Teloschistaceae

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Teloschistaceae is a large and diverse family of lichens recognized by their bright yellow, orange, or red coloration, caused by characteristic anthraquinone pigments. Members of this family range from crustose to foliose or fruticose forms and are common on rock, bark, wood, and soil, especially in well-lit, exposed habitats.

Growth Form and Thallus

The thallus may be crustose, foliose, fruticose, or squamulose, often forming thin to moderately thick patches or rosettes. Surfaces may be smooth, granular, or lobed, and some species develop radiating or fruticose projections. Color is a defining feature, with thalli ranging from lemon-yellow and golden orange to deep orange or reddish tones, sometimes intensifying in strong sunlight.

Substrate and Habitat

Species in this family grow on a wide range of substrates, including siliceous and calcareous rock, tree bark, wood, soil, and occasionally man-made surfaces such as concrete. They favor open, sun-exposed environments and are common in coastal, arid, alpine, and urban settings.

Photobiont

The photobiont is a green alga, most commonly Trebouxia.

Reproductive Structures

Sexual reproduction is common, and apothecia are often conspicuous and colorful.

• Apothecia: Typically lecanorine, with a thalline margin often matching the thallus color and a bright orange to red disc.
• Asci: Usually contain eight spores per ascus.
• Ascospores: Polarilocular (two-celled with a thick septum), colorless when young, sometimes darkening slightly with age.

Asexual reproduction is also common, with many species producing soredia, isidia, or blastidia.

Chemistry

Teloschistaceae is chemically distinctive due to abundant anthraquinone pigments, responsible for the vivid coloration. Spot tests are often strong and diagnostic, especially K+ purple or red reactions. Chemistry is a primary tool for species-level identification within the family.

Ecology and Role

Members of this family are often sun-loving and pollution-tolerant, thriving in environments with high light and moderate nutrient input. Some species are common in coastal bird-perching zones or urban areas. They contribute to early substrate colonization and are important visual components of exposed lichen communities.

Representative Genera

• Xanthoria – foliose species with broad lobes, common on nutrient-rich bark and rock
• Caloplaca – a large and diverse group of mostly crustose species
• Rusavskia – foliose to fruticose species, often on rock in exposed sites
• Athallia – crustose species formerly included in Caloplaca

Similar Lichen Families

Teloschistaceae may be confused with other yellow or orange lichen families. Candelariaceae also includes bright yellow species but lacks anthraquinone pigments and strong K+ reactions. Lecanoraceae contains some yellowish crusts but typically has less intense coloration and different chemistry. Acarosporaceae may overlap in saxicolous habitats but differs in growth form, apothecial structure, and spore characteristics.

Family overview intended for field study and photographic reference; microscopic examination and chemical tests are often necessary for confident identification.