Systematics, palaeoecology and taphonomy of Turonian oysters from the northern Gabon Coastal Basin Author Musavu Moussavou, Benjamin text Geodiversitas 2017 2017-06-30 39 2 213 224 journal article 31257 10.5252/g2017n2a3 f9e855d7-6356-4312-8dbe-c3dd884d6277 1069848 F4D33955-5823-49E9-BC9A-26DFB03038A7 Ostrea sp. B ( Fig. 4 O-R) MATERIAL . — 81 specimens (MDG/LBV/Lm-31.1 to Lm-31.81). OCCURRENCE . — Turonian of Gabon (this study). Shell is medium to large, inequivalve, inequilateral, elongated, suborbicular to elliptical shape in outline. LV slightly inflated and RV flat. Umbo is small and opisthogyrate. Ligamental area is narrow and small. Anterior margin is curved. Posterior margin is straight or curved. Ventral margin is evenly rounded. Attachment area is medium, depressed occupies the posterodorsal portion of the LV.Its ornamentation consists of numerous radial ribs which are crossing by concentric growth lamellae at irregular intervals. Ribs start at the umbonal area, occasionally carrying small spines near ventral margin. RV ornamented by concentric fine growth squamae. REMARKS Ostrea tunetana Munier-Chalmas, 1881 shows some similarity with our material but differs in having longer and more pointed umbo and straight ligamental area.