About spirals and pores: Xylariaceae with remarkable germ loci

Based on phylogenetic analyses of a multi-gene matrix of nuITS-LSU rDNA, RPB2 and TUB2 sequences and morphology, xylariaceous species with uni- to pauciperitheciate stromata and ascospores having a spirally coiling (helicoid) germ slit are revised and reclassified, including detailed descriptions and illustrations. The genus Helicogermslita is redefined and restricted to seven species with massive, erumpent, clypeus-like carbonaceous stromata, and Rosellinia somala is combined in Helicogermslita. Within the core Xylariaceae, the poorly known Leptomassaria simplex is shown to be closely related to Anthostoma insidiosum, for which the new genus Oligo­stoma is established, and Anthostoma rhenanum is demonstrated to be synonymous with O. insidiosum. The new genus Albicollum, characterised by immersed ascomata and a collar of white pseudostromatic tissues surrounding the ostioles, is established for Amphisphaeria canicollis, Anthostoma chionostomum, Sordaria (= Helicogermslita) fleischhakii and Anthostoma vincensii. Anthostoma ostropoides is synomymised with Albicollum canicolle, and Al. berberidicola, Al. longisporum and Al. novomexicanum are described as new species. Rosellinia (= Helico­germslita) gaudefroyi is transferred to the new genus Spiririma. Anthostoma amoenum and Euepixylon udum, both with a poroid germ locus, are shown to be only distantly related, and An. amoenum is reclassified within the asexual genus Digitodochium. Based on phylogeny, the genus Euepixylon is treated as a synonym of Nemania. A new species, Nemania ethancrensonii, which is closely related to the two formerly accepted Euepixylon species (E. sphaeriostomum, E. udum) but strongly deviates from the morphological concept of Euepixylon and Nemania, is described from the eastern USA. The genera Anthostomelloides, Clypeosphaeria, Digitodochium, Emarcaea, Induratia, Linosporopsis, Magnostiolata, Occultitheca and Spiririma are revealed to form a morphologically heterogeneous lineage in a basal position of Xylariaceae. Anthostoma vincensii, Quaternaria simplex and Rosellinia gaudefroyi are lectotypified, and Amphisphaeria canicollis, Anthostoma amoenum, An. rhenanum, An. vincensii, Quaternaria simplex, Rosellinia gaudefroyi and Valsa insidiosa are epitypified. Keys to uni- to pauciperitheciate xylariaceous genera with sigmoid to helicoid germ slits and to species of Albicollum are provided.