Verrucaria subdevergens

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Verrucaria subdevergens

Taxonomy
Verrucaria subdevergens is a rock-dwelling crustose lichen in the family Verrucariaceae. It was described as new to science in 2020 by Finnish lichenologists Juha Pykälä and Leena Myllys. It belongs to the Verrucaria genus and is part of the V. devergens complex, closely related to V. devergens and V. karelica. The name subdevergens reflects its close relationship to V. devergens. DNA analysis shows a 5.4–6.0% difference in the internal transcribed spacer region from its closest relative, V. kuusamoensis.

Description
The thallus (the lichen body) of V. subdevergens can be white or grey to ochraceous or pale greyish-brown. It may grow inside the rock (endolithic) or on the rock surface (epilithic), and its appearance ranges from continuous to irregularly cracked. Sometimes neighboring thalli are separated by a dark line. The perithecia (fruiting bodies) are 0.21–0.42 mm in diameter, partially immersed in the rock, and often surrounded by a collar of thalline tissue. A distinctive feature is the involucrellum, an outer layer covering half or more of the perithecium’s height; this helps distinguish it from the closely related V. devergens, which usually has a shorter involucrellum. Spores are large (23–35 μm long and 11–15 μm wide), non-septate, and enclosed by a thin perispore.

Habitat and distribution
Verrucaria subdevergens is known only from the Oulanka area in northeastern Finland, where it grows on dolomite rock outcrops and boulders. This area also hosts close relatives V. devergens and V. karelica. The species’ restricted distribution suggests it could be of conservation concern and highlights the Oulanka region as a hotspot for calcicolous (lime-loving) lichens.

See also
List of Verrucaria species

References
(Source: original description and related taxonomic work on Verrucaria in Finland.)