Stirtonia is a genus of lichen-forming fungi in the family Arthoniaceae. It contains 22 species of corticolous (bark-dwelling) crustose lichens found primarily in tropical regions.
Taxonomy
The genus was circumscribed by the British lichenologist Annie Lorrain Smith in 1926, with Stirtonia obvallata assigned as the type species. The species epithet honours the Scottish lichenologist James Stirton.
Description
The thallus of Stirtonia contains green algae as its partner. These algae belong to the genus Trentepohlia and are responsible for photosynthesis within the lichen symbiosis. Stirtonia lichens reproduce sexually through spore-producing structures called asci. These asci are found in specialised areas of the thallus known as areas. A distinctive feature of Stirtonia is the presence of interascal hyphae (fungal threads between the asci) that anastomose, or interconnect, forming a network. These hyphae are similar in appearance to the hyphae found in non-reproductive parts of the thallus and are not bound together by a jelly-like substance (hymenial gel) as seen in some other lichen genera.
The of Stirtonia have a unique structure. They are divided only by transverse septa (cross-walls), creating several segments along the length of the spore. The walls of these spores, including the septa, are thickened. This thickening results in the internal chambers () of the spores having a rounded or lens-like shape when viewed under a microscope.
Species
, Species Fungorum (in the Catalogue of Life) accepts 22 species of Stirtonia.
Stirtonia borinquensis Stirtonia byssoidea – Florida Stirtonia caribaea Stirtonia coei – Florida Stirtonia curvata Stirtonia divaricatica – Florida Stirtonia epiphylla – Seychelles Stirtonia ghattensis – India Stirtonia ibirapuitensis Stirtonia isidiata Stirtonia juaensis Stirtonia latispora – Florida Stirtonia lucida – Brazil Stirtonia microspora Stirtonia neotropica Stirtonia nitida Stirtonia nivea Stirtonia obvallata Stirtonia ochracea – Brazil Stirtonia psoromica Stirtonia punctiformis Stirtonia rhizophorae Stirtonia schummii Stirtonia viridis
References