Untold diversity: the astonishing species richness of the Notodelphyidae (Copepoda: Cyclopoida), a family of symbiotic copepods associated with ascidians (Tunicata) Author Kim, Il-Hoi 0000-0002-7332-0043 Korea Institute of Coastal Ecology, Inc., 802 - ho, 302 - dong, 397 Seokcheon-ro, Ojeong-gu, Bucheon, Gyeonggi-do 14449, Republic of Korea ® ihkim @ gwnu. ac. kr; https: // orcid. org / 0000 - 0002 - 7332 - 0043 ihkim@gwnu.ac.kr Author Boxshall, Geoff A. 0000-0002-7332-0043 Korea Institute of Coastal Ecology, Inc., 802 - ho, 302 - dong, 397 Seokcheon-ro, Ojeong-gu, Bucheon, Gyeonggi-do 14449, Republic of Korea ® ihkim @ gwnu. ac. kr; https: // orcid. org / 0000 - 0002 - 7332 - 0043 ihkim@gwnu.ac.kr text Megataxa 2020 2020-12-24 4 1 1 6 http://zoobank.org/3fdd970e-62f1-4f67-8cce-10870bdb3c01 journal article 54097 10.11646/megataxa.4.1.1 7c9bc39d-9910-46f1-9558-c0647b9cbbdb 2703-3090 4591138 Ammonixys gen. nov. Diagnosis . Body globular with swollen, almost spherical, fourthpedigerous somite. Freeurosome 5-segmented. Caudalsetae obscure. Rostrum well-developed.Antennule small, 6-segmented. Antenna 4-segmented withsmall terminal claw. Mandible with 4 teeth on coxal gnathobase; exopod fused with basis, represented by 2 setae; endopod 2-segmented with 1 and 4 setae on first and second segments, respectively. Maxillulewith 6 setaeon arthrite, 1 each on coxal epipodite and basis, 4 on exopod and 3 on endopod; coxal endite absent. Maxilla 4-segmented; syncoxa with 2 endites; basis with claw plus 1 seta; endopod 2-segmented. Maxilliped as unsegmented lobe bearing 4 setae. Legs 1–3 with 3-segmented rami. Leg 4 with 3-segmented exopod and 2-segmented endopod. Innercoxalsetaabsentinlegs 1–4. Leg 1 lacking inner distal element on basis. First and second exopodal segments of legs 1–4 lacking inner seta. First and second endopodal segments of legs 1–3 lacking inner seta. Leg 5 represented by lobe and tapering, sclerotized process located ventrodistally on somite. Typespecies . Ammonixysquadridens gen. etsp. nov. by original designation. Etymology . The name is derived from the Greek ammon (=African) and ixys , referring to the discovery of the new genus in Africa. Remarks . Ammonixys gen. nov. resembles Doroixys in the absence of the inner seta on the proximal endopodal segment(s) of legs 2–4, but the new genus exhibits a striking derived feature separating it from Doroixys and other genera, namely, the loss of a distinct mandibular exopod. The exopod is respresented only by a pair of setae originating on the surface of the fused basis plus exopod. The setation of leg 1 is also distinctive because the first and second exopodal and endopodal segments of leg 1 all lack an inner seta, and the basis of leg 1 is unarmed. This setation of leg 1 differs from that expressed by the four new genera described above, Prodoroixys gen. nov. , Notoixys gen. nov. , Borixys gen. nov. , and Cystixys gen. nov. Although the loss of inner setae from the exopod of leg 1 occurs in Loboixys , the latter genus usually retains the inner setae on the endopod of leg 1. Unlike in Ammonixys gen. nov. , the seven known species of Loboixys each have a 3-segmented antenna and carry 6 setae on the maxilliped. This constitutes an additional significant difference between Loboixys and Ammonixys gen. nov. , which has a 4-segmented antenna and carries only 4 setae on the maxilliped.