Balantiocheilos ambusticauda , Ng, Heok Hee & Kottelat, Maurice, 2007

Ng, Heok Hee & Kottelat, Maurice, 2007, Balantiocheilos ambusticauda, a new and possibly extinct species of cyprinid fish from Indochina (Cypriniformes: Cyprinidae), Zootaxa 1463, pp. 13-20: 14-17

publication ID

10.5281/zenodo.176469

publication LSID

lsid:zoobank.org:pub:6257CE18-D337-40F6-8FB0-56DE357F46EA

persistent identifier

http://treatment.plazi.org/id/A354879D-0200-9C58-FF1D-8AFE570E25AF

treatment provided by

Plazi

scientific name

Balantiocheilos ambusticauda
status

sp. nov.

Balantiocheilos ambusticauda  sp. nov.

( Fig. 1View FIGURE 1 a)

Balantiocheilos melanopterus  (non Bleeker) Bleeker, 1865 a: 35; 1865 b: 176; Sauvage, 1881: 164; Tirant, 1885: [p. 161 of 1929 reprint]); Hora, 1923: 159; Chevey, 1932: 14; Fowler, 1937: 200, Figs. 185–186; Smith, 1945: 206; Taki, 1968: 10; Kottelat, 1985: 260; Rainboth, 1996: 86; Baird et al., 1999: 25; Kottelat, 2001: 38 (not figure [a cultivated specimen]).

Type material. Holotype. MHNGAbout MHNG 2689.096, 105.1 mm SL; Thailand: Nakhon Sawan province, Bung Borapet; R. Geisler, February 1967.

Paratypes. MHNGAbout MHNG 2158.45 (3), 102.4–120.9 mm SL; data as for holotype. ANSPAbout ANSP 87831 (3), 52.6–54.6 mm SL; Thailand: Kemrat, 16 ° 2 'N 105 ° 12 'E; R. de Schauensee, 1936. ANSPAbout ANSP 87209 (2), 110.0– 116.6 mm SL; Thailand: Bangkok; R. de Schauensee, 1936. MNHNAbout MNHN A 6333 (1), 126.0 mm SL; Thailand: Chao Phraya River; M. Harmand, 1883. MNHNAbout MNHN 1847 (5), 78.6–107.5 mm SL; Thailand: Bangkok; F. Bocourt, 1862.

Diagnosis. Balantiocheilos ambusticauda  is distinguished from its sole congener, B. melanopterus  ( Fig. 1View FIGURE 1 b), in having a shorter snout (27.5–33.9 % HL vs. 33.2–39.1) that is rounded (vs. obliquely truncate) in specimens larger than ca. 80 mm SL ( Fig. 2View FIGURE 2), posteriorly directed groove at rictus curved (vs. straight; Fig. 3View FIGURE 3), and narrower black margins on the pelvic and anal fins (on distal third of both fins or less vs. on distal half or more, with pelvic fins sometimes entirely black).

Description. Morphometric data are given in Table 1. Body moderately slender and strongly compressed; scales in transverse lines ½ 5 / 1 / 4 ½ (1) or ½ 6 / 1 / 4 ½ (8). Predorsal profile gently sloping dorsally, then sloping gently ventrally from origin of dorsal fin to end of caudal peduncle; predorsal scales 11 (6) or 12 (3). Ventral profile less convex than dorsal profile, sloping gently ventrally to anal-fin origin, then sloping more steeply dorsally from there to end of caudal peduncle. Lateral line complete, with 32 + 2 (6), 33 + 2 (2) or 34 + 3 (1) scales. Scales with strongly convergent radii. Vertebrae 17 + 14 = 31 (1), 18 + 14 = 32 (4), 17 + 16 = 33 (2) or 18 + 15 = 33 (2).

