Platycephalus westraliae ( Whitley, 1938 )

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 : 194-197

Platycephalus westraliae ( Whitley, 1938)

Common English name: Yellowtail flathead ( Figs. 31–32 ; Table 12 )

Trudis bassensis westraliae Whitley, 1938: 199 (type locality: Swan River estuary, WA, Australia); Whitley, 1964: 57.

Platycephalus endrachtensis (not Quoy & Gaimard, 1825): Taylor, 1964: 287, pl. 65; Hutchins & Thompson, 1983: 78, fig. 110; Gloerfelt-Tarp & Kailola, 1984: 113, fig. 12, unnumbered fig.; Sainsbury et al. 1985: 112, unnumbered fig.; Hutchins & Swainston, 1986: 127, fig. 205; Allen & Swainston, 1988: 52, fig. 278; Paxton & Hanley, 1989: 468; Knapp, 1991: 29, tab. 3; Allen, 1997: 80, pl. 21-17; Knapp, 1999: 2408, unnumbered fig.; Hoese et al., 2006: 941; Imamura, 2006: 305, tab. 1.

Platycephalus westraliae: Imamura, 2008: 405 , figs. 1a, 6a, 7.

Platycephalus bassensis (not Cuvier in Cuvier & Valenciennes, 1829): Paxton & Hanley, 1989: 468 (in part); Hoese et al., 2006: 940 (in part).

Platycephalus indicus (not Linnaeus, 1758): Grant, 2004: 192, pl. 87.

Material examined. Holotype: AMS IA.7189, 98.7 mm SL, Swan River estuary, WA, Australia.

Paratype: AMS IA.7190, 85.8 mm SL, collected with holotype.

Other specimens (31 specimens, 63.2–553 mm SL, from western to southeastern Australia): 23 specimens listed in Imamura (2008); 8 additional specimens: AMS I.20751-005, 389.3 mm SL, 3 miles northwest of Lizard Island, Qld (14°38’S, 145°24’E), 25 m depth, 8 Feb. 1979; CSIRO CA 767, 200 mm SL, Thursday or Prince of Wales Islands, Torres Strait, Qld (10°40’S, 142°15’E); CSIRO CA 1162, 375 mm SL, east of Barrow Island, WA, date unknown; NTM S.11255-003, 330 mm SL, Caiman Creek, Port Essington, NT (11°14’S, 132°12’E), 13 May 1983; NTM S.12941-001, 369 mm SL, Arafura Sea, NT (11°29’S, 133°36’E), 22 Oct. 1990; NTM S.16160-041, 169 mm SL, Port Patterson, Quail Island, NT (12°31.36’S, 130°25.59’E), 7 Dec. 2002; QM I.28582, 1 of 20 specimens, Pine River mouth, Qld (27°17’S, 153°03’E), 27 Oct. 1997; WAM P.30645-001, 553 mm SL, Burswood Casino, Perth, WA.

Diagnosis. A species of Platycephalus with the following combination of characters: first dorsal fin with a single small isolated spine anteriorly; second dorsal- and anal-fin rays usually 13; interorbital width 6.3–17.0% HL; postorbital length 51.2–60.9% HL; snout, area anteroventral to the eye, interorbit, and occipital region scaled; upper iris lappet broad, usually slightly bilobed; a finger-like interopercular flap present; upper jaw without large caniniform teeth; teeth absent on dorsal surface of anterolateral edge of upper jaw; palatine teeth in two rows; vomerine teeth in one or two (usually one) rows anteriorly, one to four (usually one or two) posteriorly; three or four longitudinal dark bands on caudal fin; upper lobe of caudal fin with yellow blotch when fresh.

Description. Counts and measurements shown in Table 12 . Data for all specimens presented first, followed by holotype condition in parentheses.

SL (mm) 98.7 85.8 63.2–553

Counts:

*Abnormal condition.

