Phyllopsora borbonica
Phyllopsora borbonica is a species of crustose lichen in the family Ramalinaceae. It grows in humid woodland environments across several Indian Ocean islands including Mauritius and Réunion, as well as in Sri Lanka, typically found at elevations between 540 and 1255 metres. The species forms colonies with a distinctive brownish-black base layer that develops into a continuous pale green crust. It produces abundant reddish-brown reproductive structures up to 2 mm in diameter, and is characterized by its unusually long, needle-shaped spores that help distinguish it from related species.
Taxonomy
Phyllopsora borbonica was formally described as a new species in 2001 by the lichenologists Einar Timdal and Hildur Krog. The species is classified within the genus Phyllopsora primarily based on several distinctive features: a brownish black that forms colonies of pale green, scattered areas that eventually merge; reproductive structures with slightly pubescent margins; upper of type 2 ; strongly gelatinised lower tissue that merges into the surrounding tissue ; and, needle-like reproductive spores.The species shares similarities with P. mauritiana but differs in having a more extensive growth pattern and thinner prothallus. P. borbonica also has darker reproductive structures that often turn black on the underside, and longer, needle-like spores. spores are unusual in the genus Phyllopsora, being known in Africa only in the , radiate species P. longispora.
Description
Phyllopsora borbonica has a crusty thallus that is diffuse in growth pattern. The thallus is formed by a medium-thick, brownish-black prothallus and small, closely packed, pale green and smooth areolae. These discrete areolae join at their edges to form a more or less continuous crust in the central parts of the lichen. The upper cortex is 10–15 μm thick and classified as type 2, with an filling the inner part of the areolae. Neither the cortex nor the algal layer contains crystals.The reproductive structures are abundant, up to 2 mm in diameter, rounded to somewhat flexible in shape, and reddish-brown in colour. The margin is sometimes slightly pubescent when young and paler than the. The underside sometimes darkens to black. The inner tissue structure includes a pale brown to colourless inner part, pale brown to dark reddish-brown rim, dark brown to reddish-brown upper, and paler lower part, with a colourless . No crystals are present in the apothecia, but a reddish-brown pigment in the rim and hypothecium turns purple when potassium hydroxide solution is applied. The spores are needle-like, simple, and measure 20–45 by 2–3 μm. Chemical analysis indicates that this lichen does not produce any lichen products that can be detected by standard chemical spot tests.