Raphidonema is a genus of filamentous green alga comprising five species.

A single chloroplast is present in each cell, girdle- or band-shaped, lacking a pyrenoid.

Reproduction occurs asexually via the vegetative division (mitosis) of cells within filaments.

[4] For example, filaments of Raphidonema often separate into single cells akin to Koliella when placed in a liquid medium.

[5] Another similar, but poorly studied genus is Raphidonemopsis, which differs from Raphidonema in that its filaments are attached to a substrate.