Pseudogobius verticalis, Larson & Hammer, 2021

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 : 74-78

Pseudogobius verticalis n. sp.

urn:lsid:zoobank.org:act:B24A213C-7CC4-41F2-97AF-2815D7E8CB09

Blackline snubnose goby

Figs 1 and 29 , Tables 2–5, 21

Pseudogobius fulvicaudus complex [in part]— Hammer et al. 2021: 4 ( Singapore [distinct mitochondrial lineage]).

Material examined. Holotype: ZRC 61150 (ex NTM S.15344-016), 22.5 mm SL female, Sungei Buloh, Singapore, HL 97-89, H.K. Larson and party, 5 September 1997 . Paratypes: SINGAPORE: NTM S.15344-016, 14(13–23), same data as holotype . PHILIPPINES: CAS-SU 69916 , 36 (18–22) Coron, Busuanga, A.W. Herre, 22 June 1940 . BRUNEI: NTM S.14799-027, 29(11–22), Sungai Tutong, Tutong District, HL 97-74, H.K. Larson and party, 23 August 1997 .

Additional material (no data taken). SINGAPORE: CMK ex 8309, 41, Kranji mangrove, near Sungei Buloh, M. Kottelat and D. Murphy, 8 April 1997 ; NTM S.17471-010, 1, Lim Chu Kang, HL 12-7, H.K. Larson and party, 27 October 2012 ; NTM S.17475-001, 1, Kranji Stream, Sungei Buloh, SW 135428, H.K. Larson and party, 30 Oc-

tober 2012; NTM S.17901-003, 10, Mangroves , Sungei Buloh, K. Lim, 30 January 1992 ; NTM S.13957-017, 12, Sungei Pandan , HL 93-47, H.K. Larson and party, 29 December 1993 ; NTM S.15346-006, 3, Kranji, J.L. Lim and Universiti Malaysia team, 24 November 1995 ; NTM S.17468-008, 5, Sungei Mandai Besar, Ria Tan and party, 26 October 2012 [matches genetic voucher]; NTM S.13968-012, 19, Sungei Pandan, D. Hoese, K. Lim and P. Ng, 22 December 1993 ; NTM S.13959-014, 50, Bird Reserve , Sungei Buloh, HL 94-1, H.K. Larson and K. Lim, 4 January 1994 ; NTM S.13961-010, 98, Sungei Mandai Kecil, HL 94-3, H.K. Larson and D. Murphy, 6 January 1994 . BRU- NEI: NTM S.14805-031, 7, Sungai Tutong , Tutong District, HL 97-80, H.K. Larson and party, 25 August 1997 ; NTM S.14802-029, 39, Sungai Tutong , Tutong District, HL 97-77, H.K. Larson and Party, 24 August 1997 ; NTM S.14812-019, 48, Sungai Mataiang , Temburong, HL 97-87, H.K. Larson and party, 30 August 1997 ; NTM S.14800- 016, 1, Sungai Penabai , Tutong District, HL 97-75, H.K. Larson and party, 23 August 1997 . MALAYSIA: FMNH 51669 , 1 , Mankahala River, Sandakan, North Borneo , R.F. Inger , 30 April 1950 ; USNM 316203 , 2 , Mangrove swamps on island opposite Sandakan, Borneo, 29 January 1965 . VIETNAM: CMK ex14819, 5, small stream near Tran Chau village, Cat Ba Island , M. Kottelat and party, 25 September 1998 . THAILAND: NTM S.18271-001, 5, in ponds within station at Ta-Chalaab, Chantaburi Province, Mahdolia project, National Inland Fisheries Institute party, 2 June 1990 .

Diagnosis. A small Pseudogobius with second dorsal rays I,7; anal rays I,7–8; pectoral rays 12–15; 15–16; segmented caudal rays usually in 9/7 pattern, occasionally 8/7; lateral scales 22–26; TRB 7–9; predorsal scales 6–7, usually 7; opercle with 3–4 rows of cycloid scales; cheek naked; shoulder girdle with smooth edge; tongue short, blunt; in males, teeth in outer row largest and widely spaced, usually straight with pointed tips, smaller teeth may alternate with larger; in females, outer row teeth very small, close-set, evenly sized and blunt-tipped to tips somewhat rounded. First dorsal fin pointed in both sexes. Distinct black vertical to slightly oblique line from mid body through dorsum and then extending vertically through middle of first dorsal fin; two rounded dark spots at caudal fin base, upper spot largest; caudal fin transparent, though some males may have a few rows of small brown spots. Known from mangrove habitats in South-east Asia.

Description. Based on 21 specimens, 16–23 mm SL. An asterisk indicates the counts of the 22.5 mm SL female holotype ( Fig. 29E ).

