Micrasterias foliacea var. nodosa (Behre) Levanets & Janse van Vuuren, 2023

Levanets, Anatoliy & Janse van Vuuren, Sanet, 2023, Morphology, taxonomy, biogeography and ecology of Micrasterias foliacea Bailey ex Ralfs (Desmidiales, Zygnematophyceae), PhytoKeys 226, pp. 33-51 : 33

4. Micrasterias foliacea var. nodosa (Behre) Levanets & Janse van Vuuren stat. nov.

M. foliacea f. nodosa Behre 1956. "Archiv für Hydrobiologie / Supplement" 23: 84, Pl. 10, fig. 5, Basionym.

Taxon depository.

PhycoBank registration: http://phycobank.org/103725.

Nodular cell wall thickenings are unique morphological features of this variety and therefore it is proposed to raise taxonomical status of this form to the variety.

Morphology.

This taxon was described by Karl Behre (1956) as "forma Micrasterias nodosa nodosa " based on cell morphology - it differs from the type by the presence of nodular wall thickenings. Usually, thickenings are located on the inner corners and opposed points of adjacent lobes. Sometimes adjacent lobes are connected by ridge-like thickenings. It was noted that this variety is not a teratological form, because similar wall thickenings were found in numerous cells collected in several sites. Also, no transitional forms were seen between the nodular and the typical forms and the two forms occurred side by side in some samples. Dimensions: 70-74 x 80 μm, isthmus 16 μm.

Distribution.

Variety Micrasterias nodosa was rarely encountered, and only recorded from a few islands in Indonesia and the Philippines (southeastern Asia; Fig. 2 and Suppl. material 2 for more information).

Habitat and ecology.

In all cases M. foliacea var. nodosa were found in lake environments. In the Philippines the water bodies were characterized by clear water, covered by plants, containing detritus and other remains of higher plants. In Indonesia it was recorded from a crater lake (Suppl. material 2). No data on physico-chemical environmental variables was present for these water bodies.

Figures

Figure 2. Worldwide distribution of different varieties of Micrasterias foliacea.