Copytus cuspidata, Coimbra & Bergue & Ramos, 2020

Coimbra, João Carlos, Bergue, Cristianini Trescastro & Ramos, Maria Inês Feijó, 2020, Is Copytus Skogsberg, 1939 (Crustacea: Ostracoda) a neocytherideid? With description of a new family and two new species, Zootaxa 4729 (2), pp. 177-194 : 186-187

Copytus cuspidata sp. nov.

( Fig. 2 : 1–5; Tab. 1 )

2005 Copytus sp. 1 Machado et al.: 240, pl. 1, fig. 15.

Etymology. Latin, with reference to the pointed anteroventral margin.

Type locality. Southern Brazilian continental shelf, REMAC Project, sample L1-3115 (32°21’; 50°46’W, 74 m water depth, silt).

Age. Recent.

Material. 38 Recent valves of adult and juveniles, and six Quaternary fossil valves.

Holotype. MP-O-2752 LV, l: 0.68 mm, h: 0.22 mm (sample L1-3115) .

Paratypes. MP-O-2753 RV, l: 0.65 mm, h: 0.22 mm (sample L1-3115); MP-O-2754 LV, l: 0.68 mm, h: 0.23 mm (sample GVI-350) .

Diagnosis. Medium sized carapace. Anterior margin extremely protruded in the ventral half. Surface with longitudinal delicate but conspicuous ribs, somewhat concentric posteriorly, absent in the central region. Ribs and a moderately deep fossa converging anteroventrally. Inner lamella wide, particularly anteriorly.

Description. Carapace medium sized, thin shelled, and subcylindrical. Anterior margin extremely protrud- ed in ventral half, slightly convex in dorsal half. Posterior margin symmetrically rounded. Dorsal margin long and straight. Ventral margin parallel with dorsal one. Cardinal angles obtuse. Maximum length subventral. Height evenly uniform along the carapace. Height equals about 1/3 length. Shell surface with longitudinal delicate but well-defined ribs, somewhat concentric posteriorly, absent in the central region. Ribs and a moderately deep fossa converging anteroventrally. Inner lamella wide, particularly anteriorly. Anterior vestibule large, very deep. Selvage very narrow, indistinct. Marginal pore canals few, simple, short anteriorly and posteriorly. Hinge adont. As is common to the genus, the adductor scars are hidden, except in one adult valve, as follows: a subrounded group of four subtriangular imprints. Sexual dimorphism not visible in the studied isolated valves.

Geographic and stratigraphic distribution. In our study, this species was found between the Rio Grande do Sul State (33°51’S) and the Rio de Janeiro State (22°55’S) (see Tab. 1 ). Six fossil specimens were encountered in Quaternary sediments of the upper slope of Santa Catarina State in six cores (see ‘Material and Methods’). Machado et al. (2005) recorded this species off Cabo Frio town, Rio de Janeiro State, however, they did not report the number of specimens collected. In a pers. comm. in April 2018, Cláudia Pinto Machado informed the first author that the distribution by sample was not published in 2005, but that five valves of Copytus cuspidata sp. nov. were collected between 61 and 70 m on silt or fine sand.

Remarks. The present species bears some resemblance to Copytus fusiformis ( Yassini, 1979) , inasmuch as it has the anterior margin protruded in the ventral half and a ribbed surface. However, in C. cuspidata sp. nov. the carapace is much smaller, less fusiform and more ornamented, besides some differences in outline.

Figures

FIGURE 2. (1–5) Copytus cuspidata sp. nov. (1) MP-O-2752, LV, holotype; (2) MP-O-2753, RV, paratype; (3) MP-O-2754, LV, paratype, internal view; (4) MP-O-2753, detail of the anterior part; (5) MP-O-2755, detail of the central muscle scars in light microscopy. The lower imprint is partially hidden by conspicuous subelliptical and darker dirt. (6–14) Copytus wuerdigae sp. nov. (6) MP-O-2755, female RV, holotype; (7) MP-O-2756, female LV; (8) MP-O-2757, female RV, internal view; (9) MP-O- 2758 female LV internal view; (10) MP-O-2759, male LV; (11) MP-O-2760, male LV, detail of the posterior part of the hinge; (12) MP-O-2760, male LV internal view; (13) MP-O-2760, detail of the anterior part of the hinge; (14) MP-O-2761, female carapace, dorsal view. Scale bars 100 µm, unless otherwise indicated.