Frutidella
Frutidella is a genus of lichen-forming fungi in the family Lecanoraceae. It contains three species. The genus was established in 1994 by Klaus Kalb to accommodate a species previously classified in the genus Lecidea. These lichens form thin crusts that often develop distinctive wart-like swellings packed with tiny granules, and they produce small, dome-shaped fruiting bodies with a characteristic blue-green sheen. Species of Frutidella typically grow on acidic substrates, including nutrient-poor soils in upland areas and the bark of trees.
Taxonomy
The genus was circumscribed in 1994 by Klaus Kalb to contain the species formerly known as Lecidea caesioatra.Description
Frutidella grows as a thin crust that breaks into discrete, tile-like patches or develops conspicuous wart-like swellings. These swellings are packed with tiny, grain-like outgrowths that resemble miniature isidia; as they age the grains can crumble into a powder of soredia, providing a way for the lichen to spread vegetatively. Thallus colour ranges from greenish and grey to bluish or even nearly black, and a narrow white border may or may not be present. The photosynthetic partner is a single-celled green alga of the type.The fruiting bodies of Frutidella are small, dome-shaped discs. They sit directly on the thallus, sometimes half-hidden among the surface granules, and appear bluish black or dusted with a blue-grey frost when damp. Unlike lichens that recycle thallus tissue to form a rim, these apothecia lack a. Instead they are encircled by a —tightly packed hyphae that radiate like spokes and stay pale or yellowish, never becoming blackened. A crystalline pigment in the surface layer lends a bright blue-green sheen that does not react with potassium hydroxide solution. Beneath, the spore-bearing tissue contains slender, sparsely branched threads and asci of the Lecanora type, each holding eight smooth, colourless, single-celled ascospores.
Asexual reproduction takes place in minute, flask-shaped structures that have a darkened tip and release very slender, thread-like conidia. Chemical studies using thin-layer chromatography have detected the secondary metabolite compounds sphaerophorin and thiophanic acid in most specimens, with isoarthothelin or asemone present occasionally.