200 years of taxonomic confusion: Sporendonema and allies

Abstract

Abstract The genus Sporendonema was introduced in 1827 with the type species S. casei. for a red mold on cheese. Cheese is a consistent niche for this species. Sphaerosporium equinum is another species classified in Gymnoascaceae (Onygenales) and has also been reported from cheese. Recently, other habitats have been reported for both Sporendonema casei and Sphaerosporium equinum. The present study aimed to investigate the taxonomy of Sporendonema and Sphaerosporium, as well as a close neighbor, Arachniotus. Hormiscium aurantiacum, another related cheese-associated species was also included in the analyses. Strains were evaluated in terms of colony morphology, micromorphology, salt tolerance, growth rate at different temperatures, casein degradation, cellulase activity and multilocus phylogeny with sequences of the nuclear ribosomal internal transcribed spacer region, the D1-D2 region of the large subunit and partial β-tubulin locus sequences. The results showed that the analysed species were congeneric, and the generic names Arachniotus and Sphaerosporium should be reduced to the synonymy of Sporendonema. Therefore, four new combinations as well as one lectotype and one epitype were designated in Sporendonema. Two strains attributed to Sphaerosporium equinum from substrates other than cheese were found to be phylogenetically and morphologically deviant and were introduced as a new species named Sporendonema isthmoides.