Leite et al.—Limnic Ostracoda from the Lower Cretaceous of Brazil
shape in lateral view, and a more broadly rounded anterior margin, the specimens are attributed to Penthesilenula. Addi- tionally, the recovered specimens are similar to Penthesilenula
sarytirmenensis (Sharapova) sensu Mandelstam, 1947, identi- fied in Argentina by Ballent and Díaz (2012), mainly in the inclination of the dorsal margin towards the anterior, the outline of the anterior, and ventral margins. However, there is a differ- ence in size, because Penthesilenula sarytirmenensis has a very large carapace (1.080mm length). This species was described from the Middle Jurassic in Mangishlaka Peninsula, former USSR (Mandelstam, 1947) and in several localities in China (Li, 1985; Zheng, 1995) and India (Govidan, 1975), as well as in the Early Jurassic of Argentina (Ballent and Díaz, 2012).
Genus Alicenula Rossetti and Martens, 1998 emend.
Type species.—Darwinula serricaudata Klie, 1935 (Rossetti and Martens, 1998).
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 over- lapping 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 (2005). 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., 2003; Ballent and Díaz, 2012). 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 Figure 6.7–6.9
Holotype.—A carapace (CP-872), length 0.690mm, height 0.260mm, width 0.250mm. Type level 7.35m 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,
675
length 0.710mm, height 0.270mm, width 0.230mm; carapace CP-898, length 0.750mm, height 0.280mm, width 0.270mm; carapace CP-899, length 0.640mm, height 0.260mm, width 0.250mm; carapace CP-900, length 0.700mm, height 0.270mm, width 0.230mm; carapace CP-889, length 0.710mm, height 0.280mm, width 0.240mm.
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 theQuiricó River, MinasGerais 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 car- apaces; 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, 1978) 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 rightmargin over the leftmargin. 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 anteriormargin, allowed their identification as Alicenula.
Suborder Cytherocopina Gründel, 1967 Superfamily Limnocytheroidea Liebau, 2005
Figure 6. Species of the genus Penthesilenula Rossetti and Martens, 1998, Alicenula Rossetti and Martens, 1998, and Timiriasevia Mandelstam, 1947 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, 1978) emend. Do Carmo et al., 2004b, 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.
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125 |
Page 126 |
Page 127 |
Page 128 |
Page 129 |
Page 130 |
Page 131 |
Page 132 |
Page 133 |
Page 134 |
Page 135 |
Page 136 |
Page 137 |
Page 138 |
Page 139 |
Page 140 |
Page 141 |
Page 142 |
Page 143 |
Page 144 |
Page 145 |
Page 146 |
Page 147 |
Page 148 |
Page 149 |
Page 150 |
Page 151 |
Page 152 |
Page 153 |
Page 154 |
Page 155 |
Page 156 |
Page 157 |
Page 158 |
Page 159 |
Page 160 |
Page 161 |
Page 162 |
Page 163 |
Page 164 |
Page 165 |
Page 166 |
Page 167 |
Page 168 |
Page 169 |
Page 170 |
Page 171 |
Page 172 |
Page 173 |
Page 174 |
Page 175 |
Page 176 |
Page 177 |
Page 178 |
Page 179 |
Page 180 |
Page 181 |
Page 182 |
Page 183 |
Page 184 |
Page 185 |
Page 186 |
Page 187 |
Page 188 |
Page 189 |
Page 190 |
Page 191 |
Page 192 |
Page 193 |
Page 194 |
Page 195 |
Page 196 |
Page 197 |
Page 198 |
Page 199 |
Page 200 |
Page 201 |
Page 202 |
Page 203 |
Page 204 |
Page 205 |
Page 206 |
Page 207 |
Page 208 |
Page 209 |
Page 210 |
Page 211 |
Page 212 |
Page 213 |
Page 214 |
Page 215 |
Page 216 |
Page 217 |
Page 218 |
Page 219 |
Page 220 |
Page 221 |
Page 222 |
Page 223 |
Page 224 |
Page 225 |
Page 226 |
Page 227 |
Page 228 |
Page 229 |
Page 230 |
Page 231 |
Page 232
