Platycephalus laevigatus 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 : 154-158

Platycephalus laevigatus Cuvier in Cuvier & Valenciennes, 1829

Common English name: Rock flathead

( Figs. 1–2 ; Table 1)

Platycephalus laevigatus Cuvier in Cuvier & Valenciennes, 1829: 248 [type locality: Western Port (as Port Western), Vic, Australia]; Quoy & Gaimard, 1834: 684, fig. 4; Castelnau, 1872: 84; McCulloch, 1929: 402; Coleman, 1980: 114, unnumbered fig.; Scott et al., 1980: 169, unnumbered fig.; Hutchins & Thompson, 1983: 78, fig. 114; Last et al., 1983: 332, fig. 28.20; Hutchins & Swainston, 1986: 127, fig. 195; Paxton & Hanley, 1989: 469; Knapp, 1991: 29, tab. 3; Kuiter 1993: 105, unnumbered fig.; Kuiter, 1994: 521, fig. 463; Grant, 2004: 192, unnumbered pl.; Hoese et al., 2006: 942; Imamura, 2006: 305, tab. 1; Gomon, 2008: 520, unnumbered fig.

Platycephalus proximus Castelnau, 1872: 85 (type locality: Melbourne market, Vic, Australia); McCulloch, 1929: 400.

Laeviprora laevigata (misspelling of Leviprora ): Whitley, 1964: 57.

Laeviprora proxima (misspelling of Leviprora ): Whitley, 1964: 57.

Material examined. Holotype: MNHN 6866, 302 mm SL, Western Port (as Port Western), Vic, Australia.

Other specimens (21 specimens, 66.7–484 mm SL, from southern Australia): AMS I. 2834, 257 mm SL, Albany, WA (35°01’S, 117°53’E); AMS I. 7543, 276 mm SL, AMS I. 7544, 271 mm SL, Melbourne market, Vic, Nov. 1905; AMS I.17610-012, 66.7 mm SL, 16 km north of Pt. Vincent, Pine Point, SA (34°46’S, 137°48’E), 23 Dec. 1973; AMS I.19676-001, 388 mm SL, AMS I.19676-002, 398 mm SL, Merimbula estuary, NSW (36°53’S, 149°56’E), 18 May 1976; AMS IB. 1961, 401 mm SL, Greenwell Point, NSW (34°50’S, 150°45’E), 1947; AMS IB. 2112, 260 mm SL, Port Albert, Vic (38°45’S, 146°41’E), 1948; AMS IB. 3554, 431 mm SL, Nowra, NSW (34°53’S, 150°36’E), 1956; AMS IB. 7589, 484 mm SL, AMS IB. 7592, 287 mm SL, Tooradin, Vic (38°13’S, 145°23’E); CSIRO CA 596, 281 mm SL, St. Kilda, SA, 24 Jan. 1975; CSIRO T 1644, 145 mm SL, North East River, Flinders Island, Tas; CSIRO T1678, 78.5 mm SL, Norfolk Bay, Tas (43°00’S, 147°45’E), 21 Apr. 1978; CSIRO T 1719, 113.6 mm SL, North East River, Flinders Island, Tas (39°47’S, 147°58’E), 31 Jan. 1978; MNHN A4285 (holotype of Platycephalus proximus Castelnau, 1872 ), 341 mm SL, Melbourne market, Vic; NMV A9294, 97.2 mm SL, sea-grass flats, Price Creek entrance, Yorke Peninsula, SA (35°33’S, 128°08’E), 3 Dec. 1986; NMV A18576, 85.8 mm SL, mudflat, south of boat ramp, Stony Point, Western Port, Vic (38°22’36”S, 145°13’24”E), 0.5 m depth, 9 Dec. 1996; NMV A26195 -002, 132 mm SL, subtidal reef, Port Julia, Yorke Peninsula, Gulf of St. Vincent, SA (34°39’S, 137°52’E), 15 Dec. 1994; NMV A29380-003, 159 mm SL, Corner Inlet, Port Franklin, Vic (38°41’S, 146°16’E), 0–1 m depth, 1 Mar. 2005; WAM P.27752-001, 329 mm SL, Fremantle, WA (32°03’S, 115°44’E), Aug. 1982.

Diagnosis. A species of Platycephalus with the following combination of characters: second dorsal- and analfin rays usually 14; interorbital width 3.4–7.8% HL; postorbital length 51.4–65.2% HL; head and body subcylindrical, elongate and only slightly depressed; occipital region naked; dorsal and lateral surfaces of head mostly smooth, with preopercular (2), opercular (2) and supracleithral (1) spines; upper preopercular spine longer than lower; upper jaw without large caniniform teeth; head with two dark brown bands from anterior of snout to posterior margin of opercle on both sides, area between bands whitish-brown, pale brown or brown, area below each band pale brown in specimens 159 mm SL or smaller.

Description. Counts and measurements shown in Table 1. Data for all specimens presented first, followed by holotype condition in parentheses.

Head and body subcylindrical, elongate, only slightly depressed. Snout, area anteroventral to eye, interorbit, and occipital and lower half of suborbital regions naked. Snout short, subequal or slightly longer (subequal in holotype) than orbital diameter. Interorbit much narrower than orbital diameter. Upper iris lappet simple, triangular; lower simple, weakly convex. Dorsal and lateral surfaces of head mostly smooth, but with preopercular (2) and opercular spines (2). One supracleithral spine usually present (absent on left side, present on right side). Upper preopercular spine longer than lower, not reaching opercular margin. Small or finger-like interopercular flap usually present (finger-like flap present); margin of interopercle smooth. Maxilla reaching slightly beyond anterior margin of pupil to slightly beyond middle of eye (reaching to middle of eye). Anteromedial portion of upper jaw with moderate to large conical or small caniniform (moderate conical) teeth. Palatine teeth irregularly arranged in two to four (three) rows, tending to become larger medially. Vomerine teeth irregularly arranged in one to four (three) rows anteriorly, two to six (four) rows posteriorly, becoming larger posteriorly. Fleshy sensory tubes from suborbitals and preopercle slightly developed, partly covering dorsal and ventral margins of cheek region. Posterior tip of pelvic fin usually reaching just short of anus (including holotype), or to origin of anal fin. Posterior margin of caudal fin rounded (not confirmed in holotype).

