Ayoub-Hannaa et al.—A new Middle Jurassic bivalve from North Sinai, Egypt
437
Figure 4. Modified photographs (1, 2, 5–7, 9) and sketches (3, 8) showing the variation of opisthocline ribs of articulated specimens of Costinuculana magharensis n. gen. n. sp. from the middle to upper Bathonian Kehailia Formation of Gebel Maghara: (1, 2, 4, 7) side view of left valves showing straight and arched ribs with rounded crests; (1) BSPG2014V I3b; (2) BSPG2014V I3a; (4) BSPG2014V I4b; (7) BSPG2014V 1, holotype; (3, 6, 9) right valves showing bifurcated ribs close to the ventral and postero-dorsal margin; (3) BSPG2014V I3a; (6) BSPG2014V I4b; (9) BSPG2014V 1; (5) dorsal view showing the oblique angle between ribs and postero-dorsal margin; BSPG2014V I4b; (8) sketch of posterior part of Figure 4.7 showing the irregular ribs, bifurcated close to the ventral margin and occasionally towards postero-dorsal margin. Scale bar =2mm.
Piette, 1865), described and figured by Hodges (2000, p. 45, pl. 3, figs.5,8–11, 13–17) and Aberhan et al. (2011, p. 70, pl. 1, fig. 7) from the Lower Jurassic of southwestern England and the Herforder Liasmulde, Germany, respectively, carries faint vertical threads in the posterior part of the flank, which start slightly below the postero-dorsal ridge and do not reach the ventral margin. The ribbing style of C. magharensis n. sp. is, indeed, completely different fromthat of the German material. In addition, R. texturata differs in having a very narrow and strongly elongated rostrum, strongly convex anterior and ventral margins, and in being larger (L=~42mm as opposed to 14.3mm on average) and quite compressed. Hautmann et al. (2011, p. 22, figs. 2–4) erected the new subgenus and species Trigonucula (Gonionucula) aciloides
the same transverse threads in N.(P.) calloviensis, which are therefore of no specific significance. In addition, “I.” sadharaensis differs from C. magharensis n. sp. in having a rapidly narrowing and short rostrum, less-developed postero-dorsal ridge, faint radial and commarginal ribs, and in being less inflated. N.(P.) calloviensis (Kanjilal and Singh, 1973), as figured and described by Jaitly et al. (1995), from the Callovian of Kachchh differs in having a reticulate ornamentation, which covers the entire valve, a less-elongated rostrum, and in being less inflated and smaller than the present species. The valve of Ryderia texturata (Terquem and
from the Upper Triassic of Iran based on oblique ribs along the posterior flank. Their species differs from the Egyptian material by its more complex ornamentation pattern. The ribs are chevron-like on the central part of the flank and an additional set of steeply opisthocline to nearly vertical ribs are arranged in a narrow strip on the posterior part of the flank. Apart from the ribbing style, Trigonucula (G.) aciloides differs in having less- elongated valves, a smooth escutcheon, more or less central umbones, slightly rostrate valves, and in being less inflated. Veteranella (Ledoides) langnongensis Wen and Lan in Gu et al.,
1976, as figured and described by Fang et al. (2009, p. 12, fig. 3.1–3.5), from the Upper Triassic of China differs in having a greater number of oblique to sub-vertical ribs along the posterior flank, a reticulate ornamentation on the central and anterior parts (except the umbonal area), a slightly convex ventral margin, sharp beaks, a narrower and longer rostrum, and in being much more elongated than the present species.
Costinuculana magharensis new species Figures 4.1–4.9, 5.1–5.21
2014 Nuculoidea n. sp. Abdelhady, p. 172, fig. 5.4A, 5.4B.
2014 Nuculoidea n. sp.; Abdelhady and Fürsich, p. 181, fig. 6A, 6B.
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