Platycephalus angustus Steindachner, 1866

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 : 197-198

Platycephalus angustus Steindachner, 1866

Common English name: Steindachner’s flathead ( Fig. 33 )

Platycephalus angustus Steindachner, 1866a: 20 (original type locality: Suriname, South America; revised type locality owing to designation of neotype: northeast of Darbilla Creek, Millingimbi, Northern Territory, Australia); Steindachner, 1866b: 20; Steindachner, 1866c: 312; Imamura, 2012: 5 th p.

Material examined. Neotype (designated by Imamura, 2012): NTM S.11362-026, 345 mm SL, northeast of Darbilla Creek, Millingimbi, NT, Australia (12°09’S, 134°56’E), 0–2 m depth, 24 July 1984.

Other specimens: 23 specimens, 53.6–378 mm SL, from northern Australia and western New Guinea, listed in Imamura (2012).

Diagnosis. A species of Platycephalus with the following combination of characters: first dorsal fin with two small isolated spines anteriorly; dorsal and anal soft rays usually 13; orbital diameter 11.2–21.5 % HL; interorbital width 7.3–17.3 % HL; postorbital length 55.5–67.8 % HL; suborbital length 4.7–7.2 % HL; snout, area anteroventral to eye, interorbit, and occipital region scaled; upper iris lappet simple, triangular; a finger-like interopercular flap present; upper jaw without large caniniform teeth; teeth absent on dorsal surface of anterolateral edge of upper jaw in specimens ca. 76 mm SL or longer; palatine teeth in two rows; number of vomerine tooth rows tending to increase with growth, in two to four rows in 106–184 mm SL specimens and forming a single broad band in larger specimens; three to five dark brown to black bands and spots on caudal fin.

Distribution. Known from northern Australia, from Wyndham, Kimberley region, WA (128°10’E) to Cape Pallarenda, Townsville, Qld (146°46’E) and Irian Jaya, western New Guinea, inhabiting creeks and rivers, river mouths, estuaries and coastal areas including mudflats influenced by fresh water, in depths of 0.5–2 m ( Imamura, 2012).

Size. Recorded maximum length 378 mm SL (432 mm TL) ( Imamura, 2012; this study).

Remarks. Platycephalus angustus had been overlooked until Imamura (2012) demonstrated its validity and provided a detailed description.

Platycephalus angustus can be separated from P. cultellatus , P. indicus , P. westraliae , P. endrachtensis and Platycephalus sp. 1 and sp. 2 (sensu Nakabo, 2002), having usually 13 dorsal and anal soft rays, a finger-like interopercular flap, three to five dark brown to black bands (and spots), the first dorsal fin with two small isolated spines anteriorly, a small orbit (orbital diameter 11.2–21.5 % HL), broader interorbital space (interorbital width 7.3–17.3 % HL), longer and narrower postorbital region (postorbital length 55.5–67.8 % HL, suborbital width 4.7–7.2 % HL), and vomerine tooth rows tending to increase with growth from two to four rows in 106–184 mm SL specimens and forming a single broad band in longer specimens. Platycephalus angustus is unique in having exposed teeth on the dorsal surface of the anterolateral edge of the upper jaw in specimens ca. 76 mm SL or larger. This character is not known in any other species of Platycephalus , all of which have upper jaw teeth restricted to the anterior margin and ventral surface of the jaw ( Imamura, 2012).

Figures

FIGURE 33. (A) Dorsal and (B) lateral views of Platycephalus angustus, NTM S. 11362 - 026, neotype, 345 mm SL, northeast of Darbilla Creek, Millingimbi, NT.