Introduction
The usage of limnic ostracodes in the study of sedimentary basins is largely based on their bioestratigraphic potential (Milhomem et al., Reference Milhomem, Viviers and Galm2001). Continental ostracodes are present in the pre-salt interval of Atlantic basins, especially on the Brazilian coast, and constitute important tools for the understanding of rift lacustrine systems related to the opening of the proto-South Atlantic Ocean, during the Early Cretaceous (Poropat and Colin, Reference Poropat and Colin2012b).
Ostracodes are small crustaceans with mean size of 1 mm that have a calcitic bivalve carapace and inhabit practically all types of aquatic environments, from marine to humid terrestrial (Horne et al., Reference Horne, Cohen and Martens2002). They are among the most diverse group of living crustaceans, and possess a rich fossil record due to their calcified valves being easily preserved in sediments and rocks (Cohen et al., Reference Cohen, Martin and Kornicker1998).
This work represents a detailed taxonomic study on Ostracoda from the Quiricó Formation, Lower Cretaceous of the São Francisco Basin, in the Minas Gerais State, Brazil. The samples are from three outcrops: (1) Tereza Farm, in João Pinheiro Municipality; (2) from the banks of São José creek, Presidente Olegário Municipality; and (3) from the banks of Quiricó creek, Presidente Olegário Municipality (Fig. 1).
Figure 1 Locality map and access routes of the studied outcrops.
The Quiricó Formation is the only Mesozoic unit of the São Francisco Basin that contains ostracodes (Do Carmo et al., Reference Do Carmo, Tomassi and Oliveira2004a; Campos and Do Carmo, Reference Campos and Do Carmo2005; Bittencourt et al., Reference Bittencourt, Kuchenbecker, Vasconcelos and Meyer2015). The taxonomy, paleoecology, and stratigraphic and geographic distribution of the ostracode species herein identified can supply information on the chronostratigraphic positioning of the Quiricó Formation. These data contribute to the knowledge on the Cretaceous biodiversity in Brazilian continental deposits, improving the biostratigraphic correlation with other Cretaceous basins, especially those on the South America and Africa continental margins, for the Berremian–Aptian interval.
Geologic setting
The intracratonic São Francisco Basin has little deformation in its central portion, despite being somewhat deformed on the borders due to the Brasília and Araçuaí compressional mobile belts, in the west and in the east, respectively. The Proterozoic sedimentary rocks are covered by Phanerozoic ones, the latter composed of remaining sedimentary spots of Permian–Carboniferous age, Early Cretaceous sedimentary rocks, Late Cretaceous volcanic rocks, and a plateau composed of Late Cretaceous sandstones. From base to top, the São Francisco Basin was filled in by four supersequences: (1) rift, (2) intracratonic, (3) intracratonic/foreland, and (4) sanfranciscan (Zalán and Silva, Reference Zalán and Silva2007).
The rift supersequence (Paleoproterozoic–Mesoproterozoic) consists of the Espinhaço Supergroup and Arai Group. In the Neoproterozoic, the intracratonic supersequence consists of two groups, Macaúbas and Paranóa, and the Bambuí Group forms the intracratonic/foreland supersequence (Zalán and Silva, Reference Zalán and Silva2007).
The Phanerozoic sequence spreads among the Minas Gerais, Bahia, and Piauí states. It is composed, from base to top, by the Santa Fé (Permian–Carboniferous), Areado (Lower Cretaceous), Mata da Corda (Upper Cretaceous), and Urucuia (Upper Cretaceous) groups (Fig. 2) (Campos and Do Carmo, Reference Campos and Do Carmo2005; Zalán and Silva, Reference Zalán and Silva2007). The Santa Fé Group consists of glacial records with fluvial-glacial, glacial-lacustrine, and eolic periglacial facies. The Areado Group consists of sedimentary rocks. The Mata da Corda Group consists of pyroclastic alkaline volcanic rocks and epiclastic proximal sedimentary rocks. The Urucuia Group consists of eolic sandstones and fluvial sandstones, conglomerates, and pelitic rocks (Campos and Do Carmo, Reference Campos and Do Carmo2005).
Figure 2 Chronostratigraphic column representing the Phanerozoic sequence of the São Francisco Basin (Do Carmo et al., Reference Do Carmo, Tomassi and Oliveira2004a, adapted according to Campos and Dardenne, Reference Campos and Dardenne1997).
The Areado Group is distributed throughout the basin, and its wide lateral variation of lithofacies results from simultaneous action of several depositional environments. Its formations, from base to top, are Abaeté, Quiricó, and Três Barras. To the south, the Abaeté Formation is composed of alluvial fan deposits, which produced immature matrix-supported conglomerates; in the rest of the basin, the Abaeté Formation consists of mature clast-supported conglomerates, deposited by interlaced rivers. The Quiricó Formation was deposited in a lacustrine system, with interstratified siltstones that prevail at the base of the sequence, besides fine-, medium-, and coarse-grained sandstones, and more frequently in the upper part of the sequence, shales and limestones. Locally, in the region of Presidente Olegário, the Quiricó Formation is a dark, fossiliferous, calcareous, papyraceous shale that is rich in organic matter. The Três Barras Formation has more lithological diversity and rock volume. It was deposited in fluvial, fluvial-deltaic, and eolic systems and is composed of heterogeneous sandstones (Campos and Dardenne, Reference Campos and Dardenne1997; Campos and Do Carmo, Reference Campos and Do Carmo2005).
About nine genera of ostracodes are known from the Quiricó Formation, all of which are from the Sono River, in João Pinheiro, and Carmo do Paranaíba municipalities (Do Carmo et al., Reference Do Carmo, Tomassi and Oliveira2004a; Campos and Do Carmo, Reference Campos and Do Carmo2005; Bittencourt et al., Reference Bittencourt, Kuchenbecker, Vasconcelos and Meyer2015). In these localities, conchostacans and coelacanthiform fishes from the genus Mawsonia Woodward in Mawson and Woodward, Reference Mawson and Woodward1907, were also recorded, in pelitic rocks (Carvalho and Maisey, Reference Carvalho and Maisey2008; Bittencourt et al., Reference Bittencourt, Kuchenbecker, Vasconcelos and Meyer2015). Palynomorphs and amorphous organic matter were also found in dark fossiliferous shale from the region of Presidente Olegário, together with the fish species Dastilbe moraesi Silva-Santos in Scorza and Santos, Reference Scorza and Silva-Santos1955 and leaf impressions. Dastilbe moraesi is restricted to the Lower Cretaceous, and commonly is considered a fresh-water dweller (Davis and Martill, Reference Davis and Martill1999). The palynomorphs present in the shale layers indicate a Barremian Age, or earlier (Campos and Do Carmo, Reference Campos and Do Carmo2005), while pollen found in upper levels indicates an Aptian Age (Bittencourt et al., Reference Bittencourt, Kuchenbecker, Vasconcelos and Meyer2015).
Materials and methods
We collected and analyzed 168 samples. The rocks described in the Tereza farm correspond to a lower portion of the Quiricó Formation and are predominantly composed of sandstones. The other two outcrops (São José farm, on the banks of the São José and Quiricó rivers) correspond to an upper portion, with the presence of shale layers. During fieldwork, complete lithostratigraphic columns were made for each outcrop, with detailed sampling.
The samples were processed in the Micropaleontology Laboratory, according to the following protocol: (1) they were fragmented into small parts, and further with the help of hydrogen peroxide; (2) washed through a sequence of sieves, with opening of 600, 250, 150, 90, and 53 µm, withsediments <53 µm also retained; and (3) material from each sieve was oven dried and picked under stereomicroscope.
Repository and institutional abbreviation
The samples are housed in the Micropaleontology Collection (MP) of the Geosciences Museum of the University of Brasília. The specimens illustrated are part of the Research Collection (CP) of the Geosciences Museum of the University of Brasília.
Systematic paleontology
Suprageneric taxonomy follows Hou et al. (Reference Hou, Gõu and Chén2002), Liebau (Reference Liebau2005), and Sames (Reference Sames2009, Reference Sames2011). The morphological terminology is based on Kesling (Reference Kesling1951) and Do Carmo et al. (Reference Do Carmo, Coimbra, Whatley, Antonietto and De Paiva Citon2013). Sixteen ostracode species were recovered from the Quiricó Formation.
Subclass Ostracoda Latreille, Reference Latreille1802
Order Podocopida Sars, Reference Sars1866
Suborder Cypridocopina Jones, Reference Jones1901
Superfamily Cypridoidea Baird, Reference Baird1845
Family Quadracyprididae Hou et al., Reference Hou, Gõu and Chén2002
Subfamily Quadracypridinae Hou et al., Reference Hou, Gõu and Chén2002
Genus Harbinia Tsao, Reference Tsao1959 emend. Hou, Reference Hou1984
Type species
Harbinia hapla Tsao, Reference Tsao1959.
