Giesbrecht, 1888
Short Description:
Euchirella curticauda is an aetideid calanoid copepod known after both sexes (female 3.50-4.55 mm male 3.14-4.30 mm) from the Atlantic, Pacific and Indian oceans from epi- and mesopelagic.
Taxonomic Description:
Female. Total length 3.50-4.55 mm. Cephalothorax 5-6 times longer than abdomen. Crest present, comparatively high, triangular (lateral view). Rostrum rudimentary, nearly absent. Th5 posterior corners rounded, with slightly prolonged tops (lateral and dorsal view). Genital segment symmetrical, nearly 1.5 times longer than wide. Abd3 with conical projection (right view). A1 nearly as long as cephalothorax. Ri A2 about one fourth of Re length, coxo- and basipodite and Ri1 A2 with 1 seta, Ri2 A2 with 2 setae on internal and 3-4 setae on external lobes. Md palp base and Ri1 Md with 1 seta each. Ri2 Md with 9 setae. Mx1 gnathobase with 3 setae on posterior surface, second internal lobe with 4, third with 2 setae (3 setae after Von Vaupel Klein (1984)); on protopodite near the Ri base 3 setae, and on Ri itself 3 setae; on Re 11 setae, on external lobe 9 setae. Mx2 typical of the genus. Mxp protopodite with small projection in distal part near external border. First spine on Re P1 exceeding the midlength of following spine. P4 coxopodite with 6-8 spines (after Park (1976b) with 13, after Tanaka and Omori (1969a) with 8-11, after Bradford and Jillett (1980) with 12-13).
Male. (Description after Park (1976b) and Bradford and Jillett (1980) with modifications). Total length 3.14-4.30 mm. General appearance close to that in female. Crest slightly lower than in female. Rostrum nearly absent. Both P5 of about same length, biramous. Ri P5 left well developed, reaching nearly the middle of its Re1 P5. Re2 P5 right transformed into comb-like structure and supplied with row of teeth. P5 rami not transformed into tongs.
Vertical distribution:
The species was found in epipelagic (Grice, 1962; Tanaka and Omori, 1969a, b; Bradford and Jillett, 1980), some authors recorded species also from mesopelagic, where species was found by Park (1976b) and Markhaseva (1996). Park recorded the species to 3000 m, but noted the major numbers of specimens between 500-1000 m in daytime and in the upper 100 m at night. The species also found in total hauls from 700-1400 m.
Geographical distribution:
Atlantic Ocean: the species is widespread in the Atlantic, northernmost locality about 66°N, southernmost locality 11°S; Pacific Ocean: to the North up to 55°N and to the South up to New Zealand (Bradford and Jillett, 1980), also recorded in the tropical part of the Indian Ocean (Vervoort, 1963).
Type locality: the equatorial part of the Pacific Ocean (Giesbrecht, 1888).
Material examined:
8 females and 1 male from samples: 170, 390, 400, 401, 419, 573. See examined samples module.