Spirotaenia minuta Thuret (1856: 157) (Fig. 17)

Cells 5 times longer than wide, fusiform with narrowly apices, chloroplast ribbon-shaped, parietal, constituted by a single loosely twisted helical ribbon. Cell length 32–33 μm, breadth 6 μm.

Geographic distribution: Europe: Austria, France, Germany, Ireland, Latvia, Netherlands, Norway, Poland, Russian Federation, Spain, Ukraine, United Kingdom; North America: USA; Africa: South Africa (Cholnoky 1955), Asia: South Korea; Oceania: Australia and New Zealand (Guiry & Guiry 2023); South America: Argentina (Guarrera & Kuhnemann 1949, Tell 1985), Bolivia (Borge 1906).

Ecology: Occurs in both hard- and soft-water situations (Prescott et al. 1972).

Note: Spirotaenia minuta has been reported in Bolivia (Borge 1906), but the taxonomic information is limited to cell dimensions (32–33 µm in length, 6 µm in width, Borge 1906). Tell (1985) referenced Guarrera & Kuhnemann (1949) for Tierra del Fuego (Argentina), but did not provide detailed information. Therefore, further studies are recommended to confirm the occurrence of this species in the Neotropics.