Calanoidea: Families

J.M. Bradford-Grieve


Megacalanidae Sewell, 1947

Description. Female. Anterior head in dorsal view rounded or bluntly triangular. Rostrum with 2 filaments, or without filaments; rostral margin extends into 2 points, 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 separate. Posterior corners of prosome in lateral view bluntly rounded, or triangular or obtusely pointed; dorsal view symmetrical. Genital double-somite symmetrical in dorsal view. Caudal rami symmetrical.

Mouthparts. Antenna 1 with 25 free segments; ancestral segments X and XI fused. Antenna 2 exopod with 7 free segments; 8-12 setae; basis and endopod separate. Mandible basis with 4 setae; endopod terminal segment with 8 setae, or 11 setae. Maxilla 1 basal exite seta present; exopod extends as far as endopod distal border. Maxilla 2 coxal epipodite seta present. Maxilliped coxal endite 2 with 4 setae.

Legs. Leg 1 basis outer seta absent; endopod with 2 segments, or with 3 segments; exopod with 3 segments; exopod segment 1 with outer distal spine, or without outer distal spine; exopod segment 3 with 4 inner setae. Leg 2 endopod with 3 segments; exopod with 3 segments; exopod segment 3 with 3 outer spines. Leg 3 basis outer distal spine present; endopod segment 3 with 8 setae. Legs 3 and 4 endopod with 3 segments; exopod with 3 segments; exopod segment 3 with 3 outer spines; exopod segment 3 with 5 inner setae. Leg 4 endopod segment 3 with 7 setae. Legs 2-4 surfaces naked; terminal spine with outer border serrated. Leg 5 present; similar to legs 2-4; coxa inner border without seta; exopod segment 2 inner distal border with ordinary seta. Leg 5 exopod segment 3 outer border with 2 spines; inner border with 4 setae.

Mode of life. Pelagic, in oceanic waters.

Depth distribution. Bathypelagic (greater than 1000 m).

Generic composition. This family contains three genera: Bathycalanus Sars, 1905; Bradycalanus A. Scott, 1909; Megacalanus Wolfenden, 1904.


(Variant) Male (sexually dimorphic characters).

Description. Male. Anterior head in dorsal view pointed.

Mouthparts. Mouthparts well-developed. Antenna 1 similar, neither geniculate, or geniculate on right; geniculation between ancestral segments XX and XXI. Maxilliped endopod segments 5 and 6 with outer setae normal.

Legs. Right leg 5 biramous; endopod 3-segmented; exopod similar to that of female and other swimming legs, 3-segmented. Left leg 5 biramous; exopod similar to that of female and other swimming legs, 3-segmented, segment 2 with inner distal projection.



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