Rhinogobius leavelli (Herre, 1935)

Maeda, Ken, Kobayashi, Hirozumi, Iida, Midori & Tran, Hau Duc, 2024, Taxonomy of freshwater gobies of the genus Rhinogobius (Oxudercidae, Gobiiformes) from central Vietnam, with descriptions of two new species, Zootaxa 5493 (5), pp. 507-541 : 528-530

Rhinogobius leavelli (Herre, 1935)

( Figs. 2 , 6g, h , 10d–f , 13–15 ; Tables 1 , 2 , 4–7 , 9 )

Ctenogobius leavelli Herre, 1935b: 396 (type locality: hill streams around Wuchow , Kwangsi Province, China).

Rhinogobius leavelli : Herre 1938: 436 (Lung T’au Shan, Kwangtung Province, China): 436; Kottelat 2001b: 157 ( Laos); Chen et al. 2002: 269 (Hainan, China); Chen & Kottelat 2005: 1427 (northern Vietnam); Serov et al. 2006: 294 (but photo of R. similis shown as R. leavelli ; central Vietnam); Wu & Zhong 2008: 604 ( China).

Ctenogobius cervicosquamus Wu, Lu & Ni in Wu & Ni, 1986: 291 (type locality: Changhua River, Qiongzhong, Hainan, China); Wu 1991: 485 (Hainan, China).

Ctenogobius brunneus (not of Temminck & Schlegel): Luo 1989: 349 (Pearl River in Guangdong, Guangxi, and Guizhou); Wu 1991: 483 (Guangdong).

Material examined. Sixteen specimens from Da Nang City and six specimens from Thua Thien Hue Province , Vietnam .

Da Nang City. HNUE-F 347–349 , 1 male (31.8 mm SL) and 2 females (31.3–31.7 mm SL), Suoi Mo, a tributary of Song Han , Hoa Vang District (16°00’01.3”N 108°03’33.2”E), 17 June 2019 ; HNUE-F 350 , male (37.5 mm SL), Suoi Hoa, a tributary of Song Han, Hoa Vang District (15°58’01.9”N 108°02’08.5”E), 17 June 2019 ; NSMT-P 147887 , female (41.1 mm SL), Suoi Mo, a tributary of Song Han, Hoa Vang District (15°59’57.7”N 108°04’10.0”E), 1 March 2016 ; NSMT-P 147888 , male (43.8 mm SL), Suoi Hoa, a tributary of Song Han, Hoa Vang District (15°57’60.0”N 108°01’44.2”E), 2 March 2016 ; OISTICH 256–258, 2 males (29.5–42.5 mm SL) and 1 female (33.4 mm SL), Suoi Mo, a tributary of Song Han, Hoa Vang District (15°59’57.7”N 108°04’10.0”E), 1 March 2016 ; OISTICH 259, female (40.9 mm SL), Suoi Hoa, a tributary of Song Han, Hoa Vang District (15°57’60.0”N 108°01’44.2”E), 2 March 2016 ; OISTICH 260–261, 1 male (29.0 mm SL) and 1 female (38.8 mm SL), Suoi Mo, a tributary of Song Han, Hoa Vang District (15°59’58.1”N 108°04’12.7”E), 27 January 2018 ; OISTICH 262, male (29.1 mm SL), Suoi Mo, a tributary of Song Han, Hoa Vang District (16°00’01.3”N 108°03’33.2”E), 17 June 2019 ; OISTICH 263–265, 1 male (35.5 mm SL) and 2 females (34.2–34.4 mm SL), Suoi Hoa, a tributary of Song Han, Hoa Vang District (15°58’01.9”N 108°02’08.5”E), 17 June 2019 .

Thua Thien Hue Province. OISTICH 266–268, 3 males (27.3–37.7 mm SL), a tributary of Song Bo in Hong Ha , A Luoi District (16°18’00.0”N 107°19’29.1”E), 20 June 2019 ; OISTICH 269–271, 1 male (40.5 mm SL) and 2 females (27.0– 39.1 mm SL), a tributary of Song Huong flowing along the border between Binh Thanh and Huong Tho, Huong Tra District (16°20’22.4”N 107°32’35.1”E), 21 June 2019 .

