Candolleomyces cladii-marisci established as new fungal combination

A formal nomenclatural study has transferred the species Psathyrella cladii-marisci into the refined genus Candolleomyces , establishing the accepted combination Candolleomyces cladii-marisci (Sicoli, N.G. Passal., De Giuseppe, Palermo, Pellegrino, D. Deschuyteneer & Voto) N.G.

Passal. & Sicoli. The paper is a taxonomic combination rather than a new field discovery or a fresh molecular analysis: it places an existing species within a genus delimited using morphological and molecular evidence. The species was originally described from southern Italy and subsequently reported from Belgium, while a later record was also made in Thailand.

When P. cladii-marisci was described, its placement in Psathyrella rested on a combination of macroscopic and microscopic characters. The reported basidiomata were small to medium-sized, thin, fragile and non-deliquescent, with grayish to pale clay-colored or deep brown surfaces. Lamellae formed the hymenium, and the basidiospores were described as smooth, truncated and dark.

Versiform hymenial cystidia occurred together with sphaeropedunculate and clavate cells along the gill edge. These features supported assignment to the broad genus concept of Psathyrella used at the time, but the authors now regard that concept as overly broad and superseded. The decisive taxonomic framework came from a 2020 study led by Wächter and Melzer, which combined morphological and molecular evidence to refine Psathyrella sensu lato.

That work divided the former broad concept into three genera: Britzelmayria , Candolleomyces and Olotia . Some species previously classified in Psathyrella were transferred to these newly delimited groups. A 2021 report on two new Candolleomyces species from China proposed a molecularly informed combination for the Italian taxon on the basis of internal transcribed spacer, or ITS, sequence analysis.

A subsequent Thai record was identified using morphology together with ITS and large-subunit, or LSU, ribosomal DNA evidence, further supporting recognition of the species within Candolleomyces . The new combination also corrects a problem in the name’s publication history. The earlier proposed Candolleomyces combination was based on Psathyrella cladium-mariscii , but that name had been invalidly published because its protologue did not cite an identifier issued by a recognized repository, as required under the relevant botanical naming rules.

The attempted combination was consequently invalid as well. In 2022, Sicoli and colleagues validly published Psathyrella cladii-marisci , integrating corrections to the original description with additional information from the European detection. By basing the present combination on that validly published name, the authors establish Candolleomyces cladii-marisci as the appropriate name under the revised generic classification.

The change therefore resolves both the broader placement of the species and the technical defect affecting the earlier name. The holotype documents the species’ type locality in Calabria, southern Italy. It was collected on 10 April 2018 by Antonio Biagio De Giuseppe and Giovanni Sicoli in a marsh at the base of cut culms of Cladium mariscus at the Orto Botanico Università della Calabria in Rende, Cosenza.

The plants had been transplanted from Lago dell’Aquila in Laureana di Borrello, Reggio Calabria. The site is specified at 39°21′25.05″ north, 16°13′44.57″ east and 220 metres above sea level, at the corner of a concrete tank maintained full of water. The holotype is deposited as CLU F302.

Subject of Research: Nomenclatural transfer of Psathyrella cladii-marisci to the morphologically and molecularly refined genus Candolleomyces

Article Title:  Candolleomyces cladii-marisci ( Psathyrellaceae ), a new combination

Article References: Passalacqua, N. G., & Sicoli, G. (2022). Candolleomyces cladii-marisci (Psathyrellaceae), a new combination. Italian Botanist, 14, 95-97. https://doi.org/10.3897/italianbotanist.14.96281

Image Credits: AI Generated

DOI: 10.3897/italianbotanist.14.96281

Keywords: fungal taxonomy, Candolleomyces, Psathyrella, Psathyrellaceae, new combination, ITS sequencing, LSU sequencing, botanical nomenclature, Cladium mariscus, wetland fungi, cladii-marisci, combination