Pseudogobius fulvicaudus Huang, Shao and Chen, 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 : 31-34

Pseudogobius fulvicaudus Huang, Shao and Chen, 2014

Yellowfin snubnose goby

Figs 1 and 11 , Tables 1–5, 11

Pseudogobius sp. 11— Larson & Williams 1997: 370 (Channel Island).

Pseudogobius sp.— Tran et al. 2013: 144 (Mekong Delta, Vietnam).

Pseudogobius fulvicaudus — Huang, Shao and Chen, 2014 in Huang et al. 2014b: 110–113, figs 2e, 3 (Matang mangrove, Malaysia).

Pseudogobius fulvicaudus complex— Hammer et al. 2021: 2 ( Malaysia, Singapore, Vietnam, Australia [four distinct mitochondrial DNA lineages]).

Material Examined. MALAYSIA: NTM S.15547-010, 37(7–17), turbid pools in disturbed mangroves and around sluice-gate and bund, Sungei Sementa, Sementa kampung, Klang, H.K. Larson and party, 16 October 2002 ; NTM S.15552-014, 4 of 18(10–16), Sementa River , Klang, HL 02-02, H.K. Larson and party, 5 October 2002 . VIET- NAM: S.17896-002, 2(16–16), Soc Tran, K. Shibukawa, L.X. Tran and H . V. Mai , 16 May 2012 . AUSTRALIA, NORTHERN TERRITORY: NTM S.13478-001, 2(16.5–17.5), sample site 3 patch F, by Channel Island bridge, Darwin, M. Burke, 14 July 1991 ; NTM S.13474-005, 1(13.5), sample site 3 patch M, by Channel Island bridge, Darwin, M. Burke, 2 July 1991 ; NTM S.18270-001, 13(16–19), Rapid Creek mangroves, Darwin , MH 14-07 , M. Hammer , 28 April 2014 ; NTM S.13518-014, 28(14.5–18), small mangrove channel off Home Creek, Bing Bong area, Gulf of Carpentaria , H.K. Larson, K. Akerman and R. Lau , 5 September 1992 .

Additional material (no data taken). VIETNAM: NTM S.17896-002, 2, Soc Tran, K. Shibukawa and party, 16 May 2012 . THAILAND: USNM 316211 , 5 , Klong Tana , T. Roberts and P. Wongrat, 9 May 1970 . SINGAPORE: NTM S.17901-002, 2, Mangroves , Sungei Buloh, K. Lim, 30 January 1992 ; NTM S.13957-016, 20(10-20), Sungei Pandan , HL 93-47, H.K. Larson and party, 29 December 1993 . BRUNEI: NTM S.14794-011, 17, Sungai Raya, Sungei Temburong, HL 97-69, H.K. Larson and party, 21 August 1997 ; NTM S.14812-018, 4, Sungai Mataiang , Temburong, HL 97-87, H.K. Larson and party, 30 August 1997 . AUSTRALIA: AMS I.23281-025, 16, Mission River Mouth, Weipa , Queensland, D.F. Hoese and D. Rennis, 11 October 1982 ; NTM S.17346-006, 5, first creek upstream from Maningrida, Liverpool River , Northern Territory, M. Hammer and Waterhouse Club, 16 May 2012 ; NTM S.14962-012, 4, Sandfly Beach, West Alligator Head , Northern Territory, HL 99-4, H.K. Larson and party, 8 September 1999 ; NTM S.17970-009, 1, drain along Dinah Beach Road , Darwin , MH 15-07 , M. Hammer and party, 9 October 2015 ; NTM S.10419-004, 3, creek at Elizabeth River mouth, Darwin Harbour, HL 82-6, H.K. Larson, 29 March 1982 ; NTM S.18301-004, 9, East Arm boat ramp, Darwin harbour , MH 19-03 , M. Hammer and M. Borok, 21 February 2019 .

