A STUDY OF BRITISH LICMOPHORA SPECIES AND A DISCUSSION OF ITS MORPHOLOGICAL FEATURES

Abstract

The taxonomy and ecology of fifteen Licmophora species collected around the British coasts are recorded and re-described using light and electron microscopy. To date no extensive study of Licmophora species has been made using electron microscopy. Aspects studied and discussed here are habitat, host, seasonality, colony formation, cell morphology, plastid arrangement and valve structure. A new term, multiscissura, is proposed for the apical slit field. The important morphological features (namely valve shape, rimoportulae, striae and areolae) of this genus are discussed and compared with those of similar taxa.

It has been suggested that the genus could be split (Round et al. 1990, p. 404) and indeed studying variation of each character, within the genus Licmophora, discrete groups of species do emerge: e.g. i) six species have three rimoportulae per cell and nine species have two per cell; ii) two species have no valvocopula septa, three species have deep septa and ten species have shallow to moderately deep septa: iii) several species have transapically elongate areolae, four species have apically elongate areolae and one species no vimines to distinguish areolae. Groups of species possessing the same character, however, do not correlate with other different characters. As a result the genus has not been split into sub-groups, thus leaving Licmophora a discrete genus.