Apatococcus F. Brand, 1925

Veselá, Veronika, Malavasi, Veronica & Škaloud, Pavel, 2024, A synopsis of green-algal lichen symbionts with an emphasis on their free-living lifestyle, Phycologia 63 (3), pp. 317-338 : 326

Apatococcus F. Brand .

Apatococcus typically has spherical cells, which can sometimes be angularly flattened ( Fig. 14 ). During division, irregular packages or multi-layered clusters of cells are formed. The chloroplast is parietal, without a pyrenoid, and in older cells it partially detaches from the cell wall. It reproduces by aplanospores or zoospores (Ettl & Gärtner 2013). According to Li et al. (2021), Apatococcus is closely related to the order Watanabeales and to the genus Symbiochloris .

This genus consists of five taxonomically recognized species ( Guiry & Guiry 2022). Apatococcus lobatus is the most common and widespread aerophytic algal species. Watanabe et al. (1997) obtained isolates morphologically similar to this species from several marine lichen taxa. However, Beck (2002), questions this identification and considers the isolated algae as contaminants. To date, the occurrence of A. lobatus in lichens has not received any support in the form of molecular data ( Zahradníková et al. 2017). In contrast, a newly described species A. fuscideae , was shown to associate with lichens of the genus Fuscidea ( Zahradníková et al. 2017) . Probably due to its recent discovery, this species has not been recorded in free-living state.

Figures

Figs 1–18. Lichen photobiont genera (including nonlichenized species) belonging to classes Trebouxiophyceae and Chlorophyceae. Fig. 1. Asterochloris lobophora. Fig. 10. Prasiola crispa. Fig. 2. Myrmecia incisa. Fig. 11. Pseudochlorella pringsheimii. Fig. 3. Trebouxia impressa. Fig. 12. Stichococcus sp. Fig. 4. Vulcanochloris symbiontica. Fig. 13. Auxenochlorella protothecoides. Fig. 5. Chloroidium saccharophilum. Fig. 14. Apatococcus sp. Fig. 6. Jaagichlorella luteoviridis. Fig. 15. Leptosira sp. Fig. 7. Coccomyxa sp. Fig. 16. Symbiochloris tschermakiae. Fig. 8. Elliptochloris subsphaerica. Fig. 17. Uvulifera verrucariae (Lorenz 2016). Fig. 9. Diplosphaera chodatii. Fig. 18. Bracteacoccus. sp. Scale bars: 10 μm (Figs 1-9, 11-18), 200 μm (Fig. 10).