Gymnoderma Nyl.
Thallus dimorphic. Primary thallus squamulose, linear or flabellate. Photobiont green, Trebouxia. Podetia very short, solid, lacking a central canal and an internal cartilaginous layer. Apothecia sessile on the tips of podetia. Ascospores simple, colourless, 8 per ascus.
Gymnoderma, a genus of 4 described species included in the family Cladoniaceae, is still rather poorly known and there is no monograph of the known species. It is related to Cladonia but is distinguished by the short, solid podetia which lack symbiotic algae. Gymnoderma possibly represents an ancestral form of Cladonia and is disjunctly distributed in Eastern Asia, the Southern Appalachian Mountains (USA), eastern Australia (including Tasmania), and one species occurs widely throughout New Zealand.*
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* The date of description of Gymnoderma given by Farr, Leussink and Stafleu (1979) in Index Nominum Genericorum (Plantarum) as 1860 [Nylander, Flora 43: 546 (1860)] is in error, since Gymnoderma Nyl., in this cited paper is mentioned only in passing and no formal description is given.
