Acanthocobitis pictilis
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Ordo: Cypriniformes
Familia: Nemacheilidae
Genus: Acanthocobitis
Name
Acanthocobitis pictilis Kottelat, Maurice, 2012 – Wikispecies link – Pensoft Profile
- Acanthocobitis pictilis Kottelat, Maurice, 2012, Zootaxa 3327: 45-51.
Materials Examined
Holotype.MHNG2727.066, 71.8 mm SL; Myanmar: Kayin State: stream 'Chon Son' between Kyondaw and Phadaw, about 20 km northwest of Payathouzu (at border with Thailand near Chedi Sam Ong, Three Pagoda Pass); approx 15 ° 25 'N98 ° 15 'E; K. Kubota, December 2002.
Paratypes.CMK 17509, 5, 65.4–80.0 mm SL; Myanmar: Zami drainage near Kyandaw, approx. 15 ° 18 'N98 ° 18 'E [Kyandaw is about 20 km northwest of Chedi Sam Ong (Three Pagoda Pass)]; K. Kubota, June 2002. — MHNG2727.067, 2; ZRC53376, 1; CMK 17777, 5; 55.6–63.1 mm SL; same data as holotype. — CMK 17967, 2, 64.1–64.3 mm SL; same locality as holotype; K. Kubota, 1 June 2003. — ZRC53377, 1, 77.1 mm SL; CMK 18429, 1, 91.5 mm SL; same locality as holotype; M. Kottelat & K. Kubota, 1 May 2004. — CMK 14601, 1, 69.6 mm SL; Thailand: Kanchanaburi Prov.: Mae Nam Khwae Noi basin: Nam Khung near Ban Huai Pak Khung; 14 ° 39 ' 35 "N98 ° 32 '02"E; M. Kottelat & K. Kubota, 4 April 1998. — CMK 17249, 2, 63.0–69.8 mm SL; same locality; M. Kottelat et al., 29 March 2002.
Diagnosis
Diagnosis.Acanthocobitis pictilis is distinguished from all other species of the genus by its colour pattern, especially the dark brown triangular saddles in the upper half of the body, strongly slanted anteriorly and becoming almost vertical posteriorly. In larger specimens, the median part of the saddles become paler and it may appear as a pair of dark brown lines. Other characters useful to distinguish the species, but not unique to it are: lateral line complete; 12 ½ or 13 ½ branched dorsal-fin rays; 8 + 8 or 7 + 8 branched caudal fin rays; males with deep slit on the cheek (Fig. 2 a), extending from lower margin of eye to above base of posterior rostral barbel; 6–8 vertical lines or rows of spots on caudal fin; and 6–7 longitudinal lines or rows of spots on dorsal fin.
Description
Description. See Figure 1 for general appearance and Table 1 for morphometric data of holotype and 16paratypes. A moderately elongate nemacheilid (sensu Šlechtová et al., 2007) with body depth increasing until slightly in front of dorsal-fin origin. Behind dorsal fin, body depth decreasing slowly to caudal-fin base. Head slightly compressed; body compressed. Largest recorded size 91.5 mm SL.