Snout, area anteroventral to eye, interorbit and occipital region scaled; lower half of suborbital region naked. Interorbit narrower than orbital diameter in 369 mm SL or smaller specimens, wider than latter in larger specimens. Upper iris lappet broad, usually slightly bilobed (including holotype), rarely pointed or mostly straight in some specimens; lower weakly convex. Nasal spine present in smaller specimens, tending to disappear with growth, absent in 330 mm SL or larger specimens (present in holotype). Preorbital spine absent. One suborbital spine usually present below posterior margin of eye in 149 mm SL or smaller specimens (including holotype), usually absent in larger specimens; one additional suborbital spine sometimes present below and slightly anterior to middle of eye (absent in holotype). Lower preopercular spine slightly longer than upper, not reaching opercular margin. Supplemental preopercular spine usually present in 123 mm SL or smaller specimens (including holotype), absent in larger specimens. Finger-like interopercular flap present; margin of interopercle smooth. Maxilla reaching from just before anterior margin of pupil to posterior margin of eye (reaching to near anterior margin of pupil). Upper jaw with moderate or large conical or small caniniform teeth anteromedially (large conical teeth). Palatine teeth in two rows, villiform in outer row, moderate conical in inner row. Vomerine teeth usually in one (including holotype), rarely two rows (in 375 mm SL specimen) anteriorly, usually one or two (two) rows, rarely three (in 330 mm SL specimen) posteriorly, tending to become larger posteriorly. Fleshy sensory tubes from suborbitals and preopercle not covering cheek region. Posterior tip of pelvic fin reaching from anus to base of fourth anal-fin ray (base of third anal-fin ray). Posterior margin of caudal fin slightly rounded, mostly straight, or slightly concave (mostly straight).

Color in alcohol. Holotype discolored, but retaining brownish spots on side of body, and first and second dorsal, pectoral and pelvic fins, melanophores between ninth and last anal-fin rays, and three black longitudinal bands on caudal fin ( Fig. 32 ). In other specimens ( Fig. 31 ), ground color of head and body pale brown to dark brown above, paler below. Dorsal surface of head and body with small dark spots. Side of body with or without gray or brown band, or spots. Body below second dorsal fin with or without distinct or indistinct darker bands. First and second dorsal, pectoral and pelvic fins with small pale to dark brown spots. Anal fin pale in 291 mm SL or smaller specimens, with melanophores on membranes between 11th to last rays in 330 to 389 mm SL specimens, dusky in largest (553 mm SL) specimen. Caudal fin with three or rarely four (in a few specimens) brown to black longitudinal bands. Upper lobe of caudal fin with yellow blotch when fresh (e.g., Gloerfelt-Tarp & Kailola, 1984; Sainsbury et al. 1985; Hutchins & Swainston 1986).

Distribution. Known from Australia (except Vic, Tas and SA), from Fremantle, WA (32°03’S) across northern Australia to Port Hacking, NSW (32°04’S), including NT and Qld, and also from the southern coasts of Papua New Guinea and Java (e.g., Hutchins & Swainston 1986; Knapp 1999; Imamura, 2008; this study).

Size. Maximum length 1 m ( Hutchins & Swainston, 1986). The largest specimen examined during the present study was 553 mm SL (635 mm TL).