First dorsal VI; second dorsal I,6–7 (usually I,7); anal I,7; pectoral rays 12–15 (usually 14); segmented caudal rays usually 9/7, 8/ 7 in 3; branched caudal rays 6/7–9/7, usually 7/6; lateral scale count 22–26 (usually 23); TRB 7–9 (usually 8); predorsal scale count 6–7 (nearly always 7). Gill rakers on outer face of first arch 2+5 (in 1).

Body slender, compressed; females much larger than males. Head wider than deep, HL 23.5–29.3% SL (mean 26.2%). Depth at posterior preopercular margin 58.6–70.5% HL (mean 63.4%). Width at posterior preopercular margin 64.6–77.3% HL (mean 72.2%). Mouth small, subterminal, very slightly oblique, jaws reaching to vertical through mid-eye, females with jaws reaching to below anterior half of eye; upper jaw length in males 29.5–38.6% HL (mean 34.8%) and 25.5–32.7% HL (mean 29.5%) in females; lips thin, lower lip broadly fused across chin anteriorly. Eyes lateral, high on head, 27.5–37.0% HL (mean 31.8%). Snout rounded and inflated, 18.2–37.0% HL (mean 24.7%). Interorbital moderate, 10.3–17.4% HL (mean 14.4%). Body depth at anal origin 17.6–20.9% SL (mean 19.1%). Caudal peduncle compressed, length 26.9–33.7% SL (mean 30.9%). Caudal peduncle depth 10.7–13.8% SL (mean 12.5%).

First dorsal fin low, triangular, with somewhat rounded margin, first to third spines longest (usually second). Appressed first dorsal fin may just reach base of second dorsal fin spine in adult males; always falling short of second dorsal fin in females; appressed fin length 15.9–24.4% SL (mean 18.2%). Second dorsal spine length 14.2– 21.3% SL (mean 16.2%). Third dorsal spine length 15.7–16.1% SL (mean 15.8%). Second dorsal and anal fin moderately 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 18.0–23.8% SL (mean 21.4%). Pelvic fins oval, rather narrow, just reaching anus, 17.5–23.3% SL (mean 20.8%). Caudal fin moderately narrow, rounded posteriorly, upper half of fin slightly longer than lower, 27.0–31.9% SL (mean 29.3%).

Anterior nostril in very short tube, very close to upper lip. Posterior nostril oval, with very low rim, placed at mid-level of eye. Gill opening extending forward to just under opercle to nearly mid-opercle. Gill rakers on outer face of first arch very short stubs, upper limb rakers longest. Shoulder girdle with smooth edge. Tongue tip short, blunt. Upper jaw teeth in two rows: in males, teeth in outer row largest and widely spaced, usually straight with pointed tips, smaller teeth may alternate with larger, teeth in inner row very small and difficult to discern); in fe- males, outer row teeth very small, close-set, evenly sized and blunt-tipped to tips somewhat rounded, inner row teeth mostly concealed in flesh and often not possible to see. Lower jaw teeth in two rows, teeth small, conical, close-set, with rather blunt to sharp tips in both sexes, inner row of very tiny close-set pointed teeth.

Body scales ctenoid to pectoral fin base, cycloid scales on predorsal; pectoral fin base without scales; opercle with 3–4 rows of cycloid scales, cheek naked; belly scales finely ctenoid to cycloid. Sensory papillae and canal pores similar to that of P. hoesei ( Fig. 12 ).

Coloration of preserved material. Head and body whitish to pale yellowish brown, with darker brown markings, white to yellowish ventrally ( Fig. 29 ). Head with pale brown mottling and short lines on snout, nape with irregular brown spots and mottling, nape scales with dark brown margins and broad brown line toward rear of each scale. Side of head with an indistinct broad brown bar from front of eye to end on jaw about halfway between anterior nostril and corner of mouth; second brown bar from lower edge of eye running ventrally past end of jaws and ending just above ventral margin of preopercle; always a paler area on each side of brown bars. Cheek and opercle with variable scattered dark brown mottling and irregular small spots; some specimens with narrow dark brown bar or blotch from lower edge to eye to rear edge of preopercle. Iris red-brown to dull golden. Lips partly edged with brown, in both sexes. Underside of head plain whitish to yellowish white.

Side of body with mid-lateral series of five dark brown X-shaped to elongate spots, which may fuse to form four elongate blotches, anteriormost spot usually subsumed by anteriorly oriented to vertical dark brown band from below rear of first dorsal fin and ending above abdomen, band may be very distinct and almost black, broken-up or indistinct, but remnants always visible. Body scales with dark brown edges. Remainder of body with scattered small dark spots and blotches, which may form irregular rows or pairs of markings, lowermost markings often form short oblique narrow bars. Dorsum with 6–7 dark brown blotches or small saddles, these often indistinct. Breast and belly plain whitish to yellowish. Peritoneum black dorsally, fading on sides to silver ventrally. Four internal grey to blackish blotches along ventral midline, two above anal fin and two on caudal peduncle, joined with blackish midventral line (may not be visible in older specimens). Posteriormost dark brown mid-lateral blotch placed at mid-base of caudal fin. On scaly base of caudal fin itself, two dark brown to blackish rounded spots, placed above and below last mid-lateral spot, upper caudal base spot may coalesce with elongate mid-lateral spot on fin base, lower base spot usually smaller and darker than upper and not in contact with mid-base spot.

