Flora of New Zealand Series

Type : Megaspora verrucosa (Ach.) Hafellner & V. Wirth  Urecolaria verrucosa Ach.]

Description : Thallus crustose, areolate, verrucose, effuse or continuous, occasionally ± effigurate. Photobiont green, Trebouxia -like. Ascomata apothecia, zeorine with a thalline margin and a proper exciple, immersed in verrucae, punctiform then subimmersed, urceolate–deformed, ontogeny hemiangiocarpous. Hamathecium of reticulately branched, septate paraphysoids. Hypothecium hyaline, to 20 μm thick. Hymenium hyaline I+ yellow-brown. Asci cylindrical to cylindrical–clavate and thick-walled, the outer wall staining faintly blue in I, with a thickened apical cap and without an ocular chamber (Aspicilia -type), 6–8-spored. Ascospores large, simple, with a thick, two-layered wall, lacking a gelatinous sheath. Conidiomata pycnidia, with type-III conidiophores. Conidia filiform. Chemistry negative.

Megaspora is closely related to both Aspicilia and Pertusaria (Lumbsch et al. 1994c). Two species are known in the genus (Kirk et al. 2001) one of which occurs in alpine habitats in southern New Zealand where it is found on soil or on decaying vegetation. Since Megaspora has several characters in common with the Pertusariaceae (viz. hemiangiocarpous ascoma development, zeorine apothecia with a cupulate excipulum, and branched paraphysoids forming the epithecium), it is placed in the order Pertusariales. However, since it differs in some respects from the Pertusariaceae, viz. the presence of pale amyloid asci and the absence of a "chambre oculaire" (in Megaspora), it is accommodated in the monogeneric family Megasporaceae (Lumbsch et al. 1994c; Eriksson et al. 2004; Pennycook & Galloway 2004; Eriksson 2005). A recent molecular study (Ivanova & Hafellner 2002) has shown that Megaspora is closer to Aspicilia than to Pertusaria or Ochrolechia, and that both Megaspora and Aspicilia belong to the same family.