Aetideopsis carinata is an aetideid calanoid copepod known after both sexes (female 2.66-2.96 mm and male 2.4 mm). The species is known from the south-eastern, tropical and northern parts of the Atlantic Ocean, mostly mesopelagic species.
Female. Total length 2.66-2.96 mm. Cephalothorax about 3.3 times longer than abdomen. Anterior part of cephalon acute-angled (dorsal view) and obtuse-angled (lateral view). Rostrum with widely spaced and strongly divergent rami. Posterior Th5 corners wing-like, strongly divergent (dorsal view). Points of Th5 posterior corners covering nearly the middle of length of genital segment. Genital segment with lateral swellings in its anterior half (dorsal view) and with ventral swelling much more developed than in other species of genus. A1 reaching Th3-Th4. Equipment at A2 typical of the genus, at Re2 A2 there is medial seta. Md palp base with 2 setae [Bradford (1969a) noted 1], Ri1 Md also with 2 setae and 9 (7 terminal and 2 posterior) at Ri2 Md. In proximal part of Mxp protopodite there is external projection, P1 with external spines at Re1 and Re2, exceeding the base of next spine, P2 with one-jointed Ri and 3-jointed Re, at terminal spine there are 26 denticles. P3 with 2-jointed Ri and 3-jointed Re, terminal spine with 29 denticles (Bradford, 1969a). P4 with 3-jointed rami and terminal spine with 30 denticles (Bradford, 1969a) at terminal spine.
Male. (Description after Bradford, 1969a). Total length 2.4 mm. Cephalothorax 2.7 times longer than abdomen. Shape of body is like that in female. Th4-Th5 partly fused. Points of posterior Th5 corners reaching posterior border of Abd1, not divergent. A1 extending beyond Th3, 23-jointed. Oral parts in comparison with that in female rudimental. Segmentation of P1-P2 as that in female; external spines at Re significantly shorter than that in female. P3-P4 with 3-jointed rami, at Re3 terminal spines 30 and 33 denticles correspondingly. P5 of characteristic for the genus structure, at left Re2 P5 - 2 thin spines arranged distally.
Species found in hauls with known sampling ranges from mesopelagial (Roe, 1975) and from total haul from 300 m (Bradford, 1969a).
The south-eastern part of the Atlantic Ocean: off African coast (Bradford, 1969), the northern part of the Atlantic Ocean from the region of 18°N 25°W and 28°N 14°W (Roe, 1975), from tropical Atlantic of the region of the Canary Islands (Vives, 1982; Brenning, 1983, 1985).
Type locality: 21°09'S 12°44'E (Bradford, 1969a).
5 females from sample: 573. See examined samples module.