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Abstract:
A new extant marine diatom, Pseudopodosira boltovskoyi sp. nov. (Pseudopodosiraceae, Bacillariophyta), is described with light and scanning electron microscopy from Argentinean coastal waters. Pseudopodosira boltovskoyi sp. nov. is morphologically distinct with the following combination of characters: (1) cells with numerous lenticular chloroplasts; (2) frustules commonly heterovalvate; (3) valves with concave central area generally occupied by one to several bulges, rarely without bulges; (4) oblique striae located on a horizontal, convex shelf of the valve surface; (5) valve mantle unperforated internally and with variable number of rimmed pores located below the flange externally; (6) one ring of rimoportulae irregularly spaced, not visible externally. Pseudopodosira calyciflos (Tempère & Brun) is formally designated as the generitype, and a new name Pseudopodosira jouseana nom. nov. is proposed to replace for Pseudopodosira pileiformis based on the fact that the protologue quoted the former taxon as a synonym of the latter. We compare the new species with the morphologically allied extinct species Pseudopodosira modesta, P. wittii, P. bella, P. westii, P. hyalina and P. himilis. Although most species of Pseudopodosira are extinct, P. westii, P. calyciflos and P. echinus were recorded as extant. Nevertheless, the survival of P. westii on European coastal sediments is problematic. Pseudopodosira calyciflos was only mentioned in the protologue as living in the Hawaiian Islands but is illustrated by a figure that only shows one valve. As far as we can determine, P. echinus and Pseudopodosira boltovskoyi sp. nov. are the only extant species.
ACKNOWLEDGEMENTS
We thank Sergei Genkal and his colleagues for their help in the search of Russian literature, Andrés Boltovskoy for invaluable assistance in translating the texts of key Russian authors, the late Pierre Compère for helpful discussion on nomenclatural issues and Augusto Varela for characterization of the sediments of Anegada Bay. We are very grateful to François Straub for invaluable collaboration in obtaining original material of the Brun Collection and to Bart Van der Vijver, Bank Beszteri and Michel Coste for helping us search the ‘Calcaire de Yedo’. Grateful thanks are extended to the two anonymous reviewers who helped us to improve the manuscript. The research was supported by grants from the Universidad Nacional de La Plata 11/N722 and from the Consejo Nacional de Investigaciones Científicas y Técnicas, PIP0067. Funding was also provided by the Luxembourg Institute of Science and Technology (TAXODIA project).