Diagnosis. A small Pseudogobius with second dorsal rays I,6–7; anal rays I,6–7; pectoral rays 13–16; 15–16 segmented caudal rays in 8/7 or 9/7 pattern; lateral scales 23–27; TRB 7–8; predorsal scales 6–7; opercle with 2–4 rows of cycloid scales; cheek naked; shoulder girdle with smooth narrow flange or smooth edge; tongue short, usually blunt; in males, teeth in outer row largest and widely spaced, slightly flattened and usually straight with pointed tips; in females, outer row teeth very small, close-set, evenly sized and usually blunt-tipped; head and body translucent to pale yellowish with 5–6 diffuse greyish saddles on dorsum that may extend ventrally as indistinct bars and mid-side of body with five brownish blotches; on scaly base of caudal fin, two blackish rounded spots, placed above and below last mid-lateral brownish spot and broad half-moon shaped to vertical yellow bar extending from these dark spots onto caudal fin itself; known from mangrove habitats in South-east Asia and northern Australia.

Description. Based on 27 specimens, 13.5–19 mm SL. First dorsal VI; second dorsal I,6–7 (usually I,7); anal I,6–7 (usually 7); pectoral rays 13–16 (usually 15); segmented caudal rays usually 9/7, rarely 8/7; branched caudal rays 6/6–8/6, usually 7/6; lateral scale count 23–27 (usually 25); TRB 7–8 (usually 8); predorsal scale count 6–7 (nearly always 7). Gill rakers on outer face of first arch very short, 1+4 (1), 2+5 (1).

Body slender, compressed; females larger than males. Head rounded, wider than deep, HL 25.3–30.6% SL (mean 27.8%). Depth at posterior preopercular margin 57.1–69.0% HL (mean 62.1%). Width at posterior preopercular margin 65.3–82.2% HL (mean 73.8%). Mouth small, subterminal, very slightly oblique, jaws reaching to vertical through mid-eye, upper jaw in males 31.7–39.5% HL (mean 35.8%) and 26.5–37.3% HL (mean 33.1%) in females; lips thin, lower lip broadly fused to chin anteriorly. Eyes lateral, high on head, 25.0–35.6% HL (mean 31.0%). Snout rounded and slightly inflated, 20.8–29.8% HL (mean 25.3%). Interorbital moderately wide, 16.3–26.1% HL (mean 20.2%). Body depth at anal origin 18.8–24.4% SL (mean 20.6%). Caudal peduncle slender, compressed, length 28.4–34.2% SL (mean 31.3%). Caudal peduncle depth 11.3–14.7% SL (mean 12.9%).

First dorsal fin low, triangular, with somewhat rounded margin, second to third spines longest (usually second). Appressed first dorsal fin falling short of second dorsal in both sexes; appressed fin length 16.6–21.3% SL (mean 18.0%). Second dorsal spine length 13.7–19.4% SL (mean 15.7%). Third dorsal spine length 13.5–17.1% SL (mean 14.9%). Second dorsal and anal fin both short-based, low, fins pointed posteriorly with posteriormost rays longest, rays falling well short of caudal fin base when appressed. Pectoral fin oval to slightly pointed, central rays longest, extending back to vertical above anus, length 15.3–25.3% SL (mean 21.9%). Pelvic fins oval, rather narrow, just reaching anus, 17.4–22.0% SL (mean 20.2%). Caudal fin narrow, rounded posteriorly, upper half of fin longer than lower, 24.3–33.1% SL (mean 29.7%).

Anterior nostril in short tube, very close to upper lip and oriented down over lip. Posterior nostril oval, with very low rim, placed at mid-level of eye. Gill opening extending forward to under mid-opercle. Gill rakers on outer face of first arch very short stubs. Shoulder girdle with smooth narrow flange or edge. Tongue tip short, usually blunt; in some specimens bluntly rounded. Upper jaw teeth in two rows; in males, teeth in outer row largest and widely spaced, slightly flattened and usually straight with pointed tips; teeth in inner row very small, sharp (and very difficult to discern); in females, outer row teeth very small, close-set, evenly sized and usually blunt-tipped. Lower jaw teeth in 2–3 rows, small, conical, close-set, with rather blunt to sharp tips in both sexes.

Body scales ctenoid to pectoral fin base, cycloid scales on predorsal; pectoral fin base usually naked, occasionally with few thin cycloid scales ventrally or anteriorly (these usually covered by branchiostegal membrane); opercle covered with 2–4, usually 3, rows of cycloid scales, cheek naked; belly scales cycloid. Sensory papillae and canal pores illustrated in Huang et al. (2014b: fig. 3).

