Geminella (alga)

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Geminella is a genus of green algae in the phylum Chlorophyta. It belongs to the family Chlorellaceae, within the class Trebouxiophyceae and the order Chlorellales. The type species is Geminella interrupta.

Habitat: Geminella mostly lives in freshwater environments such as swamps, ponds, and lakes, and is often found with desmids. It can also occur in terrestrial habitats.

Form and cells: It forms uniseriate (single-row), unbranched filaments that can be free-floating or attached to a surface. The cells are usually separate and evenly spaced, or occur in pairs, and are surrounded by a thick mucilaginous sheath. Cells are cylindrical to ellipsoidal to barrel-shaped with broadly rounded ends.

Chloroplasts and pyrenoids: Each cell has a single parietal chloroplast that partly encircles the protoplast, and there is usually one central pyrenoid.

Reproduction: Reproduction occurs by fragmentation of filaments or by forming akinetes, which are resting cells with thick brown walls. Sexual reproduction or zoospores have not been observed.

Relation to Gloeotila: Geminella is similar to the genus Gloeotila, and some scientists treat them as the same group. Others distinguish them based on morphology (for example, whether cells are strictly contiguous or whether pyrenoids are present), but the differences are unclear and require more study.

Species: The genus includes several species, but a complete list is not provided here.