Chaceon, MANNING & HOLTHUIS, 1989

Martin, Joel W. & Haney, Todd A., 2005, Decapod crustaceans from hydrothermal vents and cold seeps: a review through 2005, Zoological Journal of the Linnean Society 145 (4), pp. 445-522 : 493-494

GENUS CHACEON MANNING & HOLTHUIS, 1989 CHACEON AFFINIS (MILNE- EDWARDS &

BOUVIER, 1894)

Type locality: Atlantic Ocean, Azores, east of Corvo ; 844 m (from Manning & Holthuis, 1981: 111) .

Known range: North-eastern Atlantic Ocean, from Iceland to Cape Verde, including the Azores, Madeira, Canary Islands and Cape Verde Islands, at depths of 130–2047 m ( Manning & Holthuis, 1981 [as Geryon affinis ], 1989).

Occurrence at vents or seeps: restricted to the Menez Gwen site of the MAR ( Biscoito, 1997, in Desbruyères & Segonzac, 1997; Colaço et al., 1998; Desbruyères et al., 2000; Colaço, Dehairs & Desbruyères, 2002).

Material: M. Segonzac (pers. comm.) informs us that some specimens were collected but were eaten on board; Colaço et al. (2002) mentioned three specimens.

Remarks: Biscoito (1997, in Desbruyeres & Segonzac, 1997) noted that this species usually occurs on hard and soft substrates of the upper continental slope (see also Pinho et al., 2001). At Menez Gwen, ‘several specimens were observed over pillow lavas, near active vent sites. At least one specimen was observed eating dead mussels.’ Perhaps for this reason Biscoito described the species as necrophagous. Desbruyères et al. (2000: table 4) listed the species as rare/patchy at Menez Gwen. Biscoito & Saldanha (2000) observed the species ‘on the fringe of a hydrothermal vent site’, though M. Segonzac (pers. comm.) reports that specimens were seen among mussels. Colaço et al. (1998) also noted this species at the periphery of the Menez Gwen site. Weinberg et al. (2003) examined genetics of several species of Chaceon , including C. affinis . P. Chevaldonné (pers. comm.) informs us that MacAvoy et al.’s (2002) report of Chaceon quinquedens may refer instead to a species of Geryon (see below); the crab in question was reported as a vagrant but had a depleted δ 13 C value, more indicative of primary feeding at seeps.