Studies of Some Tremellaceae. IV. Exidiopsis

SUMMARY

The genus Exidiopsis is characterized by resupinate basidiocarps with effused to abrupt margins. The basidiocarps are indeterminate, both in thickness and in width. The tremellaceous basidia are subglobose, ovate, obovate, clavate, or rarely pyriform with an enucleate stalk and arise from lateral proliferations through or near sub-basidial clamp-connections. The basidiospores are varied within the genus but are generally characteristic within the species. They are capable of germinating by repetition. Dikaryophyses may be present or absent. If present, they may consist of slender branching structures only, or as in some species, cylindrical structures may also be present. Clamp-connections are found throughout the dikaryotic hyphae.

Within the genus Exidiopsis four subgeneric groupings are apparent, none, however, are sufficiently distinct to warrant a taxonomic designation.

Fifteen species are assigned to the genus, eight are treated as dubious, and eighteen species, which have been assigned to the genera Sebacina or Eichleriella by other authors, are excluded. Seven new combinations are proposed. A key is presented for the identification of the accepted species.

The numbers of available collections of most species are insufficient for an accurate determination of the geographic ranges. The collections of Exidiopsis calospora, E. prolifera, E. glaira, E. molybdea, E. fugacissima, and E. calcea examined are mainly from temperate regions. Those of E. candida, E. mucedinea, E. sublivida, and E. alliciens examined are mainly from subtropical and tropical regions. E. grisea seems to be cosmopolitan, whereas the collections made to date of E. fuliginea, E. laccata, E. macrospora, and E. leucophaea are from limited regions of the world.