Remarks
The suprafamilial classification follows Liebau (Reference Liebau2005); for family and other infrafamilial taxa, classification follows Hou et al. (Reference Hou, Gõu and Chén2002), who proposed the family Quadracyprididae, subfamily Quadracypridinae, encompassing the genera Quadracypris, Nanxiongium, Harbinia, and Sinocypris. The genus Harbinia is widely discussed by Do Carmo et al. (Reference Do Carmo, Whatley, Queiroz Neto and Coimbra2008) due to its similarity to Pattersoncypris Bate, Reference Bate1972. The type species Pattersoncypris micropapillosa Bate, Reference Bate1972 is considered a junior synonym of Harbinia Tsao, Reference Tsao1959. The subspecies described by Krömmelbein and Weber (Reference Krömmelbein and Weber1971) belonging to Hourcqia Krömmelbein, Reference Krömmelbein1965b (i.e., Hourcqia angulata angulata Krömmelbein and Weber, Reference Krömmelbein and Weber1971; Hourcqia angulata salitrensis Krömmelbein and Weber, Reference Krömmelbein and Weber1971; Hourcqia angulata sinuata Krömmelbein and Weber, Reference Krömmelbein and Weber1971; and Hourcqia angulata symmetrica Krömmelbein and Weber, Reference Krömmelbein and Weber1971) were reassigned to Harbinia and elevated to the level of species. A revision of Hourcqia Krömmelbein, Reference Krömmelbein1965b, Pattersoncypris Bate, Reference Bate1972, and Harbinia Tsao, Reference Tsao1959 by Poropat and Colin (Reference Poropat and Colin2012a) led to revalidation of the genus Pattersoncypris, encompassing the species Harbinia micropapillosa, H. salitrensis, and H. sinuata. They also proposed the new genus Kroemmelbeincypris Poropat and Colin, Reference Poropat and Colin2012a, including in it the species Harbinia angulata and H. symmetrica. That proposal was based on the inclined posterior margin, which would differentiate those species from Harbinia. Several characteristics described for Kroemmelbeincypris (e.g., valve overlap, outline, and ornamentation pattern) are also present in Harbinia. Tomé et al., (Reference Tomé, Lima Filho and Neumann2014) invalidated the genus Kroemmelbeincypris due to the small variation associated with polymorphism present in some species of Harbinia, and accepted the validity of Pattersoncypris.
Harbinia aff. Harbinia angulata (Krömmelbein and Weber, Reference Krömmelbein and Weber1971)
Figure 3 Species of the genus Harbinia Tsao, Reference Tsao1959 emend. Hou, Reference Hou1984 from the outcrop by the São José River, São José Farm, Presidente Olegário municipality, Minas Gerais State, southeastern Brazil. (1–3) Harbinia aff. H. angulata (Krömmelbein and Weber, Reference Krömmelbein and Weber1971), adult (CP-855), right lateral view (RLV), left lateral view (LLV), and dorsal view (DV). (4–6) Harbinia symmetrica (Krömmelbein and Weber, Reference Krömmelbein and Weber1971), adult (CP-859), right lateral view (RLV), left lateral view (LLV), and dorsal view (DV). (7–9) Harbinia aff. H. salitrensis (Krömmelbein and Weber, Reference Krömmelbein and Weber1971); (7, 9) adult (CP-857), right lateral view (RLV), and dorsal view (DV); (8) adult (CP-858), left lateral view (LLV). (10–12) Harbinia alta Antonietto et al., Reference Antonietto, Gobbo, Do Carmo, Assine, Fernandes and Lima e Silva2012, adult (CP-854), right lateral view (RLV), left lateral view (LLV), and dorsal view (DV). (13–15) Harbinia aff. H. crepata Do Carmo et al., Reference Do Carmo, Coimbra, Whatley, Antonietto and De Paiva Citon2013, adult (CP-856), left lateral view (LLV), right lateral view (RLV), and dorsal view (DV). Scale bars are 200 µm.
1971? Hourcqia angulata angulata Reference Krömmelbein and WeberKrömmelbein and Weber, p. 81, pl. 6, figs. 23–26.
2002? Pattersoncypris angulata angulata (Krömmelbein and Weber); Reference Coimbra, Arai and CarreñoCoimbra et al., p. 691, fig. 4.29.
2008? Harbinia angulata (Krömmelbein and Weber); Reference Do Carmo, Whatley, Queiroz Neto and CoimbraDo Carmo et al., p. 795, fig. 6.11.
2012b? Kroemmelbeincypris angulata (Krömmelbein and Weber); Reference Poropat and ColinPoropat and Colin, p. 709, fig. 4.5.
2014? Pattersoncypris angulata (Krömmelbein and Weber); Reference Tomé, Lima Filho and NeumannTomé et al., p. 165, fig. 10G–I.
Holotype
A carapace (BfB, type Nr. 7795) from the Post-Bahia Series, Riachuelo layers, Alagoas State, Brazil (Krömmelbein and Weber, Reference Krömmelbein and Weber1971).
Occurrence
Brazil: Sergipe-Alagoas Basin, Riachuelo Formation, upper Aptian (Krömmelbein and Weber, Reference Krömmelbein and Weber1971); Araripe Basin, Santana Formation, Romualdo Member, Aptian (Poropat and Colin, Reference Poropat and Colin2012b); Cedro Basin, deposits correlated to the Crato Formation, Aptian (Tomé, Reference Tomé2007); Jatobá Basin, Serra Negra, in deposits correlated to the Crato Formation, upper Aptian (Tomé et al., Reference Tomé, Lima Filho and Neumann2014); São Francisco Basin, Quiricó Formation, Lower Cretaceous, Aptian.
Materials
Four intervals from São José creek, São José Farm, Presidente Olegário, Minas Gerais State, southeastern Brazil: MP-2882, two carapaces; MP-2883, 40 carapaces; MP-2889, 35 carapaces; MP-2922, six carapaces.
Remarks
This species is easily identified by the marked posterior cardinal angle that coincides with the greatest length of the carapace, forming also a posterior lump in some instars (Tomé et al., Reference Tomé, Lima Filho and Neumann2014). The recovered individuals are poorly preserved, with evidence of dissolution.
Harbinia symmetrica (Krömmelbein and Weber, Reference Krömmelbein and Weber1971)
1971 Hourcqia angulata symmetrica Reference Krömmelbein and WeberKrömmelbein and Weber, p. 81, pl. 6, fig. 25.
1990 Cultella sp. 1 Reference Dépêche, Bérthou and CamposDépêche et al., p. 308, pl. 2, fig. 2.
1990 Pattersoncypris cf. angulata angulata (Krömmelbein and Weber); Reference MusacchioMusacchio, p. 564, pl. 1, fig. 4.
1990 Hourcqia angulata symmetrica Krömmelbein and Weber; Reference Silva-Telles and VianaSilva-Telles and Viana, p. 325, pls. 1, 3, fig. 8.
1999 Pattersoncypris angulata symmetrica (Krömmelbein and Weber, Reference Krömmelbein and Weber1971); Reference BateBate, p. 289.
2002 Pattersoncypris angulata symmetrica (Krömmelbein and Weber); Reference Coimbra, Arai and CarreñoCoimbra et al., p. 691, Fig. 4.30.
Figure 4 Species of the genus Brasacypris Krömmelbein, Reference Krömmelbein1965b from the outcrop on the banks of the São José and Quiricó rivers, São José Farm, Presidente Olegário municipality, and species of the genus Cypridea Bosquet, Reference Bosquet1852 from the outcrop at Tereza Farm, João Pinheiro municipality, Minas Gerais State, southeastern Brazil. (1–6) Brasacypris ovum Krömmelbein Reference Krömmelbein1965b emend. (1–3) Female adult (CP-861), right lateral view (RLV), left lateral view (LLV), and dorsal view (DV); (4–6) male adult (CP-862), right lateral view (RLV), left lateral view (LLV), and dorsal view (DV). (7–9) Brasacypris fulfaroi Dias-Brito et al., Reference Dias-Brito, Musacchio, Castro, Maranhão, Suárez and Rodrigues2001, adult (CP-860), right lateral view (RLV), left lateral view (LLV), and dorsal view (DV). (10–14) Cypridea hystrix Krömmelbein, Reference Krömmelbein1962 emend. (10–12) Female adult (CP-865), right lateral view (RLV), left lateral view (LLV), and dorsal view (DV). (13, 14) Male adult (CP-866), left lateral view (LLV) and right lateral view (RLV). Scale bars are 200 µm.
2004a Harbinia symmetrica (Krömmelbein and Weber); Reference Do Carmo, Tomassi and OliveiraDo Carmo et al., p. 144, fig. 4.1.
2004a Harbinia sp. 1 Reference Do Carmo, Tomassi and OliveiraDo Carmo et al., p. 144, fig. 4.2.
2006 Harbinia aff. Harbinia symmetrica (Krömmelbein and Weber); Reference Ramos, Rossetti and PazRamos et al., p. 344, fig. 4M–P.
2008 Harbinia symmetrica (Krömmelbein and Weber); Reference Do Carmo, Whatley, Queiroz Neto and CoimbraDo Carmo et al., p. 795, fig. 6.9.
2012b Kroemmelbeincypris symmetrica (Krömmelbein and Weber); Reference Poropat and ColinPoropat and Colin, p. 709, fig. 4.4.
Holotype
A carapace (BfB, type Nr. 7797), from the Codó layers, Maranhão State, Brazil (Krömmelbein and Weber, Reference Krömmelbein and Weber1971).
Occurrence
Brazil: Araripe Basin, Rio da Batateira Formation, and Santana Formation, Crato, Ipubi, and Romualdo members, Aptian (Coimbra et al., Reference Coimbra, Arai and Carreño2002), Harbinia spp. 201–218 Zone, coded as NRT-O11 (Do Carmo et al., Reference Do Carmo, Whatley, Queiroz Neto and Coimbra2008), Alagoas Stage (Schaller, Reference Schaller1968; Moura, Reference Moura1987), upper Aptian–lower Albian (Antonietto et al., Reference Antonietto, Gobbo, Do Carmo, Assine, Fernandes and Lima e Silva2012); Parnaíba Basin, Codó Formation (Krömmelbein and Weber, Reference Krömmelbein and Weber1971; Ramos et al., Reference Ramos, Rossetti and Paz2006); São Francisco Basin, Quiricó Formation, Lower Cretaceous, Aptian. Africa: Gabon Basin, Gamba Formation; Congo and Cabinda basins, Chela Formation (Grosdidier et al., Reference Grosdidier, Braccini, Dupont and Moron1996; Bate, Reference Bate1999).
Materials
Four levels from Quiricó creek, São José Farm, Presidente Olegário, Minas Gerais State, southeastern Brazil: MP-2879, five carapaces; MP-2882, two carapaces; MP-2883, 50 carapaces; MP-2885, two carapaces.
