Sticta is a genus of lichens in the family Peltigeraceae. The genus has a widespread distribution, especially in tropical areas, and includes about 114 species. These lichens have a leafy appearance, and are colored brown or black. Sticta species with cyanobacteria as photobionts can fix nitrogen from the atmosphere, and due to their relative abundance and high turnover, they contribute appreciably to the rainforest ecosystem. They are commonly called spotted felt lichens.
Description
The vegetative bodies of the Sticta, the thalli, are foliose, or leafy in appearance. They typically have dimensions of 2 to 5 centimetres (0.8 to 2.0 in) in diameter, although specimens with diameters of up to 10 centimetres (4 in) have been recorded. The lobes are rounded, and the upper surface is black or brown, while the lower surface has a light to dark brown layer of fine hairs (a tomentum), with a few craters, called cyphellae. Thalli often smell of shrimp or fish. The vegetative reproductive structures called isidia or soredia are often present on species in this genus; apothecia (cup-shaped spore-bearing structures) are rarely found. Sticta species are usually found growing on bark, wood, or mossy rock.
Photobiont partners of Sticta species include members of the green algae genera Chloroidium, Coccomyxa, Elliptochloris, Heveochlorella, and Symbiochloris.
The liverwort genus Monoclea contains lichen-like organisms completely unrelated to, but readily confused with Sticta.
Distribution and habitat
Sticta species are primarily tropical in distribution, but some species have been reported from as north as Norway, and as far south as the southern tip of South America.
Most species of Sticta grow on bark, wood, or mossy rock, usually in humid areas.
