Pseudogobius eos, 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 : 25-30

Pseudogobius eos n. sp.

Eastern bluespot goby

urn:lsid:zoobank.org:act:D324832A-C101-4280-807C-5FDACFBA2CB1

Figs 1 , 9–10 , Tables 2–5, 9–10

Lizagobius olorum [in part]— Whitley 1964: 125 (Victoria), South and Western Australia, northward to the Hill River ; Tasmania ).

Pseudogobius olorum — Gee & Gee 1991: (Cowan Water;Appletree Bay, NSW); [in part] Kuiter 1993: 358 (southern Queensland to western Victoria); [in part] Gomon et al 1994: 804 (Victoria, Tasmania, New South Wales, southern Queensland); Gee & Gee 1995: 80 (Hawksbury River, NSW).

Pseudogobius sp. 9—[in part] Larson & Hoese 1996: 222–223 (Moreton Bay, Queensland to western Victoria and Tasmania); Hammer et al. 2021: 2 (south-eastern Australia, Agnes Water to Glenelg River [diagnosable at nuclear markers and with a distinct mtDNA lineage, with a hybrid zone in the west]).

Pseudogobius species—[in part; photo is of Chlamydogobius ranunculus ] Allen et al. 2002: 282 (Bundaberg, Qld to the Victoria-South Australia border; northern Tasmania).

Pseudogobius sp. 4 [in part]— Ford et al. 2004: 65 (Manly, Moreton Bay, Queensland).

Pseudogobius sp.—[in part] Hoese & Larson in Gomon et al. 2008: 768 (New South Wales, Victoria, Tasmania).

Material Examined. Holotype: AMS I.17459-002, 30.5 mm SL female, Port Hacking, Audley National Park, New South Wales, Australia , R. Kuiter , 5 January 1974 . Paratypes: QUEENSLAND: AMS I.35824-001, 2(26–26.5), Bulimba Creek, Tingalpa, Brisbane , R. McKay and J. Johnson, 31 March 1977 ; QM I.25239, 34(20–30.5), Boggy Creek, Brisbane River mouth, J. Johnson, P. Short and P. Lawless, 12 July 1988 ; QM I.33606, 18(19–28.5), Maroochy River , C. Harris, 22 August 2002 . NEW SOUTH WALES: AMS I.16960-002, 24(16.5–32.5), Hen and Chicken Bay, Parramatta River, Macquarie University fish class, 80 m seine, 12 August 1972 ; AMS I.16961-002, 14(16–31.5), Hen and Chicken Bay, Parramatta River , Macquarie University fish class, 30 m seine, 12 August 1972 ; AMS I.15909-005, 5(18.5–29.5), Warrell Creek , Scotts Head, Macquarie University fish class, seine, 24 August 1970 ; AMS I.16907-006, 15(22–31), Narrabeen Lake, Sydney, D.F. Hoese and party, 3 m seine and hand nets, 13 January 1972 ; AMS I.42948-003, 27(21–33), Sydney Olympic Park, Narawang, Sydney, J. Pogonoski, P. Gerarty and J. Stokes, 19 November 2003 ; AMS I.17596-004, 10 (23–36), Nadgee Nature Reserve, Wally Newtons Beach, J. Paxton and party, seine net, 29 November 1973 . VICTORIA: AMS I.24715-001, 2(30.5–33), beside jetty, Gippsland Lakes, Melbourne University students, 3 October 1978 ; AMS I.16972-001, 62 (14–34.5), Lake Bunga, D. Hoese and W. Congleton, hand net, 14 March 1972 ; AMS I.23456-002, 27 (19–27), Stoney Point, Western Port Bay, D. Hoese and party, hand net, 5 October 1975 ; NMV A 32250 -001 , 4 (27–31), Cherry Lake outlet, Melbourne , ANGFA Victoria, dip net, 4 October 2013 ; NTM S.17884-001, 6 (25.5–32), Cherry Lake outlet, Melbourne , ANGFA Victoria, dip net, 4 October 2013 . TASMANIA: AMS I.17570-003, 5 (25.5–33), Dennison River mouth, D. Hoese and W. Ivantsoff, seine net, 5 December 1972 .