Remarks
Poropat and Colin (Reference Poropat and Colin2012b) included this species in the genus Kroemmelbeincypris based on its outline. However, Tomé et al. (Reference Tomé, Lima Filho and Neumann2014) invalidated this genus, justifying that these differences resulted from environmentally induced polymorphism.
Harbinia aff. H. salitrensis (Krömmelbein and Weber, Reference Krömmelbein and Weber1971)
1971? Hourcqia angulata salitrensis Reference Krömmelbein and WeberKrömmelbein and Weber, p. 81, pl. 6, fig. 26.
1972? Pattersoncypris angulata salitrensis (Krömmelbein and Weber); Reference BateBate, p. 389, Fig. 11.
2006? Harbinia salitrensis (Krömmelbein and Weber); Reference Ramos, Rossetti and PazRamos et al., p. 344, fig. 4Q–T.
2008? Harbinia salitrensis (Krömmelbein and Weber); Reference Do Carmo, Whatley, Queiroz Neto and CoimbraDo Carmo et al., p. 795, fig. 6.8.
2012? Harbinia salitrensis (Krömmelbein and Weber); Reference Antonietto, Gobbo, Do Carmo, Assine, Fernandes and Lima e SilvaAntonietto et al., p. 662, fig. 4.1–4.10.
2012b? Pattersoncypris salitrensis (Krömmelbein and Weber); Reference Poropat and ColinPoropat and Colin, p. 709, fig. 4.3.
2014? Pattersoncypris salitrensis (Krömmelbein and Weber); Reference Tomé, Lima Filho and NeumannTomé et al., p. 165, fig. 10G–I.
Holotype
A carapace (BfB, type Nr. 7798), from the Santana layers, Pernambuco State, Brazil (Krömmelbein and Weber, Reference Krömmelbein and Weber1971).
Occurrence
Brazil: Araripe Basin, Santana Formation, Romualdo Member, Aptian (Krömmelbein and Weber, Reference Krömmelbein and Weber1971; Poropat and Colin, Reference Poropat and Colin2012b; Antonietto et al., Reference Antonietto, Gobbo, Do Carmo, Assine, Fernandes and Lima e Silva2012; Tomé et al., Reference Tomé, Lima Filho and Neumann2014); Grajaú Basin, Codó Formation, Aptian (Do Carmo et al., Reference Do Carmo, Whatley, Queiroz Neto and Coimbra2008); São Francisco Basin, Quiricó Formation, Lower Cretaceous, Aptian.
Materials
Five levels from São José creek, São José Farm, Presidente Olegário, Minas Gerais State, southeast Brazil: MP-2879, 17 carapaces; MP-2882, two carapaces; MP-2883, 25 carapaces; MP-2890, two carapaces; MP-2922, six carapaces.
Remarks
Harbinia salitrensis was redescribed by Antonietto et al. (Reference Antonietto, Gobbo, Do Carmo, Assine, Fernandes and Lima e Silva2012) due to the absence of illustrations and incomplete description in Krömmelbein and Weber (Reference Krömmelbein and Weber1971), because the holotype was deformed. The individuals herein studied are deformed and with dissolution.
Harbinia alta Antonietto et al., Reference Antonietto, Gobbo, Do Carmo, Assine, Fernandes and Lima e Silva2012
1989 Hourcqia angulata angulata Krömmelbein and Weber; Reference Viana, Brito and Silva-TellesViana et al., p. 216, fig. 2a–c.
1990 Hourcqia angulata angulata Krömmelbein and Weber; Reference Dépêche, Bérthou and CamposDépêche et al., p. 304, pl. 1, figs. 1, 2.
1990 Hourcqia angulata angulata Krömmelbein and Weber; Reference Silva-Telles and VianaSilva-Telles and Viana, p. 320, pl. 3. Fig. 3.
2006 Harbinia angulata (Krömmelbein and Weber); Reference Ramos, Rossetti and PazRamos et al., p. 344, fig. 4E–H.
2006 Harbinia sp. Reference Ramos, Rossetti and PazRamos et al., p. 344, fig. 4U–Y.
2012 Harbinia alta Reference Antonietto, Gobbo, Do Carmo, Assine, Fernandes and Lima e SilvaAntonietto et al., p. 662, fig. 4.11–4.20.
2013 Harbinia alta Antonietto et al.; Reference Do Carmo, Coimbra, Whatley, Antonietto and De Paiva CitonDo Carmo et al., p. 94, fig. 3.5–3.8.
Holotype
A carapace (CP-584) from the Romualdo Member, Santana Formation, Pernambuco State, Brazil (Antonietto et al., Reference Antonietto, Gobbo, Do Carmo, Assine, Fernandes and Lima e Silva2012).
Occurrence
Brazil: Grajaú Basin, Codó Formation, upper Aptian (Ramos et al., Reference Ramos, Rossetti and Paz2006); Araripe Basin, Santana Formation, Crato, Ipubi, and Romualdo members, Aptian–Albian (Viana et al., Reference Viana, Brito and Silva-Telles1989; Silva-Telles and Viana, Reference Silva-Telles and Viana1990; Antonietto et al., Reference Antonietto, Gobbo, Do Carmo, Assine, Fernandes and Lima e Silva2012), Harbinia spp. 201–218 Zone, coded as NRT-O11 (Do Carmo et al., Reference Do Carmo, Whatley, Queiroz Neto and Coimbra2008), Alagoas Stage (Schaller, Reference Schaller1968; Moura, Reference Moura1987), upper Aptian–lower Albian (Antonietto et al., Reference Antonietto, Gobbo, Do Carmo, Assine, Fernandes and Lima e Silva2012); Potiguar Basin, Alagamar Formation, middle–upper Aptian (Do Carmo et al., Reference Do Carmo, Coimbra, Whatley, Antonietto and De Paiva Citon2013); São Francisco Basin, Quiricó Formation, Lower Cretaceous, Aptian.
Materials
Three levels from São José creek, São José Farm, Presidente Olegário, Minas Gerais State, southeastern Brazil: MP-2879, 50 carapaces; MP-2881, four carapaces; MP-2889, 40 carapaces.
Remarks
Species identified as Hourcqia angulata angulata Krömmelbein and Weber, Reference Krömmelbein and Weber1971 in Viana et al. (Reference Viana, Brito and Silva-Telles1989), Dépêche et al. (Reference Dépêche, Bérthou and Campos1990), and Silva-Telles and Viana (Reference Silva-Telles and Viana1990), and Harbinia angulata (Krömmelbein and Weber, Reference Krömmelbein and Weber1971) identified in Ramos et al. (Reference Ramos, Rossetti and Paz2006) belong to Harbinia alta. They are different from the species described by Krömmelbein and Weber (Reference Krömmelbein and Weber1971), especially in the height-length ratio and ornamentation. The specimens recovered are either dissolved or poorly preserved, and represented by several ontogenetic instars.
Harbinia aff. H. crepata Do Carmo et al., Reference Do Carmo, Coimbra, Whatley, Antonietto and De Paiva Citon2013
1990 Gen. indet. sp. aff. 207 Reference Silva-Telles and VianaSilva-Telles and Viana, p. 326, pl. 2, figs. 1, 3.
2013? Harbinia crepata Reference Do Carmo, Coimbra, Whatley, Antonietto and De Paiva CitonDo Carmo et al., p. 96, fig. 3.9–3.18.
Holotype
A carapace (MP-O-1579), from the Alagamar Formation, Ceará State, Brazil (Do Carmo et al., Reference Do Carmo, Coimbra, Whatley, Antonietto and De Paiva Citon2013).
Occurrence
Brazil: Araripe Basin, Santana Formation, Crato Member, Aptian (Silva-Telles and Viana, Reference Silva-Telles and Viana1990); Potiguar Basin, Alagamar Formation, middle–upper Aptian (Do Carmo et al., Reference Do Carmo, Coimbra, Whatley, Antonietto and De Paiva Citon2013); São Francisco Basin, Quiricó Formation, Lower Cretaceous, Aptian.
Materials
Two intervals from São José creek, São José Farm, Presidente Olegário, Minas Gerais State, southeastern Brazil: MP-2883, 20 carapaces; MP-2889, 35 carapaces.
Remarks
Harbinia crepata Do Carmo et al., Reference Do Carmo, Coimbra, Whatley, Antonietto and De Paiva Citon2013 differs from H. sinuata (Krömmelbein and Weber, Reference Krömmelbein and Weber1971), H. salitrensis (Krömmelbein and Weber, Reference Krömmelbein and Weber1971), and H. micropapillosa (Bate, Reference Bate1972) in its subtriangular elongated outline and its less-inclined hinge line (Do Carmo et al., Reference Do Carmo, Coimbra, Whatley, Antonietto and De Paiva Citon2013). The recovered specimens are better preserved than Harbinia alta and Harbinia aff. H. angulata, however they also show some degree of dissolution.
Family Cyprididae Baird, Reference Baird1845
Subfamily Cypridinae Baird, Reference Baird1845
Genus Brasacypris Krömmelbein, Reference Krömmelbein1965b
Type species
Brasacypris ovum Krömmelbein, Reference Krömmelbein1965b.
Diagnosis
Large carapace, with length ~1.2 mm. Oval shape in lateral view. Dorsal margin nearly straight to smoothly convex; ventral margin smoothly convex. Normal overlap. Surface smooth. In dorsal view, greatest width posterior to mid length.
Remarks
The suprafamiliar classification follows Liebau (Reference Liebau2005). Originally, this genus was left in Incertae Family. Brasacypris differs from Cyprinotus Brady, Reference Brady1886, another member of the Subfamily Cypridinae, in the oval outline in lateral view and the convex margin (Do Carmo et al., Reference Do Carmo, Tomassi and Oliveira2004a; Do Carmo et al., Reference Do Carmo, Coimbra, Whatley, Antonietto and De Paiva Citon2013). However, Brasacypris is placed into the same suprageneric position as Cyprinotus. Krömmelbein (Reference Krömmelbein1965b) 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 (Reference Krömmelbein1965b), 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, Reference Krömmelbein1965b emend.
