Rhinogobius sulcatus, Chen & Kottelat, 2005

Chen, I-Shiung & Kottelat, Maurice, 2005, Four new freshwater gobies of the genus Rhinogobius (Teleostei: Gobiidae) from northern Vietnam, Journal of Natural History 39 (17), pp. 1407-1429 : 1413-1417

Rhinogobius sulcatus new species

( Figures 3 , 7 , 11 ) Rhinogobius duospilus: Kottelat 2001a, p 61 , Figure 142.

Material examined

Holotype: ZRC 49208, 27.0 mm SL, Vietnam: Quang Ninh Province, Cam Pha District , small coastal stream, at about km 10 on road from Mong Duong to Tien Yen, 21 ° 059380N, 107 ° 219020E, coll. M. Kottelat et al., 5 October 1998 . Paratypes: CMK 14981, eight specimens , ZRC 49209, four specimens , 20.6–27.6 mm SL, other data same as above.

Diagnosis

Rhinogobius sulcatus is distinguished from all congeners by the unique combination of the following features: cheek and opercle with three (rarely four) oblique brownish black bands and one to two stripes, respectively; branchiostegal membrane greyish with 14–17 round light spots (red or orange in life) in male; first dorsal fin with a median brownish black blotch in front of third spinous ray in male; pectoral fin whitish, base with two conspicuous black spots in adults; caudal fin base with a median black spot; body with six to seven conspicuous deep brown blotches on lateral trunk; second dorsal fin rays modally eight; anal fin rays modally seven; pectoral fin rays modally 15; longitudinal scale rows 26–29; predorsal median series 8–11; and vertebrae modally 27.

Description

Body cylindrical anteriorly, compressed posteriorly. Body proportions in Table I. Head moderately large, slightly depressed anteriorly. Eye large, lips thick. Mouth oblique, rear edge reaching beyond vertical through anterior margin of pupil in both sexes. Both jaws with three to four rows of conical teeth, outer rows enlarged. Tongue margin rounded. Anterior nostril a short tube, posterior one a round hole. Gill opening extending to vertical through margin of preopercle. Isthmus broad. 10211+16217527228 vertebrae (mode 27).

Fins. D1 V–VI (mode VI); D2 I/7–9 (mode 8); A I/6–7 (mode 7); P 15–17 (mode 15); V I/ 5+I/5 (frequency distribution in Table II). D1 rays about equal, III, IV longest, rear tip extending to base of first branched ray of D 2 in male, not reaching origin of D 2 in female. A origin below second branched ray of D2. P large, rear margin extending to vertical of anus in male, not reaching this point in female. V disc rounded, spinous rays with pointed membranous lobe. C elliptical, rear edge rounded.

Scales. Body with large ctenoid scales, anterior part of predorsal area naked; scales on posterior predorsal region and belly cycloid; scales in longitudinal series 26–29 (mode 28); transverse series nine (mode nine); predorsal median series 8–11 (mode 10); series between first dorsal and upper pectoral fin origin six (frequency distribution in Table III). Head including opercle, preopercle and prepelvic areas naked. Predorsal squamation with slightly trifurcate anterior edge, anterior extension of median series reaching midline vertical of gap between anterior and posterior oculoscapular canals.

Head lateral-line system. Canals: nasal extension of anterior oculoscapular canal with terminal pores S in front of posterior nostrils. Anterior interorbital section of oculoscapular canal separated, with paired pores l. A single pore K in posterior interorbital region. Pore v present at posterior edge of eye. Gap between anterior and posterior oculoscapular canals about equal to length of posterior oculoscapular canal. Preopercular canal with three pores c, d, E.

Sensory papillae: row a reaching midline of orbit. Length of row b about half of orbit. Row c, d long, not reaching vertical of pore a. A single cp papilla. Row f paired. Opercular rows ot and oi well separated.

Coloration in alcohol. Head and body light yellowish brown. Body with six to seven conspicuous deep brown blotches on flank and five deep brown blotches in dorsal region. Marking of scale pocket indistinct. Dorsal side of snout with a pair of brown lines united at tip of snout. A longitudinal brown line behind orbit. Nape with some irregular brown marks. Cheek and opercle always with three (rarely four) oblique brownish black stripes and one to two stripes, respectively. A brown blotch below eye in female. Branchiostegal membrane greyish with 14–17 round light spots (red or orange in life) in male, uniformly light yellowish in female.

First dorsal fin with light margin and a median brownish black blotch in front of third spinous ray in male, none in female. Second dorsal fin grey with two basal rows of blackish brown spots in male, whitish with three rows of longitudinal brown spots in female. Anal fin greyish, with light margin. Pectoral fin whitish, base with two conspicuous black spots in adults of both sexes. Caudal fin greyish in male, pale white in female, with three to six rows of vertical greyish brown spots and base with a median black spot. Pelvic fin greyish in male, pale white in female.

Distribution

Rhinogobius sulcatus is definitively known only from the type locality, a small coastal stream north of Cam Pha , on the north-eastern coast of Vietnam . It was collected together with R. variolatus . The specimen figured in Kottelat (2001a, Figure 142) probably represents the same species, but this cannot be confirmed as the material is no longer available. This material was from a small hill stream in the Song Lo drainage (a tributary of Song Hong), in north-western Vietnam.

Etymology

From the latin sulcatus (scarred). An adjective (feminine: sulcata; neuter sulcatum).

Remarks

Rhinogobius sulcatus is more similar to R. duospilus ( Herre, 1935a) (a species endemic to Hong Kong) than to any other species in southern China. However, they can be distinguished by the following combinations of features: (1) body scales: body with fewer lateral scales in R. sulcatus than in R. duospilus (always 27–28 versus 30–31); (2) pectoral fin rays: fewer pectoral fin rays in R. sulcatus than in R. duospilus (usually 15 versus 16–17); and (3) coloration pattern in male: opercle with one to two brownish black stripes in R. sulcatus versus none on upper region of opercle in R. duospilus .

Figures

Figure 3. Head lateral-line system of Rhinogobius sulcatus, paratype, CMK 14981, 25.4 mm SL. Scale bar: 1 mm.

Figure 7. Rhinogobius sulcatus, holotype, ZRC 49208, 27.0 mm SL, cephalic colour pattern of male. Scale bar: 1 mm.

Figure 11. Rhinogobius sulcatus. (A) Male, holotype, ZRC 49208, 27.0 mm SL; (B) female, paratype, ZRC 49209, 26.8 mm SL.