Ephebe (lichen)

Ephebe is a genus of filamentous cyanolichens belonging to the family Lichinaceae. These lichens are characterized by their dark, often blackish or brownish, thread-like or coralloid (coral-like) thalli. They are typically found growing on calcareous or siliceous rocks in moist or intermittently wet habitats.

Morphology and Anatomy:

• Thallus: The thallus of Ephebe species consists of tangled, branching filaments. These filaments are composed of cyanobacterial photobionts (typically Scytonema or a related genus) arranged within a matrix of fungal hyphae (the mycobiont). The color of the thallus is usually dark due to pigments produced by the cyanobacteria and the melanization of the fungal hyphae.

• Photobiont: The cyanobacterial photobiont is responsible for photosynthesis, providing the lichen with sugars. The filaments of the cyanobacteria are typically enveloped by the fungal hyphae.

• Mycobiont: The fungal component provides structure and protection to the photobiont and facilitates nutrient and water uptake. The fungal hyphae form a dense network that holds the cyanobacterial filaments together.

• Reproduction: Ephebe lichens can reproduce asexually through fragmentation of the thallus or the formation of hormogonia (motile filaments of cyanobacteria). Sexual reproduction in the fungal component, although less commonly observed, involves the production of apothecia (cup-shaped fruiting bodies) that contain ascospores. The apothecia, when present, are small and inconspicuous, often embedded within the thallus.

Ecology and Distribution:

Ephebe species are primarily found in temperate to arctic regions, often in habitats that experience periodic wetting and drying. They are common on rocks near streams, waterfalls, and other moist environments. Their distribution is influenced by factors such as rock type, light availability, and moisture levels.

Taxonomy:

The classification of Ephebe species has been subject to revision based on molecular and morphological data. Distinguishing species can be challenging due to their relatively simple morphology and variability within species.

Key Characteristics:

• Filamentous or coralloid thallus
• Dark coloration (blackish or brownish)
• Cyanobacterial photobiont (e.g., Scytonema)
• Growth on rocks in moist habitats
• Small, inconspicuous apothecia (when present)