Oithona bjornbergae Ferrari F. D. & Bowman 1980

Oithona bjornbergae

MATERIAL,—Numerous and from PN-1-60, PN-5-60, PN-6-60, PN-7-60, and PN-8-60.

FEMALE.—Length range (30 specimens) 0.44–0.51 mm; Pr/Ur-1.4. Head rounded in dorsal view; rostrum absent (Figure 3a). Ur2–4 fringed on posterolateral margin; Ur2 and 3 with 1 transverse row of minute hairs on ventral surface near posterior margin (Figure 3d); Ur4 with 2 rows. CR length 2 times width; apical seta 2 and 3 thickened, with shorter, more dense plumes than other setae, (Figure 3e). A1 and 2 similar to other species of Oithona. B2Md (Figure 3h) with 2 thick, curved spines of equal length, bearing fine spinules; Ri with 4 plumose setae; Re 4-segmented with 4 setae. B2Mx 1 (Figure 3i) with 2 thin spines bearing thick spinules; Ri absent; Re with 3 setae. Mx2 and Mxp as in Figure 3j, k; Se ReP1–4: 1–1–2, 1–1–2, 0–1–1; 0–0–1; Si Re1P1 absent. Both

Setae on Ri2P4 and proximal seta on Ri3P4 modified; all straight; proximal seta of Ri2 with small serrate flange on distal ; flange well developed on distal of distal seta of Ri; proximal seta of Ri3 slightly thicker than others with flange on distal Knob near genital opening armed with a small spine (Figure 3c).

MALE.—Length range (30 specimens) 0.41–0.48 mm; Pr/Ur-1.4. Head rounded dorsally, laterally slightly more acuminate than female (Figure 4a). As in O. oculata, Cph with triangular extension posteriorly toward ventral margin. Articulation along dorsal part of triangle poorly developed as shown by broken line in Figure 4a and thinner line in Figure 4b. Cph with few unorganized sensory hairs and pores, which differ in structure from those of pore signature in most oithonids. Ur3–6 fringed on posterior edge; Ur3 and 4 with 1 transverse row of minute hairs on ventral surface near posterior margin; Ur5 with 2 rows (Figure 4d). All apical spines and dorsal spine of CR thickened. Genital flap with 1 large seta; below it several tiny toothlike spines. A1 as in Figure 4e; remaining appendages similar to female except Ri2 and 3P4, which lack modified setae.

MATERIAL.—Female holotype (USNM 172183), 37 and 28 paratypes (USNM 172184, 172185) from PN-7-260, 01°27.8'S, 48°29.2′W, mouth of Rio Araca Granda, Para, Brazil; 11 Jun 1977.