Freespine Flathead

description

Description. Dorsal fin rays I + VIII + I- 11 (I + VIII + I- 10 or 11, 10 in one); anal fin rays 12; branched caudal fin rays 12 (11 – 13, usually 12 or 13, smallest specimen with 11 rays); pectoral fin rays 2 + 10 + 8 = 20 (2 or 3 + 10 – 12 + 6 to 8 = 19 or 20); pelvic fin rays I, 5; scales in lateral line 54 (53 or 54), anterior 6 (3 – 7) scales with spine; posteroventrally slanted oblique scale rows above lateral line 75 (71 – 78); anteroventrally slanted oblique scale rows above lateral line 84 (80 – 93); gill rakers 1 + 6 = 7 (1 + 5 – 8 = 6 – 9). See table 1 for selected proportional measurements. Head length 2.6 (2.4 – 2.7) in SL. Snout rather robust, its length 3.2 in HL (3.1 – 3.3 in HL, ratio as % HL slightly decreasing proportionally with growth) (fig. 9). Iris lappet broad and simple dorsally, absent ventrally (rarely absent dorsally, and usually broad and simple ventrally) (fig. 5 a). Interorbital width 14.1 (10.3 – 22.2) in HL. Nasal bone without distinct spines, but with tubercles (smallest specimen, 54.4 mm SL, with single spine and without tubercles) (fig. 4 a). Lachrymal with four (2 – 7) anterolaterally directed spines. Single (rarely two) preocular spine in front

Taxonomic revision of the genus Ratabulus (Teleostei: Platycephalidae), with descriptions of two new species from Australia

diagnosis

Diagnosis. A species of Ratabulus with 80 – 93 anteroventrally slanted oblique scale rows above lateral line; snout length 29.5 – 32.3 % HL, slightly decreasing proportionally with growth; pectoral fin length 13.9 – 15.8 % SL; pelvic fin length 22.1 – 28.5 % SL; nasal bone with tubercles in larger specimens; dorsal surface of head with large, pale to dark-brown irregularly shaped spots, body without spots dorsally; pelvic fin with large brown spots.

Taxonomic revision of the genus Ratabulus (Teleostei: Platycephalidae), with descriptions of two new species from Australia

discussion

Remarks. Ratabulus diversidens is easily separable from R. megacephalus and R. fulviguttatus in having 80 – 93 anteroventrally slanted oblique scale rows above the lateral line (versus 94 – 112 in R. megacephalus and 99 – 113 in R. fulviguttatus), the snout length 29.5 – 32.3 % HL, becoming slightly shorter proportionally with growth (versus 31.2 – 35.7 % HL in R. megacephalus and 30.4 – 34.8 % HL in R. fulviguttatus) (fig. 9), nasal bone with tubercles in larger specimens (versus lacking tubercles in R. megacephalus and R. fulviguttatus) (fig. 4), the dorsal surface of the head with large, irregularly shaped, pale to dark-brown spots, the body without spots dorsally (versus dorsal surface of head and body with small, round, pale or dark-brown spots in R. megacephalus and R. fulviguttatus) (fig. 3). R. diversidens resembles R. ventralis in having tubercles on the nasal bone, but differs from it in having a shorter pectoral fin (13.9 – 15.8 % SL in R. diversidens versus 15.8 – 18.6 % SL in R. ventralis) (fig. 10) and large, irregular spots on the head (versus a head with small, round, brown spots in R. ventralis) (fig. 3). This species can be separated from the other three by the la

Taxonomic revision of the genus Ratabulus (Teleostei: Platycephalidae), with descriptions of two new species from Australia

distribution

Distribution. Eastern Australia from Townsville, Queensland (17 ° 51 ' S) to Lakes Entrance, Victoria (38 ° 17 ' 52 ² S), recorded at depths of at least 30 – 345 m (McCulloch, 1914; Paxton et al., 1989) (fig. 1).

Taxonomic revision of the genus Ratabulus (Teleostei: Platycephalidae), with descriptions of two new species from Australia