Diplotomma Flot.
=DIPLOICIA A.Massal., 1852
Type : Diplotomma alboatrum (Hoffm.) Flot. [=Lichen alboater Hoffm.]
Type : Diploicia canescens (Dicks.) A.Massal. [=Lichen canescens Dicks.]
Description : Flora (1985: 161).
Key
Diplotomma, a genus of c. 23 species (Kirk et al. 2001), is included in the family Physciaceae (Erikkson et al. 2004; Pennycook & Galloway 2004). It differs from Buellia in the crystalline-granular cortex, immersed apothecia and septate to submuriform, dark ascospores (Nimis 1993). However, Nordin (1996) considers that Diplotomma is better placed in Buellia. In a study of phylogeny in the family Physciaceae, inferred from ITS sequence analysis, Lohtander et al. (2000) report Diplotomma alboatrum as a distinct clade grouping closely with another clade comprising Amandinea, Buellia and Dimelaena, the two clades forming a sister group to the rest of the Physciaceae. Recent molecular studies using ITS rDNA and mitochondrial SSU rDNA sequence data from taxa included in both Diploicia and Diplotomma (Molina et al. 2002; Crespo et al. 2004a), showed taxa from these two formerly separate genera form a monophyletic clade distinct from species of Buellia, and further, these authors accept Diplotomma as a distinct genus with the later genus name Diploicia A.Massal., treated as a synonym, a view adopted here. Three species [one of which comprises two distinct chemodemes treated as subspecies] are known from New Zealand.
