Cristacoxidae Huys, 1990

Huys, Rony & Kihara, Terue Cristina, 2010, Systematics and phylogeny of Cristacoxidae (Copepoda, Harpacticoida): a review, Zootaxa 2568, pp. 1-38 : 4-5

Family Cristacoxidae Huys, 1990

Diagnosis (amended). Laophontoidea. Body cylindrical, no clear demarcation between prosome and urosome. First pedigerous somite fused to cephalosome. Pleurotergites of pedigerous somites slightly developed. Cephalic shield with pattern of cuticular pits. Rostrum large and broad, completely defined at base; with two sensilla and a ventral, subapical tube-pore. Genital and first abdominal somites completely fused in Ƥ, forming genital double-somite; original segmentation marked by almost continuous internal, transverse chitinous rib, and by surface ornamentation both laterally and dorsally. Anal operculum moderately developed; pseudoperculum absent. Caudal rami with 7 setae (seta V longest, sometimes bi-articulate); setae V and VI not forming a setal complex in copepodid I and seta V expressed as the principal seta during the entire copepodid development; with large spinous processes at inner distal corner and around posterior margin between setae III and IV, and smaller ones at the bases of setae I, III and VII. Sexual dimorphism in antennule, endopod P3 (distal inner and outer apical setae strongly reduced or absent in 3; outer spine ( Cubanocleta ) or proximal inner seta ( Noodtorthopsyllus ) modified into an apophysis (ramus secondarily subdivided into 2 pseudosegments in Noodtorthopsyllus ), P5, P6 and in genital segmentation; sometimes in P1 (length of inner seta on enp-1), P2 endopod, P4 (both rami), and caudal rami.

Antennule short, with posterior spinous process on segments I (prominent) and II (weakly developed); with numerous pinnate setae and spines; 4-segmented in female, with aesthetasc on segment III; 5-segmented and modified (segment IV extremely swollen, segments distal to geniculation fused) in male with geniculation between segments IV and V and with aesthetasc on segment IV and sometimes V (as part of apical acrothek). Antenna with allobasis; abexopodal seta and exopod absent; endopod with 2 spines and 1 vestigial seta medially, and 6 elements (2 pinnate spines, 3 geniculate setae, 1 vestigial seta) distally. Labrum undivided. Mandible with 2-segmented uniramous palp, comprising unarmed basis and 1-segmented endopod with 4 setae. Paragnaths well developed, strongly ornamented lobes. Maxillule with 1-segmented, bisetose exopod; endopod incorporated into basis, represented by 3 setae; basal endites well defined, proximal one with 2 setae, distal one with 1 geniculate claw and 2 setae. Maxillary syncoxa with 2 or 3 endites, praecoxal endite (when present) vestigial, with 1 seta; proximal coxal endite with modified, basally fused spine and 2 setae; distal coxal endite with 3 setae; endopod incorporated into basis, with 2–3 setae. Maxilliped with syncoxa bearing 1 seta; basis unarmed; endopod 1-segmented with 1 long claw and 2 accompanying setae.

P1 with well developed 3-segmented protopod; praecoxa (one) and coxa (two) with conspicuous serrate crests (cristae) around outer margin; basis with inner spine/seta located on anterior surface near the inner margin, without genuine pedestal for insertion of endopod; exopod 3-segmented, exp-3 with 4 geniculate setae; endopod prehensile, 2-segmented with elongated enp-1 (sometimes bearing inner seta) and short enp-2 with 1 short claw and 1 long, geniculate claw. P2–P4 outer margin of coxa with serrate crista (P2–P3) or sometimes lobate outgrowth (P4); exopods 3-segmented; endopods 1- (P3–P4; sometimes P2) or 2-segmented (sometimes P2); outer elements of exp-3 typically elongate and setiform. Spine and setal formula as follows (variation shown in brackets):

Exopod Endopod

P1 0.0.0 22 [0–1].020

P2 0.[0–1].122 1.120 or 220 (Ƥ)

[0–1].120 or 220 (3)

P3 0.[0–1].222 22[0–1]

P4 0.0.222 [1–2]20

Fifth pair of legs not fused medially, defined at the base, remnant of intercoxal sclerite present, no distinction between exopod and baseoendopod; with 8 setae in both sexes.

Female gonopores not fused medially and each covered laterally by vestigial P6 bearing 2 tiny setae and sometimes very long seta; copulatory pore large, located in median depression; seminal receptacles paired, well defined. One egg-sac.

Male sixth pair of legs asymmetrical, with 2 setae each; either left or right P6 fused to ventral wall of genital somite, other member articulating and closing off single functional gonopore. Spermatophore extremely long, up to 1/3 of body length, with long curled neck. Male grasping terminal setae of caudal rami of female during precopulatory mate guarding.

Marine, interstitial, freeliving.

Included genera: Noodtorthopsyllus Lang, 1965 (type), Cubanocleta Petkovski, 1977 .