Chaceon albus, Davie & Ng & Dawson, 2007

Davie, Peter J. F., Ng, Peter K. L. & Dawson, Elliot W., 2007, A new species of deep-sea crab of the genus Chaceon Manning & Holthuis, 1989 (Crustacea: Decapoda: Brachyura: Geryonidae) from Western Australia, Zootaxa 1505 (1), pp. 51-62 : 52-54

publication ID	https://doi.org/ 10.11646/zootaxa.1505.1.4
publication LSID	lsid:zoobank.org:pub:18DEBC4F-FFAF-4A68-B8BC-1952E043BBB2
persistent identifier	https://treatment.plazi.org/id/03C95058-C361-9A5D-5D85-FCFA7DA4D965
treatment provided by	Felipe
scientific name	Chaceon albus
status	sp. nov.

Treatment

Chaceon albus View in CoL sp. nov.

( Figs 1A View FIGURE 1 ; 2A View FIGURE 2 ; 3 View FIGURE 3 ; 4A View FIGURE 4 ; 5A, C, E View FIGURE 5 ; 6A, C View FIGURE 6 ; 7A View FIGURE 7 )

Chaceon bicolour — Wadley & Evans, 1991: 40, 2 figs; Jones & Morgan, 1994: 163, 164, colour fig.; Ng, 1998: 1134 (part); Davie, 2002: 187–188; Poore, 2004: 406 (part). (not Chaceon bicolor Manning & Holthuis, 1989 View in CoL )

Chaceon sp. — Jones & Morgan, 2002: 164, colour fig.

Material examined. Holotype: WAM C38286 (ex ZRC 1998.849 View Materials ), male (171.9 x 154.7 mm), off Albany, Western Australia , coll. from fishing boats by S. H. Tan & S. K. Koh, 1 October 1998 . Paratypes: ZRC 1998.849 View Materials , 1 male (131.8 x 115.0 mm), 1 female (141.8 x 123.2 mm), same data as holotype. MNZ-CR 011194, 2 males (145.9 x 126.5, 92.5 x 77.4 mm), 1 female (142.3 x 121.6 mm), Western Australia without specific locality, 2002 . ZRC 2000.2366 View Materials , 2 males (166.1 x 147.2, 183.1 x 160.8 mm), Western Australia , purchased in Singapore market from direct importer, 15 April 2000 . QM / ZRC 2000.2365 View Materials , 4 males (170.0 x 155.0, 161.0 x 141.0, 162.0 x 145.0, 160.0 x 147.0 mm), Western Australia , purchased in Singapore market from direct importer, December 1999 . ZRC 2002.0014 View Materials , 3 males (131.3 x 116.0, 182.0 x 165.0, 136.5 x 121.0 mm), Western Australia , purchased in Singapore market from direct importer, 23 January 2002 . ZRC 2004.0744 View Materials , 1 female (dried, 137.0 x 119.0 mm), Western Australia , purchased in Singapore market from direct importer, 23 January 2002 . QM-W28174, 1 male (130.9 x 112.7 mm), Western Australia , donated by exporter, J. Gleeson (Jobfish), 1998 .

Description. — Large-size species, exceeding 180 mm cw in adults; carapace 1.1–1.2 wider than long in adults. Median pair of frontal teeth prominent, narrower than laterals in males, but wider at least in females less than about 140 mm cw; extending further anteriorly than laterals, separated by U-shaped emargination. Second and fourth anterolateral teeth reduced, second tooth usually distinctly pointed in females, fourth tooth typically obsolete in both sexes, but may be slightly pointed in younger specimens. Distance from first to second anterolateral teeth less than that from third to fourth teeth, distance from first to third teeth subequal to that from third to fifth teeth. Dorsal surface of carapace distinctly granulated and, striated mesial to fifth tooth, and on protogastric, cardiac, and branchial regions; hepatic region moderately granular; protogastric region moderately inflated in larger specimens. Suborbital tooth prominent, sharply pointed, slightly sharper in females and smaller males, clearly visible in dorsal view, suborbital margin evenly curved, finely tuberculate.

Outer surfaces of chelipeds rough, finely tuberculate dorsally; upper margin of merus with short but sharp subdistal spine; inner margin of carpus with long anteriorly pointed spine; lateral surface rough, lacking outer spines in adults; propodus unarmed distally.

Meri of walking legs with anterior margin prominently and evenly convex; posterior walking legs with distinct distal dorsal projection, most obvious on P4 and P5. Dactyli of walking legs laterally compressed, height at mid-length greater than width. P5: merus 4.4 times longer than high in single young female measured, 4.1–4.5 times longer than high in males (no juveniles examined); merus length 0.6 times cw in female, 0.6–0.7 times carapace breadth in males; carpus armed with small spinules dorsally; propodus distinctly longer than dactylus, 5.2 times longer than high in female, 4.5–4.8 in males. P4 relatively more robust, more convex anteriorly than P5: merus 3.9 times longer than high in single young female, 3.7–4.2 times longer than high in males; total length of P4 measured from base of merus, 1.7 times cw in female, 1.9–2.0 in males.

Adult male abdomen with penultimate segment about 2.5 times wider than long; telson elongated, apically rounded, 1.4–1.5 times wider at base than long; telson about 1.6 times longer than penultimate segment. Male G1 curved outwards, distal part tapering ( Fig. 6C View FIGURE 6 ).

Colour. Generally pale, with carapace variably fawn-coloured to beige across anterior half, and extending posteriorly over the cardiac and intestinal regions. Occasionally golden yellow to almost white. An off-cream band often extending across the frontal region and behind the orbits. Posterior branchial regions, walking legs and claws predominantly off-cream. In larger specimens, the gastric regions and other median parts may be brownish-orange to orange.

Distribution. Western Australia from about North West Cape (21°47'S) to Esperance (33°52' S) (R. Melville-Smith, pers. comm.). Bathymetric range: 200–2000 m ( Jones & Morgan, 1994).

Etymology. From albus, Latin for white, in reference to the characteristic pale colour of the crab, commonly referred to in Western Australia as the ‘Snow Crab’ or more recently ‘Crystal Crab’.

Comparative material examined: Chaceon bicolor Manning & Holthuis, 1989 : USNM 205976 View Materials , 1 paratype male, Passe GoogleMaps de Saint Vincent, New Caledonia, 22º02'S, 165º57'E, 800m, in traps, coll. B. Richer de Forges, 1985. USNM 205978 View Materials , 1 paratype male, southeast of Newcastle, New South Wales, Australia, 33º11- 09'E, 152º24–25'E, 732m, coll. D. Brown, F. R.V. Kapala , station K77–23–10, 7 December 1977. USNM 205977 View Materials , 1 paratype male, 1 paratype female, east of Broken Bay , New South Wales, Australia, 33º35–33'S, 152º00–02'E, 823m, coll. D. Brown, F. R. V. Kapala , station K77–23–12, 8 December 1977 . ZRC 2000.2380 View Materials , 1 male (152.0 x 136.0 mm), 1 female (141.0 x 124.0 mm), station K77–2313, east of Terrigal , ca. 33°27–25’S, 152°09-11’E, 482–500 fathoms, New South Wales, Australia, coll. New South Wales State Fisheries Department, D. Brown, F. R. V. Kapala , 12 August 1977 . Chaceon imperialis Manning, 1992 : USNM 205974 View Materials , 3 paratype females, Kinmei Seamount , Emperor Seamount Chain, 35º17.50'N, 171º25.98'E, 150 fathoms, coll. Townsend Cromwell, cruise 82-05, station 57, 11 November 1982 GoogleMaps .