Cocconeis thalassiana sp. nov., a new alveolate diatom (Bacillariophyta) from the Mexican Caribbean

Abstract

Based on light and scanning electron microscopy observations, a detailed description of a new marine alveolate Cocconeis Ehrenberg, C. thalassiana sp. nov., is presented. This large Cocconeis was found in samples collected from a shallow marine coastal lagoon of the Mexican Caribbean, as an epiphyte on the marine seagrass Thalassia testudinum Banks ex König. Among alveolate Cocconeis, the presence of long alveoli for every stria opening into the frustule interior by two long internal apertures of the sternum valve (SV) is a unique character. Other typical frustule features are: bilayered, convex SV thicker than the concave raphe–sternum valve (RSV), the inner face of the SV with hyaline areas between the two apical rows of apertures, the monolayered RSV with a narrow submarginal hyaline area following the valve outline, and the girdle consisting of only two valvocopulae (one for each valve).

Keywords:

• Cocconeidaceae
• Thalassia testudinum
• seagrasses
• epiphytes

Acknowledgements

We gratefully recognize the excellent support from D.A. Siqueiros-Beltrones, as well as O. Ubisha for SEM images. OER was partially supported by the Spanish Council of Scientific Research (CSIC). The comments and suggestions of two anonymous reviewers and the editors of Diatom Research greatly improved this work.