Pseudogobius taijiangensis Chen, Huang and Huang, 2014

Larson, Helen K. & Hammer, Michael P., 2021, A revision of the gobiid fish genus Pseudogobius (Teleostei, Gobiidae, Tridentigerinae), with description of seven new species from Australia and South-east Asia, Zootaxa 4961 (1), pp. 1-85 : 71-74

Pseudogobius taijiangensis Chen, Huang and Huang, 2014

Taijiang snubnose goby

Figs 1 and 28 , Tables 1–5, 20

Pseudogobius sp. 3— Zhou & Gao 2011: 295 (Taiwan).

Pseudogobius taijiangensis Chen, Huang and Huang, 2014: 131–134 , figs 1–2 (mangrove of Beimen District, Tainan City, Taiwan); Hammer et al. 2021: 2 ( Taiwan [distinct mitochondrial DNA lineage, based on whole mitogenome available on GenBank]).

Material Examined. CAS / SU 32833 , 2 (27–30), Canton, China, A.W. Herre, 7 January 1936 ; NTM S.17900-001, 2(27–28.5), vicinity of Haiphong, north Vietnam, Pham Dinh Trong, March 2000 .

Additional material (no data taken). NTM S.18391-001, 1, Tin Shui Wai , Hong Kong, Agriculture, Fisheries and Conservation Department, F 2584, 14 May 2000 ; ROM 6778 , vicinity of Haiphong, north Vietnam, Pham Dinh Trong , March 2000 .

Diagnosis. A moderate-sized Pseudogobius with second dorsal rays I,7; anal rays I,7; pectoral rays 15–16; 16 segmented caudal rays in 9/7 pattern; lateral scales 25–27; TRB 81/2 –9; predorsal scales 8–9; opercle with 3–4 rows of cycloid scales, cheek naked; shoulder girdle smooth; tongue blunt; in males, teeth in outer row large, widely spaced, conical, fairly straight with slightly pointed tips, in females, upper jaw teeth small, evenly sized and sharp; diagnostic oblique dark bar from lower rear margin of eye joining large dark blotch on lower part of preopercle, small round black or blue spot at rear of first dorsal fin and a rather indistinct speckled and marbled body colour pattern; found in shallow estuaries and artificial ponds of East Asia.

Description. This description is based only on four available specimens, 27–30 mm SL. For additional data see Chen et al.’ s (2014a) original description.

First dorsal VI; second dorsal I,7; anal I,7; pectoral rays 15–16; segmented caudal rays 9/7; branched caudal rays 7/6 or 8/7; lateral scale count 25–27; TRB 8½–10; predorsal scale count 8–9.

Body stout and rounded anteriorly, compressed posteriorly. Head wider than deep, HL 24.1–26.0% SL (mean 25.4%). Depth at posterior preopercular margin 63.1–70.1% HL (mean 66.7%). Width at posterior preopercular margin 70.3–80.5% HL (mean 75.8%). Mouth just subterminal, very slightly oblique; jaws reaching to below anterior part of eye in females and rear margin of eye in males; upper jaw 35.1–44.6% HL (mean 38.8%); lips thin, fused to chin anteriorly. Eyes lateral, high on head, top usually forming part of dorsal profile, 23.0–31.4% HL (mean 27.9%). Snout rounded and slightly inflated, 23.1–31.2% HL (mean 26.4%). Interorbital moderate, 14.3–15.7% HL (mean 15.1%). Body depth at anal origin 20.7–22.2% SL (mean 21.5%). Caudal peduncle compressed, length 29.6–31.9% SL (mean 30.7%). Caudal peduncle depth 13.3–14.0% SL (mean 13.6%).

First dorsal fin low, rounded, third spine longest but no spines elongate; fin just reaching back to fall well short of second dorsal fin in both sexes; 16.3–19.6% SL (mean 18.0%). Third dorsal spine length 12.3–14.1% SL (mean 13.4%). Second dorsal and anal fin heights low, rays falling well short of caudal fin base when appressed. Pectoral fin oval, central rays longest, not quite reaching back to above anus, 18.7–20.4 % SL (mean 19.7%). Pelvic fins short, rounded, reaching about halfway to anus, 14.4–17.0% SL (mean 16.1%). Caudal fin moderate, rounded posteriorly, 23.3–29.8% SL (mean 26.0%).

Anterior nostril in short tube, oriented down over upper lip. Posterior nostril oval, with very low rim, placed at mid-level of eye. Gill opening restricted to pectoral base or extending forward to just under opercle. Shoulder girdle smooth. Tongue tip blunt. Upper jaw teeth in 2–3 rows; in males, teeth in outer row large, widely spaced, conical, fairly straight with slightly pointed tips; in females, upper jaw teeth small, evenly sized and sharp; teeth in inner rows very small, close-set and sharp. Lower jaw teeth in both sexes in 2–3 rows, small, sharp and close-set.

Nape scales relatively small, those behind eyes not enlarged. Body scales ctenoid to behind pectoral fin base; cycloid scales on belly, predorsal and pectoral fin base; opercle with 3–4 rows of cycloid scales. For sensory papillae and pores of holotype, see Chen et al. (2014: fig. 1).

