Sars, 1905
Short Description:
Gaetanus latifrons is an aetideid calanoid copepod known after both sexes (female 4.40-5.40 mm and male 4 mm in length) from the Atlantic, Pacific and Indian oceans in meso-bathypelagic.
Taxonomic Description:
Female. Total length 4.40-5.40 mm (after Wolfenden (1911) 3.75 mm). Cephalothorax about 3-4 times longer than abdomen. Frontal spine present, robust, beginning from anterior-dorsal part of cephalon and its base directed forward (lateral view), its top often slightly curved to rostrum. Spines on posterior Th5 corners removed to ventral side of specimen (lateral view), curved, they are usually longer than genital segment. When looking dorsally they are slightly divergent. A1 reaching the midlength of abdomen, or exceeding caudal rami by 3 last segments. Re1 A2 with 1, Re2 A2 with 3 setae. Md palp base with 2, Ri1 Md with 2, Ri2 Md with 9 terminal and 3 short posterior setae. Mxp protopodite with lateral plate. P1 with 3-segmented Re, supplied with external spines on each segment. Ri P2 2-segmented. P4 coxopodite with 15-19-25 spines.
Male. (Description after Park (1975b), with modifications). Total length about 4 mm. Frontal spine small, directed to rostrum. Spines on Th5 posterior corners as in female removed to ventral side of specimen (lateral view), long, exceeding the posterior border of genital segment. A1 reaching distal end of Abd2. Re1 and Re2 A2 without setae. Third internal Mx1 lobe with 3 small setae, Ri Mx1 with 11 setae, external lobe with 9 setae. P1 with 3-segmented Re, Re1 and Re2 supplied with small external spines, Re3 also with external spine. Re2 P5 right longer than Re1. Ri P5 left is less than a fourth of Re1 length, Re3 P5 left bilobated, not stylet-like, short, it is about two thirds of Re2 length.
Vertical distribution:
The species mostly found in meso-, bathypelagic (Farran, 1908, 1926; Park, 1975b; Deevey and Brooks, 1977, Markhaseva, 1996).
Geographical distribution:
Widespread in the northern part of the Atlantic Ocean, the northernmost finding in the region of 61-65°N (With, 1915), the southernmost: in the Gulf of Guinea (Vervoort, 1963); in the Indian Ocean found in the Bay of Bengal (Sewell, 1929; 1947), the southernmost finding in the region of 29°S (Grice and Hulsemann, 1967), and in the south-eastern part to 45-48°S (Vervoort, 1957; Markhaseva, 1996); in the Pacific Ocean: the northernmost finding in the Japanese waters (Tanaka and Omori, 1970a), the southernmost region of 47°N (Bjornberg, 1973).
Type locality: North Atlantic (Sars, 1905).
Material examined:
10 females from samples: 387, 392, 400, 401, 403, 419. See examined samples module.