ABSTRACT: A redescription is made of Omphalina meridionalis, a lichenized agaric with Botrydina thallus, recently described from Sardinia (Italy). Since lichenization in Omphalina is connected to loss of clamps and of a pure tetrasporic state, several Spanish collections have been compared with the holotypus. The former are clampless and show both bi- and tetrasporic basidia. In addition, and contrary to the original description, the holotype is also devoid of clamps. A taxonomic discussion, mainly related to morphological and ecological differences of O. meridionalis with other lichenized European Omphalina species, is also provided. The new combination Omphalina aurantiaca is also proposed.

KEYWORDS: Tricholomatales, Omphalina, Phytoconis, Omphalina meridionalis, lichenized agarics, Spain

NOMENCLATURAL NOVELTIES:
Omphalina aurantiaca (Redhead & Kuyper) Barassa & Esteve-Rav., p. 278