Additional material (no data taken). QUEENSLAND: AMS I.19578-012, 8, Toorbul, Morton Bay , CSIRO, 1 October 1974 ; NTM S.18208-001, 2, Bridgewater Creek, Cooparoo, Brisbane, M. Hammer and M.H. Hammer, 1 May 2010 ; QM I.26872, 3, Tooway Creek , Coloundra, J. Short, 9 September 1990 ; QM I.25226, 2, Doboy Creek , Brisbane, J. Johnson, 22 June 1988 ; QM 21149, 1, North Pine River , G. Leiber, May 1984 ; QM I.23448, 6, Lake Weyba , Noosa, A Nimmo, 10 April 1987 . NEW SOUTH WALES: NTM S.18269-001, 6, Macleay River, Stuarts Point, P. Unmack and party, 7 May 2015 ; ANSP 135496 , 20 , Parramatta River, Hen and Chicken Bay , MUF 76-3, 7 August 1976 ; AMS I.16475-016, 4, Smiths Lake, J. Paxton, 21 May 1972 ; NTM S.16391-002, 1, D. Farrell, Botany Bay , Sydney, 9 February 1979 ; NTM S.16870-002, 3(20-25), Babbage Creek, Roseville, Sydney Harbour, M. Abell and ANGFA party, 10 December 2006 ; AMS I.16015-010, 6, Smiths Lake, Macquarie University, May 1971 ; AMS I.16954-017, 9, Cowan Creek, Hawkesbury River, J. Paxton and H. Recher, 22 November 1972 ; AMS I.16957-004, 10, Balls Head Bay, Sydney Harbour, Macquarie University , 1972; AMS I.6959-001, 4, Parramatta River , Cabarita Park, Macquarie University, 12 August 1972 ; NTM S.17273-001, 2, Camden Haven River, Laurieton, M. Cranfield, 26 December 2011 ; NTM S.14206-001, 2, Shelley Lagoon, Byron Bay, J. Esdaile, September 1993 ; AMS I.20042- 002, Ratshead Creek, Narooma, D Hoese and I Briggs, 18 September 1974 . VICTORIA: NTM S.17742-001, 4(21- 24), Lake King, G. Briggs, 20 June 2014 ; NTM S.17741-001, 5(19-22), Paynesville, G. Briggs, 20 June 2014 ; NTM S.17744-001, 4(22-28), Shallow Inlet Road, Yanakie, PU 14-87 , P. Unmack and C. Brumley, 10 July 2014 ; NTM S.17743-001, 22(13-30), Old Welshpool, SE Gippsland, PU 14-89 , P. Unmack and C. Brumley, 10 July 2014 ; AMS I.16973-003, Lake King at Metung, D. Hoese and W. Congleton, 15 march 1972 ; AMS I.21443-001, 10, Tambo River, Red Cliffs , T Berra and party, 18 October 1979 ; NTM S.17673-001, 3(23-24), Merri River, Warrnambool, N. Romanowshi, February 2012 . TASMANIA: AMS I.17546-005, 21, Browns River, Kingston, D. Hoese and W. Ivantsoff, 30 November 1972 ; AMS I.17565-004, 5, Fortesque Bay, D. Hoese and W. Ivantsoff, 2 December 1972 .

Diagnosis. A moderate-sized Pseudogobius with second dorsal rays usually I,7 (rarely 6 or 8); anal rays usually I,7 (rarely 6 or 8); pectoral rays 13–17; 16–19 segmented caudal rays, usually in 9/7 pattern; lateral scales 25–27; TRB usually 8; predorsal scales 7–10; opercle with several rows of small cycloid scales, uppermost row scales may be ctenoid; cheek usually naked but some specimens with up to three cycloid scales on lower cheek; shoulder girdle usually smooth, may have narrow bony to fleshy or knobbly flange along edge; tongue short with tip blunt to round- ed; upper jaw teeth in outer row always largest, stout and conical, curved to fairly straight with slightly pointed to almost blunt tips; side of body with six mid-lateral small dark brown round to elongate spots, which may be joined by brown cross-hatching on scales; caudal fin narrow, with horizontal Y or double-spot pattern at base of fin; known from temperate estuarine to freshwater areas in south-eastern Australia (Victoria to Queensland and Tasmania).

