Park, 1968
Short Description:
Euchirella unispina is an aetideid calanoid copepod known after both sexes (female 4.28-4.89 mm and male 3.84-4.03 mm in length) from the Pacific Ocean and Malay Archipelago, mainly epipelagic.
Taxonomic Description:
Female. (Description after Park (1968) with modifications). Total length 4.28-4.89 mm. Cephalothorax 4.3 times longer than abdomen. Crest absent. Posterior Th5 corners rounded. Genital segment with nearly equal length and width, slightly asymmetrical: elongated on the left posteriorly (dorsal view). A1 reaching the end of caudal rami, some segments with aesthetascs. Ri A2 shorter than Re1-Re2 A2 together, latter without setae; coxopodite, basipodite and Ri1 A2 with 1 seta each, Ri2 A2 with 8 setae on internal and 7 on external lobes. Md palp base with small seta on posterior surface, Ri1 Md without setae, Ri2 Md with 9 setae. Mx1 with 3 setae on posterior surface of gnathobase, second internal lobe with 4, third with 3 setae, protopodite near Ri base with 3 setae, Ri with 5 setae, Re with 11, external lobe with 8 setae. Mx2 and Mxp typical of the genus. P1-P4 segmentation typical of the genus, line of fusion between Ri P2 segments sometimes visible. P4 coxopodite with 1 robust spine.
Male. Total length 3.84-4.03 mm. Cephalothorax 3.7 times longer than abdomen. Body segmentation as in female. Posterior Th5 corners rounded. Posterior border of Abd1-3 with thin spinules. A1 reaching the end of Abd2. Ri A2 better developed than in female, of two third of Re length, basipodite and Re1 without setae. Oral parts in comparison with those in female reduced. P1 with Re1 lacking external spine, Ri P2 with the line of fusion between segments not visible. P4 coxopodite without spines. P5 with uniramous left leg and well developed biramous right one. Right P5 basipodite well developed, reaching the middle of Re1 P5 left.
Remarks. This species is close to E. truncata , but female differs in smaller size and shape of genital segment. Males of this species are characterized by the shape of teeth on left Re3 P5 and number and shape of projections on Re and Ri of right P5.
Vertical distribution:
The species was found in hauls from epipelagic (Park, 1968; Von Vaupel Klein, 1984).
Geographical distribution:
The species is distributed in the north-eastern part of the Pacific Ocean (Park, 1968); the region of the Malay Archipelago (Von Vaupel Klein, 1984).
Type locality: 31°54'N 155°00'W (Park, 1968).
Material examined:
The species absent in the collections of the Zoological Institute, Russian Academy of Sciences, St. Petersburg.