Bacidia

Bacidia is a large and diverse genus of crustose lichens in the family Ramalinaceae. These lichens are characterized by their apothecia (fruiting bodies) which are typically sessile (sitting directly on the substrate) or immersed, and often brightly colored.

Bacidia species are found worldwide, inhabiting a variety of substrates including bark, wood, rock, and soil. They play a significant ecological role as primary colonizers and contribute to the weathering of rock surfaces.

Identification of Bacidia species can be challenging due to the variability in morphology and chemistry, as well as the presence of numerous cryptic species. Microscopic examination of the apothecia and ascospores (sexual spores) is often necessary for accurate identification. Chemical spot tests and thin-layer chromatography (TLC) can also be used to aid in species determination.

The taxonomy of Bacidia has undergone several revisions, and some species formerly classified within the genus have been moved to other genera based on phylogenetic analyses.

Bacidia species contribute to biodiversity and are indicators of environmental health. Some species are sensitive to air pollution and can be used as bioindicators of air quality.