Chamicola, Ohtsuka & Boxshall & Torigoe, 2000

Ohtsuka, Susumu, Boxshall, Geoffrey A. & Torigoe, Kenji, 2000, A new genus and species of the family Mantridae (Copepoda: Cyclopoida) infesting the bivalve Pseudochama retroversa from the Seto Inland Sea, western Japan, Journal of Natural History 34 (10), pp. 1967-1976 : 1969-1970

Chamicola new genus

Diagnosis. First pedigerous somite separate from cephalosome. Rostrum de®ned at base. Antenna with basis and endopod separate; endopod two-segmented, ®rst segment with single vestigial seta, second segment bearing robust claw, two strong curved spiniform setae, two long and two short setae terminally. Labrum with pair of pointed processes laterally. Maxillule with two setae on coxal epipodite and ®ve setae on distal basal endite. Maxilliped bearing 1, 2, 2 setae on syncoxal endites, and six setae on endopod. Legs 1±4 each with outer seta on basis. Leg 5 with outer seta on basis. Female leg 6 represented by one spine and one seta. Male leg 6 with two setae. Caudal rami with long terminal setae.

Host. Pseudochama retroversa .

Type species. Chamicola nagasawai n. sp. (by monotypy).

Remarks. The new genus is readily distinguishable from Mantra and Nearchinotodelphys as follows: (1) the rostrum separated at base; (2) the endopod of antenna distinctly two-segmented, the second to fourth ancestral endopodal segments being completely fused; (3) the antenna with one vestigial seta on the ®rst endopodal segment; (4) the labrum with a pair of large processes laterally; (5) the maxillule with ®ve setae on the distal basal endite; (6) the maxilliped syncoxa bearing 1, 2, 2 setae on the ®rst to the third endites, respectively; (7) the male leg 6 with only two setae.

The new genus also exhibits a mixture of features of both other genera: (1) the cephalosome is separate from the ®rst pedigerous somite (as in Mantra ); (2) the antenna has the basis and endopod separated (as in Nearchinotodelphys ); (3) the antenna bears three terminal claws (as in Mantra ); (4) the mandible carries four setae on the ®rst endopodal segment in the female (as in Nearchinotodelphys ); (5) the maxillule has two setae on the coxal epipodite (as in Mantra ); (6) the maxilliped bears six setae on the endopod (as in Nearchinotodelphys ); (7) legs 1±4 each have an outer seta on the basis (as in Nearchinotodelphys ); (8) the proximal segment of leg 5 has a single outer seta (as in Nearchinotodelphys ); (9) the caudal rami carries long terminal setae (as in Mantra ). DiOEerences between the armature of the antennules of all three genera are summarized in table 1. However, since the antennules of both sexes of Nearchinotodelphys were more or less inadequately described, this is only a tentative comparison and is not robust enough to permit a

ae 5 aesthetasc; p 5 process. cladistic analysis. DiOEerences are found in the 2nd (III±V), 5th (XI), 8th (XVIII), 9th (XIX), 12th (XXII±XXIII), 13th (XXIV), 14th (XXV) and 15th segments (XXVI±XXVIII) of the female, and in all segments except for the 3rd (VI±IX), 4th (X) and 9th to 11th (XV±XIX) in the male.

Both Mantra speciosa and the new genus infest the same bivalve family, the Chamidae , whereas Nearchinotodelphys indicus parasitizes a rock-boring species of the Mytilidae ( Ummerkutty, 1960) .

Etymology. The new generic name is derived from the host bivalve Chama , and the Latin colo, meaning to inhabit. Gender feminine.