Bulgariella pulla, a Leotiomycete of uncertain placement, with an uncommon type of ascus opening

Bulgariella pulla (Leotiomycetes) is redescribed with the addition of characters of the ascus, spores, and habitat that were previously unconsidered. The ascus dehiscence mechanism in Bulgariella is unusual among Leotiomycetes. In this genus, asci lack a pore and open by splitting to form valves. Phylogenetic analyses of partial sequences of translation elongation factor 1-α (TEF1-α), the second largest subunit of RNA polymerase II (RPB2), and the 18S and 28S nuc rRNA genes determined that Bulgariella belongs within Leotiomycetes but without conclusive assignment to an order or family. A comparison of the nuc rDNA internal transcribed spacers 1 and 2 plus the 5.8S gene (ITS) determined that Bulgariella isolates from the USA, Norway, and Sweden had 100% sequence similarity, and an isolate from Chile had 99.3% similarity with these isolates. These results support the proposition that these collections represent a single species, B. pulla. Bulgariella sphaerospora, a more recently described species, is confirmed as conspecific with B. pulla.