL vs. 27.6–32.5) and spine (15.7–19.9 % SL vs. 23.3–28.3), caudal fin (19.9–23.7% SL vs. 28.2–33.2), nasal barbel (11–20% HL vs. 20–30) and inner mandibular barbel (24–36% HL vs. 39–49), a longer interdorsal distance (16.2–20.3% SL vs. 10.7–16.2) and caudal peduncle (18.0–21.0% SL vs. 15.4–17.0), a narrower interorbital width (24–27% HL vs. 29–36), and a broader (vs. narrower) thoracic adhesive apparatus (see Fig. 2 here and fig. 2 in Ng & Conway, 2013), and from P. kapuri by having a shorter pelvic fin (13.4–15.8% SL vs. 15.3–17.9) which does not reach (vs. reaching) the anal-fin origin, caudal fin with a narrower (vs. broader) hyaline cross band at the middle of each lobe, band incomplete (vs. complete), and tip of upper lobe with small and indistinct (vs. broad and distinct) hyaline tip (compare Fig. 1 here and fig. 5a in Ng, 2005a).

Pseudolaguvia austrina Radhakrishnan et al., 2010 and P. lapillicola Britz et al., 2013 are the only species known from southern peninsular India, the former from the Kunthi River (tributary of the Bharathapuzha River) at Mannarkkad, in the state of Kerala, and latter from the Subramanya, Kumaradhara River in the state of Karnataka.

Pseudolaguvia magna is distinguished from P. austrina and P. lapillicola by having a narrower head (19.7–23.0% SL vs. 24.2–27.0) and interorbital width (24–27% HL vs. 30–43), a shorter nasal barbel (11–20% HL vs. 25–47), and fewer vertebrae (27–29 vs. 33–34); further from P. austrina by having a longer and shallower caudal peduncle (length 18.0–21.0% SL vs. 8.8–14.7 and depth 7.5–9.2% SL vs. 10.3–14.7), a larger eye (9–15% HL vs. 4–8), a shorter pelvic fin (13.4–15.8% SL vs. 16.0–20.9), caudal fin (19.9–23.7% SL vs. 25.7–43.9), interdorsal distance (16.2–20.3% SL vs. 29.5–32.7), and externally by having a shorter adipose-fin base (see Fig. 1 here and fig. 1 in Radhakrishnan et al., 2010), and from P. lapillicola by having a shallower head (depth12.3–16.5% SL vs. 19.4–20.7), a longer snout (51–60% HL vs. 34–42), and a shorter caudal fin (19.9–23.7% SL vs. 28.6–30.3). It can be further distinguished externally by having the caudal fin with a narrower and incomplete (vs. broader and complete) hyaline cross band in the middle, with dark-brown (vs. hyaline) median rays, the upper lobe with a small and indistinct (vs. large and distinct) hyaline tip, and without (vs. with) prominent dark brown to black spots on body (see Fig. 1 here and fig. 1 in Britz et al., 2013).

Description. General body shape as in Figure 1 ; biometric data are given in Table 1 . Head dorsoventrally depressed, broad, degree of depression increasing towards anterior snout margin, lateral side gently sloping from pectoral-fin origin to snout tip, roughly V-shaped when viewed dorsally. Anterior snout margin truncate to round. Eye small, ovoid, located entirely on dorsal half of head, situated closer to end of operculum than tip of snout. Dorsum of head and body with round to ovoid tubercles running from level of anterior margin of nostril to base of occipital process, minute tubercles scattered on operculum and cheek region, running along entire length either side of dorsal mid-line of body, also scattered on fleshy base of adipose fin. Lateral line complete, midlateral; total vertebrae 27 and 29 in two specimens.

Body elongate, greatest depth at dorsal-fin origin, deeper than wide, moderately compressed anteriorly, degree of compression increasing from insertion of dorsal fin to caudal-fin base. Dorsal profile rising abruptly from snout tip to anterior margin of nostril, thereafter evenly rising to dorsal-fin origin, then gently descending posteroventrad to caudal-fin base. Ventral profile almost horizontal from mouth to pelvic-fin origin, thereafter very gently rising towards caudal-fin base.

Mouth subterminal, broad, consisting of fleshy papillated lips, upper jaw projecting over lower jaw, more than two-thirds of premaxillary tooth-band exposed with mouth closed. Gill openings wide, extending obliquely from posttemporal to isthmus, and almost meeting each other on venter. Supraoccipital spine strong,broad, terminating very closer to nuchal shield. Weberian lamina well developed, narrower than supraoccipital spine, almost of equal length, running parallel to margin of supraoccipital spine. Upper lip continuing into maxillary barbel, with barbel bases connected to sides of head through a small triangular skin flap at base, just above corner of mouth.