Color in alcohol. Color of holotype considerably faded, but retaining small brownish spots on sides of head and body, first and second dorsal, pectoral, pelvic and caudal fins ( Fig. 2 A). In other specimens ( Fig. 1 A, B), ground color of head and body dark brown above, paler below. Side of head and body with dark brown spots. First and second dorsal, pectoral, pelvic and caudal fins with many small brownish, dark brownish and blackish spots; those on pectoral and pelvic fins tending to form bands. Anal fin without melanophores in 132 mm SL or smaller specimens, with melanophores along rays by 159 mm SL, with dark spots posteroventrally by 257 mm SL and with spots ventrally in larger specimens. In 159 mm SL or smaller specimens, head with dark brown band from anterior part of snout to posterior margins of opercles on both sides; area between bands whitish-brown, pale brown or brown; areas below bands pale brown ( Fig. 1 C).

Holotype Holotype of P. proximus Non-types

MNHN 6866 MNHN A4285 n = 20 SL (mm) 477 341 66.7– 484 Counts:

Distribution. Known from southern Australia, from NSW (31°01’S), across SA, Vic and Tas, to Local Waters, WA (32°03’S), occurring on weed-covered reefs and sea-grass beds in depths from 0.5 to 20 m (e.g., Last et al., 1983; Kuiter, 1993, 1994; Hoese et al., 2006; this study).

Size. Maximum length 80.8 cm ( Hutchins & Swainston, 1986). The largest specimen examined during this study was 484 mm SL (573 mm TL) ( Fig. 1 A, B).

Remarks. Platycephalus laevigatus is easily separable from congeneric species in having the head and body subcylindrical, elongate and only slightly depressed (well depressed in others), occipital region naked (vs. scaled, except in P. chauliodous ), dorsal and lateral surfaces of the head mostly smooth, only two distinct preopercular, two opercular and one supracleithral spine [vs. some or many other spines and ridges, including lachrymal and preocular spines (but preocular spine rarely absent in P. chauliodous )] and the upper preopercular spine longer than the lower [vs. lower spine longer than upper, except in some smaller specimens of P. caeruleopunctatus and P. chauliodous (upper spine about equal to or longer than lower)]. Although P. laevigatus and P. chauliodous share several other characters setting them apart from other species, P. laevigatus is further distinguished from P. chauliodous in having the upper jaw without large caniniform teeth (such teeth medially on the anterior part of the upper jaw in the latter). In addition, the head coloration in 159 mm SL or smaller specimens of P. laevigatus is unique, thereby allowing distinction from other members of the genus ( Fig. 1 C).

Although interorbital width becomes relatively broader with growth in all species of Platycephalus ( Imamura, 2012, 2013a), P. laevigatus has the narrowest interorbit of all at comparable sizes (interorbital width 3.4–7.8% HL in P. laevigatus ). Comparison of interorbital width in all examined specimens of P. laevigatus and six species of Platycephalus is characterized by interorbital width narrower than orbital diameter, as shown in Fig. 3 A (viz. 7.4–11.7% HL in P. aurimaculatus , 7.2–12.8% in P. bassensis , 7.4–14.1% in P. conatus , 6.9–12.3% in P. grandispinis , 5.8–14.6% in P. speculator and 10.1–15.7% in P. richardsoni ; in all other species of Platycephalus , interorbital width becomes greater than orbital diameter with growth). In addition, P. laevigatus is also separable from the above same six species in having a longer postorbital region (postorbital length 51.4–65.2% HL in P. laevigatus vs. 49.1–56.9%, 49.6–57.1%, 49.7–56.2%, 48.5–54.4%, 51.2–59.1% and 49.7–56.2%, respectively) ( Fig. 3 B).

The synonymy of P. laevigatus and P. proximus Castelnau, 1872 ( Fig. 2 B) has been recognized by Paxton & Hanley (1989), Kuiter (1994) and Hoese et al. (2006), but without justification. Platycephalus proximus , known only from the holotype from Melbourne market, agrees well with P. laevigatus , having the above mentioned characters, and other counts and proportional measurements similar, without any remarkable differences ( Table 1). The present study confirms the priority of P. laevigatus over P. proximus .

Figures

FIGURE 1. (A) Dorsal and (B) lateral views, and (C) dorsal view of head of Platycephalus laevigatus. A and B, AMS IB. 7589, 484 mm SL, Tooradin, Vic; C, NMV A 26195 - 002, 132 mm SL, Port Julia, Yorke Peninsula, Gulf of St. Vincent, SA.

FIGURE 2. Dorsal views of holotypes of (A) Platycephalus laevigatus, MNHN 6866, 302 mm SL, Western Port (as Port Western), Vic and (B) Platycephalus proximus, MNHN A 4285, 341 mm SL, Melbourne market, Vic.

FIGURE 3. Comparison of (A) interorbital width and (B) postorbital length versus standard length in Platycephalus laevigatus (solid circles), P. aurimaculatus (open diamonds), P. bassensis (open circles), P. grandispinis (open squares), P. conatus (open triangles), P. speculator (solid squares) and P. richardsoni (solid triangles). Holotypes labeled by capitalized initial of specific names. P, holotype of Platycephalus proximus.