Verrucaria subdevergens
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| Verrucaria subdevergens | |
|---|---|
 | |
| Image of holotype specimen; scale bar = 0.5 mm | |
Scientific classification  | |
| Kingdom: | Fungi |
| Division: | Ascomycota |
| Class: | Eurotiomycetes |
| Order: | Verrucariales |
| Family: | Verrucariaceae |
| Genus: | Verrucaria |
| Species: | V. subdevergens |
| Binomial name | |
| Verrucaria subdevergens Pykälä & Myllys (2020) | |
 Holotype: Oulanka National Park, Finland | |
Verrucaria subdevergens is a species of saxicolous (rock-dwelling) crustose lichen in the family Verrucariaceae.[1] It occurs in northeastern Finland.
Verrucaria subdevergens was described as new to science in 2020 by the Finnish lichenologists Juha Pykälä and Leena Myllys. It belongs to the genus Verrucaria, a group of lichens characterised by their small, flask-shaped fruiting bodies (perithecia) and crustose growth form. It is closely related to V. devergens and V. karelica, forming part of the "V. devergens complex". The species epithet subdevergens reflects its close relationship to V. devergens. Despite its morphological similarities to these species, V. subdevergens is genetically distinct, with DNA analysis of the internal transcribed spacer region showing a sequence divergence of 5.4–6.0% from its closest relative, V. kuusamoensis.[2]
Description
The thallus (lichen body) of Verrucaria subdevergens varies in colour from white or grey to ochraceous or pale greyish-brown. It can be endolithic (growing within the rock) or thinly epilithic (growing on the surface), and its appearance ranges from continuous to irregularly cracked. In some specimens, adjacent thalli are separated by a dark line.[2]
The perithecia are moderately large (0.21–0.42 mm in diameter) and partially immersed in the rock substrate, leaving shallow to deep pits. They are often surrounded by a collar of thalline tissue.[2]
A key diagnostic feature of V. subdevergens is its involucrellum, an outer layer covering the perithecium. In this species, the involucrellum typically covers half or more of the perithecium's height, occasionally enveloping it entirely. This feature helps distinguish it from the closely related V. devergens, which usually has a shorter involucrellum.[2]
The spores of V. subdevergens are large, measuring 23–35 μm long and 11–15 μm wide. They are non-septate (lacking internal divisions) and enclosed in a thin perispore.[2]