Cercidospora
Type : * Cercidospora ulothii Körb.
Description : Lichenicolous. Ascomata perithecioid pseudothecia, globose, black, immersed in host tissue, scattered, or often with several perithecia united by a common perithecial wall. Perithecial wall in section blue-black, bluish violet or blue-green to olive-brown at apex, pale-blue, brownish or colourless basally, cells small, rounded, forming a textura intricata. Hamathecium of septate, branched-anastomosing paraphysoids, 1–2 μm thick. Periphyses short, distinctly developed or absent. Asci fissitunicate, cylindrical to clavate with a distinctly developed foot, and a thickened endoascus with a small ocular chamber, 4–6–8-spored. Ascospores 1-septate, colourless, apices rounded at one end and pointed at the other, with a smooth perispore, and sometimes (in young ascospores) thinly halonate.
Cercidospora is a genus of lichenicolous fungi, included in the Dothideomycetes incertae sedis (Eriksson et al. 2004; Pennycook & Galloway 2004; Eriksson 2005), and found on the following hosts: Arthrorhaphis spp., Caloplaca, Lecanora muralis, L. polytropa, Rhizoplaca melanophthalma, Solorina crocea, Stereocaulon sp., Xanthoria elegans. Currently some 24 species are known worldwide, with at least nine additional taxa awaiting description (Hafellner 1987; Triebel 1989; Alstrup & Hawksworth 1990; Grube & Hafellner 1990; Santesson 1993; Hafellner & Obermayer 1995; Navarro-Rosinés et al. 1996, 2004; Zhurbenko & Triebel 2003; Santesson et al. 2004; McCune & Ponzetti 2005). Most known species of Cercidospora are lichenicolous on crustose, or more rarely, fruticose lichens on soil and rocks. All are confined to Lecanoralean hosts and species inhabit different parts of the host lichen (hymenium, cephalodia, and thalline tissues), developing a wide range of biological relationships. A table showing key characters and the host lichens of all known species of Cercidospora is given in Zhurbenko & Triebel (2003: 209–212). One species is known from New Zealand; collected as a parasite on Arthrorhaphis alpina (Hafellner & Obermayer 1995). The species * C. epipolytropa (Mudd) Arnold should be searched for on thalli and apothecia of Lecanora intricata and L. polytropa.