Four pairs of barbels. Maxillary barbel tip almost reaching pectoral-fin origin; barbel base broad, with large proximal skin flap, its posterior end in cross section extending to level of posterior margin of nostril. Nasal barbel arising from internarial septum, extending almost halfway between naris and anterior orbital margin. Outer mandibular barbel slender with pointed tip, terminating at same level as maxillary barbel tip. Inner mandibular barbel short, originating from same level as outer mandibular barbel base, extending only half distance of outer mandibular barbel. Anus and urogenital opening situated slightly nearer to pelvic-fin origin than to anal-fin origin.

Thoracic adhesive apparatus rhomboid, slightly longer than broad, mostly extending to middle between base of last pelvic-fin ray and its tip, rarely to its tip, anterior portion wider than posterior, extending from isthmus to almost level of tip of last pectoral-fin ray, somewhat elevated, slightly longer than broad, with indistinct central median depression, open posteriorly, and followed by a series of indistinct small to moderate, round to ovoid cream tubercles running along each side and terminating closer to insertion of pelvic fin in some mature individuals.

Dorsal-fin origin located about two-fifths along body or almost midway between snout tip and posterior end of adipose-fin base and almost midway between pectoral-fin and pelvic-fin origins; dorsal fin longer than pelvic, anal, and adipose fins but shorter than pectoral and caudal fins, with 5,i (11) rays, anterior margin slightly convex, posterior margin obliquely straight. Dorsal spine compressed, stout, with sharply pointed tip, anterior margin smooth, posterior margin with 4–7 small serrae, erect spine extending only to perpendicular of body axis.

Adipose fin short, roughly triangular, anterior margin straight, posterior margin straight to slightly convex with incised posterior end, fin origin slightly anterior of vertical through pelvic-fin origin. Interdorsal distance equals post-adipose distance.

Pectoral fin with dorsoventrally depressed strong spine with sharply pointed tip, with i,5*(9); or i,5,i (2) rays. Pectoral spine equals snout length. Anterior spine margin with 5–7 serrae, distally directed, along its distal half, granulate to smooth along proximal half, posterior margin with 6–9 well developed serrae; first branched ray longest, tip of adpressed fin extending to vertical through base of third to last ray of dorsal fin. Pectoral girdle with moderate, stout postcoracoid processes, covered by thick skin, extending slightly beyond end of pectoral fin base. Pectoral spine movable backward only (perpendicular to horizontal laterally). Ventral skin of paired fins not plaited.

Pelvic fin soft, with i,5*(9) or i,5,i (2) rays, anterior margin slightly convex, posterior margin obliquely straight, first and second branched rays longest. Adpressed fin extending beyond anus, tip of last ray reaching middle to posterior margin of anus in adult specimens, reaching slightly beyond anus in juveniles, never reaching anal-fin origin. Pelvic-fin origin almost perpendicular to base of last dorsal-fin ray. Anal fin soft, with iv,4,i (2); iv,5 (5); iii,5,i (3); iii,7,i* (1) rays, anterior margin straight, posterior margin obtusely rounded. Distance between pectoral-fin and pelvic-fin origins equal to distance between pelvic fin and posterior insertion of anal-fin base.

Caudal fin moderately deep, longer than all other fins except pectoral fin, than which it is slightly shorter, with i,7,8,i* (9); i,6,7,i (1) or i,7,9,i (1) principal rays. Upper and lower caudal-fin lobes pointed, with lobes of equal length, lower lobe slightly broader than upper. Procurrent rays symmetrical, extending anteriorly only to hypural margin.

Coloration in preservative. In 70% alcohol: Dorsolateral surface of head brown, darker on occipital region. Dorsal surface of body brown, fading to light grayish brown along flank from dorsal-fin origin to caudal-fin base, juveniles darker than adults. Brown to dark-brown tubercles running dorsally from level of anterior margin of nostril to base of occipital process, scattered on operculum and cheek region, along entire length of the body either side of dorsal mid-line, and on fleshy base of adipose fin. Head, body, all barbels, fin bases, and central median depression of thoracic adhesive apparatus consisting of minute dark-brown spots, longitudinal striae of thoracic adhesive apparatus, mouth region and remaining ventral surface of head faint yellowish to cream. Supraoccipital spine and nuchal plate pale brown to cream, with a small elongated dark brown to black marks at the base of supraoccipital spine. Two pairs of spots and three pairs of marks on body: first, a round, weakly depressed cream spot, closer to tip of weberian lamina, second, a somewhat elongate to ovoid pale spot below dorsal-fin origin, third a moderately elongate faint pale to cream short mark on ventrolateral side of body, just above anus, fourth, a short to elongate faint cream to brown mark each on dorsolateral and ventrolateral side of caudal peduncle (indistinct in adults, somewhat distinct in juveniles, appearing to coalesce to form a thin band). A pale round spot on lateral side of head almost perpendicular to mid-eye.

