Platycephalus bassensis Cuvier

Imamura, Hisashi, 2015, Taxonomic revision of the flathead fish genus Platycephalus Bloch, 1785 (Teleostei: Platycephalidae) from Australia, with description of a new species, Zootaxa 3904 (2), pp. 151-207 : 159-162

Platycephalus bassensis Cuvier in Cuvier & Valenciennes, 1829

Common English name: Southern sand flathead ( Figs. 4–5 ; Table 2)

Platycephalus bassensis Cuvier in Cuvier & Valenciennes, 1829: 247 [type locality: Western Port (as Port Western), Vic, Australia]; Quoy & Gaimard, 1834: 683, fig. 3; Castelnau, 1872: 83; McCulloch, 1929: 400; Coleman, 1980: 111, unnumbered fig.; Last et al., 1983: 331, fig. 28.18; Hutchins & Swainston, 1986: 127, fig. 198; May & Maxwell, 1986: 274, unnumbered fig.; Paxton & Hanley, 1989: 468 (in part, including P. westraliae ; see Remarks); Knapp, 1991: 29, tab. 3; Kuiter 1993: 103, two unnumbered figs.; Kuiter, 1994: 519, fig. 462; Grant, 2004: 189, unnumbered pl.; Hoese et al., 2006: 940 (in part, including P. westraliae ); Imamura, 2006: 304, tab. 1; Gomon, 2008: 520, unnumbered fig.

Platycephalus tasmanius Richardson, 1842: 96 (name also on p. 72) (type locality: Port Arthur, Tas, Australia).

Trudis bassensis: Whitley, 1931a: 327 ; Whitley, 1931b: 157; Whitley, 1964: 57.

Platycephalus bassensis bassensis: Scott et al., 1980: 168 , unnumbered fig.

Material examined. Holotype: MNHN 1437, 233 mm SL, Western Port, Vic, Australia.

Other specimens (26 specimens, 114–418 mm SL, from southeastern Australia): 7 specimens were listed in Imamura (2008); 14 additional specimens: AMS A. 16458, 242 mm SL, AMS A. 16459, 274 mm SL, Hobsons Bay, Vic (37°51’S, 144°56’E), 1883; AMS E. 4953, 267 mm SL, Hobart Wharf, Tas (42°50’S, 147°15’E), 1914; AMS E. 5457, 358 mm SL, Recherche Bay, Tas (43°33’S, 146°54’E), 15 m depth, 24 July 1914; AMS I. 6274, 272 mm SL, Tamar River Heads, Tas (41°20’S, 147°02’E), 1903; AMS I. 7541, 401 mm SL, data unknown; AMS I. 7542, 324 mm SL, Derwent Estuary, Tas (43°02’S, 147°22’E), 1913; AMS I.20194-050, 2 specimens, 213–218 mm SL, Investigator Strait, SA (35°20’S, 137°50’E), 20 m depth, 14 May 1978; BMNH 1855.9.19.56–57 and BMNH 1855.9.19.67–68, included in a single jar, 4 syntypes of Platycephalus tasmanius Richardson, 1842 (loc. Port Arthur, Tas, Australia) and one non-type (loc. unknown), all specimens lacking individual labels; one specimen with damaged snout ( SL unmeasured), remaining four specimens 170–303 mm SL; CSIRO A 741, 137 mm SL, Kettering, D’Entrecasteaux Channel, Tas (43°09’S, 147°16’E), 1 May 1951; CSIRO CA 3690, 283 mm SL, Great Australian Bight, SA (32°12’S, 131°25’E – 32°13’S, 131°24’E), 60 m depth, 8 Dec. 1981; NSMT-P 112668, 418 mm SL, northwest coast of Tas, 28 m depth, Dec. 17 1975; NMV A29215-018, 215 mm SL, off Plank Point, Spencer Gulf, SA (33°25’42”S, 137°29’36”E), 22–29 m depth, 13 Oct. 2005; QM I. 22312, 368 mm SL, Lakes Entrance, Vic (37°53’S, 148°02’E), 14 Aug. 1985.

