Freespine Flathead, Ratabulus diversidens (McCulloch 1914)
A Freespine Flathead, Ratabulus diversidens, from off Newcastle, New South Wales (33°08'S, 151°56'E), 125–130 m, 7 September 1978 (scale bar = 5 cm). Source: Ken J. Graham / NSW Fisheries. License: All rights reserved
A large flathead with 4–6 narrow black longitudinal stripes on the outer part of the tail (the lower stripes merging to form an elongate blotch in some specimens), and small brown spots on the upper part of the tail. Large, irregular, pale to dark-brown spots cover the top of the head, and the pelvic fin has large brown spots.
The Freespine Flathead has a small free spine between the two dorsal fins, slender canine teeth on the upper jaw, numerous spines on the suborbital ridge, and the iris lappet is broad and simple.
Freespine Flathead, Ratabulus diversidens (McCulloch 1914)
More Info
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Distribution |
Endemic to tropical and temperate waters of eastern Australia, from off Townsville, Queensland, to Lakes Entrance, Victoria, at depths to about 345 m. |
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Features |
Dorsal fin IX,I or I,VIII,I, 11; Anal fin 11 or 12 (usually 12); Pectoral fin 18-20 (usually 19 or 20); Pelvic fin I, 5; Lateral line scales (pored) 52-55 (usually 53 or 54); Gill rakers on first arch 7-9 (usually 7 or 8). Body elongate, slightly depressed. Head elongate (length ~41-42 % SL), moderately depressed, strong stria over temporal and upper preopercular region; supraorbital ridge smooth anteriorly, serrated posteriorly; eyes large (~20% HL), no ocular flap; suborbital ridge with numerous spines and serrations, largest 2 below eye; preocular and preorbital spine present; teeth in jaws and on palate long, needle-like, some depressible, vomerine teeth in 2 parallel longitudinal bands; two or three preopercular spines, upper longest, with basal accessory spine, third spine rarely present, minute; interopercular flap absent. Scales small, finely ctenoid dorsally, cycloid ventrally, covering body and most of head behind eyes; Diagonal scale rows slanting backward above lateral line 64 to 79. Lateral-line scales 52 to 55 (usually 53 or 54), anterior 2 to 8 scales bearing a small spine. First dorsal fin spinous with short base, short first spine variably present, detached, last spine very small, detached from preceding spine. Second dorsal fin with moderately long base, anterior rays longest, nearly as long as longest first dorsal spines. Anal fin similar in shape, opposite and slightly longer-based than second dorsal fin. Caudal fin truncate to slightly rounded. Pectoral fins moderate in size. Pelvic fins long, based below centre of pectoral fins, reaching past anal fin insertion. |
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Size |
To about 39 cm TL. |
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Feeding |
Feeds on fishes and crustaceans. |
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Fisheries |
May be taken as by-catch in commercial trawls. |
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Remarks |
Records from northwestern Australia represent Ratabulus fulviguttatus Imamura & Gomon 2010. |
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Etymology |
The specific name diversidens is from the Latin diversus (= different, diverse) and dens (= teeth), in reference to the teeth being larger than usual in the genus Insidiator. |
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Species Citation |
Insidiator diversidens McCulloch, 1914, Biol. Results "Endeavour" 2(3): 148, Fig. 13; Pl. 31 (fig. 1). Type locality: from seven miles S.21°W. of Port Stephens Lighthouse, New South Wales, in 48 fathoms. |
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Author |
Australian National Fish Collection, CSIRO & Bray, D.J. 2024 |
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Resources |
Freespine Flathead, Ratabulus diversidens (McCulloch 1914)
References
Barnes, L.M., Gray, C.A. & Williamson, J.E. 2011. Divergence of the growth characteristics and longevity of coexisting Platycephalidae (Pisces). Marine and Freshwater Research 62: 1308-1317. https://doi.org/10.1071/MF11045
Barnes, L.M., Gray, C.A. & Williamson, J.E. 2021. Reproductive characteristics of Ratabulus diversidens and Ambiserrula jugosa (Pisces: Platycephalidae) from continental shelf waters of south-eastern Australia. Journal of the Marine Biological Association of the United Kingdom 101(4): 725-734 https://doi.org/10.1017/S0025315421000540
Imamura, H. & M.F. Gomon. 2010. Taxonomic revision of the genus Ratabulus (Teleostei: Platycephalidae), with descriptions of two new species from Australia. Memoirs of Museum Victoria 67: 19-33. http://doi.org/10.24199/j.mmv.2010.67.03
McCulloch, A. R. 1914. Report on some fishes obtained by the F. I. S. "Endeavour" on the coasts of Queensland, New South Wales, Victoria, Tasmania, South and South-western Australia. Part II. Biological Results Endeavour 2(3): 77-165, Pls. 13-34. See ref at BHL