1965a Brasacypris ovum Reference KrömmelbeinKrömmelbein, p. 213, pl. 15, fig. 19.
2004a Brasacypris ovum?; Reference Do Carmo, Tomassi and OliveiraDo Carmo et al., p. 144, fig. 4.4.
Holotype
A carapace (SMF Xe 5369) from the Itaparica and Candeias formations, Bahia State, Brazil (Krömmelbein, Reference Krömmelbein1965a).
Diagnosis
Large carapace, with rounded to oval shape in lateral view, and greatest length ventromedianly. Anterior cardinal 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, Reference Krömmelbein1965a), Itaparica Formation–Lower Candeias Formation interval (Krömmelbein, Reference Krömmelbein1966), Rio da Serra Stage, Berriasian (Caixeta et al., Reference Caixeta, Bueno, Magnavita and Feijó1994; Costa et al., Reference Costa, Milhomem, Bueno, Lima e Silva and Kosin2007); 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 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. Fourteen levels from Tereza Farm, João Pinheiro, Minas Gerais State, southeastern Brazil: MP-3318, five carapaces; MP-3326, 35 carapaces; 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., Reference Dias-Brito, Musacchio, Castro, Maranhão, Suárez and Rodrigues2001
1960 Gen. et sp. indet Reference GrekoffGrekoff, p. 32, pl. 6, figs. 37, 38.
2001 Brasacypris fulfaroi Reference Dias-Brito, Musacchio, Castro, Maranhão, Suárez and RodriguesDias-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., Reference Dias-Brito, Musacchio, Castro, Maranhão, Suárez and Rodrigues2001).
Occurrence
Brazil: Paraná Basin, Bauru Group, Adamantina Formation, Upper Cretaceous (Dias-Brito et al., Reference Dias-Brito, Musacchio, Castro, Maranhão, Suárez and Rodrigues2001); 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.
Remarks
The recovered specimens are well preserved; however, they are smaller than specimens described by Dias-Brito et al. (Reference Dias-Brito, Musacchio, Castro, Maranhão, Suárez and Rodrigues2001). It is important to mention, however, that according to the original illustration (pl. 6, figs. 9–14), the holotype length is ~1.683 mm.
Family Cyprideidae Baird, Reference Baird1845 emend. Martin, Reference Martin1940
Subfamily Cyprideinae Martin, Reference Martin1940
Genus Cypridea Bosquet, Reference Bosquet1852
Type species
Cypridea granulosa Sowerby, Reference Sowerby1836 (designated by Sylvester-Bradley, Reference Sylvester-Bradley1949).
Remarks
The suprafamilial classification follows Liebau (Reference Liebau2005), and Sames (Reference Sames2011) for family and other infrafamilial taxa. When Bosquet (Reference Bosquet1852) proposed the genus, he did not provide a diagnosis, indicating only the ventral beak as the main characteristic. Jones (Reference Jones1885) described the genus in greater detail, and determined a diagnosis based on the ventral beak, notch, and carapace ornamentation. During the following years, several authors (Anderson, Reference Anderson1939; Sylvester-Bradley, Reference Sylvester-Bradley1949; Martin, Reference Martin1958; Moore and Pitrat, Reference Moore and Pitrat1961; Van Morkhoven, Reference Van Morkhoven1963; Horne and Colin, Reference Horne and Colin2005; Do Carmo et al., Reference Do Carmo, Whatley, Queiroz Neto and Coimbra2008; Sames, Reference Sames2011) proposed diagnoses for the genus, with some variability, as well as several subgenera and subspecies. Sylvester-Bradley (Reference Sylvester-Bradley1949), particularly, determined the ventral beak in each valve, as well as the ventral notch, as a distinct diagnostic characteristic. Do Carmo et al. (Reference Do Carmo, Whatley, Queiroz Neto and Coimbra2008), following Van Morkhoven (Reference Van Morkhoven1963), included the genus Hourcqia Krömmelbein, Reference Krömmelbein1965a as a synonym of Cypridea. On the other hand, Sames (Reference Sames2011) followed Moore and Pitrat (Reference Moore and Pitrat1961), where several subgenera are included.
Cypridea hystrix Krömmelbein, Reference Krömmelbein1962 emend.
1962 Cypridea hystrix Reference KrömmelbeinKrömmelbein, p. 507, pl. 55, fig. 18.
1962 Cypridea hystricoides Reference KrömmelbeinKrömmelbein, p. 507, pl. 55, fig. 19.
Holotype
A carapace (SMF Xe 4173) from the lower Ilha Formation layers, upper portion, Bahia State, Brazil (Krömmelbein, Reference Krömmelbein1962).
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, Reference Krömmelbein1962; Poropat and Colin, Reference Poropat and Colin2012a); 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., Reference Viana, Gama Junior, Simões, Moura, Fonseca and Alves1971; Cunha and Moura, Reference Cunha and Moura1979; Regali and Viana, Reference Regali and Viana1989), Valanginian (Caixeta et al., Reference Caixeta, Bueno, Magnavita and Feijó1994); São Francisco Basin, Quiricó Formation, Lower Cretaceous, Valanginian.
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 pronounced. Anterior margin rounded. Posterior margin sub-rounded, slightly smaller than the anterior one. Reticulated ornamentation. Two pronounced nodules in each valve, in posterior to mid-height region. Smaller nodules lined and concentrated on the anterior margin. Smaller nodules scattered throughout the surface. In dorsal view, greatest width posteriorly. 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 carapace; 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, Reference Krömmelbein1962, 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., Reference Leite, Do Carmo and Antonietto2016). Krömmelbein (Reference Krömmelbein1962) noted that Cypridea hystricoides and Cypridea hystrix are very similar, and some type of relationship can be established, however 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 (Reference Krömmelbein1962), placing Cypridea hystricoides as a junior synonym of Cypridea hystrix.
Cypridea conjugata Krömmelbein and Weber, Reference Krömmelbein and Weber1971 emend.
Figure 5 Species of the genus Cypridea Bosquet, Reference Bosquet1852 and Neuquenocypris Musacchio, Reference Musacchio1973, from the outcrop at Tereza Farm, João Pinheiro municipality, Minas Gerais State, southeastern Brazil. (1–7) Cypridea conjugata Krömmelbein and Weber, Reference Krömmelbein and Weber1971 emend. (1–3) Adult with nodules (CP-863), right lateral view (RLV), left lateral view (LLV), and dorsal view (DV); (4, 5) adult without nodules (CP-864), right lateral view (RLV) and left lateral view (LLV); (6, 7) adult with nodules (CP-863), porecanals details. (8–13) Cypridea infima Krömmelbein and Weber, Reference Krömmelbein and Weber1971 emend. (8–10) Adult (CP-867), right lateral view (RLV), left lateral view (LLV), and dorsal view (DV); (11–13) adult (CP-867), detail of the porecanals in nodule region and detail of porecanals on the surface of the carapace. (14–16) Cypridea jequiensis Krömmelbein and Weber, Reference Krömmelbein and Weber1971, adult (CP-868), right lateral view (RLV), left lateral view (LLV), and dorsal view (DV). (17–19) Neuquenocypris (Protoneuquenocypris) antiqua Musacchio and Simeoni, Reference Musacchio and Simeoni1991, adult (CP-869), right lateral view (RLV), left lateral view (LLV), and dorsal view (DV). (1–5, 14–19) Scale bars are 200 µm; (6, 7) scale bars are 5 µm; (8–10) scale bars are 100 µm; (11–13) scale bars are 20 µm.
1971 Cypridea conjugata Reference Krömmelbein and WeberKrömmelbein 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, Reference Krömmelbein and Weber1971).
Diagnosis
Medium-size carapace. Straight and pronounced beak, exceeding the ventral margin. Reticulated ornamentation all through the surface. Right valve larger than left valve. Surface with or without nodules. When present, nodules are in ocular region, positioned dorsally to medianly. Smaller nodules distributed along the surface.
Occurrence
Brazil: Recôncavo Basin, São Sebastião Formation, Lower Cretaceous (Krömmelbein and Weber, Reference Krömmelbein and Weber1971; Poropat and Colin, Reference Poropat and Colin2012a), Barremian (Silva et al., Reference Silva, Caixeta, Milhomem and Kosin2007). São Francisco basin, Quiricó Formation, Lower Cretaceous, Valanginian.
Description
Medium-size carapace, sub-rectangular in lateral view, with greatest height anteriorly, and greatest length along mid-height. Right valve larger than left valve, overlapping the anterior, posterior, and ventral margins of the carapace. Dorsal margin nearly straight, with inconspicuous hump anteriorly; ventral margin nearly straight, sub-parallel to the dorsal margin. Anterior margin rounded; posterior margin sub-rounded. Reticulated ornamentation all through the carapace. May exhibit nodules along the surface of the carapace, a smaller number of nodules, or complete absence of them. When present, nodules are in the ocular region, dorsally to medianly, and smaller ones scattered. Normal porecanals present in eye region, rounded. In dorsal view, larger nodules are evident, with greatest width posteriorly to mid-length.
Materials
Four levels from Tereza Farm, João Pinheiro, Minas Gerais State, southeastern Brazil: MP-3324, two carapaces; MP-3326, four carapaces; MP-3431, one carapace; MP-3434, 25 carapaces.
