Verrucaria bifurcata

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Verrucaria bifurcata is a rock-dwelling crustose lichen from the Verrucariaceae family. It was described in 2020 by Finnish scientists Juha Pykälä, Annina Kantelinen and Leena Myllys. It belongs to the Verrucaria subtilis complex, a group of species known for large spores, perithecia that leave pits in the rock, and a pale, thin thallus.

Description
- Thallus: very thin, pale grey to whitish, typically endolithic (grows inside calcareous rock rather than on the surface).
- Perithecia: small (0.13–0.26 mm in diameter) and mostly sunken into the rock, creating shallow to deep pits.
- Involucrellum: outer layer around the perithecia that can range from absent to covering the entire structure.
- Spores: relatively large for Verrucaria, measuring 21–30 μm long and 9–13 μm wide; they are non-septate (not divided).

Taxonomy
- Binomial name: Verrucaria bifurcata
- Authors: Pykälä, Kantelinen & Myllys, 2020
- It is genetically distinguished from closely related species (such as V. cavernarum, V. difficilis, and V. subtilis) by DNA analysis of the internal transcribed spacer (ITS) region.

Habitat and distribution
- Habitat: grows on calcareous rocks, with a preference for loose pebbles and stones in disused limestone quarries. It tolerates both sunny and shaded conditions.
- Distribution: currently known only from southern Finland, specifically Varsinais-Suomi and Etelä-Savo. This southern restriction sets it apart ecologically from many related Verrucaria species that occur further north.

See also
- List of Verrucaria species

References
- Pykälä, Kantelinen & Myllys (2020). Taxonomy of Verrucaria species characterized by large spores, perithecia leaving pits in the rock and a pale thin thallus in Finland. MycoKeys.