Leite et al.—Limnic Ostracoda from the Lower Cretaceous of Brazil
Family Cyprididae Baird, 1845 Subfamily Cypridinae Baird, 1845
Genus Brasacypris Krömmelbein, 1965b Type species.—Brasacypris ovum Krömmelbein, 1965b.
Diagnosis.—Large carapace, with length ~ 1.2mm. Oval shape in lateral view. Dorsal margin nearly straight to smoothly con- vex; ventral margin smoothly convex. Normal overlap. Surface smooth. In dorsal view, greatest width posterior to mid length.
Remarks.—The suprafamiliar classification follows Liebau (2005). Originally, this genus was left in Incertae Family. Brasacypris differs from Cyprinotus Brady, 1886, another member of the Subfamily Cypridinae, in the oval outline in lateral view and the convex margin (Do Carmo et al., 2004a; Do Carmo et al., 2013). However, Brasacypris is placed into the same suprageneric position as Cyprinotus. Krömmelbein (1965b) considered the diagnosis of Brasacypris ovum as the genus’ diagnosis, since it was until then monospecific. The sexual dimorphism was not taken into account as well, in spite of some variation in dorsal view in females and males. The original diagnosis also does not include variations in the carapace outline, mainly in the dorsal margin, considering that it might be nearly straight and the cardinal angles pronounced, although some species do not show these characteristics. The present work proposes a new diagnosis for the genus, emended from Krömmelbein (1965b), assuming that in lateral view, the dorsal margin shows variations, and in dorsal view, the greatest width is posterior to the mid length.
Brasacypris ovum Krömmelbein, 1965b emend. Figure 4.1–4.6
1965a Brasacypris ovum Krömmelbein, p. 213, pl. 15, fig. 19. 2004a Brasacypris ovum?; Do Carmo et al., p. 144, fig. 4.4.
Holotype.—A carapace (SMF Xe 5369) from the Itaparica and Candeias formations, Bahia State, Brazil (Krömmelbein, 1965a).
Diagnosis.—Large carapace, with rounded to oval shape in lateral view, and greatest length ventromedianly. Anterior car- dinal angle rounded. Posterior cardinal angles slightly rounded and visible only in right lateral view. Left valve larger than right valve, overlapping it at all margins. Smooth surface. Biconvex in dorsal view, with greatest width in the posterior third.
Occurrence.—Brazil: Tucano Basin, Itaparica and Candeias formations, Lower Cretaceous (Krömmelbein, 1965a), Itaparica Formation–Lower Candeias Formation interval (Krömmelbein, 1966), Rio da Serra Stage, Berriasian (Caixeta et al., 1994; Costa et al., 2007); São Francisco Basin, Quiricó Formation, Lower Cretaceous, Valanginian–Aptian.
Description.—Large carapace, rounded to oval in lateral view, with greatest height antero-medianly, and greatest length at mid-height. Left valve larger than right valve, overlapping all the
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margins of the carapace, more pronounced in the ventral and posterior margins. Dorsal margin smoothly convex, inclined to the posterior end, and ventral margin convex. Anterior cardinal angle curved; posterior cardinal angle smoothly curved, visible only in right lateral view. Anterior margin rounded and broader than the posterior one. Posterior margin sub-rounded, with inconspicuous convexity in the posteroventral region. Surface smooth. Inflated in dorsal view,with greatest width posteriorly to mid-length. Sexual dimorphism present, with males less inflated than females in dorsal view, and more elongated in lateral view.
Materials.—Two levels from São José creek, São José Farm, Presidente Olegário, Minas Gerais State, southeastern Brazil: MP-2895, four carapaces; MP-2960, three carapaces. One level from Quiricó creek, São José Farm, Presidente Olegário, Minas Gerais State, southeastern Brazil: MP-3421, 12 carapaces. Four- teen levels from Tereza Farm, João Pinheiro, Minas Gerais State, southeastern Brazil: MP-3318, five carapaces; MP-3326, 35 car- apaces; MP-3327, one carapace; MP-3335, two carapaces; MP-3426, one carapace; MP-3428, one carapace; MP-3429, six carapaces; MP-3431, 22 carapaces; MP-3434, 31 carapaces; MP-3436, four carapaces;MP-3437, 11 carapaces;MP-3438, four carapaces;MP-3442, two carapaces;MP-3443, two carapaces.
Remarks.—The recovered specimens are of two morphotypes: one that is short in lateral view, with the greatest height, and in dorsal view, with the greatest width; the other one is elongated in lateral view,with a smaller height, when compared to the first morphotype, and a smaller width in dorsal view. Considering the occurrence of two morphotypes, the first one is attributed to females, while the second one to males. We provide a new description for the species, as well as a new diagnosis. The specimens attributed to younger instars are in an advanced state of dissolution and/or deformed.
Brasacypris fulfaroi Dias-Brito et al., 2001 Figure 4.7–4.9
1960 Gen. et sp. indet Grekoff, p. 32, pl. 6, figs. 37, 38.
2001 Brasacypris fulfaroi Dias-Brito et al., p. 295, pl. 6, figs. 9–14.
Holotype.—A carapace (UNESPλ-BU45) from the Adamantina Formation, São Paulo State, Brazil (Dias-Brito et al., 2001).
Occurrence.—Brazil: Paraná Basin, Bauru Group, Adamantina Formation, Upper Cretaceous (Dias-Brito et al., 2001); São Francisco Basin, Quiricó Formation, Lower Cretaceous, Valanginian–Aptian?
Materials.—One level from Quiricó creek, São José Farm, Presidente Olegário, Minas Gerais State, southeastern Brazil: MP-3421, 26 carapaces; ten levels from Tereza Farm, João Pinheiro,Minas Gerais State, southeastern Brazil: MP-3318, two carapaces; MP-3322, one carapace; MP-3326, 17 carapaces; MP-3333, one carapace;MP-3429, four carapaces;MP-3431, 10 carapaces; MP-3434, two carapaces; MP-3436, one carapace; MP-3442, three carapaces; MP-3443, four carapaces.
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