Remarks
Due to the presence of specimens with and without nodules, it is necessary to propose a new diagnosis and description to Cypridea conjugata. Leite et al. (Reference Leite, Do Carmo and Antonietto2016) discussed the similarity between specimens with and without nodules, in outline and in size, as well as valve relation. However, specimens with poorly developed nodules were not recovered. In the present work, such middle-ground specimens are recorded for the first time. Besides the small quantity, they always occur in specific regions of the carapace, and show marked normal porecanals. Do Carmo et al. (Reference Do Carmo, Whatley and Timberlake1999) suggested that the growth of nodules in Theriosynoecum kirtlingtonense Bate, Reference Bate1965 indicates high salinity, caused by the reinforcement of the excretory system to maintain osmoregulation. In the same way, some porecanals in ostracodes are part of the excretory system, when present in nodule region, indicating that nodules are of phenotypical origin as in Cyprideis torosa (Jones, Reference Jones1850) (Do Carmo et al., Reference Do Carmo, Whatley and Timberlake1999). In the present work, considering the good preservation, the presence of individuals with and without nodules, a new description and diagnosis are proposed, emended from Krömmelbein (Reference Krömmelbein1962).
Cypridea infima Krömmelbein and Weber, Reference Krömmelbein and Weber1971 emend.
1971 Cypridea infima Reference Krömmelbein and WeberKrömmelbein and Weber, p. 71, pl. 1, fig. 3.
Holotype
A carapace (BfB, type Nr. 7770) from the Candeias layers, lower and middle portions, Bahia State, Brazil (Krömmelbein and Weber, Reference Krömmelbein and Weber1971).
Diagnosis
Very small carapace, with oval outline in lateral view. Reticulated surface, with normal porecanals throughout the carapace. Left valve with prominent angular projection in the posteroventral region.
Occurrence
Brazil: Recôncavo Basin, Candeias Formation, lower and middle portions, Lower Cretaceous, (Krömmelbein and Weber, Reference Krömmelbein and Weber1971; Poropat and Colin, Reference Poropat and Colin2012a), Berriasian–Valanginian (Silva et al., Reference Silva, Caixeta, Milhomem and Kosin2007); São Francisco Basin, Quiricó Formation, Lower Cretaceous, Valanginian–Hauterivian/Aptian?
Description
Very small carapace, sub-oval in lateral view, with greatest height antero-medianly, and greatest length in mid-height. Left valve larger than right valve, overlapping all the margins of the carapace, especially the ventral margin. Left valve with prominent angular projection in the posteroventral region. Dorsal margin convex, inclined posteriorly; ventral margin nearly straight to smoothly convex. Pronounced ventral beak and notch without exceeding the ventral margin. Anterior margin rounded. Posterior margin sub-rounded and smaller than the anterior one. Punctate ornamentation. Small nodules present throughout the carapace. Surface covered by very tiny rounded porecanals, also present in nodule region. In dorsal view, greatest width posteriorly.
Materials
Nine levels from Tereza Farm, João Pinheiro, Minas Gerais State, southeastern Brazil: MP-3318, two carapaces; MP-3322, three carapaces; MP-3427, five carapaces; MP-3428, five carapaces; MP-3431, three carapaces; MP-3433, two carapaces; MP-3434, three carapaces; MP-3444, two carapaces.
Remarks
Krömmelbein and Weber (Reference Krömmelbein and Weber1971) described only the porecanals through the carapace. In the present work, the good preservation of material allowed observation of a punctate ornamentation, and that the porecanals are present along the carapace and in the small nodules. For this reason, a new description and diagnosis are herein presented, emended from Krömmelbein and Weber (Reference Krömmelbein and Weber1971).
Cypridea jequiensis Krömmelbein and Weber, Reference Krömmelbein and Weber1971
1971 Cypridea jequiensis Reference Krömmelbein and WeberKrömmelbein and Weber, p. 75, pl. 3, fig. 11.
Holotype
A carapace (BfB, type Nr. 7781) from the Post-Bahia Series, Jiquiá layers, Alagoas State, Brazil (Krömmelbein and Weber, Reference Krömmelbein and Weber1971).
Occurrence
Brazil: Sergipe-Alagoas Basin, Jiquiá Formation, Post-Bahia Series, Lower Cretaceous (Krömmelbein and Weber, Reference Krömmelbein and Weber1971; Poropat and Colin, Reference Poropat and Colin2012a; Antonietto, Reference Antonietto2015), Penedo Formation?, Barremian?–Aptian, Cypridea faveolata Subzone, coded as BRT-O09.3, upper portion of Petrobrasia diversicostata Zone, coded as NRT-O09 (Moura, Reference Moura1987; Rangel et al., Reference Rangel, Esteves, Feijó and Martins1994); São Francisco Basin, Quiricó Formation, Lower Cretaceous, Valanginian.
Materials
Four levels from Tereza Farm, João Pinheiro, Minas Gerais State, southeastern Brazil: MP-3318, four carapaces; MP-3324, 15 carapaces; MP-3325, one carapace; MP-3327, four carapaces.
Remarks
After extensive revision of the Cypridea Bosquet, Reference Bosquet1852 species occurring in Brazil, the species found in the Quiricó Formation are attributed to Cypridea jequiensis Krömmelbein and Weber, Reference Krömmelbein and Weber1971 due to the smooth surface and trapezoidal shape. However, it must be noticed that in the São Francisco Basin, these occurrences are of Valanginian age.
Family Ilyocyprididae Kaufmann, Reference Kaufmann1900
Genus Neuquenocypris Musacchio, Reference Musacchio1973
Type species
Ilyocypris (Neuquenocypris) calfucurensis Musacchio, Reference Musacchio1973
Remarks
The classification follows Liebau (Reference Liebau2005). Originally, Neuquenocypris was described as a subgenus of Ilyocypris Brady and Norman, Reference Brady and Norman1889. Posteriorly, Neuquenocypris was repositioned to genus level, and three subgenera were described: Neuquenocypris (Neuquenocypris), Neuquenocypris (Protoneuquenocypris), and Neuquenocypris (Alleniella) (Musacchio and Simeoni, Reference Musacchio and Simeoni1991). Species of Neuquenocypris usually have the right valve larger than the left one, smooth anterodorsal sulcus and nodules, and carapace well ornamented with spines, nodules, pustules, papillae, and denticles (Musacchio and Simeoni, Reference Musacchio and Simeoni1991).
Neuquenocypris (Protoneuquenocypris) antiqua Musacchio and Simeoni, Reference Musacchio and Simeoni1991
1991 Neuquenocypris (Protoneuquenocypris) antiqua Reference Musacchio and SimeoniMusacchio and Simeoni, p. 368, figs. 9, 11, 14–17.
2011 Neuquenocypris antiqua (Musacchio and Simeoni); Reference Ballent, Carignano, Iglesias and PoiréBallent et al., p. 545, figs. 3.1, 3.6.
2017 Neuquenocypris (Protoneuquenocypris) antiqua Musacchio and Simeoni; Carignano et al., Reference Carignano, Paredes, Olazábal and Valle2017, p. 211, fig. 5A-B.
Holotype
A carapace (BA-G-CM 91/1) from Pozo D-129 Formation, Cerro Chenques, in Chubut Province, Argentina (Musacchio and Simeoni, Reference Musacchio and Simeoni1991).
Occurrence
Argentina: Pozo D-129 Formation in Cerro Chenques, Chubut Province, Barremian–Aptian (Musacchio and Simeoni, Reference Musacchio and Simeoni1991; Carignano et al., Reference Carignano, Paredes, Olazábal and Valle2017); Austral Basin, Piedra Clavada Formation, Santa Cruz, lower to upper Albian (Ballent et al., Reference Ballent, Carignano, Iglesias and Poiré2011). Brazil: São Francisco Basin, Quiricó Formation, Lower Cretaceous, Valanginian.
Materials
Three intervals from Tereza Farm, João Pinheiro, Minas Gerais State, southeastern Brazil: MP-3318, three carapaces; MP-3429, three carapaces; MP-3434, two carapaces.
Remarks
All the characteristics of Neuquenocypris antiqua recognized from the Quiricó Formation correspond to those described in the type material (Musacchio and Simeoni, Reference Musacchio and Simeoni1991; Ballent et al., Reference Ballent, Carignano, Iglesias and Poiré2011). There is no mention of a taxonomic reassignment for Neuquenocypris (Protoneuquenocypris) antiqua in Ballent et al. (Reference Ballent, Carignano, Iglesias and Poiré2011); however, the species is mentioned as Neuquenocypris antiqua. Due to the absence of this reassignment, the species is herein maintained as Neuquenocypris (Protoneuquenocypris) antiqua.
Suborder Darwinulocopina Sohn, Reference Sohn1988
Superfamily Darwinuloidea Brady and Norman, Reference Brady and Norman1889
Family Darwinulidae Brady and Norman, Reference Brady and Norman1889
Genus Penthesilenula Rossetti and Martens, Reference Rossetti and Martens1998
Type species
Darwinula incae Delachaux, Reference Delachaux1928 (Rossetti and Martens, Reference Rossetti and Martens1998).
Remarks
The classification follows Liebau (Reference Liebau2005). A taxonomic review of Darwinulidae from Recent and Holocene resulted in the description of three new genera (Rossetti and Martens, Reference Rossetti and Martens1998). The genus Penthesilenula Rossetti and Martens, Reference Rossetti and Martens1998 differs from both Darwinula Brady and Robertson, Reference Brady and Robertson1870 and Alicenula Rossetti and Martens, Reference Rossetti and Martens1998 on the square shape of the valves in lateral view, and the presence of internal teeth on the left valve. The height-length ratio shows that the greatest height corresponds to almost half of the length, giving a less elongate and more sub-quadrate outline compared to other darwinulids.
