Esterly, 1911
Short Description:
Undeuchaeta incisa is an aetideid calanoid copepod known after both sexes (female 5.70-6.60 mm and male 4.08 mm in length) from the Atlantic and Pacific oceans, mainly meso-bathypelagic.
Taxonomic Description:
Female. Total length 5.70-6.60 mm. Cephalothorax about 3.4-4.0 times longer than abdomen. Crest present. Th5 posterior corners slightly asymmetrical, left one more prolonged than right one, their shape varying. Genital segment asymmetrical: on the right side there is a small projection (dorsal view). Small spine present near genital field on the right (lateral and ventral view). Genital field with "spectacle-like" structure, similar to that in Batheuchaeta . A1 24-segmented, reaching about the end of genital segment. Re1 A2 without seta, Re2 with 2 very small setae. Mx1 protopodite near Ri base with 5 setae, Ri with 14-15 setae. Oral parts and P1-P4 typical of the genus. P4 coxopodite with few small spinules near the base of internal seta (Grice, 1964; Park, 1978; Bradford and Jillett, 1980), in original material such spinules were not visible.
Male. Total length 4.08-5.58 mm. Cephalothorax about 3.0-3.2 times longer than abdomen. Crest present, lower than in female. Cephalon and Th1 as well as Th4-Th5 fused. Posterior Th5 corners slightly asymmetrical, rounded. A1 slightly shorter than body, 24-segmented. Oral parts reduced in comparison with female. P1-P4 as in female, separation between Re1 and Re2 more complete. Left Ri P5 nearly by one third of its length shorter than Re1; right Ri about as long as Re1 with 2 projections in proximal part of the segment.
Vertical distribution:
The species was often found in total hauls from mesopelagic (Grice and Hulsemann, 1968; Park, 1978; Bradford and Jillett, 1980; Markhaseva, 1996); once in total haul from 3000 m. Most likely upper bathypelagic, mesopelagic species.
Geographical distribution:
The species is widespread in the Atlantic Ocean: goes to the North till 65°N (With, 1915), to the South till 35°S (Wolfenden, 1911), recorded in its boreal and subtropical zones (Grice, 1964; Wolfenden, 1911). In the western Pacific Ocean distributed from the Sea of Okhotsk till the region off New Zealand (Tanaka, 1957b; Bradford and Jillett, 1980; Markhaseva, 1996); in the eastern Pacific Ocean known of the region off California (Esterly, 1911), off Peru (Grice and Hulsemann, 1968), from southern subtropical zone of the Ocean (Markhaseva, 1996) and its antarctic sector (Park, 1978; Markhaseva, 1996).
Type locality: The north-eastern part of the Pacific Ocean, region off California (Esterly, 1911).
Material examined:
6 females and 1 male from samples: 201, 390, 432. See examined samples module.