Chelipygus, Kim & Boxshall, 2020

Kim, Il-Hoi & Boxshall, Geoff A., 2020, Untold diversity: the astonishing species richness of the Notodelphyidae (Copepoda: Cyclopoida), a family of symbiotic copepods associated with ascidians (Tunicata), Megataxa 4 (1), pp. 1-6 : 400-403

Chelipygus gen. nov.

Diagnosis. Body of female consisting of swollen prosome and narrow, cylindrical urosome. Cephalosomewelldefinedbydorsalcephalic shield.Metasome unsegmented, strongly inflated, forming brood pouch incorporatingfifth pedigeroussomite. Freeurosome 5-segmented. Caudal ramus armed with 4 spines + 2 setae, or 3 spines + 3 setae. Rostrum present. Antennule 8- to 10-segmented. Antenna uniramous and 4-segmented, composed of coxa, basis and 2-segmented endopod. Mandible as in Doropygus ; exopod with 5 setae (distalmost seta may be vestigial); endopod with 4 setae on first segment and 8 or 9 setae on second. Maxillule armedwith 3 setae on basis, 4 setae on exopod and 2 on endopod. Maxilla lacking claw on basis; endopod 3-segmented with 3 or 4 setae on terminal segment. Maxilliped indistinctly 2-segmented, armed with 9 setae on first segment and 2 setae on second. Leg 1 with 3-segmented rami; basis with inner distal spine. Legs 2–4 each with 3-segmented exopod and 2- or 3-segmented endopod. Third exopodal segment of leg 4 armed with only 8 armature elements. Leg 5 consistingof protopod and free exopodal segment bearing 2 distal elements.

Etymology. The name of the new genus is from the Greek chel (=claw) and pygus, the ending of many taxa within the family Notodelphyidae . It refers to the presence of the spines on the caudal ramus. Gender masculine.

Type species. Chelipygus bulbosus gen. et sp. nov., by original designation.

Other included species. Chelipygus dinardensis gen. etsp. nov. and C. catalai ( Illg, 1970) comb. nov. (originally Doropygus catalai Illg, 1970 ).

Remarks. Chelipygus gen. nov. is superficially similarto Bonnierilla inhavingthebroodpouchof theadult female consisting of the entire unsegmented metasome (comprising pedigeroussomites 1 to 4). However, it differs from Bonnierilla because it is characterised by the endopod of the maxilluleusually being armed with 4 setae, the 2-segmented condition of the maxilliped which has an elongate second segment, legs 1 and 2 usually lack the inner coxal seta, the elongate exopods of the swimming legs, and the enlarged outer seta on the basis of leg 1.

Chelipygus gen. nov. is similarto Notopygus gen. nov. in having an inflated prosome and spines on the caudal rami, but can be separated from the latter genus by the possession of 5 setae (or 4 setae plus a vestigial seta) on the mandibular exopod, less than 10 setae on the mandibular endopod, 4 and 2 setae on the exopod and endopod, respectively, of themaxillule (instead of 3 setae on both rami as in Notopygus gen. nov.), no differentiated claw on the basis of the maxilla, and a total of 8 armature elements on the third exopodal segment of leg 4 (instead of 9 elements as in Notopygus gen. nov.).

Doropygus catalai Illg, 1970 wasoriginallydescribed as an associate of Ascidia sydneiensis samea (Oka, 1935) sampled in New Caledonia ( Illg, 1970). Kim (2012) rediscovered this species in Korea and observed that its caudal rami carry 3 spines and 3 setae, and it shares the other character states of Chelipygus gen. nov., as listed in the generic diagnosis. It is here transferred to the new genus as Chelipygus catalai ( Illg, 1970) comb. nov.