Coloration of fresh material. Based on photographs of captive and fresh dead specimens by Michael Hammer and Gianluca Polgar (and see Fig. 11 ).

Head and body transparent to translucent pale yellowish, white ventrally. Five to six diffuse grey saddles on dorsum, may extend down sides as indistinct narrow grey bars. Side of head whitish to very pale brown with broad (sometimes diffuse) brown bar from lower edge of eye running past end of jaws and ending just before ventral margin of preopercle; second narrow (and usually distinct) brown bar from eye to end on jaw about halfway between anterior nostril and corner of mouth; may be third thin brown line from eye to corner of mouth. Cheek and opercle with scattered dusky grey to dark brown mottling and irregular small spots; usually a third narrow dark brown bar from lower rear edge of eye to middle edge of preopercle. Lips narrowly edged with dark brown, in both sexes. Underside of head plain whitish.

Side of body with most of body scales narrowly outlined by brown, darkest on dorsum; mid-lateral series of five diffuse brownish blotches, narrow anteriorly diagonal dark brown band from below rear of first dorsal fin, ending above abdomen (band may be quite narrow or diffuse); may be a pair of dark brown spots just behind base of diagonal dark bar on lower side. Breast and belly plain whitish to grey to brown. Peritoneum black dorsally, remain- der whitish. Four internal greyish to blackish blotches along ventral midline, two above anal fin and two on caudal peduncle. Posteriormost dark brown mid-lateral blotch at mid-base of caudal fin, usually elongate, may extend upward partly on to fin. On scaly base of caudal fin itself, two blackish rounded spots, placed above and below last mid-lateral spot, lowermost caudal base spot usually smaller and darker than upper and not in contact with mid-base spot; broad half-moon shaped to vertical bar of yellow extends out from these dark spots onto caudal fin itself.

First dorsal fin transparent to translucent yellow, with broad brown to greyish submarginal band and second central greyish to blackish band ending in black spot on membrane between fourth to sixth spines; brown bands may become indistinct but black spot always present. Second dorsal fin transparent to faintly grey with two rows of grey small vertical streaks that may form two dusky grey stripes with yellow area between them, markings fading or coalescing toward rear of fin; fin margin clear to whitish. Anal fin translucent to dusky grey, may have whitish or clear margin. Caudal fin transparent to faintly grey, with no markings other than yellow area at base. Pectoral fin base whitish; fin transparent. Pelvic fins translucent whitish.

Coloration of preserved material. Very similar to live colour, but yellow areas absent.

Comparisons. This species can be separated from its congeners most easily by its colour pattern of the two black spots at caudal fin base and associated semicircular to vertical band of bright yellow on anterior part of caudal fin which is usually otherwise transparent (lacking dark spots); the four diffuse narrow bars evenly spaced along the body, and its small adult size (19 mm SL).

Distribution. Recorded from Vietnam, Thailand, Malaysia, Brunei, Singapore and northern Australia.

Ecology. Found in mangrove habitats, in shallow tidal areas. Often sympatric with P. poicilosoma , and sometimes with P. avicennia and P. verticalis n. sp.

Remarks. Type specimens were not available for study, but as our Malaysian material is syntopic with Huang et al.’s type specimens, we are confident that they are the same species; plus their photo of the holotype ( Huang et al. 2014b: 110, fig. 2e) shows the diagnostic yellow patch on the base of the caudal fin. Preliminary genetic analysis from mitochondrial DNA sequence data involving multiple deep lineages suggests this could be a species complex for further investigation ( Hammer et al. 2021); one of the lineages corresponded to a distinct morphotype described herein as P. verticalis n. sp.

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 11. Pseudogobius fulvicaudus, South-east Asia and northern Australia, (A) captive male, Channel Island, Darwin Harbour; (B) captive female, Rapid Creek, Darwin; (C) fresh male (top) and female from East Arm, Darwin Harbour, NTM S.18301-003; (D) and preserved topotypic specimen, 17 mm SL female, NTM S.15547-010, Sungei Sementa, Malaysia. Photos by MPH.