Skyttea
Type : * Skyttea nitschkei (Körb.) Sherwood, D.Hawksw. & Coppins [* Nesolechia nitschkei Körb.]
Description : Lichenicolous, commensalistic. Ascomata apothecia, ascohymenial, immersed, becoming erumpent, small, initially closed, opening by a pore, remaining deeply urceolate and perithecioid, even at maturity. Exciple dark-brown or olive-green, non-carbonised, composed of small-celled pseudoparenchyma, lined near the summit with colourless to brown, thin-walled, smooth hairs. Hamathecium of paraphyses, simple to sparingly branched, septate, sometimes enlarged above. Asci with thin lateral walls, thick-walled at apex, functionally unitunicate, I−; apex thickened but without any obvious aparatus or pore, 8-spored. Ascospores colourless, smooth, oval to narrowly ellipsoidal, simple to 3-septate. Anamorph not known.
Skyttea is a genus of lichenicolous fungi included in the Helotiales incertae sedis (Diederich & Etayo 2000; Hawksworth 2003; Lawrey & Diederich 2003; Eriksson et al. 2004; Pennycook & Galloway 2004; Eriksson 2005), colonising living lichen thalli. It is characterised by urceolate ascomata with a narrow pore at first; a greenish or brownish, rarely a reddish exciple of conglutinate hyphae with subglobose to ±cylindrical lumina, bordered near the margin with hyaline to greenish or brownish, usually smooth, straight hairs; the absence of periphyses; rarely branched and apically scarcely thickened paraphyses; asci and a hymenium that are I−; a thin lateral and a very thick apical ascus wall with a small ocular chamber; and normally simple ascospores. When first described, seven species were recognised (Sherwood et al. 1980), but at present at least 17 species are now known (Diederich 1986; Diederich & Etayo 2000, 2004; Etayo 2002). The hosts normally appear healthy when infected with Skyttea, suggesting that this fungus is a parasymbiont rather than a parasite. Most species of Skyttea are highly specialised taxa, with the majority being known from only one lichen genus and in some cases even restricted to a single species of lichen (Diederich & Etayo 2000). Most lichen hosts are crustose with more species of Skyttea occurring on corticolous lichens than on saxicolous ones. One species is so far recorded from New Zealand.
