Gyalecta

Gyalecta is a genus of crustose lichens in the family Gyalectaceae. These lichens are characterized by their apothecia, which are immersed or sessile and often have a prominent margin. The thallus is typically crustose, meaning it forms a flat, closely adherent layer on the substrate.

Characteristics:

• Thallus: Crustose, varying in color from whitish to greenish-gray, or sometimes brownish. It may be smooth, granular, or rimose (cracked).

• Apothecia: Usually immersed in the thallus at first, eventually becoming sessile or emergent. They are generally round to irregular in shape and often have a distinct margin (exciple). The disc color varies, and can be pinkish, brownish, or black.

• Ascospores: Typically ellipsoid to oblong, hyaline (translucent), and multi-septate (divided by internal walls).

• Chemistry: Chemical spot tests are helpful for species identification. Different species of Gyalecta may contain various lichen substances, leading to different reactions with standard reagents.

Habitat and Distribution:

Gyalecta species are found on a variety of substrates, including bark, rock (calcareous and siliceous), and soil. They have a worldwide distribution, occurring in temperate, boreal, and tropical regions.

Taxonomy:

The genus Gyalecta has a complex taxonomic history, and the classification of species within the genus has been subject to revision. DNA sequencing and phylogenetic analyses have played a significant role in resolving species relationships.

Distinguishing Features:

Gyalecta can be differentiated from other similar crustose lichens based on a combination of morphological characters, including the type of thallus, the shape and color of the apothecia, the size and septation of the ascospores, and chemical spot tests. Microscopical examination is often necessary for accurate identification.