Head narrow, snout produced, with a rounded tip. Nostrils small and situated in front of eye. More than 50 % of eye in anterior half of head, visible from ventral, but not dorsal, aspect. Suborbital bones fairly large, narrowest directly below eye. Mouth subterminal, with well-developed groove separating lips from both upper and lower jaws. Lips thick and fleshy, with numerous longitudinal striae. Upper lip produced, entirely visible from below when mouth is closed. Lower lip with prominent lobe produced posteriorly; lobe deeply incised medially to form chevron-shaped posterior margin, and with short, curved groove extending posteriorly at rictus ( Fig. 3View FIGURE 3). Gill membranes separate at isthmus. First gill arch with 4 + 7 (3), 5 + 10 (4) or 6 + 10 (2) rakers. Gill rakers short, 25 % length of opposing filaments on epibranchial and 20 % length of opposing filaments on ceratobranchial. Pharyngeal bones stout, with three rows (2,3,5–5,3,2) of hook-shaped, conical teeth.

Dorsal fin moderately high, with ii, 8 ½ (9) rays and concave distal margin, sharply pointed at apex; origin slightly anterior to pelvic-fin origin. Tip of adpressed dorsal fin reaching vertical through base of first anal-fin ray. Last unbranched ray longest, osseous proximally; spinous part with 12–15 serrations on posterior edge.

Pectoral fin long, with i, 12,i (1), i, 13,i (4) or i, 14,i (4) rays and extending almost to pelvic-fin origin (reaching to 1–2 scale rows anterior to pelvic-fin origin); distal margin slightly convex. Pelvic fin with i, 8 (1); i, 8,i (1) or i, 9 (7) rays, extending to slightly more than midway between pelvic-fin origin and anterior part of anal-fin base; distal margin slightly convex. Anal fin with ii, 5 ½ (9) rays, strongly concave distal margin and last three posterior rays approximately equal in length; when adpressed against body, extending to middle of caudal peduncle. One scale row between urogenital opening and anal-fin origin. Caudal peduncle strongly compressed and moderately long; circumpeduncular scales ½ 3 / 1 / 3 ½ (9). Caudal fin deeply forked, with i,8,8,i (1) or i,9,8,i (8) rays. Upper and lower caudal lobes pointed; lower lobe slightly longer than upper.

Pronounced sexual dimorphism absent. Breeding tubercles absent and body depth between sexes not different.

Coloration. Preserved material with a brown body and head. Dorsal, anal and caudal fins hyaline with a thick black margin band. Proximal anterior part of dorsal fin dark brown. Dorsal and ventral margins of upper and lower caudal fin lobes with faint dark band in some individuals. Posterior third of pelvic fin black. Pectoral fin hyaline.

Distribution. Lower and middle Mekong and Chao Phraya river drainages in mainland Southeast Asia ( Fig. 4View FIGURE 4). The original distribution of this species included the Chao Phraya River drainage from Bangkok upriver to the lower Nan River ( Smith, 1945) and in the Mekong from Vietnam and the Great Lake (Tonle Sap) to the lower Nam Ngum River ( Taki, 1968). The specimen identified as Balantiocheilus  from Chiengmai by Fowler (1934: 127) is actually a juvenile Poropuntius  .

Etymology. The name of this species comes from the Latin ambustus (burned around, scorched) and cauda (tail), in allusion to the black edge of the caudal fin. This name evokes the Thai name for the fish (pla hang mai, meaning “burnt tail fish”; Smith, 1945: 206). A noun in apposition.

TABLE 1. Morphometric data for Balantiocheilos ambusticauda (n = 9: 52.6 – 120.9 mm SL) and B. melanopterus (n = 18: 63.6 – 177.4 mm SL).

  B. ambusticauda B. melanopterus
Body depth at dorsal origin
MHNG

Museum d'Histoire Naturelle

ANSP

Academy of Natural Sciences of Philadelphia

MNHN

Museum National d'Histoire Naturelle

Kingdom

Animalia

Phylum

Chordata

Class

Actinopterygii

Order

Cypriniformes

Family

Cyprinidae

Genus

Balantiocheilos

Loc

Balantiocheilos ambusticauda

Ng, Heok Hee & Kottelat, Maurice 2007

2007
Loc

Balantiocheilos melanopterus

Kottelat 2001: 38
Baird 1999: 25
Rainboth 1996: 86
Kottelat 1985: 260
Taki 1968: 10
Smith 1945: 206
Fowler 1937: 200
Chevey 1932: 14
Hora 1923: 159
Sauvage 1881: 164
Bleeker 1865: 35

1865