Flora of New Zealand Series

Type : Lithothelium cubanum Müll.Arg.

Description : Thallus crustose. Photobiont green, Trentepohlia. Ascomata perithecia, black, often with fused ostioles and/or walls, often with non-carbonised pseudostromatic tissues. Ascocarp wall carbonised. Hamathecium colourless, often I+ blue or partly blue, partly orange, Asci with or without a rounded or sagittiform (annular) ocular chamber, the latter found nowhere else within the Melanommatales. Ascospores 8 per ascus with 3 or more distosepta, with a trace of eusepta (submuriform), colourless to brown. Conidiomata pycnidia. Conidia colourless, filiform.

Lithothelium is a genus of c. 20 species of corticolous and saxicolous lichens of wide distribution (Kirk et al. 2001), including several pantropical taxa and a few restricted to temperate Europe or North America. It is included in the family Pyrenulaceae (McCarthy 2001b; Eriksson et al. 2003; Pennycook & Galloway 2004). The genus is characterised by solitary or fused, black, perithecioid ascomata with apical, eccentric or lateral ostioles; an amyloid or non-amyloid hymenium; and colourless to brown, 3(–9)-distoseptate or submuriform ascospores. Most species are epiphytic, but several are restricted to lava or limestone (Aptroot 1991a; Harris 1995; Harada 1997; McCarthy 2001b). One species is recorded from the New Zealand region, being found on limestone in the Chatham Is (Aptroot & Mayrhofer 1991).