Chelonocytherois, Tanaka & Hayashi, 2019

Tanaka, Hayato & Hayashi, Ryota, 2019, Chelonocytherois omutai gen. et sp. nov. (Crustacea: Ostracoda) from the back of loggerhead sea turtles, Zootaxa 4624 (4), pp. 507-522 : 510

Genus Chelonocytherois gen. nov.

http://zoobank.org/03eec7bf-edc6-4813-91ac-7f7a20d69e3e

Type species. Chelonocytherois omutai sp. nov., here designated.

Diagnosis. Carapace of male larger than female. Carapace surface with numerous shallow horizontal striations. Pore system consisting of large sieve pores. Antennal exopodite (spinneret seta) long and four-segmented. Sixth podomere of antenna consisting of one short simple postero-medial seta, one stout comb-like seta, and one large stout distal claw with sharpened tip and several spines on posterior margin. Fifth to seventh limb bearing one stout sclerotized distal hook with several spines on ventral margin. Male copulatory organ asymmetric; copulatory duct existing only in left hemipenis. Female genital opening unpaired (left one absent).

Etymology. The generic name is a combination of the Greek word “ chelone ” (turtle) referring to the association of the species to the loggerhead sea turtle, and the subfamily name Cytheroisinae.

Remarks. The carapace morphology of Chelonocytherois gen. nov. is the most similar to that of Redekea de Vos, 1953 , which belongs to the subfamily Cytheroisinae Schornikov, 1993. Both genera have a system of quite large sieve pores, which are absent in all other genera of Paradoxostomatidae , even in Podocopida . The new genus can easily be distinguished from Redekea by the morphology of the soft parts. The palp of the mandibula in the genus Redekea has reduced a chaetotaxy and possesses a strong terminal claw in male specimens; in contrast, the palp of Chelonocytherois gen. nov. is developed normally, similar to that of other representatives of the Cytheroisinae but without a claw. The maxillular morphology shows several differences between Chelonocytherois gen. nov. and Redekea : 14 setae on the branchial plate in Chelonocytherois versus only one in Redekea ; presence of reflexed setae in Chelonocytherois versus absence in Redekea ; large amount of setae on the maxillular palp and endites in Chelonocytherois versus only a few in Redekea . The fifth to seventh limb of Chelonocytherois gen. nov. have a hook-like strong terminal claw, while the claws in Redekea are normal. Sexual dimorphism is present in the fifth limb in Redekea , while absent in Chelonocytherois gen. nov.