New Amphicocconeis species off Mascarenes (Western Indian Ocean) and related taxa

Two new species were found on coral sediments of Mascarene archipelago: Amphicocconeis mascarenica sp. nov., relatively frequent in Reunion and rare in Rodrigues Islands, and A. rodriguensis sp. nov., relatively rare in Rodrigues and scarce in Reunion. Comparison was made with A. disculoides and A. debesii (Hustedt) De Stefano, and with species pertaining to Psammococconeis Garcia (P. brasiliensis and P. disculoides sensu Garcia). The Mascarenes taxa do not have simple raphe endings but terminal raphe fissures bent to the same side, which is a characteristic feature shared by Amphicocconeis taxa. Amphicocconeis rodriguensis has a raphe valve relatively similar to that of A. debesii (Hustedt) De Stefano, but with a denser striation; furthermore, the valvocopula of the sternum valve is narrow with simple to chiselled fimbriae. Amphicocconeis rodriguensis sternum valve is close to that of A. debesii (Hustedt) De Stefano. Amphicocconeis mascarenica shows a number of striae relatively low on both valves and both valvocopulae are generally extended and present rows of alternated small holes, which seems a unique feature for Amphicocconeis.