Lithotrichon Darienko & Pröschold

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 : 328

Lithotrichon Darienko & Pröschold .

Members of this genus, previously accommodated by Dilabifilum , form cushion-like thalli composed of heterotrichous filaments when mature ( Fig. 24 ). The cushion-like appearance is caused by the sarcinoid form of the prostrate system. The erect system, formed by short filaments, branches from the edges of the prostrate system. The cells contain parietal chloroplasts with pyrenoids and reproduce by division and zoospore production. These morphological features are, however, not sufficient for successful determination of this genus ( Darienko & Pröschold 2017).

The genus, with two accepted species ( Guiry & Guiry 2022), was long believed to be strictly freshwater ( Darienko & Pröschold 2017; Liu et al. 2019). Lithotrichon pulchrum , for example, inhabits the thallus of freshwater lichens Verrucaria rheitrophila (= Hydropunctaria rheitrophila ; Darienko & Pröschold 2017). Recently, the same algal species was isolated from a marine water sample collected in the Samcheok Harbor, Republic of Korea ( Kwon et al. 2022).

Figures

Figs 19–30. Lichen photobiont genera (including nonlichenized species) belonging to classes Ulvophyceae and Klebsormidiophyceae. Fig. 19. Cephaleuros virescens (Darienko 2017). Fig. 20. Phycopeltis arundinacea. Fig. 21. Trentepohlia sp. Fig. 22. Blidingia marginata. Fig. 23. Halofilum ramosum (Darienko 2008). Fig. 24. Lithotrichon pulchrum (Darienko 2016b). Fig. 25. Paulbroadya prostrata (Darienko 2016a). Fig. 26. Pseudendoclonium sp. Fig. 27. Rindifilum verrucariae. Fig. 28. Undulifilum symbioticum. Fig. 29. Urospora penicilliformis. Fig. 30. Interfilum terricola. Scale bars: 10 μm (Figs 19, 21-30), 50 μm (Fig. 20).