Description. Based on 65 specimens, 23–36 mm SL. An asterisk indicates the counts of the 30.5 mm SL female holotype ( Fig. 10C ).

First dorsal VI*; second dorsal I,6–8 (usually 7*); anal I,6–8 (usually I,7, 8 in holotype); pectoral rays 13–17 (usually 15*); segmented caudal rays 9/7–10/9, usually 9/7*; branched caudal rays 7/6 (in 7), 7/7 (6), 8/6* (15), 8/7 (31), 8/8 (1), 9/7 (4); lateral scale count 25–27* (usually 26); TRB 8*–10 (usually 8); predorsal scale count 7*–10 (usually 8). Gill rakers on outer face of first arch 2+5 (in 2), 2+6 (2), 3+6 (5).

Body rounded anteriorly, compressed posteriorly. Head rounded, slightly wider than deep (HL 22.8–27.1% SL (mean 25.2%). Head depth at posterior preopercular margin 60.6–74.4 HL (mean 65.4%). Head width at posterior preopercular margin 62.5–79.2% HL (mean 69.8%). Mouth small, subterminal, horizontal to very slightly oblique; jaws reaching to vertical through mid-eye or slightly further back in adult males and to just anterior to mid-eye in females; upper jaw 15.2–48.1% HL (mean 35.2%), jaws in male larger than in female (mean 39.4% of HL versus 32.1% in females); lips relatively thin to fleshy, lower lip fused to chin anteriorly; Eyes lateral, high on head, top forming part of dorsal profile, 24.4–40.9% HL (mean 28.3%). Snout rounded and may be slightly inflated, 22.7–30.5% HL (mean 26.6%). Interorbital moderate, 9.5–19.5% HL (mean 14.5%). Body depth at anal origin 16.8–23.3% SL (mean 19.5%). Caudal peduncle compressed, length 27.0–33.7% SL (mean 29.7%). Caudal peduncle depth 10.8–18.1% SL (mean 12.3%).

First dorsal fin low, roughly triangular with rounded margin, with first to third spines longest, first or second usually longest (first spine longest in 14 of those measured; second spine longest in 15). Appressed first dorsal fin falling just short of second dorsal fin origin or barely reaching fin in adult males, fin always falling short of second dorsal fin in females; fin length 16.7–19.6% SL (mean 17.8%). First dorsal spine length 16.2–18.9% SL (mean 17.0%). Second dorsal spine length 13.2–18.9% SL (mean 14.5%). Third dorsal spine length 13.1–14.3% SL (mean 13.5%). Second dorsal and anal fin heights moderate, fins rounded (females) to pointed (males) posteriorly with an- teriormost rays longest, fin falling well short of caudal fin base when appressed in females and just reaching caudal fin rays in males. Pectoral fin oval, central rays longest, reaching back to vertical just before anus or slightly before, 18.9–24.2% SL (mean 21.5%). Pelvic fins rounded, just reaching anus in males, shorter in females, 19.3–23.6% SL (mean 21.2%). Caudal fin oval, narrow, can appear almost rectangular, bluntly rounded posteriorly, 23.9–41.1% SL (mean 30.5%); fin usually longer in males.

Anterior nostril in very short tube, oriented down over upper lip. Posterior nostril rounded to oval, with very low rim, placed close by mid-level of eye. Gill opening extending from pectoral fin base or to under mid-opercle, usually well under opercle. Gill rakers on outer face of first arch short and fleshy. Shoulder girdle usually smooth, may have narrow bony to fleshy or knobbly flange along edge. Tongue short with tip blunt to rounded, occasionally slightly concave. Upper jaw teeth in 2–3 rows, teeth in outer row always largest, stout and conical, curved to fairly straight with slightly pointed to almost blunt tips; teeth in inner rows very small, close-set and sharp. Lower jaw teeth in about three rows, conical, and curved to almost upright in outermost row, with sharp tips; no symphyseal canines present. Teeth in females always smaller than in males.