First dorsal fin transparent to translucent, with broad brown to black vertical bar extending from close to bases of fourth to fifth spines to tip of fin, bar may be darkest at base. Second dorsal fin transparent with two blackish brown lines, one crossing lower third of fin and one submarginal; fin margin transparent; males may have whole fin covered with fine blackish speckles also. Anal fin plain translucent to pale greyish, darkest in males. Caudal fin transparent with fin rays edged with brown; large males with few scattered rows of brown spots near fin base. Pectoral fin base plain yellowish white with brown square blotch or bar on uppermost part near fin rays. Pectoral fin transparent, with rays edged in brown. Pelvic fins translucent to whitish.

Coloration of fresh material. No information as to live colour. Freshly dead specimens ( Fig. 29 ) may show some orange colour on the first dorsal fin, above and below the dark spotting on the second dorsal fin and the proximal part of the anal fin. A yellow blotch or yellow half-moon shape is present on the base of the caudal fin, wrapping around the two basal black spots, and a yellow area may be present on abdomen above anus in females. The opercle and pectoral fin base shows some bluish iridescence. The peritoneum shows through the body wall as silvery white, black dorsally.

Comparisons. Similar in appearance to juvenile P. poicilosoma (compare Figs 25 and 29 ) but matures at a smaller size (never reaches 25 mm SL when adult, versus up to 34.5 mm SL in adult P. poicilosoma ), has a more slender body (body generally more robust, with caudal peduncle depth averaging 12% of SL versus 14%), having a black line through the middle of the first dorsal fin with transparent membrane on either side of line (first dorsal with two dark brown bands with lower band ending in black spot on membrane toward rear of fin) and by lacking dark spots in the caudal fin (rows of dark brown to blackish spots visible by 13–17 mm SL).

The distinctive vertical-oriented dorsal fin marking distinguishes P. verticalis from the very similar small species P. fulvicaudus (which has two blackish bands in the first dorsal fin). Both species share a distinctive caudal marking: freshly dead P. verticalis have a yellow blotch or yellow half-moon shape on the caudal fin base ( Fig. 29 ), although live colour as yet unknown, and P. fulvicaudus similarly has the caudal fin base yellow when alive ( Fig. 11 ).

Distribution. Known from Singapore, Malaysia, Philippines, Brunei, Thailand and Vietnam.

Ecology. Found in mangrove habitats, in shallow tidal areas. Can be sympatric with P. poicilosoma (often) and P. fulvicaudus (less often; five sites detected in Singapore and one in Brunei). A small species, with a gravid female noted at 17 mm SL, males with obvious genital papillae smaller still (15.5 mm SL).

Etymology. Named verticalis (from the Latin for overhead or straight up and down) in reference to the distinctive vertical line through the middle of the first dorsal fin in this species.

Remarks. This species is the genetic sister to P. fulvicaudus ( Hammer et al. 2021) ; the genetic material used was collected during the 2016 Mega Marine Survey in Singapore.

Unassigned Species

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.

FIGURE 12. Pseudogobius hoesei n. sp., sensory papillae and lateral canal pores, 34 mm SL female, WAM P.31299-004, Timika, Papua, Indonesia (note that cheek scale behind eye often absent). Drawing by HKL.

FIGURE 25. Pseudogobius poicilosoma, East Asia, South Asia and South-east Asia, (A) wild male (right side reversed), Hong Kong, photo by copyright H.T. Cheng; (B) fresh male (top) and female from Mekong Delta, Vietnam, photos by K. Shibukawa (courtesy FIMSEA Working Group); (C) well preserved topotypic specimen, 27.5 mm SL male, CMK 6083, south of Tanjung Pasir, Java, Indonesia, photo by MPH; (D) holotype of Gobius gastrospilos, RMNH 4676, 30 mm SL male, Batavia [Jakarta], Java, photo by S.-P. Huang.

FIGURE 29. Pseudogobius verticalis n. sp., South-east Asia, (A) and (B) fresh male and female from Brunei, photos G. Polgar; (C) and (D) preserved male and female, Sungai Tutong, Brunei, NTM S.14802-029; (E) preserved holotype, 22.5 mm SL female, Sungei Buloh, Brunei, ZRC 61150, photos MPH.