Two isolates of Penicillium, belonging to section Exilicaulis series Restricta, were obtained from Vaccinium boninense roots on the Bonin Islands. Molecular phylogenetic analyses (BenA, CaM, and RPB2), supported by GCPSR evaluation and ASAP species delimitation, proved that they represent an independent species-level entity. The branch lengths in the concatenated phylogenetic tree and the high sequence homology in the BenA locus identified P. cinereoatrum, P. heteromorphum, and P. sankaranii as the closest relatives to the isolates. Morphological and temperature tests were compared with P. cinereoatrum CBS 222.66^T and P. heteromorphum CBS 226.89^T . Through these examinations and literature data, the novel strains are distinguished from their closest relatives by differences in colony color, mycelial density, CZ exudates, CREA acid production, margins, and phialide number. Their minimum growth temperature was 10 °C, 5 °C lower than related species. In vitro inoculation on blueberry (Vaccinium virgatum) seedlings showed that all strains colonized rhizodermal cells and promoted root growth. Based on robust molecular delimitation, morphology, and physiology, P. rhizovaccinii (NBRC 116611^T ) is described, alongside descriptions of P. cinereoatrum and P. heteromorphum.

Smut fungus producing sori in flowers of a dioecious plant Rumex acetosa collected in Japan had been identified as Microbotryum kueh neanum (≡ Ustilago kuehneana). Comparative morphology and phylogenetic analyses showed that all specimens previously identified as M. kuehneanum in Japan were Microbotryum stygium (≡ Ustilago stygia). Therefore, the occurrence of M. kuehneanum in Japan is doubtful. The position and structure of sori produced by M. stygium differed between male and female flowers.