Description. Body nearly cylindrical anteriorly and somewhat compressed posteriorly. Head depressed and larger in males than females (head length 30.7–34.1 vs. 28.7–31.1% of SL; Fig. 2 , Table 9 ). Eyes located dorsolaterally. Mouth terminal and oblique with thick upper and lower lips. When mouth closed, anterior tips of upper and lower jaws very close together, but upper lip usually extending slightly beyond lower jaw. Mouth larger in males than females (upper-jaw length 11.0–15.8 vs. 8.8–11.2% of SL; Fig. 2 , Table 9 ). Upper and lower jaws usually with 2–4 rows of conical teeth; those in outermost row enlarged and those in inner rows irregularly aligned. Mental flap on chin rounded rectangular, trapezoidal (posterior end forming long side), emarginate, or lunate, and often with a small central projection. Anterior nostril short tubular, posterior nostril a pore. Cephalic sensory pore system usually with B´, C, D(S), E, F, H´, K´, and L´ in oculoscapular canal and M´, N, and O´ in preopercular canal ( Fig. 10d–f ), but two of 22 specimens lacking pore N of both left and right sides. Arrangement of cutaneous sensory papillae of head shown in Fig. 10d–f . Cheek having four longitudinal rows of papillae and no transverse row. Vertebrae 10+15=25 (n=1), 10+16=26 (n=14), or 10+17=27 (n=1; Table 1 ), P-V 3/II II I I 0/9 (n=14) or 3/II II I I I/9 (n=1; seventh pterygiophore without spine).

First dorsal fin usually with six spines, but one specimen with five spines. Second dorsal fin with one spine and seven (n=3) or eight (n=19) soft rays ( Table 2 ). First and second dorsal-fin bases separated by a small interval (1.1–7.2% of SL; Table 9 ). In female, first dorsal fin rounded, almost semi-circular; posterior tip of fin (tips of third to sixth spines) not reaching second dorsal-fin origin. In males, first dorsal fin parallelogram or triangular; third and/ or fourth spines often elongate and their tips exceeding base of fourth soft ray of second dorsal fin in longest case, but some individuals with shorter spines not reaching second dorsal-fin origin. Anal fin with one spine and seven (n=5), eight (n=16), or nine (n=1) soft rays ( Table 2 ). Caudal fin with 17 segmented rays including 12 (n=1), 13 (n=6), 14 (n=12), or 15 (n=2) branched rays, but one specimen with 14 segmented rays including 11 branched rays; posterior margin rounded. Males having larger second dorsal and anal fins than female (second dorsal-fin length 26.4–36.5 vs 24.1–28.2% and anal-fin length 24.0–30.6 vs 22.2–25.1% of SL; Fig. 2 , Table 9 ). Pectoral fin with 16–19 rays (mode 18 rays) in Da Nang City population and 18–19 rays (mode 19 rays) in Thua Thien Hue Province population ( Table 4 ). Pelvic fin with one spine and five soft rays; pelvic fins joined together to form a cuplike disc with fleshy bilobed frenum.

Ctenoid scales covering lateral, dorsal, and ventral surfaces of trunk and tail, except belly. Nape and posterior part of occipital region covered by cycloid and ctenoid scales; cycloid scales occupied dorsal surface along midline in 9/ 12 males and 4/ 10 females, but with one or two, or 1–9 ctenoid scales along dorsal midline of nape near first dorsal-fin origin in other males and females, respectively. Ctenoid and cycloid scales mixed on sides of occipital region, and side of nape covered with ctenoid scales. Scaled area usually extending anteriorly to area above opercle in both male and female, but not reaching posterior margin of opercle in four males and one female; scaled area never extending to area above preopercle. Other regions on head naked. Belly covered with cycloid scales. First and second dorsal-, and anal-fin bases, and small area behind pectoral fin covered mainly with ctenoid scales, and mixed with a few small cycloid scales. Proximal part of caudal fin covered with cycloid scales and a few ctenoid scales. Pectoral-fin base and breast (pre-pelvic area) probably naked (at least invisible without staining with alizarin red; see Suzuki et al. 2016). Longitudinal scales 29–32, transverse scales 9–10, transverse scales in caudal peduncle usually seven, but eight in one specimen; predorsal scales 3–11 ( Tables 5–7 ).

