Family Louriniidae Monard, 1927

Ceyloniidae Scott, 1909, p. 227.

Ceyloniellidae Monard, 1937 p. 83

Amended diagnosis. Copepoda Harpacticoida . Body slender and more or less cylindrical, without prominent distinction between prosome and urosome, first thoracic somite fused to cephalosome. Urosome 5-segmented in female; comprising fifth pedigerous somite, genital double-somite and three free abdominal somites. Genital double-somite longer than wide, subdivided by discontinuous lateral sutures. Paired genital apparatus located ventrally on genital double-somite; copulatory pore located on ventral midline. Anal operculum straight. Urosome 6-segmented in male; comprising fifth pedigerous somite, genital somite and four free abdominal somites. Caudal rami with six setae. Rostrum well developed, with rounded tip, anteroventrally directed. Antennule 7-segmented; third segment longest; fourth segment with aesthetasc fused basally to seta and arising from pedestal. Antennule 9-segmented in male; haplocer. Antenna biramous; with separate coxa; allobasis unarmed; endopod 1-segmented; exopod 1-segmented with two setae. Mandible with well developed coxal gnathobase; palp reduced. Maxillule with well developed praecoxal arthrite; with coxa. Maxilla with two syncoxal endites; allobasis represented by claw. Maxilliped vestigial, represented by tapering process, unsegmented with a seta distally. P1–P4 with 3-segmented exopods and 2-segmented endopods. Male P3 with 3-segmented endopod; second segment with apophysis. Spine and setal formula of P1–P4 as follows:

P5 confluent; with well developed baseoendopod; exopod separate. Male P5 confluent, exopod fused to baseoendopod.