Chaulionyx, Kihara & Huys, 2009

Kihara, Terue & Huys, Rony, 2009, A new genus of Ectinosomatidae (Copepoda, Harpacticoida) from sublittoral sediments in Ubatuba, São Paulo State, Brazil, including an updated key to genera and notes on Noodtiella Wells, 1965, ZooKeys 17 (17), pp. 57-88 : 61-62

Chaulionyx gen. n.

urn:lsid:zoobank.org:act:1B8DB116-F0E1-4EEF-A0FD-756998F9DD0D

Diagnosis. Ectinosomatidae . Small-sized. Body fusiform, greatest width measured at posterior margin of cephalothorax; body somites strongly chitinized; hyaline frill of cephalic shield and somites bearing P2–P4 plain, that of other somites minutely serrate; no distinct surface ornamentation except for anterodorsal spinule rows on all body somites, ventral spinule rows on abdominal somites and large middorsal pores. Pseudoperculum weakly developed. Sexual dimorphism in antennule, P1, P5, P6, genital segmentation, abdominal ornamentation and caudal ramus.

Rostrum large, hyaline, broadly rounded, not defined at base. Antennule 5-segmented in female, 7-segmented in male with geniculation between segments 5 and 6. Antenna with 3-segmented exopod (formula 0-1-2); distal endopod segment with 2 lateral and 5 apical elements. Labrum with frontal spinous projection. Mandible with small gnathobase and biramous palp; basis with 3 setae, exopod minute with 3 setae, endopod with 3 lateral and 7 apical elements. Maxillule with well developed arthrite; coxa represented by a single seta; exopod bisetose with the lateral seta typically outwardly reflexed; basis and endopod fused, with 10 setae in total. Maxilla prehensile, robust; syncoxa with 3 endites (formula 4-1-3); allobasis with 3 lateral and 1 apical setae; endopod 2-segmented (ancestral segments 2-3 fused). Maxilliped stenopodial, 3-segmented, slender; syncoxa with 1 seta; endopod with 1 lateral and 3 terminal setae.

P1 with an inner and an outer seta on the basis; exopod 3-segmented; endopod prehensile, 2-segmented, enp-2 with bifid outer claw. P2–P4 with outer seta on basis; rami 3-segmented; inner seta of enp-2 distinctly short. Armature formula:

P5 of both sexes with separate exopod and baseoendopod; exopod with 1 surface and 3 marginal setae; endopodal lobe with 2 spines/setae.

Female gonopores fused forming a median genital slit, covered by the pair of P6 each bearing 1 long seta; midventral copulatory pore small.

Male P6 asymmetrical, unarmed; functional member represented by small operculum, other member fused to genital somite.

Caudal ramus short, with 7 setae; setae IV–V basally fused, without fracture planes.

Type and only species. Chaulionyx paivacarvalhoi sp. n.

Etymology. The generic name is derived from the Greek chaulios (outstanding, prominent) and onyx (nail, claw), and refers to the modified, claw-like, bifid outer spine on the P1 endopod. Gender: feminine.