Park, 1975c
Short Description:
Euchirella pseudotruncata is an aetideid calanoid copepod known after both sexes (female 4.30-4.66 and male 3.32-3.80 mm) from the Sargasso Sea, the Gulf of Mexico and the Caribbean Sea in epi- and mesopelagic.
Taxonomic Description:
Female. (Description after Park (1975c) with modifications). Total length 4.30-4.66 mm. Cephalothorax 4 times longer than abdomen. Rostrum present, small. Crest absent. Posterior corners of Th5 rounded, slightly rectangular (dorsal view). Genital segment slightly asymmetrical, with rounded projection on the left; it is slightly longer than wide (dorsal view). A1 slightly exceeding the caudal rami. Ri2 A2 slightly shorter than half Re length, Re1-Re2 A2 incompletely fused, Re1 A2 with triangular appendix; coxopodite, basipodite and Ri1 A2 with 1 seta each, Ri1 A2 with 7 setae on external and 8 setae on internal lobes. Md palp base and Ri1 Md without setae. Mx1 with 13 setae on gnathobase, 4 and 3 setae on the second and third internal lobes respectively, 3 setae on protopodite near the Ri base, with 5 setae on Ri, 11 setae on Re and 8 setae on external lobe. Mx2 and Mxp typical of the genus. Re P1 first external spine reaching nearly the midlength of second spine. P2-P4 typical of the genus. P4 coxopodite with 1 long spine.
Male. Total length 3.32-3.80 mm. Cephalothorax about 3.5 times longer than abdomen. Segmentation of cephalothorax as in female. Rostrum present. Crest absent. Th5 posterior corners rounded. A1 reaching the distal Abd2 end. Ri A2 well developed and is two thirds of Re length. Oral parts reduced: Md without gnathobase, Mx1 internal lobes reduced, its protopodite without setae, Ri weakly developed with 5 setae; Re with 11 setae and external lobe with 7 setae. Mx2 strongly reduced. Mxp is very weak. Re P1 with single reduced spine. P2-P4 segmentation as in female, P4 coxopodite without spine. P5 with uniramous left leg and well developed biramous right one. Right basipodite reaching about the midlength of Re1 P5 left, right Ri P5 present as curved spine-like projection.
Vertical distribution:
In the Gulf of Mexico the species was found at all sampled depths between 200 and 2000 m, it was not found in upper 100 m. Also recorded in epipelagic of the Sargasso Sea (Park, 1975c).
Geographical distribution:
Reported from the Sargasso Sea, the Caribbean Sea, the Gulf of Mexico (Park, 1975c; Von Vaupel Klein, 1984).
Type locality: the Gulf of Mexico.
Material examined:
The species absent in the collections of the Zoological Institute, Russian Academy of Sciences, St. Petersburg.