Body scales ctenoid to behind pectoral fin; usually cycloid scales on predorsal (four specimens from Narrabeen Lake, Sydney, and one from Maroochy River, Queensland, with ctenoid predorsal scales on midline; opercle with several rows of small cycloid scales, uppermost row of scales occasionally ctenoid; cheek usually naked but may have up to three cycloid scales on lower rear part; pectoral fin base with cycloid scales; belly with ctenoid scales anteriorly, often cycloid near anus, or all scales ctenoid. Lateral canals, pores and sensory papillae pattern similar to those of P. olorum but for (occasionally) scales on cheek ( Fig. 9 ).

Coloration of preserved material. Head and body whitish to pale yellowish brown, with darker brown markings. Head with plain grey to brown snout; nape with irregular brown mottling and small spots. Cheek and opercle with variable scattered dusky grey to dark brown small spots; may be small brown blotch or short bar at lower rear edge of eye. Lips pale to dark brown in both sexes, darkest in adult males. Underside of head whitish in females, with few scattered melanophores; underside, including breast, dusky grey to dark brown in males. Side of body with six mid-lateral widely spaced small dark brown round to elongate spots, which may be joined by brown crosshatching present on scales. Dorsum with 5–6 short dark brown blotches, commencing on mid-nape; blotches often coalescing with grey pigment on upper half of body; scales on dorsal half of body may have thin dark brown margin. Lower half of body with scattered small dark brown spots; scales with brown cross-hatching. Predorsal with brown mottling and indistinct spots. Breast and belly plain whitish in females; dusky grey to brownish in males. Peritoneum very dark brown to black dorsally, becoming silvery on sides and transparent ventrally. Four internal greyish to brown narrow blotches along ventral midline, two above anal fin and two on caudal peduncle. On scaly base of caudal fin, two dark brown to blackish rounded spots, placed above and below posteriormost mid-lateral spot; upper caudal fin spots may partly coalesce with mid-lateral spot; lowermost caudal fin spot may be placed slightly further away from mid-lateral spot.

First dorsal fin transparent to slightly dusky brown, with 2–3 brown to blackish stripes; uppermost on fin margin, lowermost more oblique, running just above fin base; distinct black spot at rear of fin between fifth and sixth spines; brown stripes variable in size and intensity. Second dorsal fin transparent to pale greyish with 3–4 brown stripes, often broken up into rows of brown spots; markings fading or coalescing toward rear of fin; margin transparent. Anal fin plain dusky grey to translucent, with indistinct broad brownish stripe in middle; fin plain pale to dark grey in adult males. Caudal fin transparent to pale greyish with 6–8 irregular curving rows of small brown spots, becoming more scattered and diffuse posteriorly. Pectoral fin base as in body colour with small dark brown square blotch on upper part. Pectoral fin transparent to slightly grey, with rays having scattered brown speckling mostly on upper part of fin (especially in males). Pelvic fins translucent with greyish speckling along fifth rays; in adult males, fin pale to dark grey-brown with sides of disc and most of frenum clear; base of frenum near breast dark brown (may form thin line or bar).

Coloration of fresh material. From photos of captive fish from New South Wales locations by Mark Abell and Nick Romanovski (and see Fig. 10 ). Head and body translucent brownish grey, whitish ventrally; scales on most body with dark brown to red-brown cross-hatched or / \ shaped markings. About 6–8 dark brown short blotches across dorsum; about five rectangular to rounded dark brown spots along lateral midline and scattered smaller dark brown spots on dorsal half of body. Dark brown spot on scaled part of caudal fin just above last mid-lateral brown spot and similar dark spot at lower base of fin. Several small dark brown blotches or spots present just above pectoral fin base. Peritoneum silvery white over abdomen, usually showing through body wall. Side of head with short dark brown bar from lower rear edge of eye across cheek, may be second short oblique dark mark from above upper jaw. Iris dull golden to orange-gold.