Ranges include values of holotype. Standard lenth (mm) Total lenth (mm) In percent of standard length Total length Head length (dorsal)Ataran drainage holotype range mean 71.8 55.8–80.0 89.2 68.1–101.1 124.3 120.6–127.1 124.2 21.8 20.8–23.4 22.2Mae Khlong drainage 69.6 69.8 63.0 83.0 85.6 76.9 119.4 122.6 122.1 20.4 20.9 21.8Head length (lateral) Predorsal length24.0 22.7–24.9 24.2 47.0 45.2–47.4 46.6 22.4 23.8 24.1 44.9 45.6 47.0Prepelvic length Pre-anus length Pre-anal length Head depth52.7 50.0–54.9 52.0 75.2 72.6–76.4 74.3 79.4 77.0–82.6 79.2 13.4 13.2–15.5 14.2 49.9 51.1 53.0 71.3 72.4 72.8 76.9 76.4 79.4 12.9 14.1 14.6Body depth at dorsal-fin origin Depth of caudal peduncle17.2 17.2–23.0 19.4 13.0 12.9–14.5 13.5 17.7 19.6 20.4 12.0 13.1 13.6Length of caudal peduncle Snout length Maximum head width Body width at dorsal-fin origin Eye diameter Interorbital width14.2 13.7–16.4 15.1 11.4 10.2–11.7 10.9 15.4 14.8–17.7 15.8 13.3 12.1–17.0 13.8 5.4 4.6–6.2 5.5 7.3 6.4–8.3 7.4 15.5 15.8 14.8 10.7 11.0 10.9 14.6 15.6 16.0 12.1 13.1 14.2 5.2 4.5 5.4 6.5 7.6 6.9Length of dorsal fin Length of upper caudal-fin lobe Length of median caudal-fin ray Length of lower caudal-fin lobe19.5 15.7–20.9 19.1 23.4 22.1–25.1 23.3 22.5 19.6–25.0 22.2 24.8 21.7–25.7 24.3 18.0 18.4 18.4 20.7 22.5 22.9 19.9 20.2 22.0 21.7 22.5 24.2Length of anal fin Length of pelvic fin17.9 15.0–18.4 17.3 17.4 15.7–19.0 17.2 17.0 16.2 17.1 16.2 16.7 16.1Length of pectoral fin In percent of dorsal head length Snout length Eye diameter Interorbital width In percent of lateral head length20.4 19.0–22.3 20.5 52 46–54 49.3 25 21–28 24.8 33 29–37 33.2 20.0 19.3 19.6 52 53 50 26 21 25 32 36 32Snout length Eye diameter Interorbital width47 41–48 45.1 22 19–26 22.7 30 27–34 30.4 48 46 45 23 19 23 29 32 29 Dorsal fin with 4 simple and 12 ½ (10) or 13 ½ (7) branched rays; distal margin slightly concave. Pectoral fin with 1 simple and 12 (9), 13 (6) or 14 (1) branched rays; reaching about 2 / 3 of distance to pelvic-fin base; tip of rays projecting slightly beyond membranes. Axillary pelvic lobe present. Pelvic fin with 1 simple and 6 (1) or 7 (16) branched rays, reaching about ½ to 3 / 5 of distance to anal-fin origin, not reaching anus, which is situated about one eye diameter in front of anal fin; origin under base of branched dorsal-fin rays 3 to 4. Anal fin with 3 simple and 5 ½ branched rays. Caudal fin slightly emarginate, with 7 + 8 (3) or 8 + 8 (11) branched rays. Low ventral and dorsal crests on posterior half of caudal peduncle, which is 1.0–1.3 times longer than deep. Body entirely covered by scales, except around 4–5 first lateral line pores; scales embedded on belly. Lateral line complete, with 80–90 pores (most specimens 87–88). Cephalic lateral line system with 6 supraorbital, 4 + 10–12 infraorbital, 10 preoperculo-mandibular and 3 supratemporal pores (5 specimens examined). Anterior nostril pierced at tip of an obliquely truncate tube (Fig. 2 a). Mouth gape about twice as wide as long (Fig. 3). Lips thick, strongly papillated. A median interruption in lower lip. Processus dentiformis present. No median notch in lower jaw. Inner rostral barbel reaching almost to vertical of anterior margin of eye; outer one reaching vertical of posterior margin of eye. Maxillary barbel reaching middle of postorbital area. Intestine with a loop behind stomach, extending forward to anterior extremity of stomach (Fig. 4).
