Flora of New Zealand Series

Type : Mycobilimbia obscurata (Sommerf.) Rehm [=Lecidea sphaeroides var. obscurata Sommerf.]

Description : Thallus crustose to squamulose, mostly whitish, rarely brownish. Photobiont green, Trebouxia -like. Ascomata apothecia, black, sessile, often aggregated–conglomerate (blackberry-like when well-developed), with proper exciple of radiating or pseudoparenchymatous hyphae. Hamathecium of paraphyses, simple to branched. Asci Bacidia -type, 8-spored. Ascospores simple to 1–2-septate, colourless, with an epispore. Conidiomata pycnidia. Conidia filiform.

Mycobilimbia is a genus of c. 6 species included in the family Porpidiaceae (Hafellner 1989a; Kirk et al. 2001; Eriksson et al. 2004; Ekman 2004d; Kantvilas et al. 2005b). It is probably heterogeneous as here circumscribed. Although accepted by several authors pending a thorough revision (e.g. Wirth 1987, 1995b; Hafellner 1989a; Nimis 1993; Santesson 1993, Ekman 1996a, 2004d; Sérusiaux et al. 1999; Øvstedal & Lewis Smith 2001; Sarrión et al. 2003; Santesson et al. 2004; Kantvilas et al. 2005b), it is still maintained in Lecidea by others (e.g. Foucard 1990; Printzen 1995; Coppins 2002b). According to Hafellner (1984, 1989a), Mycobilimbia is separated from Biatora by its well-developed thalli, ascospores with an epispore, and K/I+ dark-blue, Mycobilimbia -type asci. In contrast, most species of Biatora have crustose, granular or effuse thalli, ascospores lacking an epispore, and K/I+ dark-blue Biatora -type asci. These differences are reinforced by different apothecial ontogeny in the two genera (Printzen 1995). Differences between Bacidia and Mycobilimbia are based mainly on thallus and apothecial morphology, apothecial ontogeny, shape lumen and walls of excipular hyphae, ascus structure and ascospores (Ekman 1996). Toninia is distinguished from Mycobilimbia by differences in the hamathecium of paraphyses, ascus structure and ascospores (Timdal 1991). Recently, several taxa accommodating the Bacidia sabuletorum group were segregated from Mycobilimbia s. lat. as the genus Myxobilimbia (q.v.) (Hafellner & Türk 2001). A recent account of the genus in cool temperate areas of the Southern Hemisphere (Kantvilas et al. 2005b) records three species from Tasmania,with one of these known also from New Zealand and southern South America. One species of Mycobilimbia is at present known from New Zealand, in subalpine to high-alpine areas where it colonises soil, but the genus is still very poorly collected and understood here and additional taxa should be searched for.