Ostracods (Crustacea: Ostracoda) of the Vitoria-Trindade Chain, Southwestern Atlantic Author Luz, Nathália Carvalho Da 0000-0001-5426-2450 Universidade Federal do Rio Grande do Sul, Programa de Pós-Graduação em Geociências / Paleontologia, Porto Alegre-RS, Brazil. ncarvalho. luz @ gmail. com; https: // orcid. org / 0000 - 0001 - 5426 - 2450 & Museu Paraense Emílio Goeldi, Coordenação de Ciências da Terra e Ecologia, 66077 - 830, Belém-PA, Brasil. ncarvalho.luz@gmail.com Author Coimbra, João Carlos 0000-0002-8980-6531 Universidade Federal do Rio Grande do Sul, Departamento de Paleontologia e Estratigrafia, Caixa Postal 15001, 91501 - 970, Porto Alegre-RS, Brazil. joao. coimbra @ ufrgs. br; https: // orcid. org / 0000 - 0002 - 8980 - 6531 joao.coimbra@ufrgs.br text Zootaxa 2022 2022-09-20 5188 4 301 329 journal article 148091 10.11646/zootaxa.5188.4.1 a393c65c-bd62-4f10-b6a6-d37eba7b9400 1175-5326 7095512 764AFF3F-2C0A-44C3-A398-31D66535C5AC 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 ).