‘Omphalina Patch Disease' and the Rickenellaceae

Purpose: A condition resulting in vernal patches of stunted or dying cereal crops was called 'Omphalina
Patch Disease' (OPD) in England after they were linked to coincidental, co-located basidiomes identified
as Omphalina pyxidata. Original OPD vouchers from the 1980-90s were located in the Royal Botanic
Gardens, Edinburgh, where they had been sent for identification. These were analysed both molecularly
and anatomically to confirm or correct the identification. A recently published 2018 analysis on the
biological status of the Hymenochaetales suggested the genus Loreleia be split between two families in
two orders. In order to address this question and to resolve the generic placement of the patch fungus,
an in-depth investigation was conducted to clarify the taxonomy of agaric genera in the Rickenellaceae.
Methods: DNA cloning, followed by screening of the clones using higher resolution gel electrophoresis,
and plasmid DNA sequencing were required to resolve the phylogenetic signatures of the old herbarium
material and of the type species of Loreleia, L. postii.
Results and conclusions: Neither patch disease sample is O. pyxidata (Tricholomataceae, Agaricales).
Both were conspecific with each other; a species of agaric in the Rickenellaceae (Hymenochaetales). We
determined that Loreleia is not split between two families and orders and that a misdetermined voucher
had led to an erroneous conclusion. Additionally, Contumyces and Loreleia remain phylogenetically
distinct but both require new circumscriptions.