Color in life and fresh ( Figs. 13 and 14 ): in males, background of head and body grey or yellowish-brown, but whitish on ventral side. Reddish-brown stripes connected posterior margin of center of upper lip and anterior margin of left and right eyes. Short, horizontal reddish-brown stripe on upper part of cheek just below eye. Many reddish-brown, small spots scattered on cheek. Larger reddish-brown markings with various shapes scattered on opercle. Opercular membrane, interopercle, and lower part of subopercle grey with many orange stripes running along margin of preopercle and opercle. Five dark-brown, indefinite blotches aligned along lateral midline of body from flank to caudal-fin base; these blotches sometimes subdivided, or smaller blotch sometimes inserted between blotches. These blotches united with dark-brown irregular blotches on dorsal side to form various shapes. Scales on sides of body with orange edges. A male showed a higher contrast with black bands and white intervals when it courted a female ( Fig. 14a ).

First dorsal fin reddish-brown, with 1–3 black spots on proximal parts of membranes between anterior 2–4 spines (usually two black spots between first and third spines); upper parts of black spots light blue. Second dorsal fin reddish-brown with three to five olive or whitish-grey stripes across fin. A large orange blotch at proximal part of caudal fin; remainder of caudal fin reddish-brown with four to six olive or whitish-grey bands across fin. Anal fin reddish-brown, but olive or whitish-grey proximally and dark brown distally with a bluish-white margin; sometimes with orange spots on membrane. Pectoral fin greyish translucent or dark grey, but its proximal part olive or light yellowish-brown with two reddish-brown bands along base; a band on base clear and another faint. Pelvic disc grey or dark grey.

In females, markings and background color of head and body similar to those of male, but cheek without small reddish-brown spots, and opercular membrane, interopercle, and lower part of subopercle yellowish-brown without orange stripes. First dorsal fin with dark-brown spines and translucent membranes; faint yellow or grey markings partly. Spine and soft rays of second dorsal fin with 3–5 dark-brown spots; membranes translucent with faint yellow or grey markings partly. Caudal-fin rays with 4–6 dark-brown spots and white interval; membranes translucent. In anal fin, distal half of soft rays dark brown, but other parts almost translucent. Pectoral fin translucent, but its proximal part light yellowish-brown with two reddish-brown bands along base; band on base clear and another faint. Pelvic disc white.

Color in preservative ( Fig. 6g, h ): background of head and body cream. Reddish-brown markings observed in life become dark brown. Orange markings disappeared. Olive, whitish-grey, and light yellowish-brown parts of fins become light brown. Black spots of first dorsal fin of male remained, but blue spots disappeared.

Remarks. Populations of R. leavelli in central Vietnam observed in this study differ somewhat in morphology from populations in northern Vietnam. There are slight differences between specimens from Da Nang City and Thua Thien Hue Province, even within central Vietnam. Pectoral-fin ray counts are 16–19 (usually 16–18) in Da Nang, but 18–19 (usually 19) in Thua Thien Hue, and 18–19 (almost same frequency) in northern Vietnam ( Table 4 ). The caudal peduncle is lower and longer in Da Nang than Thua Thien Hue, and those are further lower and longer in northern Vietnam ( Fig. 15 ). Body coloration is also slightly different. Fish in central Vietnam usually have five, dark-brown lateral bands which are often V-shaped or triangular saddles, while the body usually has seven indistinct blotches regularly aligned along the lateral midline in northern Vietnamese populations ( Fig. 9i, j ).

However, differences in counts and measurements overlap. Coloration is variable and also differs individually; therefore, the difference between localities is not clear. In the present study, only specimens from a few localities were compared, and it is unclear whether the differences are continuous, or if there is a geographical boundary.

