Biogeographic distribution of three phylotypes (T1, T2 and T6) of <i>Ammonia</i> (foraminifera, Rhizaria) around Great Britain: new insights from combined molecular and morphological recognition

Abstract. Ammonia is one of the most widespread foraminiferal genera worldwide. Three phylotypes (Ammonia sp. T1, T2 and T6), commonly encountered in northeast Atlantic, are usually associated with morphospecies tepida. The biogeographic distribution these three types was previously investigated coastal environments around Great Britain based on genetic assignations. A new method recently developed to recognize morphological criteria (i.e. pore size suture elevation spiral side), avoiding need use molecular analyses identify them. results presented here allow us validate consistency morphometric determination but also define more precisely variability each phylotypes, which a main criterion for their recognition. Moreover, results, combined earlier data, enable refine established by alone. biogeographical pattern supports putatively invasive character T6, suggesting that this phylotype currently spreading out over large areas supplanting autochthonous (T1 T2) along coastlines British Isles northern France. In fact, only southwest coast England Ireland northwest France have not been colonized T6 yet. Our suggest within may find refuges inner parts estuaries. We further absence western part English Channel be explained general surface current circulation pattern, impedes expansion. high reliability morphology allows quickly generate datasets sub-recent fossil material. This will make it possible gain an understanding ecological differences between historical changes patterns (for example due changing anthropogenic factors). Finally, confirm or invalidate putative T6.