Diceratus, 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 : 503

Diceratus gen. nov.

Diagnosis. Body form as in Doroixys . Dorsal cephalic shield bearing 2 pairs of horn-like processes posterolaterally. Freeurosome 5-segmented. Rostrum well-developed. Antennule 7- or 8-segmented. Antenna 3-segmented, consistingof coxa, basis, and unsegmented endopod bearing terminal claw. Mandible with enlarged distaltoothand 1 or 2 subsidiaryteethoncoxal gnathobase; basiswith 1 setaonmedial margin; exopodwith 5 setae; endopod with 1 and 7 setaeon first and second segments, respectively. Maxillulewith 5 or 6 setaeon arthrite, 1 on epipodite, 2 on basis, 4 onexopodand 3 on endopod; coxal endite absent. Maxilla 4-segmented, armedwith 3, 2, and 2 setae on first to third syncoxal endites, respectively, strong claw plus 2 setae on basis, and with1 and 3 setae on first and second endopodal segments, respectively. Maxilliped unsegmented with 2 setae. Legs 1–4 biramous. Inner coxal seta absent in legs 1–4. Leg 1 with inner distal setaon basis; endopod 2- or 3-segmented; exopodwith 2, 2, and 7 armature elements on first to third segments, respectively. Legs 2–4 with 3-segmented rami; first and second segments of exopods and endopods lacking inner setae. Leg 5 consisting of digitiform outer protopodal process tipped with 1 seta, and claw-like inner exopodal process bearing 1 setaon outer margin.

Etymology. The generic name is derived from the Greek di (=double) and cerat (=horn), referring to the presence of the double posterolateral processes on the dorsalcephalic shield.

Type species. Diceratus unidentatus gen. et sp. nov. by original designation.

Other included species. Diceratus bispinosus (Ooishi, 1998) comb. nov. (originally described as Doroixys bispinosa Ooishi, 1998 )

Remarks. Ooishi (1998) originally placed Diceratus bispinosa (Ooishi, 1998) comb. nov. in the genus Doroixys . Detailed comparison of this species with the newly discovered Diceratus unidentatus gen. et sp. nov. revealsthatthey sharenumerousdistinctivefeatureswhich justify their placement in an independent new genus. The shared features of these two species include the presence of twopairs of cephalic processes, the enlargeddistal tooth on the coxal gnathobase of the mandible, the presence of 2 setae on the basis of the maxillule, and the presence of only 2 setae on the maxilliped.