Glyptothorax maceriatus, Ng, Heok Hee, 2012

Ng, Heok Hee, 2012, Glyptothorax maceriatus, a new species of sisorid catfish (Actinopterygii: Siluriformes) from north-eastern India, Zootaxa 3416, pp. 44-52 : 45-47

Glyptothorax maceriatus , new species

( Figs. 1 , 2 )

Type material. Holotype: PUCMF 12014, 83.8 mm SL; India: Mizoram, Tlawng River at Sairang, 23°48'36.0"N 92°39'14.4"E; Lalramliana, 26 January 2010.

Paratypes: PUCMF 12015 (2), 90.1–95.5 mm SL; data as for holotype. PUCMF 12016 (5), 45.3–68.3 mm SL; India: Mizoram, Tuirial River in the vicinity of Melriat, 23°38'31.0"N 92°43'23.0"E; Lalramliana, 14 January 2010. PUCMF 12017 (1), 53.5 mm SL; India: Mizoram, Tuivai River drainage, Sur Luite River in the vicinity of NE Khawdungsei village, 23°59'3.2"N 93°14'29.9"E; Lalramliana & Kawlengmawia, 25 March 2010. PUCMF 12018 (2), 58.5–59.5 mm SL; India: Mizoram, Tuivai River drainage, Mausam River in the vicinity of NE Khawdungsei village, 23°57'33.0"N 93°12'34.0"E; Lalramliana & Kawlengmawia, 23 February 2011.

Diagnosis. Glyptothorax maceriatus is diagnosed from congeners from rivers draining the Ganges Delta in having a combination of the following characters and character states: nasal barbel not reaching anterior orbital margin; interorbital distance 27.0–31.4% HL; head length 23.7–25.3% SL; head depth 12.5–14.2 % SL; thoracic adhesive apparatus with narrow elliptic central depression that is almost wholly enclosed posteriorly by skin ridges (striae) and with single, non-diverging series of striae running along its edges; width of adhesive apparatus 55.8–72.1% its length; unculiferous ridges of adhesive apparatus not extending anteriorly onto gular region; absence of striae on first pectoral- and pelvic-fin elements; pectoral-fin length 20.7–24.9% SL; smooth posterior edge of dorsal spine; dorsal-to-adipose distance 17.8–23.6% SL; body depth at anus 11.3–13.8% SL; pelvic-fin length 15.9–19.1% SL; length of anal-fin base 13.9–16.2% SL; caudal peduncle length 21.4–23.9% SL; and caudal peduncle depth 6.4–7.6% SL (3.1–3.4 times in its length). In addition to the characters above, it is diagnosed from congeners in the Kaladan River drainage in eastern Mizoram in having dorsal-spine length 13.0–17.1% SL.

Description. Biometric data as in Table 1 . Head depressed, body subcylindrical. Dorsal profile rising evenly from tip of snout to origin of dorsal fin, sloping gently ventrally from origin of dorsal fin to end of caudal peduncle. Ventral profile flat to anal-fin base, sloping gently dorsally from anal-fin base to end of caudal peduncle. Anus and urogenital openings located at vertical through middle of adpressed pelvic fin. Caudal peduncle long, thin, its depth 3.1–3.4 times in its length. Skin almost smooth, with minute tubercles on sides of body. Lateral line complete, midlateral. Vertebrae 17+18=35 (2), 18+17=35 (1), 17+19=36 (1), 18+18=36* (6) or 18+19=37 (1).

Head depressed, broad; triangular in lateral view. Snout prominent. Anterior and posterior nares large, separated only by base of nasal barbel. Gill openings broad, extending from post-temporal to isthmus. Bony elements of dorsal surface of head covered with thick, tuberculate skin. Eye ovoid, its horizontal axis longest; located entirely in dorsal half of head.

Barbels in four pairs. Maxillary barbel long, slender; extending just beyond base of last pectoral-fin ray. Nasal barbel slender, extending to midway between its base and anterior orbital margin. Inner mandibular-barbel origin close to midline, extending to midway between its base and that of pectoral spine. Outer mandibular barbel originating posterolateral of inner mandibular barbel, extending to base of pectoral spine.

Mouth inferior, premaxillary tooth band not exposed with mouth closed. Oral teeth small, villiform; in irregular rows on all tooth-bearing surfaces. Premaxillary teeth in a single broad semilunate band. Dentary teeth in two narrow crescentic bands separated at midline.

Thoracic adhesive apparatus present, consisting of ridges of skin (striae) in oblong field extending from isthmus to level of middle of pectoral-fin base, with narrow elliptic median depression on posterior half almost enclosed posteriorly by skin ridges ( Fig. 2 ); its width 55.8–72.1% of its length. Striae uninterrupted; medial striae orientated anteriorly, lateral ones anterolaterally.

