Calanoidea: Families

J.M. Bradford-Grieve

Euchaetidae Giesbrecht, 1892

Description. Female. Anterior head in dorsal view pointed, or rounded or bluntly triangular. Rostrum without filaments; rostral margin extends into 1 point. Cephalosome and pedigerous somite 1 fused or partly fused; pedigerous somites 4 and 5 fused or partly fused. Posterior corners of prosome in lateral view bluntly rounded, or triangular or obtusely pointed; dorsal view symmetrical. Genital double-somite symmetrical in dorsal view, or asymmetrical in dorsal view; with pair of seminal receptacles. Caudal rami symmetrical; seta VII located ventrally.

Mouthparts. Supralabrum present. Antenna 1 with 24 free segments; ancestral segments X and XI fused. Antenna 2 exopod with 7 free segments; 8-9 setae; basis and endopod separate. Mandible basis with 1 seta; endopod terminal segment with 8-9 setae. Maxilla 1 basal exite seta absent; exopod extends as far as endopod distal border. Maxilla 2 coxal epipodite seta absent; endopod setae normal, or claw-like. Maxilliped coxal endite 2 with 3 setae.

Legs. Leg 1 basis outer seta absent; endopod with 1 segment; exopod with 2 segments; exopod segment 1 with outer distal spine; exopod segment 3 with 3 inner setae. Leg 2 endopod with 1 segment; 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 naked; terminal spine with outer border serrated. Leg 5 absent.

Mode of life. Pelagic, in oceanic waters.

Depth distribution. Epipelagic (0-500 m), or mesopelagic (500-1000 m), or bathypelagic (greater than 1000 m).

Generic composition. This family contains two genera: Euchaeta Philippi, 1843; Paraeuchaeta Scott, 1909.

(Variant) Male (sexually dimorphic characters).

Description. Male. Anterior head in dorsal view pointed.

Mouthparts. Mouthparts 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 with 3 segments; exopod segment 1 with outer distal spine, or without outer distal spine. Right leg 5 biramous; endopod separate from basis and 1-segmented; exopod 2-segmented, distal segment blunt distally or terminated with a spiniform process. Left leg 5 biramous; endopod 1-segmented, or 2-segmented; exopod 3-segmented, segment 1 long, segment 3 concave with proximal hairy tubercle, with 2 adjoining tufts of stiff hairs distally and a terminal spine which is either greatly developed or vestigial; exopod segment 2 extending distally into serrated lamella and with a digitiform process.

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