Copytus wuerdigae, 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 : 187-190

publication ID	https://doi.org/ 10.11646/zootaxa.4729.2.2
publication LSID	lsid:zoobank.org:pub:EC42F789-C869-4551-998E-CC819044C775
DOI	https://doi.org/10.5281/zenodo.5665887
persistent identifier	https://treatment.plazi.org/id/8C0B878F-3929-5775-49CC-FB24FE07FE09
treatment provided by	Plazi
scientific name	Copytus wuerdigae
status	sp. nov.

Treatment

Copytus wuerdigae sp. nov.

( Fig. 2 View FIGURE 2 : 6–14; Tab. 1 View TABLE 1 )

1980 Copytus sp. Madeira-Falcetta et al.: 107, pl. 3, fig. 3.

2005 Copytus sp. 2 Machado et al.: 240, pl. 1, fig. 16.

2017 Copytus sp. Morais & Coimbra: fig. 4D.

Etymology. In honour of Dr. Norma L. Würdig for her important studies on living and fossil ostracods from Brazil.

Type locality. Southern Brazilian continental shelf, Geomar VI, sample GVI-349 (31°24’; 50°30’W, 60 m water depth, biodetritic silty sand).

Age. Recent.

Material. 32 valves and one carapace of both adults and latest instars.

Holotype. MP-O- 2755 female RV, l: 0.73 mm, h: 0.25 mm (sample Geomar VI-349).

Paratypes. MP-O-2756 female LV, l: 0.77 mm, h: 0.27 mm (sample Geomar VI-349); MP-O-2757 female RV, l: 0.77 mm, h: 0.25 mm (sample Geomar VI-349); MP-O-2758 female LV, l: 0.79 mm, h: 0.25 mm (sample M6738); MP-O-2759 female C, l: 0.76 mm, h: 0.25 mm, w: 0.21 mm (sample Geomar VI-349); MP-O-2760 male LV, l: 0.68 mm, h: 0.22 mm (sample L7-3949); MP-O-2761 male LV, l: 0.68 mm, h: 0.18 mm (sample L7-3955) .

Diagnosis. Medium sized carapace, anterior end extended in ventral half, posterior end asymmetrically rounded. Surface predominantly smooth, with ventro-lateral striae that extend anteriorly as four weak subparallel marginal ribs. Inner lamella wide, particularly anteriorly; very narrow mid-ventrally.

Description. Carapace medium sized, thin-shelled, and subcylindrical. A weak ventral overlap of the LV over the RV. Anterior margin extended in ventral half, convex in dorsal one. Posterior margin asymmetrically rounded and slightly upturned. Dorsal and ventral margins straight and parallel. Cardinal angles obtuse. Maximum length subventral. Height fairly uniform along length. In dorsal view, posterior end blunt, anterior end acute, and width relatively uniform, convergent anteriorly. Shell surface predominantly smooth. The anterior third of the carapace ventro-laterally striate, extending anteriorly as four or five weak subparallel marginal ribs. Inner lamella wide, particularly anteriorly; very narrow mid-ventrally. Anterior vestibule large, very deep. Selvage quite narrow, inconspicuous. Marginal pore canals moderate in number, simple, short anteriorly and posteriorly. Hinge adont.Adductor muscle scars as for the genus, forming a very small, subrounded group of four barely visible imprints. Although this genus presents females and males distinguished by the copulatory organs, since Van Morkhoven (1963) it is known that sexual differences are not clear in the hard parts of Copytus . However, we identified sexual dimorphism in the carapace of this new species, i.e., males are smaller and lower than females.

Geographic and stratigraphic distribution. In this study, Copytus wuerdigae sp. nov. was found in modern sediments along the southern Brazilian coast between the Rio Grande do Sul State (33°52’S) and the Rio de Janeiro State (22°36’S) (see Tab. 1 View TABLE 1 ). It was reported from the Quaternary deposits of Rio Grande do Sul coastal plain (southernmost Brazil) by Madeira-Falcetta et al. (1980). Machado et al. (2005) recorded this species off Cabo Frio, in the 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 27 valves and eight carapaces were collected between 41 and 75 m on silt or fine sand.

Remarks. Notwithstanding the similarity of the present species with Copytus caligula Skogsberg, 1939 and C. malumiani Echevarría, 1987 , these three species differ in ornamentation and size. The Skogsberg’s species has a smoother and larger carapace. In turn, C. malumiani is shorter and with a rather less protruded anterior end, besides a different pattern of anteroventral ribs and a characteristic depression perpendicular to the anterodorsal margin. Neocytherideis impudicus [ impudica ] Whatley, Moguilevsky, Chadwick, Toy & Ramos, 1998, with occurrences in Argentina and Brazil, is somewhat similar to C. wuerdigae sp. nov., but in addition to the typically neocytherideid internal features, it is more elongate and larger, with a anteroventral ornamentation composed of more robust ribs arranged in a chevron pattern.