Dorsal fin above anterior third of body, with I,6 (11) rays; fin margin convex; spine broad, straight; with smooth posterior margin. Adipose fin with anterior margin straight or slightly concave, posterior margin angular. Caudal fin strongly forked, with lower lobe slightly longer than upper lobe and i,7,8,i (11) principal rays. Procurrent rays symmetrical, extending only slightly anterior to fin base. Vertical through anal-fin origin posterior to that through adipose-fin origin. Anal fin with straight anterior margin, straight or slightly concave posterior margin; with iii,8 (1), iii,9 (5), iv,8,i (1) or iv,9* (4) rays. Vertical through pelvic-fin origin posterior to that through posterior end of dorsal-fin base. Pelvic fin with slightly convex margin and i,5 (11) rays; tip of adpressed fin not reaching anal-fin origin. Pectoral fin with I,8,i (1) or I,9* (10) rays; posterior fin margin slightly concave. Pectoral spine very broad, covered with thick skin. Anterior spine margin smooth, its posterior margin with 8–14 serrae. Ventral surface of spine smooth and without striae.

Coloration. In 70% alcohol: dorsal and lateral surfaces of head and body brown, gray or dark gray, fading to cream on ventral surfaces. Faint pale mid-dorsal stripe on dorsal surface of body and midlateral stripe running along entire length of body. Dorsal, pectoral, pelvic, anal and caudal fins also dark brown, particularly on rays. Adipose fin dark brown basally, fading to lighter brown along distal margin. Nasal and maxillary barbels dark brown dorsally, light grayish brown ventrally; all mandibular barbels light grayish brown. Life coloration similar, with darker body coloration and more prominent pale mid-dorsal and midlateral stripes.

Etymology. The specific name comes from the Latin adjective maceriatus (masculine), meaning enclosed or walled in, in allusion to the narrowly elliptic central depression in the thoracic adhesive apparatus being almost completely enclosed by skin ridges.

Habitat. Glyptothorax maceriatus was collected from clear, shallow, moderately flowing streams with a predominantly sandy bottom. Associated fishes include Garra spp. ( Cyprinidae ), Balitora cf. brucei (Balitoridae) , Botia cf. almorhae (Botiidae) , Lepidocephalichthys sp. ( Cobitidae ), Schistura spp. ( Nemacheilidae ), Amblyceps laticeps (Amblycipitidae) , Glyptothorax botius (Sisoridae) , G. telchitta (Sisoridae) , and Channa sp. ( Channidae ).

Distribution. Known from the Mausam, Sur Luite (both tributaries of the Tuivai River), Tlawng and Tuirial rivers in Mizoram, northeastern India ( Fig. 3 ). The Tlawng, Tuirial and Tuivai rivers form part of the Barak River drainage, which is itself part of the Surma-Meghna River system.

Figures

FIGURE 1. Glyptothorax maceriatus, PUCMF 12014, holotype, 83.8 mm SL; dorsal, lateral and ventral views.

FIGURE 2. Glyptothorax maceriatus, PUCMF 12015, paratype, 95.5 mm SL; thoracic adhesive apparatus.

FIGURE 3. Map showing collecting localities of Glyptothorax maceriatus. Each point represents two localities.

Tables

TABLE 1. Biometric data for Glyptothorax maceriatus (n = 11).

	holotype PUCMF 12014	range	mean±SD
Standard length (mm) Percent of standard length Predorsal length	83.8 34.5	45.3–95.5 33.3–35.5	34.1±0.69
Preanal length Prepelvic length	65.9 47.5	63.4–66.1 44.7–47.5	64.5±1.02 46.4±0.85
Prepectoral length Length of dorsal-fin base Dorsal-spine length Length of anal-fin base	19.3 14.2 16.3 16.2	19.2–21.0 13.1–14.8 13.0–17.1 13.9–16.2	19.7±0.62 13.7±0.62 15.3±1.42 15.0±0.67
Pelvic-fin length Pectoral-fin length	19.1 23.3	15.9–19.1 20.7–24.9	17.7±0.97 22.9±1.12
Pectoral-spine length Caudal-fin length Length of adipose-fin base Dorsal to adipose distance Post-adipose distance Caudal-peduncle length	16.3 27.5 12.9 20.5 22.9 22.6	14.9–18.0 25.8–29.1 11.4–14.1 17.8–23.6 21.6–24.6 21.4–23.9	17.0±0.96 27.7±1.09 12.3±0.89 20.7±1.84 23.0±0.88 22.8±0.82
Caudal-peduncle depth Body depth at anus Head length Head width	6.9 13.2 25.3 18.4	6.4–7.6 11.3–13.8 23.7–25.3 16.8–20.0	7.1±0.35 13.0±0.76 24.2±0.51 18.2±0.95
Head depth Percent of head length	13.2	12.5–14.2	13.1±0.53
Snout length Interorbital distance Eye diameter Nasal barbel length	50.9 27.4 8.5 20.3	46.8–52.2 27.0–31.4 8.5–12.6 20.3–29.4	49.7±1.81 29.2±1.51 10.6±1.15 24.1±3.01
Maxillary barbel length Inner mandibular barbel length	92.0 26.4	86.5–105.6 26.4–37.2	94.7±6.66 32.1±3.26
Outer mandibular barbel length	45.8	43.4–54.0	50.0±3.83