Remarks. Platycephalus westraliae had been considered as a subspecies ( Whitley, 1938, 1964) or junior synonym of P. bassensis ( Paxton & Hanley, 1989; Hoese et al., 2006) until Imamura (2008) showed it to be a valid species in its own right. In addition, up to that time, specimens had often been identified as “ P. endrachtensis ”. Of the species of Platycephalus with usually 13 second dorsal- and anal-fin rays, and two or more brown to black longitudinal bands on the caudal fin, P. westraliae differs from P. angustus and P. cultellatus in having the first dorsal fin with a small isolated spine anteriorly [usually two in the latter (but rarely one in P. angustus )] and a shorter postorbital region at a given length (51.2–60.9% HL in P. westraliae vs. 55.5–67.8% HL in P. angustus and 51.8–66.8% HL in P. cultellatus ) ( Fig. 30 B). The former character is also useful for separating P. westraliae from Platycephalus sp. 1 and 2 (sensu Nakabo, 2002). Platycephalus westraliae also differs from P. angustus in having teeth absent on the dorsal surface of the anterolateral edge of the upper jaw (teeth present in P. angustus ), from P. australis sp. nov. (described below) in having a shorter postorbital region at a given length (postorbital length 51.2–60.9% HL in P. westraliae vs. 51.6–63.6% HL in P. australis sp. nov.) ( Fig. 30 B) and from P. indicus in having a narrower interorbit at a given length (interorbital width 6.3–17.0% HL in P. westraliae vs. 7.2–18.4% HL in P. indicus ) ( Fig. 30 A). Platycephalus westraliae is separable from the above mentioned six species in having a broad bilobed upper iris lappet [vs. usually simple triangular, although sometimes broad bilobed in P. australis sp. nov. and P. i n di c us (see Remarks under P. endrachtensis )]. Finally, in fresh specimens the yellow blotch on the upper portion of the caudal fin is useful for distinguishing P. westraliae , although P. australis sp. nov. and P. indicus both have a yellow band on the middle of the caudal fin when fresh (e.g., Knapp, 1999; Imamura, 2009; this study).

Figures

FIGURE 30. Comparison of (A) interorbital width and (B) postorbital length versus standard length (mm) in Platycephalus endrachtensis (solid circles), P. angustus (solid diamonds), P. cultellatus (open circles), P. indicus (open squares), P. australis sp. nov. (solid triangles), P. westraliae (open triangles), Platycephalus sp. 1 (solid squares) and Platycephalus sp. 2 (open diamonds). H, holotype; N, neotype.

FIGURE 31. (A) Dorsal and (B) lateral views of Platycephalus westraliae, AMS I. 20978 - 084, 291 mm SL, Lizard Island, Qld.

FIGURE 32. Dorsal view of holotype of P. westraliae, AMS IA. 7189, 98.7 mm SL, Swan River estuary, WA.

Tables

TABLE 12. Comparison of counts and proportional measurements of Platycephalus westraliae. Holotype Paratype Non-types AMS IA. 7189 AMS IA. 7190 n = 31

D1	I + VII + 0	I + VII + I	I + VI–VIII + 0–I
			(often I + VII + I)
D2	13	13	12–13 (usually 13)
A	13	I, 13*	13–14 (usually 13)
P1	2 + 10 + 7 = 19	2 + 11 + 6 = 19	1–2 + 11–14 + 5–7 = 18–20
C	12	12	11–12 (usually 12)
LLS (spines)	78 (2)	76 (0)	70–83 (1–2, usually 1)
OBS	85	–	79–106
GR	2 + 8 = 10	2 + 8 = 10	1–3 + 5–8 = 7–10
As % SL:
HL	31.8	32.4	30.5–35.0
PDL	34.1	34.5	31.8–35.7
LD1B	16.6	34.8	15.6–21.9
LD2B	35.4	56.5	31.8–37.5
LAB	37.7	37.9	34.6–41.4
SNL	8.7	8.9	8.0–9.4
OD	6.3	6.4	3.8–7.9
UJL	12.0	12.1	11.3–13.3
LJL	16.3	17.6	15.1–18.4
IW	2.3	2.6	2.2–5.2
POL	17.3	17.2	17.1–20.2
SW	2.9	2.8	2.5–3.3
P1L	16.0	16.6	12.8–17.1
P2L	24.3	23.4	20.9–26.3
CL	18.9	18.6	13.4–19.0
As % HL:
SNL	27.4	27.3	25.9–28.1
OD	19.7	19.8	12.4–22.6
UJL	37.6	37.4	35.7–41.0
LJL	51.3	54.3	49.1–54.7
IW	7.3	7.9	6.3–17.0
POL	54.5	53.2	51.2–60.9
SW	9.2	2.5	7.2–10.5