Orectolobus

Charlie Huveneers, 2006, Redescription of two species of wobbegongs (Chondrichthyes: Orectolobidae) with elevation of Orectolobus halei Whitley 1940 to species level., Zootaxa 1284, pp. 29-51 : 48-50

[[ Genus Orectolobus ]]

Discussion

The very poor description of O. halei (Whitley, 1940) makes it impossible to quantitatively compare diagnostic features between the neotype herein designated and the previous description. The neotype was therefore assigned from the differing characters in “the color pattern and the form of the tentacles” as highlighted by Whitley (1940).

The aim of this paper was to define and redescribe O. halei and O. ornatus to facilitate species identification. Unfortunately, juvenile O. halei (smaller than 1100 mm) were not collected despite intensive searching over two years. The ranges of sizes of O. ornatus and O. halei examined did not overlap and thus differences in morphometry should be interpreted with caution due to allometric factors. Juvenile O. halei (smaller than 900 mm) are needed to confirm morphometric differences identified in this study.

The two species can, however, be differentiated using counts of precaudal vertebrae (greater than 105 in O. halei and less than 105 in O. ornatus ) and/or spiral valves (greater than 26 in O. halei and less than 26 in O. ornatus ). However, these characters are impractical for application in the field. Therefore, simpler but equally robust methods are needed to differentiate species under field conditions.

Total length is the simplest field character for differentiating NSW species. Any wobbegong exceeding 110 cm is either O. halei or O. maculatus (but not O. ornatus ) and these two can be easily differentiated using color pattern and dermal lobes. Wobbegongs smaller than 110 cm are harder to identify. In the case of small males, if the claspers are calcified, the species is O. ornatus . For immature males or females, other traits have to be used. Color pattern may help identification with O. ornatus , which is freckled and green/ gray (browner in O. halei ), and lacks black edges along its saddle markings (otherwise present). However, coloration is highly variable in these species and O. ornatus specimens have been observed with an halei-like color pattern. Care must therefore be taken when using coloration alone to identify Orectolobus species.

Three further key features to differentiate between the two species are the number of dermal lobes at the posterior preorbital group, the position of the pelvic fins, and the supraorbital knobs. Orectolobus ornatus usually has only three lobes at the posterior preorbital group, consisting of two branched lobes at the extremities and a shorter unbranched lobe in the middle (more lobes are present in O. halei ). However, both O. ornatus and O. halei have been observed with four lobes. Pelvic fins are located further back on O. halei with the pelvic-fin insertion at the level of the first dorsal midpoint ( O. ornatus has the pelvic-fin insertion anterior to the first dorsal midpoint). Lastly, O. halei has two small knobs on the supraorbit (absent in O. ornatus ).

By preference, these features should always be used together to maximize correct identification of Orectolobus species in NSW. Commercial fishers using these features should be able to identify Orectolobus species and report them accordingly. In the past, all species have been combined together as ‘carpet shark’. Commencing in 2005, NSW DPI has required fishers to report O. maculatus separately. Using the characteristics described above, fishers should now be able to report catches of O. maculatus , O. ornatus and O. halei separately. Catch rate statistics could then be used to assess each species independently to investigate potential population decline.

Key to Orectolobus species in New South Wales

1. About 6 to 10 dermal lobes at the posterior preorbital group; white O-shaped spots and white blotches............................................................................. Orectolobus maculatus

- About 3 to 6 dermal lobes at the posterior preorbital group; back with dark color variegated with blotches and prominent saddle markings....................................................2

2. Spiral valve whorl count 20-23; precaudal vertebrae count 98-104; size-at-maturity about 800 mm; about 3 to 4 dermal lobes at the posterior preorbital group; no supraocular knobs; pelvic-fin insertion slightly anterior to the first dorsal midpoint ................ ........................................................................................................ Orectolobus ornatus

- Spiral valve whorl count 29-32; precaudal vertebrae count 106-112; size-at-maturity about 1750 mm; about 4 to 6 dermal lobes at the posterior preorbital group; two distinct supraocular knobs; pelvic-fin insertion at about the level of the first dorsal midpoint .................................................................................................... Orectolobus halei