Coloration of preserved material. Male and female similar; with males slightly more heavily marked ( Fig. 28 ). Head and body yellowish white, with upper half of body speckled lightly and evenly with melanophores. Dorsal surface of head and nape with brown spotting, speckles and short vermiculate lines; two blotches on nape and vermiculate lines on snout darkest. Side of head with narrow oblique dark brown bar from lower rear edge of eye reaching to about centre of preopercle and dark brown triangular blotch on lower half of opercle. Remainder of head greyish with short brown lines and spots, mostly on upper half of head. Lips brownish. Chin speckled with dark brown in male, plain whitish in female. Breast and belly pale, unmarked. Pectoral fin base pale with blotchy brown curved patch, mostly on upper part of base. Mid-side of body with five pairs of grey-brown blotches, not easily distinguished from similar blotches, short streaks and spots, mostly on upper half of body, with single grey-brown blotch at caudal fin base. Dorsum with seven evenly spaced small dark brown blotches or saddles (plus the two nape blotches), commencing at middle of first dorsal fin. Base of caudal fin with narrow vertical dark brown bar and pair of diffuse grey-brown blotches on scaly base of fin.

First dorsal fin transparent with greyish speckling on rays and blackish blotch at rear of fin. Second dorsal fin transparent with about five irregular rows of small brown spots, becoming more diffuse and streaky posteriorly. Anal fin faintly greyish with whitish to clear margin. Pectoral fin translucent with some dark streaks on upper rays, originating from brown blotch on upper part of fin base. Pelvic fins translucent in female, faintly greyish in centre in male. Caudal fin transparent with 7–8 irregular rows of light brown spots and streaks.

Coloration of fresh material. In their original description, Chen et al. (2014a: 133, fig. 2) provide the following live colour details: “Head and body generally pale brownish yellow, middle lateral with 5–6 mainly blackish brown blotches, and with 3–4 longitudinal stripes throughout the trunk. Lateral scales with blackish brown margin. Belly usually yellow in adult male, and creamy white in female. Lower orbit region with an oblique stripe extend to central region of cheek. Pectoral fin base with a blackish brown spot. Caudal fin base with 2 blackish brown bars vertical to each other. First dorsal fin membrane with a circle spot at rear region, the spot usually blue in male and black in female. Second dorsal fin membrane with 2–3 rows of longitudinal blackish brown lines. Anal fin greyish black in adult male, and pale greyish white in female. Caudal fin membrane pale yellow in male and greyish white in female. The caudal fin membrane with 4–7 rows of black lines in both sexes.” Zhou and Gao (2011: 295) illustrate a captive fish that appears to be this species, based on shape and colour (see also Fig. 28 ).

A male paratype ( Fig. 28B , upper fish) is pale brownish yellow with dark brown spots, speckling and mottling and five dark grey irregular blotches (which appear to be pairs of blotches partly coalesced) along mid-side of body; above and mid-lateral blotches partly joined together by broken brown blotchy lines above and below the mid-line of the body. Caudal fin base with a vertically oriented pair of blackish spots. Predorsal and upper part of head with dark brown spots and mottling. Side of head with distinctive oblique broad dark brown bar running from lower rear margin of eye toward large internal blackish blotch on the lower part of the opercle; dark brown bar from anteroventral edge of eye to upper lip, running just below nostrils. First dorsal fin with bright blue spot at rear, rest of fin pale reddish brown with indistinct brown streaks. Second dorsal fin with dark brown spots on fin rays arranged in 2–4 rows; membrane pale reddish brown near base, becoming more translucent distally. Anal fin pale greyish with reddish orange streaks beside most rays. Caudal fin translucent reddish brown with 4–7 rows of dark brown to blackish spots forming irregular lines. Pectoral fin faintly greyish; pelvics whitish. The female ( Fig. 28B , lower fish) is similar but paler and the spot in the first dorsal is black.

Comparisons. This species can be distinguished from other Pseudogobius by the combination of its rounded first dorsal fin, diagnostic broad oblique dark bar from the lower rear margin of the eye to join a large dark blotch on the lower part of the preopercle, small round black or blue spot at rear of first dorsal fin and its rather indistinct speckled and marbled body colour pattern.

Distribution. Known so far from China, Taiwan, Hong Kong and Vietnam.

Ecology. Found in shallow estuaries, mangroves and artificial earth-bank ponds.

Remarks. Chen et al. (2014a) give a pectoral fin ray count of 14–17, with 17 as modal count; all their specimens were from Taiwan but for one lot of 20 from Haimen Island, Fujian, China.

Figures

FIGURE 1A. Distribution maps of species in the genus Pseudogobius, based upon material examined and inspected (circles) with the type localities indicated (squares).

FIGURE 28. Pseudogobius taijiangensis, East Asia, (A) captive male, Hong Kong, photo copyright H.T. Cheng; (B) fresh male (top) paratype from Xiaofanli River, Taoyuan County, Taiwan, NTOUP 2012-05-14, and fresh female paratype from Tainan City, Taiwan, NTOUP 2012-05-146, photos S.-P. Huang; (C) and preserved female, 24 mm SL, vicinity of Haiphong, north Vietnam, ROM 6778, photo MPH.