Ratabulus, Jordan & Hubbs, 1925

Imamura, Hisashi & Gomon, Martin F., 2010, Taxonomic revision of the genus Ratabulus (Teleostei: Platycephalidae), with descriptions of two new species from Australia, Memoirs of Museum Victoria 67, pp. 19-33 : 20

Genus Ratabulus

( Figures 2–8 )

Ratabulus Jordan and Hubbs, 1925: 286 (original description, type species: Thysanophrys megacephalus Tanaka, 1917 ).

Rutabulus Jordan and Hubbs, 1925: 93 (incorrect original spelling and unavailable name; see ‘Remarks’).

Diagnosis. A genus of Platycephalidae with I + VII to IX + 0 or I-10 to 12 dorsal fin rays (usually I + VIII + I-12); 11 or 12 anal fin rays (usually 12); 18–21 pectoral fin rays (usually 19 or 20); 52–56 pored lateral line scales; 1 + 5 to 8 gill rakers (usually 1 + 6 or 7); body depressed and elongate, mostly covered with ctenoid scales, some cycloid scales on undersurface; head flattened; postorbital region, opercle, interorbit and nape scaled; upper surface of eye without papillae or flaps; iris lappet usually broad and simple dorsally; interorbit moderately narrow and slightly concave; posterior margin of orbit lacking distinct pit; interopercular flap absent; moderate to long and slender canines on upper jaw, palatine, and in two separate patches on vomer; tooth band on upper jaw without distinct notch; lip margins without papillae; suborbital and preopercular sensory tubes absent on cheek; pored lateral line scales with a single exterior opening posteriorly; first dorsal fin originating slightly posterior to opercular margin; pectoral fin rounded posteriorly, its posterodorsal corner weakly pointed; innermost pelvic fin ray unbranched, others branched; fourth pelvic fin ray longest; and posterior margin of caudal fin slightly oblique, upper lobe longer.

Remarks. The genus Ratabulus includes the following four species: R. diversidens from eastern Australia, R. megacephalus from the Northwest Pacific, R. fulviguttatus sp. nov. from northwesternAustralia and R. ventralis sp.nov. from northeastern Australia. Ratabulus can be easily distinguished from other genera of Platycephalidae in usually having one small free spine between the dorsal fins, iris lappet usually broad and simple dorsally, suborbital ridge with many small to large spines, moderate to long and slender canines on the upper jaw, palatine and in two separate patches on the vomer, no sensory tubes from the suborbitals and preopercle in the cheek region, and pored lateral line scales with one posterior exterior opening.

Although Jordan and Hubbs (1925: 286) proposed the name Ratabulus for this genus, Rutabulus appeared in the list of new genera on an earlier page (96) of the same publication. As no-one has dealt with this discrepancy, we, as first revisers, consider Ratabulus to be the correct spelling, since it has been used by most subsequent authors (e.g. Matsubara and Ochiai, 1955; Paxton et al., 1989; Shao and Chen, 1993; Imamura, 1996; Kim et al., 2005; Knapp, 1999; Hoese et al., 2006). Rutabulus, therefore, is regarded as an incorrect spelling and an unavailable name ( ICZN, 1999: Arts. 24.2.3, 32.4).

Key species of Ratabulus

1 Anteroventrally slanted oblique scale rows above lateral line 80–93; dorsal surface of head with large and pale to dark-brown spots of irregular shapes; pelvic fin with large brown spots R. diversidens

— Anteroventrally slanted oblique scale rows above lateral line 91–113; dorsal surface of head with small, round, brown spots; pelvic fin with small brown spots 2

2 Nasal bone with tubercles (fig. 4d); pelvic fin 19.5–25.7% SL; dorsal surface of body without spots

R. ventralis sp.nov.

— Nasal bone without tubercles (figs 4b–c); pelvic fin 25.3– 28.2% SL; dorsal surface of body with brownish or darkbrownish spots 3

3 Snout 30.4–34.8% HL; dorsal surface of head and body pale brown R. fulviguttatus sp. nov.

— Snout 31.2–35.7% HL; dorsal surface of head and body dark brown R. megacephalus

Figures

Figure 2. Lateral views of four species of Ratabulus: a, R. diversidens, AMS I.40494-001, 391 mm SL; b, R. megacephalus, HUMZ 200048, 344 mm SL; c, R. fulviguttatus sp. nov., CSIRO H4031-79, holotype, 262 mm SL; d, R. ventralis sp. nov., CSIRO H6116-02, holotype, 304 mm SL.

Figure 3. Dorsal views of four species of Ratabulus: a, R. diversidens, AMS I.40494-001, 391 mm SL; b, R. megacephalus, HUMZ 200048, 344 mm SL; c, R. fulviguttatus sp. nov., CSIRO H4031-79, holotype, 262 mm SL; d, R. ventralis sp. nov., CSIRO H6116-02, holotype, 304 mm SL.

Figure 4. Dorsal views of anterior head region in four species of Ratabulus: a, R. diversidens, AMS I.11523-010, 190 mm SL; b, R. megacephalus, BSKU 87405, 216 mm SL; c, R. fulviguttatus sp. nov., CSIRO H4031-79, holotype, 262 mm SL; d, R. ventralis sp. nov., CSIRO H6116-02, holotype, 304 mm SL. Arrows show tubercles on nasal bone. Scale bar = 10 mm.

Figure 5. Iris lappet (left eye) of four species of Ratabulus: a, R. diversidens, AMS I.45084-009, 230 mm SL; b, R. megacephalus, BSKU 87405, 216 mm SL; c, R. fulviguttatus sp. nov., CSIRO H4031-79, holotype, 262 mm SL; d, R. ventralis sp. nov., CSIRO H6116-02, holotype, 304 mm SL. Scale bar = 3 mm.

Figure 6. Dorsolateral view of pelvic fin in four species of Ratabulus: a, R. diversidens, CSIRO H630-29, 273 mm SL; b, R. megacephalus, HUMZ 200048, 344 mm SL; d, R. fulviguttatus sp. nov., CSIRO H4031-79, holotype, 262 mm SL; d, R. ventralis sp. nov., CSIRO H6116-02, holotype, 304 mm SL.

Figure 7. Dorsal (upper) and lateral (lower) views of Ratabulus diversidens, AMS E.2103, lectotype, 232 mm SL, 11 km northeast of Port Stephens Lighthouse, New South Wales.

Figure 8. Three species of Ratabulus: a, R. diversidens, off Newcastle, New South Wales (33°08'S, 151°56'E), 125–130 m, 7 September 1978, specimen discarded, scale bar = 5 cm, photo by K. Graham; b, R. megacephalus, HUMZ 199844, 264 mm SL, East China Sea (26°35.68'N, 125°04.57'E – 26°36.73'N, 125°05.78'E), 192–186 m, 5 May 2007, photo by Hokkaido University; c, R. fulviguttatus sp. nov., upper specimen CSIRO H1505-15, 189 mm SL, lower specimen H1505-06, 219 mm SL, north of Nickol Bay, Western Australia (19°07'S, 117°06'E – 19°07'S, 117°04'E), 177–184 m depth, 5 October 1988, FRV Soela, photo by CSIRO.