Giesbrecht, 1888
Short Description:
Euchirella amoena is an aetideid calanoid copepod known after both sexes (female 2.70-4.00 mm and male 3.00-3.85 mm) widespread in tropical, subtropical and temperate zones of the World's Ocean, mainly in epipelagic waters.
Taxonomic Description:
Female. Total length 2.70-4.00 mm. Cephalothorax 4-5 times longer than abdomen. Rostrum comparatively small. Posterior Th5 corners of nearly rectangular shape (dorsal view) with small knobs in distal part. Genital segment symmetrical. A1 reaching the midlength of Abd. Ri A2 very short: about fifth of Re A2 length, coxopodite and Ri1 A2 with 1 seta each, basipodite without setae (after Park (1976) with 1 seta), Ri2 A2 with 1 seta on internal and 3 on external lobes. Md palp base with spine-like, robust projection, typical of the species; Ri1 Md without setae, Ri2 Md with 9 setae. Mx1 gnathobase with 2 setae on posterior surface, second internal lobe with 4, third with 2 setae, on protopodite near insertion of Ri with 2 ( 3 after Park (1976)), Ri with 4, Re and external lobe with 8 setae. P1 with 2 spines on Re1, first external spine reaching the middle of second spine. P2 with one- segmented Ri, Re terminal spine with about 21 teeth. P3-P4 typical of the genus. P4 coxopodite with 5 very poorly visible small teeth.
Male. Total length 3.00-3.85 mm. In general appearance similar to female. Crest absent. P5 with uniramous left leg and large biramous right one. Ri P5 left absent, Ri right P5 longer than Re. Re1 P5 right with large spine-like projection in the middle of internal border, Re2 is about one third of Re1 P5 right.
Vertical distribution:
The species is known from epipelagic (Tanaka and Omori, 1969; Bradford and Jillett, 1980) and from total hauls from 2000 m.
Geographical distribution:
Species widespread in tropical, subtropical and temperate zones of the Atlantic, Pacific and Indian oceans (Vervoort, 1963). In the Pacific Ocean recorded in the south-western part (Farran, 1929; Bradford and Jillett, 1980; Von Vaupel Klein, 1984), in the south-eastern part: off Peru region (Tanaka and Omori, 1969); in the north-western and tropical parts (Tanaka and Omori, 1969; Von Vaupel Klein, 1972; Markhaseva, 1996).
Type locality: the equatorial Pacific (Giesbrecht, 1888).
Material examined:
5 females and 1 male from samples: 395, 400, 573. See examined samples module.