Penthesilenula martinsi (Silva, Reference Silva1978) emend. Do Carmo et al., Reference Do Carmo, Rafael, Vilhena and Tomassi2004b
Figure 6 Species of the genus Penthesilenula Rossetti and Martens, Reference Rossetti and Martens1998, Alicenula Rossetti and Martens, Reference Rossetti and Martens1998, and Timiriasevia Mandelstam, Reference Mandelstam1947 from outcrops on the banks of the São José and Quiricó rivers, São José Farm, Presidente Olegário municipality, and the outcrop at Tereza Farm, João Pinheiro municipality, Minas Gerais State, southeastern Brazil. (1–3) Penthesilenula martinsi (Silva, Reference Silva1978) emend. Do Carmo et al., Reference Do Carmo, Rafael, Vilhena and Tomassi2004b, adult (CP-870), right lateral view (RLV), left lateral view (LLV), and dorsal view (DV). (4–7) Penthesilenula pintoi n. sp. (4–6) Holotype, carapace (CP-871), right lateral view (RLV), left lateral view (LLV), and dorsal view (DV); (7) paratype, carapace (CP-875), right lateral view (RLV). (8–11) Alicenula longiformis n. sp. (8–10) Holotype, carapace (CP-872), right lateral view (RLV), left lateral view (LLV), and dorsal view (DV); (11) paratype, carapace (CP-876), right lateral view (RLV). (12–18) Timiriasevia sanfranciscanensis n. sp. (12–15) Holotype female adult (CP-873), right lateral view (RLV), left lateral view (LLV), dorsal view (DV), and ventral view (VV); (16–18) paratype male adult (CP-874), left lateral view (LLV), right lateral view (RLV), and dorsal view (DV). (1–11) Scale bars are 100 µm; (12–18) scale bars are 200 µm.
1978 Darwinula martinsi Reference SilvaSilva, p. 1031, pl. 1, figs 1, 2.
2004a Darwinula sp. 4 Reference Do Carmo, Tomassi and OliveiraDo Carmo et al., p. 144, fig. 4.13–4.18.
2004b Darwinula martinsi Silva; Reference Do Carmo, Rafael, Vilhena and TomassiDo Carmo et al., p. 155, fig. 3.21–3.27.
Holotype
A carapace (Number 42) from the Santana Formation, Crato municipality, Ceará State, Brazil (Silva, Reference Silva1978).
Occurrence
Brazil: Araripe Basin, Santana Formation, Crato Member, and the base of Ipubi Member (Silva, Reference Silva1978; Silva-Telles and Viana, Reference Silva-Telles and Viana1990; Colin and Dépêche, Reference Colin and Dépêche1997), Aptian (Coimbra et al., Reference Coimbra, Arai and Carreño2002); Potiguar Basin, Alagamar Formation, middle to upper Aptian (Do Carmo et al., Reference Do Carmo, Coimbra, Whatley, Antonietto and De Paiva Citon2013); São Francisco Basin, Quiricó Formation, Lower Cretaceous, Valanginian.
Description
Small carapace, sub-squarish in lateral view, with height increasing evenly to the posterior margin, and greatest length at mid height. Left valve larger than right valve, overlapping all the margins of the carapace, with a well-marked overlap at the ventral region. Dorsal margin nearly straight to smoothly curvilinear, and ventral margin with a small concavity at the end of the first third of the carapace. Anterior margin sub-rounded and lower than the posterior margin. Posterior margin rounded. Smooth surface. In dorsal view, greatest width at the posterior end.
Materials
Three levels from Tereza Farm, João Pinheiro, Minas Gerais State, southeastern Brazil: MP-3318, 50 carapaces; MP-3428, 34 carapaces; MP-3436, 13 carapaces.
Remarks
Considering that the type material for Darwinula martinsi Silva, Reference Silva1978 is misplaced, this species was redescribed by Do Carmo et al. (Reference Do Carmo, Rafael, Vilhena and Tomassi2004b) based on neotypes from the type locality. Tomé et al. (Reference Tomé, Lima Filho and Neumann2014) considered this species as a junior synonym for Alicenula leguminella (Forbes in Lyell, Reference Lyell1855). However, the material illustrated by Tomé et al. (Reference Tomé, Lima Filho and Neumann2014) is different from the material designated as neotype for Darwinula martinsi by Do Carmo et al. (Reference Do Carmo, Rafael, Vilhena and Tomassi2004b), due to the carapace contour, height/length ratio, and other diagnostic characteristics. Additionally, the specimens illustrated by Tomé et al. (Reference Tomé, Lima Filho and Neumann2014) are different from Alicenula leguminella due to the anterior margin, which is slimmer, the posterior margin, which is wider, and the marked inclination of the ventral margin to the anterior margin. Therefore, when reviewing the neotypes that once were identified as Darwinula martinsi, it was verified that the species can be transferred to Penthesilenula martinsi (Silva, Reference Silva1978). This reassignment to the genus Penthesilenula is based on the sub-quadrate shape in lateral view, a diagnostic characteristic that distinguishes it from Darwinula Brady and Robertson in Jones, Reference Jones1885 emend. Pinto and Kotzian, Reference Pinto and Kotzian1961, associated with the height/length ratio ~0.5 (Ballent and Díaz, Reference Ballent and Díaz2012). Such characteristics are observed in Darwinula martinsi, justifying the reassignment to Penthesilenula martinsi.
Penthesilenula pintoi new species
Holotype
A carapace (CP-871), length 0.680 mm, height 0.310 mm, width 0.240 mm. Type level 23.57 m from the base of the outcrop, Quiricó Formation, Areado Group, São Francisco Basin, Lower Cretaceous, Aptian, from the banks of the São José River, São José Farm, Presidente Olegário municipality, Minas Gerais State, Brazil.
Paratypes
Research Collection, Museum of Geosciences, Institute of Geosciences, Brasília, Brazil: carapace CP-875, length 0.730 mm, height 0.320 mm, width 0.320 mm; carapace CP-894, length 0.680 mm, height 0.300 mm, width 0.250 mm; carapace CP-895, length 0.680 mm, height 0.310 mm, width 0.220 mm; carapace CP-896, length 0.680 mm, height 0.300 mm, width 0.210 mm; carapace CP-897, length 0.660 mm, height 0.290 mm, width 0.200 mm.
Diagnosis
Small carapace, oblong. Left valve larger than right valve. Dorsal margin smoothly curved, with well-marked inclination to the anterior margin. Ventral margin nearly straight with small concavity by the end of the first third. Anterior margin sub-rounded and low. Posterior margin rounded and broad.
Occurrence
Brazil: Tereza Farm, João Pinheiro municipality and São José Farm, on the banks of the São José and Quiricó rivers, Minas Gerais State, southeastern Brazil, Quiricó Formation, Areado Group, São Francisco Basin, Lower Cretaceous, Valanginian to Aptian.
Description
Small carapace, sub-oval to sub-quadrate in lateral view, with height increasing evenly to the posterior margin, and greatest length at mid-height. Left valve larger than right valve, overlapping all the margins of the carapace. Dorsal margin nearly straight, inclined to the anterior margin, and ventral margin nearly straight, with small convexity anteriorly. Anterior margin sub-rounded and low. Posterior margin rounded and broader than the anterior one. Smooth surface. In dorsal view, width increasing evenly towards the posterior end.
Etymology
In honor of Professor Ricardo Lourenço Pinto, Institute of Geosciences of the University of Brasília, for rich discussions on the Darwinulidae Family.
Materials
Three levels from the São José creek, São José Farm, Presidente Olegário, Minas Gerais State, southeastern Brazil: MP-2884, four carapaces; MP-2895, 30 carapaces; MP-2960, 100 carapaces; one level from Quiricó creek, São José Farm, Presidente Olegário, Minas Gerais State, southeastern Brazil: MP-3421, three carapaces; 22 levels from Tereza Farm, João Pinheiro, Minas Gerais State, southeastern Brazil: MP-3322, one carapace; MP-3323, four carapaces; MP-3325, three carapaces; MP-3326, 200 carapaces; MP-3327, 100 carapaces; MP-3328, two carapaces; MP-3333, one carapace; MP-3335, seven carapaces; MP-3340, 14 carapaces; MP-3427, three carapaces; MP-3428, 40 carapaces; MP-3429, 40 carapaces; MP-3431, 80 carapaces; MP-3433, six carapaces; MP-3434, 200 carapaces; MP-3436, 29 carapaces; MP-3437, 60 carapaces; MP-3438, two carapaces; MP-3439, 17 carapaces; MP-3442, 40 carapaces; MP-3443, 18 carapaces; MP-3448, two carapaces.
Remarks
This species is more elongated and has the anterior margin broader than Penthesilenula martinsi (Silva, Reference Silva1978). The taxonomic revision by Rossetti and Martens (Reference Rossetti and Martens1998) resulted in the description of three new genera, and a new diagnosis for Darwinula, whose right valve overlaps the left one, through the entire margin, except in the hinge region. Additionally, in lateral view, Darwinula is more elongated, with greatest height in the posterior quarter; posterior margin more broadly rounded than the anterior one; anterior margin narrower and slightly curved towards the ventral margin; ventral margin nearly straight, and dorsal margin curved. The genus Penthesilenula is sub-rectangular in lateral view, as discussed above. The closed carapaces herein studied did not allow observation of internal characteristics. However, due to its oval to sub-rectangular shape in lateral view, and a more broadly rounded anterior margin, the specimens are attributed to Penthesilenula. Additionally, the recovered specimens are similar to Penthesilenula sarytirmenensis (Sharapova) sensu Mandelstam, Reference Mandelstam1947, identified in Argentina by Ballent and Díaz (Reference Ballent and Díaz2012), mainly in the inclination of the dorsal margin towards the anterior, the outline of the anterior, and ventral margins. However, there is a difference in size, because Penthesilenula sarytirmenensis has a very large carapace (1.080 mm length). This species was described from the Middle Jurassic in Mangishlaka Peninsula, former USSR (Mandelstam, Reference Mandelstam1947) and in several localities in China (Li, Reference Li1985; Zheng, Reference Zheng1995) and India (Govidan, Reference Govidan1975), as well as in the Early Jurassic of Argentina (Ballent and Díaz, Reference Ballent and Díaz2012).
Genus Alicenula Rossetti and Martens, Reference Rossetti and Martens1998 emend.
