Periboia, Kim & Boxshall, 2021

Kim, Il-Hoi & Boxshall, Geoff A., 2021, Copepods (Cyclopoida) associated with ascidian hosts: Ascidicolidae, Buproridae, Botryllophilidae, and Enteropsidae, with descriptions of 84 new species, Zootaxa 1, pp. 1-286 : 265

Periboia gen. nov.

Diagnosis. Female. Body vermiform, divisible into prosome consisting of cephalosome and first to fourth pedigerous somites, and urosome comprising fifth pedigerous somite, genital double-somite and unsegmented abdomen. Caudal rami elongate, unarmed. Antennule 2-segmented, armed with few seta. Antenna digitiform, 3-segmented, unarmed. Labrum rudimentary, unarmed and unornamented. Mandible forming powerful claw. Maxillule unsegmented, unequally bilobed, with 2 apical setae on inner lobe and 1 seta on small outer lobe. Maxilla bilobate, with unarmed proximal part; inner lobe (endite of syncoxa) tipped with 1 seta; outer lobe armed with 1 seta on lateral margin and 2 spines distally. Maxilliped absent. Legs 1-4 each consisting of tapering, unsegmented process formed by fusion of protopod and endopod, plus small, lamellate, free exopod. Exopods tipped with small claw, but fused protopod and endopod unarmed. Leg 5 small, lamellate, unarmed.

Type species. merẚbçẚa tahẚtẚensẚs gen. et sp. nov. by original designation.

Etymology. In Greek mythology, merẚbçẚa was a princess of the giants, daughter of the giant king Porphyrion. Gender feminine.

Remarks. merẚbçẚa gen. nov. is undoubtedly closely related to Mçnnẚçtẚcçpa gen. nov. In both genera, the mandible forms a powerful claw, the antenna is digitiform and distinctly segmented, and the maxillule is bilobed. However, several significant features prevent its type species from being accommodated within Mçnnẚçtẚcçpa gen. nov. The most significant diagnostic feature of the new genus is found in the swimming legs, which consist of a small, free exopod and an elongate, unsegmented protopod-endopod complex. Within the Enteropsidae , a similar form of swimming legs is present in iequerrea canuẚ Illg & Dudley, 1980 (Illg & Dudley, 1980), but the genus iequerrea can be clearly differentiated from merẚbçẚa gen. nov. by the lack of antennae and by the structure of the mouthparts.

The body of female merẚbçẚa gen. nov. is clearly divisible into prosome and urosome, and this can be considered as a diagnostic feature of the genus, because the prosome-urosome division is obscured by fusion of the fourth and fifth pedigerous somites in all known species of Enteropsidae . The caudal rami are also distinctive in merẚbçẚa gen. nov.; they are elongate and unarmed, which differs from the broad caudal ramus, uniformly armed with 1 major and several vestigial setae in known species of Mçnnẚçtẚcçpa gen. nov.