Leite et al.—Limnic Ostracoda from the Lower Cretaceous of Brazil
Remarks.—The recovered specimens are well preserved; how- ever, they are smaller than specimens described by Dias-Brito et al. (2001). It is important to mention, however, that according to the original illustration (pl. 6, figs. 9–14), the holotype length is ~1.683mm.
Family Cyprideidae Baird, 1845 emend. Martin, 1940 Subfamily Cyprideinae Martin, 1940
Genus Cypridea Bosquet, 1852
Type species.—Cypridea granulosa Sowerby, 1836 (designated by Sylvester-Bradley, 1949).
Remarks.—The suprafamilial classification follows Liebau (2005), and Sames (2011) for family and other infrafamilial taxa. When Bosquet (1852) proposed the genus, he did not provide a diagnosis, indicating only the ventral beak as the main characteristic. Jones (1885) described the genus in greater detail, and determined a diagnosis based on the ventral beak, notch, and carapace ornamentation. During the following years, sev- eral authors (Anderson, 1939; Sylvester-Bradley, 1949; Martin, 1958; Moore and Pitrat, 1961; Van Morkhoven, 1963; Horne and Colin, 2005; Do Carmo et al., 2008; Sames, 2011) proposed diagnoses for the genus, with some variability, as well as several subgenera and subspecies. Sylvester-Bradley (1949), particu- larly, determined the ventral beak in each valve, as well as the ventral notch, as a distinct diagnostic characteristic. Do Carmo et al. (2008), following Van Morkhoven (1963), included the genus Hourcqia Krömmelbein, 1965a as a synonym of Cypri- dea. On the other hand, Sames (2011) followed Moore and Pitrat (1961), where several subgenera are included.
Cypridea hystrix Krömmelbein, 1962 emend. Figure 4.10–4.14
1962 Cypridea hystrix Krömmelbein, p. 507, pl. 55, fig. 18.
1962 Cypridea hystricoides Krömmelbein, p. 507, pl. 55, fig. 19.
Holotype.—A carapace (SMF Xe 4173) from the lower Ilha Formation layers, upper portion, Bahia State, Brazil (Krömmelbein, 1962).
Diagnosis.—Medium-size carapace, with trapezoidal shape. Pronounced anterior cardinal angle. Ventral beak and notch well developed. Pronounced nodules, mainly in the ocular region and posterior regions. Smaller nodules throughout the carapace, mainly in the anterior region. Porecanals spread throughout the surface of the carapace.
Occurrence.—Brazil: Recôncavo Basin, Ilhas Formation, Rio da Serra Stage, Lower Cretaceous (Krömmelbein, 1962; Por- opat and Colin, 2012a); Paracypridea brasiliensis Zone, coded as NRT-O04, with occurrence well marked in the Paracypridea bicallosa and Paracypridea maacki subzones, coded as NRT- O04.3 and NRT-O04.4, respectively (Viana et al., 1971; Cunha and Moura, 1979; Regali and Viana, 1989), Valanginian (Caixeta et al., 1994); São Francisco Basin, Quiricó Formation, Lower Cretaceous, Valanginian.
669
Description.—Medium-size carapace, sub-oval to sub- rectangular in lateral view, with greatest height anteriorly and greatest length at mid-height. Left valve larger than right valve, overlapping all the margins of the carapace. Dorsal margin nearly straight, with inconspicuous anterior hump; ventral margin nearly straight, with both ventral beak and notch pro- nounced. Anterior margin rounded. Posterior margin sub-roun- ded, slightly smaller than the anterior one. Reticulated ornamentation. Two pronounced nodules in each valve, in posterior to mid-height region. Smaller nodules lined and con- centrated on the anterior margin. Smaller nodules scattered throughout the surface. In dorsal view, greatest width poster- iorly. Sexual dimorphism present: males longer in lateral view, with lower anterior margin, and narrower compared to the females.
Materials.—Seven intervals from Tereza Farm, João Pinheiro, Minas Gerais State, southeastern Brazil: MP-3323, one car- apace; MP-3324, one carapace; MP-3325, one carapace; MP- -3326, six carapaces; MP-3428, two carapaces; MP-3434, two carapaces; MP-3437, two carapaces.
Remarks.—Cypridea hystrix has an outline and dimensions similar to Cypridea hystricoides Krömmelbein, 1962, however in dorsal view, Cypridea hystrix is broader. The nodules are similar in both species, as well as the outline and size. These similarities may indicate sexual dimorphism, and that both species are one and the same (i.e., Cypridea hystrix would be the female and C. hystricoides, the male) (Leite et al., 2016). Krömmelbein (1962) noted that Cypridea hystricoides and Cypridea hystrix are very similar, and some type of relationship can be established, how- ever their stratigraphical occurrences are different: Cypridea hystricoides occurs in the upper layers of the upper portion in Ilhas Formation, while Cypridea hystrix occurs in the upper layers of the lower portion in Ilhas Formation, Recôncavo Basin. In the present work, considering the good preservation of the specimens, as well as the presence of narrower and broader individuals, a new description and diagnosis are presented, emended from Krömmelbein (1962), placing Cypridea hystricoides as a junior synonym of Cypridea hystrix.
Cypridea conjugata Krömmelbein and Weber, 1971 emend. Figure 5.1–5.7
1971 Cypridea conjugata Krömmelbein and Weber, p. 71, pl. 1, figs. 4, 5.
Holotype.—A left valve (BfB, type Nr. 7772) from the São Sebastião layers, Bahia State, Brazil (Krömmelbein and Weber, 1971).
Diagnosis.—Medium-size carapace. Straight and pronounced beak, exceeding the ventral margin. Reticulated ornamentation all through the surface. Right valve larger than left valve. Sur- face with or without nodules. When present, nodules are in ocular region, positioned dorsally to medianly. Smaller nodules distributed along the surface.
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