Corticifraga D.Hawksw. & R.Sant.
Type : * Corticifraga peltigerae (Fuckel) D.Hawksw. & R.Sant. [* Peziza peltigerae Fuckel]
Description : Lichenicolous, parasitising thalline tissues of host. Ascomata apothecia, arising singly or in small groups, immersed, at first almost perithecioid or lens-shaped, breaking through the host cortex, finally apothecioid, concave to plane, fawn to black; exciple well-developed in young apothecia, becoming excluded with age, not or scarcely extending above the surface of the disc, hyaline to dark, olivaceous-brown, of irregularly subglobose pseudoparenchymatous cells, excipular setae and periphysoids absent. Hamathecium of paraphyses, filiform, simple or sparsely branched, septate, the apices capitate and brown, or non-capitate and hyaline. Asci elongate-clavate, short-stalked, with two distinct wall layers, apices strongly thickened, I−, discharge by a short extension of the inner apical tissues, 8-spored. Ascospores biseriate, broadly fusiform to ellipsoidal or soleiform, often tapered below, (0–)1–3-septate, colourless, smooth-walled, lacking a distinct gelatinous sheath. Anamorph unknown.
The genus Corticifraga was introduced by Hawskworth & Santesson (1990) to accommodate lichenicolous fungi parasitising species of Peltigera and formerly, but erroneously, included in the genus Phragmonaevia Rehm. Corticifraga is a widespread genus in temperate areas, comprising three known species (Hawksworth & Santesson 1990; Kirk et al. 2001; Ertz 2004b; Santesson et al. 2004), presently included in the Lecanorales, genera incertae sedis (Eriksson et al. 2004; Pennycook & Galloway 2004; Eriksson 2005) and occurring on the host lichens Pertusaria, Solorina (Hawksworth & Santessson 1990) and Pseudocyphellaria (Kondratyuk & Galloway 1995a). Hawksworth & Santessson (1990) note of Corticifraga"The ascus structure of this new genus and the method of ascus discharge recalls that of the order Lecanorales, but the asci are atypical for the order in the absence of any I− blue tissues...the erumpent ascomata are also atypical for the order...the well-developed exciples characteristic of the Ostropales are not present in Corticifraga, excipular hairs and periphysoids are absent, the paraphyses are broader and in one species capitate, and most significantly the ascus apices and methods of discharge are different. Difficulty in placing many lichenicolous fungi into well-known families and orders may be primarily due to their often probably ancient origins. Species of Corticifraga are unlikely to be confused with other discomycetous fungi occurring on members of the Peltigerales. Arthonia Ach. species have broadly clavate asci with fissitunicate discharge and densely branched and anastomosed hamathecial elements; Bacidia De Not. species form clearly superficial apothecia and asci with an I+ blue tholus although sharing multiseptate spores with Corticifraga (Hafellner 1984); Pezizella Fuckel species have sessile apothecia, simple ascospores and an I+ blue apical plug in the ascus (Hawksworth 1980a); those of Scutula Tul. also have sessile apothecia and an I+ blue hymenium and asci with an I+ blue tholus. In Skyttiella D.Hawksw. & R.Sant. ascomata are almost arthonioid, waxy, the asci lack any apical thickening, and the ascospores are simple (Hawksworth & Santesson 1988)". One species of Corticifraga is recorded from New Zealand (Kondratyuk & Galloway 1995a) where it is a parasite of Pseudocyphellaria multifida.
