Phlyctocythere apua, Luz & Coimbra, 2022

Luz, Nathália Carvalho Da & Coimbra, João Carlos, 2022, Ostracods (Crustacea: Ostracoda) of the Vitoria-Trindade Chain, Southwestern Atlantic, Zootaxa 5188 (4), pp. 301-329 : 312-313

Phlyctocythere apua sp. nov.

Fig. 4 : 16–20

Type series. Holotype: MP-O-2841, RV, length: 0.437 mm, height: 0.291 mm . Paratype: MP-O-2842, LV, length: 0.443 mm, height: 0.288 mm.

Type locality. Vitoria Seamount, Sample M11001 D.

Etymology. Tupi-Guarani origin, apu’a = spherical, due to the subspherical shape of the carapace in lateral view.

Material. 3 RV, 6 LV, 2 C, and 5 juveniles (dead assemblage) .

Diagnosis. A small and ovate species of Phlyctocythere , apparently equivalve except by the subdorsal caudal process slightly upturned only in RV. Surface with three delicate but distinct concentric wrinkles subparallel to the ventro-posterior and posterior margins; the innermost nearly meets the dorsal margin, while the other two finish before reaching the caudal process. Hinge with traces of terminal elongate elements, more visible in LV. Eye tubercle few conspicuous, anterodorsally.

Description. Carapace small, thin-shelled, fragile, and ovate in lateral view. Valves almost equivalve except by the subdorsal caudal process somewhat upturned only in RV. Maximum height in the middle; maximum length subdorsal; maximum width near the middle. Valves heavily inflated, with a compressed peripheral zone similar to a very delicate flange anteriorly, large, and similar to a sharp keel ventro-posteriorly and posteriorly. Eye tubercle not conspicuous, anterodorsally. Anterior margin almost evenly rounded. Posterior end with a subdorsal caudal process slightly upturned in RV. Ventral margin sinuous. Dorsal margin strongly arched, mainly anteriorly. Surface smooth, except for a few wrinkles. Three delicate but distinct concentric wrinkles run subparallel to the ventro-posterior and posterior margins; the innermost nearly meets the dorsal margin, while the other two stop before reaching the caudal process. Inner lamella broad, except in the oral incurvature. Anterior vestibule wide; posterior vestibule narrow. Hinge consisting of a fine and smooth bar in RV and a corresponding groove in LV; traces of terminal elongate sockets in LV, correspondent RV terminal elements inconspicuous. Adductor muscle scars aligned in a slightly curved row of four compact small scars, frontal scar somewhat U-shaped. Sexual dimorphism not observed.

Remarks. See remarks of P. christophei sp. nov. As in many species of this genus, all specimens of P. apua sp. nov. show the posterior margin and the caudal process somewhat damaged.

Stratigraphic range. Holocene.

Occurrence and distribution. Vitoria, Davis, and Dogaressa seamounts ( Tab. 4 ).

Figures

FIGURE 4. 1–10: Loxocorniculum micropapillosum sp. nov. 1) MP-O-2836, female, RV; 2) MP-O-2835, female, LV, holotype; 3) MP-O-2837, male, RV, paratype; 4) MP-O-2837, male, RV, paratype, papillae detail. 5) MP-O-2837, male, RV, paratype, internal view; 6) MP-O-2835, female, LV, holotype, internal view; 7) MP-O-2837, male, RV, paratype, hinge; 8) MP- O-2835, female, LV, holotype, hinge; 9) MP-O-2837, male, RV, paratype, central muscle scars; 10) MP-O-2838, juvenile, RV, paratype, sieve-type normal pore canal. 11–15: Phlyctocythere christophei sp. nov. 11) MP-O-2839, RV, holotype; 12) MP-O- 2840, LV, paratype; 13) MP-O-2839, RV, holotype, internal view; 14) MP-O-2840, LV, paratype, internal view. 15) MP-O-2840, LV, paratype, central muscle scars. 16–20: Phlyctocythere apua sp. nov. 16) MP-O-2841, RV, holotype; 17) MP-O-2842, LV, paratype; 18) MP-O-2841, RV, holotype, internal view; 19) MP-O-2842, LV, paratype, internal view; 20) MP-O-2842, LV, paratype, central muscle scars. 21–22: Kotoracythere inconspicua. 21) MP-O-2843, RV. 22) MP-O-2844, juvenile, LV. 23) Paracytheridea inflata, MP-O-2845, male, RV. 24–25: Paracytheridea tschoppi. 24) MP-O-2847, RV, female; 25) MP-O-2848, LV, female. Scale bar: 100 µm.