Type species
Darwinula serricaudata Klie, Reference Klie1935 (Rossetti and Martens, Reference Rossetti and Martens1998).
Diagnosis
Carapace small and elongated, with internal teeth at left valve, one anteroventral tooth near the interior margin, and one posterior caudal tooth. Adont hinge. Right valve overlapping the left valve, or left valve overlapping the right valve. Dorsal margin evenly inclined, not rounded or straight, in part of its length. Central muscle scar situated at the anterior region in adult specimens. Brood chamber wide and externally visible.
Remarks
The classification follows Liebau (Reference Liebau2005). Although the genus Alicenula was not described with the presence of teeth on the internal surface of the left valve, it was later demonstrated that, in fact, there is one anteroventral tooth near the interior margin and one tooth at the posterior caudal internal surface of the left valve (Martens et al., Reference Martens, Rossetti and Horne2003; Ballent and Díaz, Reference Ballent and Díaz2012). Therefore, we propose a new diagnosis for the genus, including teeth on the internal surface of the left valve. Alicenula and Darwinula are elongated in lateral view, however the species differ in size and internal characteristics, considering that Alicenula has internal teeth on the left valve.
Alicenula longiformis new species
Holotype
A carapace (CP-872), length 0.690 mm, height 0.260 mm, width 0.250 mm. Type level 7.35 m from the base of the outcrop, Quiricó Formation, Areado Group, São Francisco Basin, Lower Cretaceous, Aptian, from the Tereza Farm, João Pinheiro municipality, Minas Gerais State, Brazil.
Paratypes
Research Collection, Museum of Geosciences, Institute of Geosciences, Brasília, Brazil: carapace CP-876, length 0.710 mm, height 0.270 mm, width 0.230 mm; carapace CP-898, length 0.750 mm, height 0.280 mm, width 0.270 mm; carapace CP-899, length 0.640 mm, height 0.260 mm, width 0.250 mm; carapace CP-900, length 0.700 mm, height 0.270 mm, width 0.230 mm; carapace CP-889, length 0.710 mm, height 0.280 mm, width 0.240 mm.
Diagnosis
Small carapace, oblong and elongated. Left valve larger than right valve. Dorsal and ventral margins nearly straight and sub-parallel. Anterior margin narrow and sub-rounded. Posterior margin sub-rounded.
Occurrence
Brazil: Tereza Farm, João Pinheiro municipality and São José Farm, on the banks of the Quiricó River, Minas Gerais State, southeast Brazil, Quiricó Formation, Areado Group, São Francisco Basin, Lower Cretaceous, Valanginian to Berriasian?.
Description
Small carapace, suboval elongated in lateral view, with height increasing evenly towards the posterior margin, and greatest length at mid-height. Left valve larger than right valve, overlapping all the margins of the carapace. Dorsal and ventral margins nearly straight and sub-parallel. Anterior margin sub-rounded, narrow, and low. Posterior margin rounded and broader than anterior margin. Smooth surface. In dorsal view, width increasing evenly towards the posterior end.
Etymology
From the Latin logum forma, which means “with elongated form.”
Materials
One level from Quiricó creek, São José Farm, Minas Gerais State, southeastern Brazil: MP-3421, two carapaces; nine levels from Tereza Farm, João Pinheiro, Minas Gerais State, southeastern Brazil: MP-3318, 14 carapaces; MP-3327, 100 carapaces; MP-3428, 23 carapaces; MP-3431, 23 carapaces; MP 3433, six carapaces; MP-3434, 40 carapaces; MP-3439, seven carapaces; MP-3443, nine carapaces; MP-3448, two carapaces.
Remarks
This species differs from Penthesilenula martinsi (Silva, Reference Silva1978) in its more elongated shape, and anterior margin more narrowly rounded. The genus Alicenula, in external view, is very similar to Darwinula, due to its elongated shape, and the overlap of the left margin over the right one, or right margin over the left margin. Internally, the genus Alicenula has teeth in the left valve. Although the studied specimens are closed carapaces, the valve overlap and the elongated shape, with a more narrowly rounded anterior margin, allowed their identification as Alicenula.
Suborder Cytherocopina Gründel, Reference Gründel1967
Superfamily Limnocytheroidea Liebau, Reference Liebau2005
Family Limnocytheridae Klie, Reference Klie1938
Subfamily Timiriaseviinae Mandelstam, Reference Mandelstam1947
Genus Timiriasevia Mandelstam, Reference Mandelstam1947
Type species
Timiriasevia epidermiformis Mandelstam, Reference Mandelstam1947.
Remarks
The supra-subfamilial classification follows Liebau (Reference Liebau2005). Sames (Reference Sames2009, Reference Sames2011) is followed for subfamily and other categories. The genus Timiriasevia Mandelstam, Reference Mandelstam1947, common in Cretaceous limnic deposits worldwide, has not been documented or recorded in Cretaceous sediments from the United States yet, however, it is found in Upper Jurassic sediments. This absence might result from misidentifications as Metacypris Brady and Robertson, Reference Brady and Robertson1870, due to the morphological similarities of young specimens of both genera (Sames, Reference Sames2009, Reference Sames2011). The genera Timiriasevia Mandelstam, Reference Mandelstam1947, Theriosynoecum Branson, Reference Branson1936, and Metacypris Brady and Robertson, Reference Brady and Robertson1870 are members of the subfamily Timiriaseviinae, due to the presence of simple porecanals, and an evident egg pouch in females. The nonsulcate genera Gomphocythere Sars, Reference Sars1924 and Timiriasevia Mandelstam, Reference Mandelstam1947, as well as some species of the monosulcate Metacypris Brady and Robertson, Reference Brady and Robertson1870, usually have some indication of sulcus, such as a wide and shallow depression, causing a lateral constriction anteriorly in dorsal view. Females of Timiriasevia and Metacypris differ in dorsal view. Metacypris has a cordiform shape, while Timiriasevia is elongated oval to piriform with a small lateral constriction anteriorly. Moreover, Metacypris has a weak sulcus, which is absent in Timiriasevia.
Timiriasevia sanfranciscanensis new species
Holotype
A female carapace (CP-843), length 1.070 mm, height 0.650 mm, width 0.740 mm. Type level at 90 cm from the base of the Quiricó Formation, Areado Group, São Francisco Basin, Lower Cretaceous, Valanginian, João Pinheiro municipality, Minas Gerais State, Brazil.
Paratype
Research Collection, Museum of Geosciences, Institute of Geosciences, Brasília, Brazil, male carapace CP-874, length 1.010 mm, height 0.600 mm, width 0.600 mm.
Diagnosis
Oval carapace, rounded in lateral view. Left valve slightly larger than right valve, with overlap of the left valve over the right one, mainly in the anterior margin, and overlap of right over left valve in the posterior margin. Ventral margin straight. Surface covered by punctuations, more evident near the margin. In dorsal view, highly inflated and piriform.
Occurrence
Tereza Farm, João Pinheiro municipality, Minas Gerais State, southeast Brazil, Quiricó Formation, Areado Group, São Francisco Basin, Lower Cretaceous, Valanginian.
Description
Medium to large carapace, oval to rounded in lateral view, with greatest height at mid length, and greatest length ventral-medianly. Left valve slightly larger than right one, overlapping it mainly in the anterior margin; right valve overlapping the left one in the posterior margin. Dorsal margin convex, inclined anteriorly; ventral margin straight, with a smooth inclination towards the anterior margin. Anterior margin sub-rounded. Posterior margin broadly rounded. Surface poorly punctuated, with ornamentation more evident near the margins, mainly in the ventral region. In dorsal view, strongly inflated and piriform, with subtle constriction anteriorly. In ventral view, broad and straight. Sexual dimorphism present: males with less-convex dorsal margin compared to the females, and narrower in dorsal view.
Etymology
After the name of the basin wherein it was described.
Materials
Four levels from Tereza Farm, João Pinheiro, Minas Gerais State, southeast Brazil: MP-3318, three carapaces; MP-3322, three carapaces; MP-3427, seven carapaces; MP-3433, one carapace.
Remarks
The genus Timiriasevia, according to Sames (Reference Sames2009, Reference Sames2011), has a rounded oblong shape in lateral view; in dorsal view, the females are piriform, with slight constriction anteriorly; there are no sulci or nodules; the ornamentation can be concentrically striated, sometimes combined with punctuation. Additionally, the recovered specimens have the ventral margin flattened and wide, in accordance to the Limnocytheridae. Timiriasevia sanfranciscana n. sp. is the first species of the genus Timiriasevia formally described in the Cretaceous deposits in Brazil.
Discussion
The species studied in the present work are important for future research on the geographic and stratigraphic distribution, as well as the correlation between Argentinian, African, and Brazilian continental and marginal basins. Aptian deposits of the marginal basins are important for oil exploration, since source rocks and/or reservoirs are present in them. Additionally, the presence of species from the Valanginian, as well as from the Barremian–Aptian interval, can lead to a new age interpretation for the Quiricó Formation and, therefore, to a new interpretation for continental Cretaceous in Brazil.
Of the 16 species identified for the Lower Cretaceous from the São Francisco Basin, 13 occur in other basins from Brazil, Argentina, and Africa: Harbinia alta, Harbinia angulata, Harbinia crepata, Harbinia salitrensis, Harbinia symmetrica, Brasacypris fulfaroi, Brasacypris ovum, Cypridea conjugata, Cypridea hystrix, Cypridea infima, Cypridea jequiensis, Neuquenocypris (Protoneuquenocypris) antiqua, and Penthesilenula martinsi.
In the Grajaú Basin: H. alta (upper Aptian) and H. salitrensis (Aptian) (Ramos et al., Reference Ramos, Rossetti and Paz2006; Do Carmo et al., Reference Do Carmo, Whatley, Queiroz Neto and Coimbra2008).
