Rhytidhysteron fruiting bodies are common on recently fallen twigs and branches of Beilschmiedia tawa and Sophora spp. (kowhai), and has also been found on cultivated Citrus. A record in PDD from Nothofagus was based on a misidentified host. Based on an ITS phylogeny there are three species known from New Zealand, the Beilschmiedia-associated and the Sophora-associted species may be undescribed and endemic. The species on Citrus has been reported from several other hosts from other parts of the world, and may be exotic. Morphologically the Sophora-associated species differs from the specimens on other hosts in having 1-septate rather than 3-septate ascospores. It is distinguished from the morphologically similar R. hysterinum by LSU sequences (isolate EB 0351, Genbank accession GU397350).

update, August 2022

NZ specimen ex Citrus
ITS a 100% match to the recently named Chinese species Rhytidhysteron ligustrum (Xu et al. 2022). Morphologically the hymenial surface of the Citrus associated specimen is deep red, perhaps matching the reddish brown discs described for R. ligustrum; ascospore sizes match. R. ligustrum is phylogenetically very close to R. camporesii, R. chromolaenae and R. hongheense.

NZ specimens ex Beilschmiedia tawa
>99% match (2 bp across ITS) to R. xiaokongense, a Chinese species known only from an asexual state. Note that a conidial state has not been noted for the species on B. tawa.

NZ specimen ex Sophora ITS is unique within Rhytidhysteron, matching no other sequence in GenBank.

Xu et al., Cryptogamie, Mycologie, 43(3):63-79 (2022) https://doi.org/10.5252/cryptogamie-mycologie2022v43a3

PRJ, July 2016