Two pale to cream mid-dorsal stripes accompanied by two patches straddling mid-line: one running along interdorsal space with a roughly rectangular to elliptical patch in middle, and another stripe between adipose and caudal fins with an indistinct elliptical to irregular patch in middle.

Dorsal fin brown except for hyaline central streak and distal margin, streak thin, usually incomplete, a minute pale to cream spot at its origin. Anal fin with proximal and subdistal dark-brown bands, otherwise hyaline, subdistal band narrow posteriorly. Pelvic and pectoral fins dusky to brown near base with dark brown subdistal band, otherwise hyaline. Caudal-fin base evenly dark brown, extending medially without interruption to tip of median rays, covering inner parts of upper and lower lobes, two minute hyaline spots usually present, aligned vertically near base; outer margin of both lobes with a thin hyaline streak contiguous with moderate to narrow hyaline streak in middle of each lobe, streaks interrupted midway, not meeting each other, not complete across each lobe. Lower lobe with a somewhat larger, conspicuous hyaline tip than upper, remaining area brown with scattered melanophores. All barbels creamy ventrally, without black rings; nasal barbel brown dorsally, maxillary and outer mandibular barbel light brown to dusky, inner mandibular barbel mostly creamy.

Etymology. The species epithet is a Latin adjective (feminine) meaning ‘great’, and allusion to this being the largest of the 20 known species of Pseudolaguvia .

Figures

FIGURE 1. Pseudolaguvia magna, ZSI / V / APRC / P- 947, holotype, 46.1 mm SL; dorsal, lateral and ventral views.

FIGURE 2. Thoracic adhesive apparatus of Pseudolaguvia magna, ZSI / V / APRC / P- 948, paratype, 45.4 mm SL.

Tables

TABLE 1. Morphometric data for Pseudolaguvia magna (n = 10): ZSI / V / APRC / P- 947 (holotype), ZSI / V / APRC / P- 948 (8 paratypes).

	Holotype range	Mean s.d.
Standard length (mm)	46.1 31.9–46.7	40.2+5.5
%SL
Predorsal length	41.8 41.3–44.8	43.2+1.2
Preanal length	70.9 66.7–73.7	70.5+1.7
Prepelvic length	51.1 47.7–56.0	51.9+2.4
Prepectoral length	24.2 23.6–27.7	25.6+1.5
Length of dorsal-fin base	13.6 13.0–17.8	14.0+1.4
Dorsal-fin spine length	13.7 13.7–18.4	16.2+1.5
Length of anal-fin base	10.8 9.1–11.8	10.9+0.8
Pelvic-fin length	14.2 13.4–15.8	14.8+0.9
Pectoral-fin length	22.8 20.7–25.5	23.5+1.5
Pectoral-fin spine length	16.7 15.7–19.9	17.6+1.3
Caudal-fin length	21.1 19.9–23.7	22.1+1.2
Length of adipose-fin base	11.8 10.7–14.2	12.5+1.3
Dorsal to adipose distance	17.9 16.2–20.3	18.1+1.2
Post-adipose distance	18.0 15.4–19.6	18.1+1.3
Caudal peduncle length	18.9 18.0–21.0	19.6+1.0
Caudal peduncle depth	8.0 7.5–9.2	8.0+0.5
Body depth at anus	15.9 13.7–17.5	15.3+1.1
Head length	28.2 28.0–31.0	29.3+1.1
Head width at pectoral fin origin	21.0 19.7–23.0	21.6+0.9
Head depth just posterior to eye	13.1 12.3–16.5	14.0+1.5
%HL
Snout length	60 51–60	54.8+2.7
Interorbital distance	25 24–27	25.4+1.1
Eye diameter	11 9–15	11.7+1.9
Nasal barbel length	20 11–20	14.7+2.6
Maxillary barbel length	70 56–73	63.0+5.6
Inner mandibular barbel length	24 24–36	30.8+3.8
Outer mandibular barbel length	45 41–56	47.4+3.9