Diagnosis. A species of Platycephalus with the following combination of characters: second dorsal- and analfin rays usually 14; pored lateral-line scales 70–82; gill rakers 4–6 + 13–16 = 17–22; a distinct interopercular flap absent; ratio of lower/upper preopercular spines 1.6–2.2; ridge and spine absent on supraoccipital; upper jaw without large caniniform teeth; many small dark dots on dorsal surface of head and body; caudal fin with a single large irregular blackish or dark brown marking, or two longitudinal dark brown or black spots posteroventrally.

Description. Counts and measurements shown in Table 2. Data for all specimens presented first, followed by holotype condition in parentheses.

Interorbit and occipital region scaled; snout and area anteroventral to eye scaled or naked (unclear in holotype), lower half of suborbital region naked. Interorbit narrower than orbital diameter. Upper iris lappet simple, triangular; lower simple, weakly convex. Nasal, preorbital and supplementary preopercular spines absent. Suborbit al spines usually absent; one suborbital spine present below posterior margin of eye in some specimens 176 mm SL or smaller. Ridges and spines absent on supraoccipital. Lower preopercular spine longer than upper, not reaching opercular margin; ratio of lower/upper spines 1.6–2.2 (>2), tending to become larger with growth (lower spine becoming relatively longer than upper). Distinct interopercular flap absent, although small flap sometimes present (on left side only); margin of interopercle smooth. Maxilla reaching beyond anterior margin of eye. Anterior portion of upper jaw with some large conical or small caniniform (small caniniform) teeth medially. Palatine teeth irregularly arranged in three to nine (ca. five) rows, becoming larger medially; row number tending to increase with growth. Vomerine teeth irregularly arranged in one or two (two) rows anteriorly, two to six (three) posteriorly, becoming larger posteriorly; anterior and posterior row numbers tending to increase with growth. Fleshy sensory tubes on suborbitals and preopercle usually not covering cheek region (including holotype); those from preopercle slightly developed and partially covering ventral margin of cheek region in some specimens. Posterior tip of pelvic fin reaching anal-fin origin or second anal-fin ray (damaged in holotype). Posterior margin of caudal fin usually slightly concave, straight in 137 and 155 mm SL specimens (damaged in holotype).

Color in alcohol. Color of holotype mostly faded, retaining a dusky spot on posteroventral portion of caudal fin ( Fig. 5 A). In other specimens ( Fig. 4 ), ground color of head and body pale brown to dark brown above, paler below. Dorsal surface of head and body with many small dark dots, that of body with two to four indistinct darker bands. Head with or without brownish band below eye. Side of body with gray or pale purple spots tending to form single band, and dark brown spots. First and second dorsal, and pectoral fins with small brownish spots; those on pectoral fin tending to form bands. Ground color of pectoral fin pale brown or brown, with paler margin ventrally and darker spots often tending to form bands. Pelvic fin brownish or dark brownish with pale outer margin but without spots, or its ground color pale brownish with brownish spots. Anal fin with melanophores on basal portion of rays. Caudal fin with single large irregular blackish or dark brown marking, or two to four longitudinal dark brown to black bands or spots posteroventrally, and several small pale brown to black spots elsewhere.

Distribution. Known from southeastern Australia, from Red Rock, NSW (29°59’S), to the Great Australian Bight, SA (131°24’–25’E), including Vic and Tas, occurring in bays and inlets and on the continental shelf in depths from 15 to ca. 100 m (e.g., Last et al., 1983; May & Maxwell, 1986; Hoese et al., 2006; this study).

Size. The largest specimen recorded during the present study was 418 mm SL (483 mm TL), exceeding the previously reported maximum length of 401 mm SL (460 mm TL) ( May & Maxwell, 1986).