Sexual dimorphism. Adult males distinguished by presence of a deep slit on cheek (termed suborbital slit), extending from lower margin of eye until above base of posterior rostral barbel (Fig. 2 a). Infraorbital canal running along ventral edge of slit. No slit in females, but in several of them a shallow groove in similar position (Fig. 2 b). Smallest individual with a slit (CMK 17777, 63.1 mm SL). Slit and groove homologous to lower margin of suborbital flap in many nemacheilids but not ending posteriorly in a flap. In males, dorsal surface of 5 or 6 anterior branched rays of pectoral fin covered by thick tissue and densely covered by small tubercles (vs. both missing in females); patches of unculi on opercle and suborbital area (vs. absent). Ripe females deeper-bodied. Coloration. Head and body background colour greyish brown (yellowish brown in material from Mae Khlong drainage, but this apparently induced by water turbidity), whitish on belly; all marks on head and body dark brown, unless mentioned otherwise. Head with 3–4 transverse lines in interorbital and occipital areas, and a few large spots on snout, cheeks and opercle. Dorsum with saddles, 4–5 predorsal, 3–4 subdorsal and 5–6 postdorsal; total 11–16, modally 12 in specimens less than about 65 mm SL, more difficult to count in larger specimens because of ontogenetic changes. In specimens less than about 65 mm SL, saddles with a slightly darker outline; with increasing size, median part of saddle becoming paler and saddles appearing as a pair of dark lines meeting in a pointing tip near lateral line. Anterior saddles oblique, directed backwards; predorsal ones strongly slanted, becoming less slanted along dorsal-fin base, and almost vertical on caudal peduncle. In smaller specimens, at level of lateral line, saddles becoming a very narrow bar, more or less vertical (posteriorly) or slightly slanted (anteriorly); tip of bars at level of pectoral-fin base; only posterior-most bars, at end of caudal peduncle, reaching ventral midline. Between bars, a spot on lateral line and one between tip of bars. In larger specimens, saddles ending at lateral line; below lateral line, bars and spots becoming dissociated and resulting in an irregular mottled pattern. A conspicuous black spot at caudal fin base, vertically elongated, close to upper extremity of fin base; on a pale background but not ocellated. Dorsal fin hyaline, with 6–7 longitudinal rows of black spots on rays and (usually) membranes. Caudal fin with 6–8 vertical rows of spots on rays and (usually) membranes. Other fins hyaline. Notes on biology. Two dissected females, CMK 17509, 65.4 mm SL, and CMK 17967, 64.1 mm SL, collected in June 2002 and 2003, respectively, had apparently ripe ovaries with eggs 0.7 mm diameter.
Distribution
Distribution.Acanthocobitis pictilis is presently known only from the Ataran drainage in Myanmar and the Mae Khlong drainage in Thailand. The two drainages are adjacent and separated by a pass at about 280 masl (Chedi Sam Ong; Three Pagoda Pass). The Ataran drains to the Andaman Sea (Indian Ocean) and the Mae Khlong to the Gulf of Thailand (South China Sea). The Mae Khlong shares a number of genera and species with the Ataran, Salween and Irrawaddy drainages that are not known in any other drainage on the Gulf of Thailand slope (e.g., Batasio, Badis, Rasbora rasbora, Schistura mahnerti, Acanthocobitis zonalternans; pers. obs. and, e.g., Kottelat 1989, 1990, Ng & Kottelat 2001, Kullander & Britz, 2002).
Etymology
Etymology. From the Latin pictilis (embroided). An adjective (pictilis, –is, –e).
Discussion
Remarks. Earlier authors (e.g. Menon 1987: 141, Kottelat 1990: 31) recognised A. botia (Hamilton, 1822) as a species distributed in Peninsular India, Sri Lanka, and the Indus, Ganges, Brahmaputra, Irrawaddy, Salween and Mae Khlong drainages in Pakistan, India, Bangladesh, Myanmar, Thailand and China. This was a very heterogeneous assemblage and, among the nominal species listed as synonyms, at least three are valid: A. mooreh (Sykes, 1839) from Peninsular India, A. urophthalmus (Günther, 1868) from Sri Lanka and A. mandalayensis (Rendahl, 1948) from Myanmar (Kottelat, in press). Some of the nominal species still remaining in the synonymy of A. botia might also be valid. The A. botia specimens from the Mae Khlong drainage reported by Kottelat (1990: 31) are A. pictilis.
Materials Examined
Comparison material. Comparison is based on descriptions in Kottelat (1990) and the following additional material: A. botia: CMK 18577, 2; India: West Bengal: Tista drainage. A. mandalayensis: NRM36248, 7; NRM40678, 24; NRM40706, 1; NRM40870, 3; NRM40899, 6; NRM40916, 13; Myanmar: Kachin State: Myitkyina. — NRM40981, 1; NRM41037, 3; Myanmar: Kachin State: Lake Indawgyi basin. A. pavonacea: CMK 5927, 3; India: Assam: Dibru drainage.
Taxon Treatment
- Kottelat, Maurice; 2012: Acanthocobitis pictilis, a new species of loach from Myanmar and Thailand (Teleostei: Nemacheilidae), Zootaxa 3327: 45-51. doi
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