FAO Species Identification Guide for Fishery Purposes Western

1114 Crabs
Goneplacidae GONEPLACIDAE
Rhomboid crabs
Diagnostic characters: Carapace hexagonal,
transversely rectangular, trapezoidal, or
transversely ovate; dorsal surface convex, usually
smooth; frontal margin usually entire, sometimes
multilobate; anterolateral margin usually armed with
1 to 4 teeth or lobes, or entire. Male abdominal
segments 3 to 5 distinct, movable or fused and
immovable. Male first gonopod moderately stout,
gently curved or sinuous; male second gonopod
relatively short to elongate, but usually shorter
than male first gonopod.
Habitat, biology, and fisheries: Benthic crabs with
diverse habits. Most species in this family are of little
or no commercial value. The relatively common and
large Carcinoplax longimanus has a minor importance
to fisheries in the Western Central Pacific.
Similar families occurring in the area
The Goneplacidae is doubtless a very heterogeneous group.Obviously, the genera included here were assigned
to this family due to lacking evidence to place them into any others of the known families. Although the angular
carapace of most goneplacids readily separates them from species of other families, a clear definition of the
Goneplacidae is not known. Accordingly, any comparisons with outside taxa are very difficult and must be done
on a genus by genus basis. Carcinoplax, the only genus in the area that includes an edible species, resembles
in general body shape some species of Xanthidae, Eriphiidae, and Carpiliidae.
Xanthidae, Eriphiidae, and Carpiliidae: compared to species of these families, in Carcinoplax, the carapace
is clearly more ovate in shape and the adult male chelipeds are extremely elongated. In addition, the male
second gonopods of Carcinoplax are intermediate in relative length between xanthids (very short, as in
pilumnids) and eriphiids (very long).
References
Guinot, D. 1989. Le genre Carcinoplax H. Milne Edwards, 1852 (Crustacea: Decapoda: Goneplacidae). In Résultats des
Campagnes MUSORSTOM, 4, edited by J. Forest. Mém. Mus. natn. Hist. nat., 144:265-345.
Tesch, J.J. 1918. The Decapoda Brachyura of the Siboga Expedition. II. Goneplacidae and Pinnotheridae. Siboga Exped.
Monogr., 39c(1):149-295.
A single species of interest to fisheries occurring in the area.
Carcinoplax longimanus (De Haan, 1833)
Frequent synonyms / misidentifications: Carcinoplax longimanus
japonicus Doflein, 1904; Carcinoplax longimanus typicus
Doflein, 1904 / None.
FAO name: En - Long-armed crab.
Diagnostic characters: Carapace ovoid; dorsal surface convex
and smooth; lateral margin with 3 strong teeth in juveniles,
becoming small to almost indiscernible in adults. Male chelipeds
very elongate. Colour: red to pink overall.
Size: Maximum carapace width 8 cm.
Habitat, biology, and fisheries: On muddy substrates, most
commonly found in deeper waters from depths of 100 to
800 m. Fished mainly in southern Japan and southern
China. Taken incidentally in major fishery operations,
mainly by bottom trawls and often in large numbers. Only
larger specimens are sold, but have a low value in most
markets.
Distribution: Japan, Taiwan Province of China, China,
Philippines, and Thailand.
male chelipeds
elongate
carapace usually angular
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