Micropodia pteridina, a misinterpreted fern-inhabiting discomycete with unclear relationship within the Helotiales
By Baral H.-O.

Vol. 15 (1) – 13 April 2023

doi: 10.25664/art-0364

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Abstract: The type species of Micropodia, M. pteridina, was described by Nylander in 1868 under the name Peziza pteridina based on a collection on dead stems of Pteridium aquilinum. When Boudier proposed the new genus Micropodia in 1885, he misinterpreted the species in the sense of a member of Psilachnum, which is very common on blackened stem bases of that fern. Boudier named the genus according to its short-stalked, superficially inserted apothecia. However, the present reexamination of the holotype of M. pteridina revealed sessile apothecia erumpent from beneath the epidermis of unblackened stems of this fern, and its gross morphology, including a denticulate-crenulate margin, suggests instead a relationship with the genus Diplonaevia. Nylander’s original description is rather brief and does not mention the apothecial base, which explains Boudier’s misinterpretation. Although the name Micropodia implies the presence of a short stalk, it is typified by the holotype of M. pteridina. As Micropodia antedates Diplonaevia, which was described by Saccardo in 1889, it would provide an earlier name for that genus, in case the two names are taken as synonyms, but its adoption would be unfortunate and should be avoided by conservation of Diplonaevia. Further misinterpretations of collections on Pteridium as M. pteridina concern Fuscolachum pteridis, Microscypha arenula and Mollisia sp. A redescription of the type of M. pteridina is presented and a comparison of the distinctive features among these five species is given. In the absence of recent records, the morphology of M. pteridina in its original sense is only known from the old holotype, therefore, the characters of the fresh fungus are unknown and no molecular data could be obtained to explore its phylogenetic relationship. Also the type of Coronellaria aquilinae, which Rehm later placed in synonymy with M. pteridina, was reexamined and found instead to be a synonym of Microscypha arenula.

Numerous generic and specific epithets of ascomycetous fungi published in the 19th century and earlier are currently in use, although their types have never been reexamined by modern morphotaxonomical standards. Because the protologues of these names are generally comparatively brief and often lack any illustration, these names may easily be misinterpreted in their current use. For a case where reexamination of a type reveals that the name is currently being misapplied, the Code (ICN) does not provide an option to conserve the current usage […]