Observations of small-celled species from the Hippodonta pseudoacceptata group

BLANCO. S.; VAN DE VIJVER, B.; VINOCUR, A.; MATALONI, G.; GOMÁ, J.; NOVAIS, M.H.; ECTOR, L.

Szczecin

Congreso; 5th Central European Diatom Meeting; 2011

Uniwersytetu Szczecinskiego

Within the c. 30 species currently ascribed to Hippodonta, several small-celled forms morphologically around Hippodonta pseudoacceptata (H. Kobayasi) Lange-Bert. constitute a rather homogeneous group characterized by rhombic to linear-rhombic outlines, relatively dense striations and comparatively short lineolae, and two shorter striae opposed in the central area. In this study, the morphological variability of H. pseudoacceptata is examined analyzing the valvar ultrastructure of different populations collected from Western Europe or published in the literature. The morphometric values provided in its protologue do not fit with the original illustrations of this taxon, therefore an emended diagnosis becomes necessary. H. pumila Lange-Bert., G. Hofmann & Metzeltin can be considered its taxonomic synonym. Additionally, H. lange-bertalotii Van de Vijver, Mataloni & Vinocur sp. nov. is described from Crater Lake, DeceptionIsland (South Shetland Islands). Blanco et al. (2011) report a detailed morphological description of this species by means of both light and scanning electron microscopy and a comparison with related taxa. The main diagnostic criteria include the rhombic outline of the valves, the comparatively narrow striae and the presence of two shortened striae delimiting the central area. The adscription of this new species to the genus Hippodonta and the differences with related taxa are briefly discussed. Blanco, S., B. Van de Vijver, A. Vinocur, G. Mataloni, J. Gomà, M.H. Novais & L. Ector (2011). Hippodonta lange-bertalotii Van de Vijver, Mataloni & Vinocur sp. nov. and related small-celled Hippodonta taxa. Nova Hedwigia Beih. In press.