In the Araripe Basin: H. alta and H. salitrensis, both from the upper Aptian (Krömmelbein and Weber, Reference Krömmelbein and Weber1971; Viana et al., Reference Viana, Brito and Silva-Telles1989; Silva-Telles and Viana, Reference Silva-Telles and Viana1990; Do Carmo et al., Reference Do Carmo, Whatley, Queiroz Neto and Coimbra2008; Poropat and Colin, Reference Poropat and Colin2012a; Antonietto et al., Reference Antonietto, Gobbo, Do Carmo, Assine, Fernandes and Lima e Silva2012; Tomé et al., Reference Tomé, Lima Filho and Neumann2014); H. symmetrica (Aptian) (Coimbra et al., Reference Coimbra, Arai and Carreño2002); H. crepata (Aptian) (Silva-Telles and Viana, Reference Silva-Telles and Viana1990); P. martinsi (Aptian); H. angulata (Aptian) (Poropat and Colin, Reference Poropat and Colin2012a).
In the Potiguar Basin: H. alta, H. crepata and P. martinsi, all from the middle–upper Aptian (Do Carmo et al., Reference Do Carmo, Coimbra, Whatley, Antonietto and De Paiva Citon2013). In the Jatobá Basin: H. angulata (upper Aptian) (Tomé et al., Reference Tomé, Lima Filho and Neumann2014). In the Sergipe-Alagoas Basin: H. angulata (upper Aptian) (Krömmelbein and Weber, Reference Krömmelbein and Weber1971); C. jequiensis (Barremian) (Krömmelbein and Weber, Reference Krömmelbein and Weber1971; Poropat and Colin, Reference Poropat and Colin2012a; Antonietto, Reference Antonietto2015).
In the Recôncavo Basin: C. conjugata (Barremian) (Krömmelbein and Weber, Reference Krömmelbein and Weber1971; Poropat and Colin, Reference Poropat and Colin2012a); C. hystrix (Berriasian to Valanginian) (Krömmelbein, Reference Krömmelbein1962; Poropat and Colin, Reference Poropat and Colin2012a); C. infima (Berriasian) (Krömmelbein and Weber, Reference Krömmelbein and Weber1971; Poropat and Colin, Reference Poropat and Colin2012a).
In the Cedro Basin: H. angulata (upper Aptian) (Tomé, Reference Tomé2007). In the Paraná Basin: B. fulfaroi (Upper Cretaceous) (Dias-Brito et al., Reference Dias-Brito, Musacchio, Castro, Maranhão, Suárez and Rodrigues2001). In the Tucano Basin: B. ovum (Berriasian) (Krömmelbein, Reference Krömmelbein1965b; Poropat and Colin, Reference Poropat and Colin2012b).
In Argentina, Pozo D-129 Formation in Cerro Chenques: N. (Protoneuquenocypris) antiqua, Aptian (Musacchio and Simeoni, Reference Musacchio and Simeoni1991) and Barremian-Aptian (Carignano et al., Reference Carignano, Paredes, Olazábal and Valle2017). In the Austral Basin: N. (Protoneuquenocypris) antiqua (lower to upper Albian) (Ballent et al., Reference Ballent, Carignano, Iglesias and Poiré2011).
In Africa, Gabon Basin and Congo and Cabinda Basin: H. symmetrica (Barremian) (Grosdidier et al., Reference Grosdidier, Braccini, Dupont and Moron1996; Bate, Reference Bate1999).
Additionally, the Zone Harbinia spp. 201–218, coded as NRT-011 (Do Carmo et al., Reference Do Carmo, Whatley, Queiroz Neto and Coimbra2008) was defined from the Araripe Basin, and comprises the Alagoas Floor (Schaller, Reference Schaller1968; Moura, Reference Moura1987), upper Aptian–lower Albian (Antonietto et al., Reference Antonietto, Gobbo, Do Carmo, Assine, Fernandes and Lima e Silva2012), where the genus Harbinia plays an important role in dating Brazilian basins, both continental and marginal (Antonietto et al., Reference Antonietto, Gobbo, Do Carmo, Assine, Fernandes and Lima e Silva2012). The Paracypridea brasiliensis Zone, coded as NRT-O04, was defined from the Recôncavo Basin, where the occurrence of Cypridea hystrix is well marked in the Paracypridea bicallosa (NRT-O04.3) and Paracypridea maacki (NRT-O04.4) subzones (Viana et al., Reference Viana, Gama Junior, Simões, Moura, Fonseca and Alves1971; Cunha and Moura, Reference Cunha and Moura1979; Regali and Viana, Reference Regali and Viana1989), of Valanginian age (Caixeta et al., Reference Caixeta, Bueno, Magnavita and Feijó1994).
The Tereza Farm outcrop has 11 species, which is the most diversified. Ostracode assemblages occur with up to eight species at the richest levels, and when this abundance lessens, ostracode assemblages occur with up to four species per level. The São José creek outcrop has seven species, where ostracode assemblages occur with up to four species at the richest levels, and with up to two species at most levels. Additionally, the abundance of specimens is less, when compared to Tereza Farm. The Quiricó creek outcrop has four species, all of them in one single level.
Only B. ovum and P. pintoi n. sp. occur at the Tereza Farm and São José and Quiricó creeks. At the São José creek outcrop there is a predominance of Harbinia species, which occur in assemblage with B. ovum and P. pintoi n. sp. only at the middle portion of the sequence. At the Quiricó creek outcrop, B. ovum and P. pintoi n. sp. occur in assemblage with A. longiformis n. sp. and B. fulfaroi.
At the Tereza Farm outcrop, C. hystrix occurrance determines a chronostratigraphic attribution of Valanginian age for the basal portion of the sequence. The species that are in assemblage with C. hystrix, and therefore are of Valanginian age, are: P. martinsi, C. conjugata, C. jequiensis, N. (Protoneuquenocypris) antiqua, and T. sanfranciscanensis n. sp. The middle portion of the sequence is of Hauterivian age, possibly up to Aptian age. The species that are either at the basal portion and the middle portion, and of Valanginian–Aptian age are: P. pintoi n. sp., A. longiformis n. sp., B. fulfaroi, B. ovum, and C. infima.
At São José creek, the occurrences of Harbinia indicate a chronostratigraphic attribution of Aptian age for the top of the basal portion and the middle and upper portions. Therefore, B. ovum and P. pintoi n. sp. occur from Valanginian to Aptian.
At Quiricó creek, there is the level of papyraceous shale where the fish fossil Dastilbe moraesi occurs, along with leaf impressions. Associated with this level, according to Lima (Reference Lima1979) and Arai et al. (Reference Arai, Dino, Milhomen and Sgarbi1995), there is the Transitoripollis crisopolensis Palynozone, coded as P-230, indicating a Barremian age. The ostracode assemblage of P. pintoi n. sp., A. longiformis n. sp., B. ovum, and B. fulfaroi occurs below the papyraceous shale level, attributed possibly to the Valanginian–Barremian interval.
Conclusions
This study analyzed 168 samples from three outcrops encompassing the São Francisco Basin, in the State of Minas Gerais, southeastern Brazil. Sixteen species were identified, of which five are unprecedented for the Quiricó Formation, and consequently for the Cretaceous of the São Francisco Basin. There is also the identification of the genus Timiriasevia, unprecedented in the paleontological record of Brazil, as well as the description of three new species: Penthesilenula pintoi n. sp., Alicenula longiformis n. sp., and Timiriasevia sanfranciscanensis n. sp. Additionally, considering the recovery of well-preserved material, new descriptions and emended diagnoses are proposed for four species: Brasacypris ovum, Cypridea conjugata, Cypridea hystrix, and Cypridea infima. The genus Alicenula is given a new diagnosis, due to the bibliographic confirmation of the presence of internal teeth on the left valve, which is a characteristic not present in the original diagnosis.
The species Brasacypris fulfaroi, Penthesilenula martinsi, Cypridea conjugata, Cypridea jequiensis, and Neuquenocypris (Protoneuquenocypris) antiqua represent herein their oldest record. The stratigraphic distribution is: B. fulfaroi, Valanginian to Upper Cretaceous; P. martinsi, Valanginian to Albian; C. conjugata, Valanginian to Barremian; C. jequiensis, Valanginian to Barremian-Aptian; N. (Protoneuquenocypris) antiqua, Valanginian to Albian. The species Brasacypris ovum presents the most recent record, with stratigraphic distribution from Berriasian to Aptian. Timiriasevia sanfranciscanensis n. sp., due to its occurrence exclusively at the Tereza Farm, is only attributed to the Valanginian. Penthesilenula pintoi n. sp. has a stratigraphic distribution from Valanginian to Aptian, and Alicenula longiformis n. sp. ranges from Valanginian to possibly Barremian. Harbinia species, recovered only at the São José creek outcrop, are of Aptian age. Therefore, the Quiricó Formation becomes attributed to the Valanginian–Aptian interval.
The new data on ostracode taxonomy presented herein improve the current understanding of distribution of limnic ostracodes from the Cretaceous of Brazil, Argentina, and Africa because it is possible to develop a correlation study with 13 other basins: Grajaú, Araripe, Potiguar, Jatobá, Sergipe-Alagoas, Recôncavo, Cedro, Paraná, and Tucano, from Brazil; Gabon, Congo, and Cabinda basins in Africa; and the Austral Basin, in Argentina. From this study, it is possible to infer that the Quiricó Formation began its deposition during the Valanginian.
Acknowledgments
The authors are grateful to “Fundação de Apoio à Pesquisa do Distrito Federal” FapDF (Research Support Foundation of the Federal District) for providing the financial aid for all the fieldwork expeditions (Notice 03/2013—Spontaneous Demand), as well as the Master’s Degree scholarship (Notice ProMD/UnB/FAPDF—Master’s and Doctoral Scholarship 2015/2016). Special thanks to Professor R. Lourenço Pinto for his great contribution during the revision on darwinulids, and especially for his contribution during the initial phase of revision. We also thank the reviewers, for the great intellectual contribution to the present work.