First dorsal fin transparent with 2–3 brown bands, broadest always along margin, remaining bands may be broken-up or missing; distinct black rounded blotch at rear of fin with bright blue area dorsally and behind black spot. Second dorsal fin transparent with 2–4 irregular rows of brownish spots and streaks. Anal fin transparent with brownish speckled on rays. Caudal fin transparent with about 5–6 irregular brownish bands, darkest near base. Pectoral fin transparent, with rounded dark brown spot at base of uppermost few rays. Pelvic fins with translucent pale golden rays.

Comparisons. This species is similar to P. olorum and can be distinguished by having a second dorsal and anal ray count of I,6-8, usually I,7 (versus I,8-9, usually I,8 second dorsal rays and I,7–9, usually I,8 anal rays in P. olorum ), fewer predorsal scales (7–10, usually 8, versus 8–11, usually 10), lower TRB count (usually 8 versus usually 10) and in a lower lateral scale count of 25–27 (versus 27–30). The two are almost identical in colour pattern, but P. olorum is typically of more robust appearance with a larger head in males (mean 25.5 in P. eos versus 27.8% SL in P. olorum ).

Distribution. Endemic to eastern Australia; known from southern Queensland (as far north as Agnes Water), New South Wales, Victoria and Tasmania. Hybrid individuals involving this species with P. olorum occur in very south-west Victoria, south-east South Australia and north-west Tasmania.

Ecology. Shallow-water estuarine, found in estuaries of rivers, streams and mangroves, at depths of 0– 3 m. Typically much more coastal in distribution than the frequently inland P. olorum (likely in part relating to the topography of higher gradient streams along the Great Dividing Range habitat of south-eastern Australia, compared to the lower relief in south-western Australia). Gee and Gee (1991, 1995; under the name of P. olorum ) conducted experiments on the air-breathing ability of this species (and six other gobies) under hypoxic conditions. Pseudogobius held an air bubble in the mouth cavity to assist in surface respiration but did not possess the abundant capillaries in the mouth cavity or skin on the dorsal surface of the head as in Chlamydogobius or Mugilogobius . Ford et al. (2004) investigated behaviour of captive specimens due to experimental increase in temperature. Co-occurs with P. aquilonius and P. jeffi n. sp. at its northern distribution extent.

Etymology. Named eos , the Greek meaning dawn or east, in reference to the distribution of this species.

Remarks. Two morphotypes have been long recognised within P. olorum with a purported split at the Glenelg River in western Victoria ( Larson and Hoese 1996). The complementary genetic analysis ( Hammer et al. 2021) provides support for a general east-west break as good species, however it indicates the central area of overlap in the two taxa (Murray Mouth to Glenelg River inclusive and north-west Tasmania) represents a hybrid zone between the taxa. The material examined for the description of the eastern form, Pseudogobius eos , deliberately avoided this area of overlap to focus on pure populations. Further morphological work, referenced to tissue vouchered material, would be beneficial to characterise hybrid individuals and to fully map the hybrid zone.

Hammer et al. (2021) found major phylogenetic structure within P. eos (their P. sp. 9) for nuclear markers with two distinct sub-groups, one in western Victoria (from Port Phillip Bay west to before the Glenelg River) and anoth- er for northern populations (New South Wales and Queensland), but with major admixture across a relatively wide area encompassing Western Port and Gippsland (all had only a single mitochondrial DNA lineage). Consequently, they concluded the genetic structure was more likely to represent admixture between sub-groups (i.e. eos A and B) rather than the presence of two species. While there are five meristic characters to aid separation of P. olorum from P. eos , a preliminary examination of data for ‘pure’ populations from the two P. eos sub-groups revealed only one character (predorsal scales) with any indication of being diagnostically informative ( Table 10), and hence there is no support for an additional species based on morphology.

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 9. Pseudogobius eos n. sp., sensory papillae and lateral canal pores, male, AMS I.16972-001, Lake Bunga, Victoria. Drawing by HKL.

FIGURE 10. Pseudogobius eos n. sp., south-eastern Australia, (A) wild male, Currambene Creek, Jervis Bay, photo by A. Green; (B), fresh male (upper) and female, AMS I.45636-021, Berringer Lake, New South Wales, photo by M. McGrouther; (C) preserved holotype, 30.5 mm SL female, AMS I.17459-002, Port Hacking, Audley National Park, New South Wales, photo by MPH.