Giesbrecht, 1903
Short Description:
Gaetanus kruppii is an aetideid calanoid copepod known after both sexes (female 4.70-5.70 mm and male 4.50-5.20 mm in length). Species widespread in the World Ocean, found mostly in meso-bathypelagic.
Taxonomic Description:
Female. Total length 4.70-5.70 mm. Cephalothorax about 3.7-4.0 longer than abdomen. Frontal spine present, not large, curved to rostrum. Spines on Th5 posterior corners in the middle of posterior Th5 margin (lateral view), straight, not reaching the middle of genital segment. A1 longer than body by 3-4 last segments. Re1 A2 lacking setae, Re2 A2 with 2 setae. Second internal Mx1 lobe with 4 setae, Ri with 15 setae. Md palp base with 2, Ri1 Md with 1, Ri2 Md with 9 terminal setae. Lateral plate on Mxp protopodite present, deeply cut. Re P1 with indistinctly 3-segmented Re, Re1 P1 lacking spine, Re2 P1 with spine reaching the last third of Re3, also supplied with external spine. Ri P2 indistinctly 2-segmented. P4 coxopodite with about 23 spines.
Male. Total length 4.50-5.20 mm. Cephalothorax about 3.0-3.4 times longer than abdomen. Frontal spine present, variable in shape, longer than in female. Spines on Th5 posterior corners small. A1 reaching the end of cephalothorax, or Abd4, or exceeding caudal rami by 2 last segments. Re1 A2 lacking setae, Re2 A2 with 2 setae. Md palp base with 1 seta, Ri2 Md with 9 setae. Mx1 with 10-11 setae on Re, 9 setae on Ri. Re P1 incompletely 3-segmented, Re1-Re2 lacking external spines. Ri P2 2-segmented. Left Ri P5 covering two thirds of Re1 P5 length, and in original specimen even slightly longer than the segment. Re3 left P5 not bilobated, stylet-like, it is longer than Re2 of its leg.
Vertical distribution:
The species was found in hauls from lower meso-, upper bathypelagic (Farran, 1926; Park, 1975b), also in total hauls from depths 600-8000 m.
Geographical distribution:
Widespread in the Atlantic, Pacific and Indian oceans (Vervoort, 1963). In the Atlantic Ocean to the North to 65°N (With, 1915) and to the South to 39°S (Wolfenden, 1911). In the Pacific Ocean: in the north-western part to the North up to Japan (Tanaka and Omori, 1970a), to the South to the Marianas Trench region, in the north-eastern part of the Pacific Ocean recorded in the region of Vancouver (Esterly, 1906), in the south-eastern part of the Pacific Ocean the most southern finding in the region of 59°S (Park, 1978), also known from the New Zealand region (Bradford and Jillett, 1980).
Type locality: the Mediterranean Sea (Giesbrecht, 1903).
Material examined:
9 females and 1 male from samples: 3, 4, 47, 201, 202, 360, 443. See examined samples module.