| Strigula | |
|---|---|
 | |
| Strigula species on plant foliage in Hawaii (possibly Strigula smaragdula) | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Fungi |
| Division: | Ascomycota |
| Class: | Dothideomycetes |
| Order: | Strigulales |
| Family: | Strigulaceae |
| Genus: | Strigula Fr. (1823) |
| Type species | |
| Strigula smaragdula Fr. (1830) | |
| Synonyms [1] | |
List
| |
Strigula is a genus of lichen-forming fungi in the family Strigulaceae. [2]
The genus was circumscribed in 1823 by the English mycologist Elias Magnus Fries. [3]
The taxonomy of the genus has undergone significant revisions based on multilocus phylogenetic analyses. Originally defined broadly to include species growing on various substrates, research revealed that foliicolous (leaf-dwelling) species formerly placed in Strigula actually form six well-defined clades that warranted recognition as separate genera. The foliicolous species have been reallocated into the following genera: [4]
Strigula, in its currently defined narrower sense, is a genus of lichen-forming fungi characterized by its distinctive foliicolous (leaf-dwelling) growth pattern. These lichens form subcuticular thalli, meaning they grow beneath the cuticle of leaves, infiltrating between cell layers rather than simply growing on the surface. The thalli (lichen bodies) of Strigula are typically thickened, with a characteristic bright green to grey-green coloration. They form rounded patches with entire to crenulate margins on leaf surfaces. Strigula species develop a symbiotic relationship with a specific algal partner ( photobiont ) in the genus Cephaleuros , which provides the lichen with carbohydrates through photosynthesis. [4]
Reproductive structures include perithecia (flask-shaped fruiting bodies) that are partially immersed in the thallus, appearing as small, basally immersed and apically erumpent black dots. The perithecial wall is carbonized , appearing jet-black in cross-section. The perithecia contain asci (spore-producing cells) that are bitunicate (double-walled) with a short tholus and narrow ocular chamber . [4]
Each ascus produces eight ascospores , which are arranged in one to two rows within the ascus. The ascospores are fusiform (spindle-shaped), single-septate (divided by one wall), colorless, and relatively small to medium-sized (7–25 × 4–6 μm). Strigula also produces asexual reproductive structures called pycnidia, which contain macroconidia (larger asexual spores) with short to medium-sized gelatinous appendages that extend only slowly when observed in laboratory preparations. [4]
