Calanoidea: Families

J.M. Bradford-Grieve


Diaixidae Sars, 1902

Description. Female. Anterior head in dorsal view rounded or bluntly triangular. Rostrum with 2 filaments, or without filaments; rostral margin extends into 1 blunt protrusion, or extends into 2 blunt protrusions, or not extended. Cephalosome and pedigerous somite 1 fused or partly fused, or separate; pedigerous somites 4 and 5 fused or partly fused, or separate. Posterior corners of prosome in lateral view bluntly rounded, or with 1 acute point; dorsal view symmetrical. Genital double-somite symmetrical in dorsal view, or asymmetrical in dorsal view; gonopores close together and totally covered by single genital operculum; with pair of seminal receptacles; with pair of copulatory pores that are completely covered by genital operculum. Caudal rami symmetrical; seta VII located ventrally.

Mouthparts. Antenna 1 with 24 free segments; ancestral segments X and XI fused. Antenna 2 exopod with 6-7 free segments; 10-11 setae; basis and endopod separate. Mandible basis without setae, or with 2 setae; endopod 2-segmented, or 1-segmented; endopod terminal segment with 4 setae, or 5 setae. Maxilla 1 basal exite seta absent; exopod extends short of endopod distal border. Maxilla 2 coxal epipodite seta absent; endopod setae of sensory type; endopod with 3 worm-like setae; endopod with 5 brush-like setae. Maxilliped coxal endite 2 without setae, or with 1 seta, or with 2 setae, or with 3 setae.

Legs. Leg 1 basis outer seta absent; endopod with 1 segment; exopod with 3 segments; exopod segment 1 with outer distal spine; exopod segment 3 with 3 inner setae. Leg 2 endopod with 2 segments; exopod with 3 segments; exopod segment 3 with 3 outer spines. Leg 3 basis outer distal spine absent; endopod segment 3 with 5 setae. Legs 3 and 4 endopod with 3 segments; exopod with 3 segments; exopod segment 3 with 3 outer spines; exopod segment 3 with 4 inner setae. Leg 4 endopod segment 3 with 5 setae. Legs 2-4 surfaces strongly spinulose, or weakly spinulose, or naked; terminal spine with outer border serrated. Leg 5 absent.

Mode of life. Benthopelagic, in oceanic waters or in coastal waters.

Distribution on sea floor. Less than 100 m, or 100-200 m, or 200-1000 m.

Generic composition. This family contains 2 genera: Anawekia Othman & Greenwood, 1994; Diaixis Sars, 1902.


(Variant) Male (sexually dimorphic characters).

Description. Male. Pedigerous somites 4 and 5 separate. Posterior corners of prosome in lateral view bluntly rounded; dorsal view symmetrical, or asymmetrical. Caudal rami seta VII absent.

Mouthparts. Mouthparts well-developed, or reduced (especially maxillae 1 and 2). Antenna 1 similar, neither geniculate. Maxilliped endopod segments 5 and 6 with outer setae normal.

Legs. Leg 1 exopod segment 1 with outer distal spine, or without outer distal spine. Right leg 5 uniramous. Left leg 5 uniramous.



Cite this publication as: 'Bradford-Grieve, J.M. (2002 onwards). Calanoida: families. Version 1: 2 October 2002. http://crustacea.net'.