A 3m thick carbonate sequence from northern Chios Island is assigned here to the latest Capitanian/earliest Wuchiapingian transitional interval. It is characterized by abundant gymnocodiacean algae, associated with some miliolate, nankinellin and nodosariate foraminifers. These strata display bioaccumulated perireefal microfacies with richthofeniid brachiopods and inozoa calcisponges. They are biostratigraphically characterized by a foraminifera assemblage composed of Reichelina cf. simplex, Dunbarula? sp., Altineria alpinotaurica together with the genera Labioglobivalvulina, Frondina and Robuloides. Other perireefal microfacies show abundant fragments of a new tubiphytid species, Tubiphytella guevenci Vachard nov. gen. nov. sp. Based on this study, the paleogeographical distribution of Altineria alpinotaurica now includes Chios, in addition to the Taurus and the NW and central Iran, whereas primitive forms of the genus are also known in Tunisia and Armenia. This paleobiogeographic distribution would suggest that all these regions still belonged to the Perigondwana margin in the early Wuchiapingian times. Consequently, it is likely that the opening of the Neotethys ocean did not begin prior to the late Wuchiapingian-early Changshingian transitional interval.