Family GERYONIDAE Colosi, 1923

Chaceon bicolor [P. Davie 2002: 187]

Museums

Regional Maps

• Geryonidae Colosi, G. 1923. Una specie fossile di Gerionide (Decapodi brachiuri). Bolettino della Societá dei Naturalisti in Napoli 2 15: 248-255 figs 1-5 [249].

Introduction

Geryonids are mostly large deep-sea crabs found in depths below 100 metres. They occur in all oceans. The first Australian species, Chaceon bicolor, was described only in 1989, following the increasing exploration of deep water faunas around Australia. Because of its large size, C. bicolor is of potential economic interest, although it is still only taken occasionally by bottom trawls. Chaceon bicolor seems to be restricted to the Coral Sea; specimens being fished under that name from north-western Australia, and marketed as 'Snow Crabs', were described as a new species, Chaceon albus by Davie, Ng & Yaldwyn, 2007). The most useful taxonomic work is that of Manning & Holthuis (1989).

Platypilumnus, with the single Australian representative, P. soelae Garth, 1997, has typically been included in the Geryonidae, but its systematic position has been debated in recent years (see Richer de Forges 1996; Ng & Chan 1997). It was formally moved into the Carcinoplacinae of the Goneplacidae by Ng et al. (2001), an action with which I concur.

Diagnosis

Carapace hexagonal; dorsal surface smooth to granular; anterolateral margins convex, armed with three to five low, sometimes indistinct teeth. Chelipeds unequal; merus with subdistal spine; carpus with strong inner spine. Walking legs with long, pointed dactyli; dactyli T-shaped in cross-section. Male abdomen with all segments appearing distinct, but segments 3–5 fused and immovable. Male genital openings coxal; female openings sternal. (After Ng 1998).

General References

Davie, P.J. F., Ng, P. K. L. & Dawson, E. 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: 51-62

Garth, J.S. 1987. Platypilumnus soelae, a new species of goneplacid crab from the North West Shelf of Australia (Crustacea: Decapoda: Brachyura). The Beagle. Occasional Papers of the Northern Territory Museum of Arts and Sciences 4(1): 35-38

Manning, R.B. & Holthuis, L.B. 1989. Two new genera and nine new species of geryonid crabs (Crustacea, Decapoda, Geryonidae). Proceedings of the Biological Society of Washington 102(1): 50-77

Ng, P.K.L. 1998. Crabs. pp. 1045-1155 in Carpenter, K.E. & Niem, V.H. (eds). The Living Marine Resources of the Western Central Pacific. FAO Species Identification Guide for Fisheries Purposes. Rome : FAO Vol. 2 687-1396 pp.

Ng, P.K.L., Wang, C-H., Ho, P-H. & Shih, H-T. 2001. An annotated checklist of brachyuran crabs from Taiwan (Crustacea: Decapoda). National Taiwan Museum Special Publication Series, Taipei, Taiwan No. 11: 1-86, 8 colour pls

Ng, P.K.L. & Chan, T.-Y. 1997. Two newly recorded crab genera (Crustacea: Decapoda: Brachyura) from Taiwan: Platypilumnus (Goneplacidae) and Trachycarcinus (Atelecylidae). Journal of the Taiwan Museum 50(2): 107-112

Richer de Forges, B. 1996. The genus Platypilumnus Alcock and description of P. jamiesoni n. sp. from New Caledonia (Crustacea, Decapoda, Brachyura). Records of the Australian Museum 48(1): 1-6

History of changes