Spirotaenia, Brebisson, 1848

Ramos, Geraldo José Peixoto, Souza, Bruna Fadul De, Ribeiro, Sylvia Maria Moreira Susini & Moura, Carlos Wallace Do Nascimento, 2023, New insights into the diversity and distribution of the genus Spirotaenia (Mesotaeniaceae, Streptophyta) in the Neotropics, including the description of S. tetrahelica sp. nov., Phytotaxa 613 (1), pp. 29-38 : 30

Key to the Neotropical species of Spirotaenia

1. Chloroplast consisting of four spiraling ribbons ............................................................................................................. S tetrahelica

- Chloroplast consisting of a single ribbon ...........................................................................................................................................2

2. Cells narrowly fusiform with acute poles...........................................................................................................................................3

- Cells cylindric with broadly rounded poles........................................................................................................................................4

3. Cells 5–8 times longer than broad, two tiny reddish dots at each end .......................................................................... S. beijerinckii

- Cells 5 times longer than broad, without reddish dots at each end ....................................................................................... S. minuta

4. Cells narrow, 17–31 times longer than broad.................................................................................................................... S. filiformis

- Cells wide, 2–10 times longer than broad ..........................................................................................................................................5

5. Cells curved ..................................................................................................................................................................... S. closteridia

- Cells straight.......................................................................................................................................................................................6

6. Cells less than 30 μm long................................................................................................................................................ S. endospira

- Cells over than 30 μm long.................................................................................................................................................................7

7. Cells less than 80 μm long, chloroplast notably red at the ends.............................................................................. S. erythrocephala

- Cells over than 80 μm long, chloroplast without red cap at the ends............................................................................ S. condensata