Holotype 5 specimens, including Non-types

MNHN 1437 4 syntypes of P. tasmanius n = 21 SL (mm) 233 170–303* 137– 418 Counts:

* Including one specimen with damaged snout and SL unmeasured.

Remarks. Among the other species of Platycephalus usually characterized by 14 second dorsal- and anal-fin rays ( P. laevigatus , P. grandispinis , P. speculator , P. caeruleopunctatus , P. conatus , P. aurimaculatus and P. richardsoni ), P. bassensis is most similar to P. grandispinis in having a somewhat longer lower preopercular spine (extremely long in P. grandispinis ), the caudal fin with a single large irregular blackish or dark brown marking, or two longitudinal dark brown or black spots posteroventrally (a single irregular blackish or dark brownish marking in P. grandispinis ), and in lacking a distinct interopercular flap, the combination of these characters not occurring in the remaining six species. The present species is easily separable from P. grandispinis in lacking a ridge and spine on the supraoccipital (vs. ridge present on supraoccipital, usually ending in a spine) and having many small dark dots on the dorsal surface of the head and body (vs. dots absent). The ratio of lower/upper preopercular spines may also help distinguish P. bassensis from P. grandispinis (ratio 1.6–2.2 in P. bassensis vs. 1.9–3.3 in P. grandispinis ; see also Imamura, 2013b: fig. 10).

Although P. bassensis is also similar to some specimens of P. conatus in having a somewhat longer lower preopercular spine (some specimens of P. conatus with lower spine more than twice length of upper spine), it is separable from the latter in having the upper jaw without large caniniform teeth, as well as from P. aurimaculatus and P. richardsoni (upper jaw with large caniniform teeth anteromedially in latter two species and P. c o na t u s). Platycephalus bassensis is distinguishable from P. caeruleopunctatus in having 70–82 pored latera-line scales (83–93 in P. caeruleopunctatus ) and P. speculator in having 17–22 gill rakers in total (11–14 in P. speculator ) (pored lateral-line scale data for P. caeruleopunctatus taken from Knapp, 1991 and the present study).

Western Australia has been included in the distribution of P. bassensis by some authors, including Paxton & Hanley (1989) and Hoese et al. (2006). They considered Trudis bassensis westraliae Whitley, 1938 , originally described on the basis of two specimens from the Swan River estuary, WA, to be a junior synonym of P. bassensis . However, Imamura (2008) showed the validity of the former (as Platycephalus westraliae ) and referred that name to the species previously recognized as “ Platycephalus endrachtensis ” (with three black bars on the caudal fin) by authors including Taylor (1964), Gloerfelt-Tarp & Kailola (1984), Allen & Swainston (1988) and Knapp (1999). In addition, as no specimens of P. bassensis from WA were found during the present study, that area is omitted from the distribution of the species recognized here. The revised westernmost record of P. bassensis is the Great Australian Bight, SA (ca. 131°E), represented by CSIRO CA3690.

The taxonomic status of Platycephalus tasmanius ( Fig. 5 B), described from four syntypes from Tasmania by Richardson (1842), has not previously been clearly demonstrated, although Paxton & Hanley (1989), Kuiter (1994) and Hoese et al. (2006) considered it a junior synonym of P. bassensis , without any reasons given. After a comparison of the type specimens of both species, the synonymy was confirmed, owing to the close similarity of the former and non-types of P. bassensis in both the taxonomic characters mentioned above, and in counts and proportional measurements ( Table 2).

Figures

FIGURE 4. (A) Dorsal and (B) lateral views of Platycephalus bassensis, AMS I. 34823 - 001, 303 mm SL, off Tathra, NSW.

FIGURE 5. Dorsal views of (A) holotype of Platycephalus bassensis, MNHN 1437, 233 mm SL, Western Port, Vic and (B) syntype of P. tasmanius, 279 mm SL, Port Arthur, Tas.