Eunotogramma litorale sp. nov., a marine epipsammic diatom from Southern California, USA

Abstract

Eunotogramma litorale sp. nov. is described from marine littoral epipsammic assemblages collected from San Diego County, Southern California, USA. The valves of this common species are semi-elliptical in outline with a curved dorsal margin and a more or less straight ventral margin. Each valve has 1–6 transapical costae. Areolae are absent on the valve face; a small rimoportula is usually present on the valve face or uppermost mantle near each pole. One or more rimoportulae are usually found in a row along the dorsal mantle between the costae. Small areolae, visible only with SEM, are typically found between costae on the ventral mantle and along the ventral portion of the pars exterior of the valvocopulae. E. litorale can be distinguished from three other Eunotogramma species with hyaline valve faces by the semi-elliptical shape of its valve outline. The similarity of the internal openings of the rimoportuale of E. litorale and some Aulacodiscus species suggests that E. litorale may be allied with Aulacodiscus, a marine genus associated with inshore beaches.