Vervoort, 1965
Short description:
Paivella inaciae is an aetideid calanoid copepod known after both sexes (female 1.42-1.46 mm and male 1.15 mm in length) off Nigeria, found in haul between 95 m and surface.
Taxonomic Description:
Female. (Description after Vervoort (1965) with modifications). Total length 1.42-1.46 mm. Cephalothorax about 3.4 times longer than abdomen. Cephalon and Th1 and Th4-Th5 completely fused, no line of fusion visible. Rostrum present, bifurcate of Aetideus structure. Th5 posterior corners of triangular shape, pointed at the ends (dorsal and lateral view), slightly exceeding the midlength of genital segment. There are no teeth along posterior borders of the Abd1-4. Caudal rami exactly twice as long as wide. A1 23-segmented, reaching the end of caudal rami. A2 coxa with 1 seta, basipodite with 2 fine setae, Re1 A2 without setae, Re2 with 3 setae; Re7 with 3 terminal and no other setae; Ri1 A2 with 2 setae, Ri2 with 8 setae on internal and 6+1 on external lobe. Md palp base with 2 setae, Ri1 Md with 2 and Ri2 Md with 9 terminal and 1 posterior setae. Mx1 gnathobase with 9 terminal setae and 4 setae on posterior surface, second internal lobe with 3, third with 4 setae, protopodite near Ri base with 4 setae, Ri with 10, Re with 11 setae, external lobe with 9 setae. Mx2 with seta on fourth endite slightly thickened into spine, and rather thickened spine on fifth endite. Mxp typical of the genus. Re1 P1 without spine, external lobe on Ri well developed, covered with spinules anteriorly. Ri P2 one-segmented, segmentation of other swimming legs rami typical of the genus. P4 coxopodite with 2 transverse rows of 6 acute spines on posterior surface.
Male. (Description after Vervoort (1965)with modifications). Total length 1.15 mm. Cephalothorax about 3.1 times longer than abdomen. Cephalon and Th1 and Th4-Th5 completely fused. Rostrum as in females, but points shorter. Th5 posterior corners rounded. Genital segment with opening on the left. Caudal rami as in females. A1 reaching the midlength of Abd2, 8-10, 20-21 and 24-25 segments fused. A2 reduced, Ri1 A2 and Ri2 A2 without setae, Re1 A2 has 2 setae, shorter than in female, Md as in female. Mx1 reduced, gnathobase lacking setae, third internal lobe with 2 setae, 3 setae on protopodite near the Ri base, and 3 setae on Ri, Re with 10 setae, external lobe with 5 setae. Mxp as in females, but number of setae reduced. P1-P4 as in female, but Re1 and Re2 P1 completely separate; Ri P2 with incomplete segmentation; P4 coxopodite without spines on posterior surface and internal seta. P5 uniramous. Left P5 elongated, 5-segmented, terminal segment ending with spine with patch of spiniform hairs. Right P5 4-segmented; terminal segment ending into needle-shaped appendage. P5 right leg shorter than left, reaching the midlength of third segment of left leg.
Vertical distribution:
The species was found between 95 m depth and surface (Vervoort, 1965).
Geographical distribution:
The species is known off Nigeria, known from type locality only.
Type locality: 5°56'N 4°26'E.
Material examined:
The species absent in the collection of the Zoological Institute, Russian Academy of Sciences, St. Petersburg.