Wolfenden, 1905
Short Description:
Euchirella maxima is an aetideid calanoid copepod known after both sexes (Female 6.50-8.70 mm and male 6.10-7.35 mm) from the Atlantic and Pacific oceans from epi-mesopelagic.
Taxonomic Description:
Female. Total length 6.50-8.70 mm. Cephalothorax nearly 6-7 times longer than abdomen. Crest present, high. Rostrum strongly reduced. Posterior Th5 corners asymmetrical, not rounded. Genital segment asymmetrical, with small projection on the right in anterior half of segment (dorsal view). Ri2 A2 with 5 setae on each lobe, Ri as long as one third of Re length, basipodite without seta, Ri1 A2 with 1 seta. Mx1 protopodite near Ri base with 3 setae, Ri with 3, Re with 11 setae. P4 coxopodite with 1 strong spine (formed by fusion of 5-8 spines).
Male. (Description after Park (1978) with modifications). Total length 6.10-7.35 mm. Cephalothorax 3.3 times longer than abdomen. Crest present. Rostrum small, but better developed than in female. Posterior Th5 corners rounded. Ri A2 is a fourth of Re A2 length, Ri2 A2 external lobe with 6 setae and internal lobe with 6 long setae and 1 small short seta. Ri2 Md with 8 setae. Mx1 and Mx2 setation strongly reduced. Re P1 with very small first external spine, second external spine rather well developed. P5 biramous, both Ri well developed. Re P5 right 2-segmented, Ri nearly equal to Re1 in length, on the external Ri surface there are 2 knobs, P5 right rami do not form tongs.
Vertical distribution:
The species was found in hauls from epipelagic and upper mesopelagic (Vervoort, 1963; Owre and Foyo, 1967; Tanaka and Omori, 1969a; Park, 1978; Von Vaupel Klein, 1984), also from total hauls from deeper layers.
Geographical distribution:
Atlantic Ocean: the species was found in the north-eastern, northern and tropical Atlantic to the North up to 63°N (Jespersen, 1940), to the South up to 35°S (Wolfenden, 1911), in the Gulf of Mexico, Gulf of Guinea (With, 1915; Sars, 1925; Wolfenden, 1905; Vervoort, 1963; Park, 1976b), species is known from the Indian Ocean and also western, northern and south-eastern parts of the Pacific Ocean (Tanaka and Omori, 1969a; Markhaseva, 1996); in the southern part of the Pacific Ocean to 34°S (Grice and Hulsemann, 1968), and from antarctic part from the region of 55°S (Park, 1978).
Type locality: Tropical Atlantic (Wolfenden, 1905).
Material examined:
2 females from samples: 444, 447. See examined samples module.