This species was originally described from Wuzhou, Guangxi in southern China by Herre (1935b), and has since been reported from a larger area encompassing southern China, Vietnam, and Laos ( Kottelat 2001b; Chen & Kottelat 2005; Wu & Zhong 2008). Ctenogobius cervicosquamus Wu, Lu & Ni in Wu & Ni, 1986 from Hainan Island is also considered a synonym ( Wu & Zhong 2008). We tentatively identify the population in central Vietnam as R. leavelli , but clarifying this issue would require extensive examination of specimens from other regions, especially southern China.

Figures

FIGURE 2. Proportions of head length, upper-jaw length, first dorsal-, second dorsal-, anal-, and caudal-fin lengths to standard length (SL) of Rhinogobius rong (red circles), R. nami (light-blue circles), R. taenigena (deep-blue diamonds), R. leavelli (orange triangles), and R. similis (green squares) collected from Da Nang City and Thua Thien Hue Province. Solid symbols represent males, open symbols represent females, and symbols filled with grey represent specimens of unknown sex (for R. similis). Symbols with an asterisk are holotypes.

FIGURE 6. Preserved specimens of Rhinogobius rong (a, b), R. nami (c, d), R. taenigena (e, f), R. leavelli (g, h), and R. similis (i, j) collected from Da Nang City and Thua Thien Hue Province, Vietnam. Specimens on left side are males, right are females. a, NSMT-P 147886, holotype, 45.6 mm SL; b, OISTICH 254, paratype, 52.7 mm SL; c, NSMT-P 147890, holotype, 24.9 mm SL; d, OISTICH 290, paratype, 27.0 mm SL; e, OISTICH 299, 23.6 mm SL; f, OISTICH 305, 34.1mm SL; g, NSMT-P 147888, 43.8 mm SL; h, NSMT-P 147887, 41.1 mm SL; i, OISTICH 240, 56.3 mm SL; j, OISTICH 241, 45.2 mm SL.

FIGURE 9. Comparative material of the genus Rhinogobius from northern Vietnam (a–l) and Japan (m–p) observed in the present study. Photographs were taken immediately after fixation. Specimens on left side are males, right are females. a, b, R. sulcatus (a, OISTICH 184, 30.4 mm SL; b, OISTICH 190, 32.4 mm SL); c, d, R. boa (c, OISTICH 161, 25.4 mm SL; d, OISTICH 160, 28.0 mm SL); e, f, R. virgigena (e, NSMT-P 147872, 36.1 mm SL; f, OISTICH 154, 33.7 mm SL); g, h, R. variolatus (g, OISTICH 169, 31.4 mm SL; h, OISTICH 170, 28.8 mm SL); i, j, R. leavelli (i, OISTICH 209, 38.1 mm SL; j, OISTICH 210, 35.4 mm SL); k, l, R. similis (k, OISTICH 222, 54.4 mm SL; l, NSMT-P 147882, 44.7 mm SL); m, n, R. similis from Okinawa Island (m, URM-P 49149, 48.6 mm SL; n, OISTICH 2, 63.6 mm SL); o, p, R. similis, from Izu Peninsula (o, OISTICH 330, 47.6 mm SL; p, OISTICH 332, 51.0 mm SL).

FIGURE 10. Arrangement of cephalic sensory pores and cutaneous sensory papillae in Rhinogobius taenigena (a–c, OISTICH 303) and Rhinogobius leavelli (d–f, NSMT-P 147888). a, d, lateral view; b, e, dorsal view; c, f, ventral view. AN, anterior naris; PN, posterior naris.

FIGURE 13. Rhinogobius leavelli immediately after fixation. a, NSMT-P 147888, male, 43.8 mm SL; b, OISTICH 265, female, 34.4 mm SL.

FIGURE 14. In situ underwater photographs of Rhinogobius leavelli in Da Nang City, Vietnam. a, male (top) and female (bottom), 13 January 2013; b, male, 12 January 2013; c, female, 12 January 2013 (photo by K. Maeda).

FIGURE 15. Relationships of caudal peduncle depth (% of standard length) and caudal peduncle length (/ caudal peduncle depth) to standard length in Rhinogobius leavelli from Da Nang City (orange triangles) and Thua Thien Hue Province (blue diamonds) in central Vietnam and Quang Ninh Province in northern Vietnam (red circles).