Fungalpedia – Note 2657, Nesolechia
Nesolechia A. Massal.
Citation when using this data: Meng QF et al. – Fungalpedia.
Index Fungorum, Faceoffungi, MycoBank, GenBank, Fig 1.
Classification: Parmeliaceae, Lecanorales, Lecanoromycetidae, Lecanoromycetes, Pezizomycotina, Ascomycota, Fungi.
Nesolechia was intrudoced by Massalong (1856) to accommodate five species, with N. oxyspora designated as the type species, originally transferred from Abrothallus oxysporus Tul. The genus is characterized by punctiform, flattened to slightly swollen, circular to subelliptical, sessile apothecia that are lecideine in form and lack of a distinct excipulum. The clavate asci are accompanied by agglutinated paraphyses with slightly thickened apices, containing eight elliptical to ovoid, transparent, unilocular spores (Massalong 1856).
Abrothallus oxysporus was initially recognized as a typical lichenicolous species before being reassigned to Nesolechia and later to Phacopsis (Tulasne 1852, Massalongo 1856). However, a six-locus phylogenetic analysis by Divakar et al. (2015) revealed that N. oxyspora is phylogenetically aligned with the Punctelia clade. Consequently, Abrothallus oxysporus was reclassified as Punctelia oxyspora by Divakar et al. (2017), however, this reassignment was made without a comprehensive morphological evaluation. As a result, Nesolechia oxyspora and Phacopsis oxyspora are now considered synonyms of Punctelia oxyspora.
Since the original type species of Nesolechia has been transferred to another genus and all five species originally described by Massalongo (1856) have been reassigned, it became necessary to designate a new type species. Among potential candidates, Nesolechia cladoniaria (Nyl.) Zopf and N. oxysporella (Nyl.) Rehm, both published in 1858, were considered. Due to the detailed description of N. oxysporella based on Massalongo’s Lich. exs. 153, this species is proposed as the neotype for the genus.
Nesolechia is defined solely by its ascocarps, asci, and spores, lacking a distinct thallus (Tulasne 1852). In contrast, the classification of Punctelia is primarily based on the presence of pseudocyphellae on the thallus, which differentiates it from Parmelia, with only brief descriptions provided for its apothecia and spores (Krog 1982). Due to the simplistic and vague morphological descriptions of spores in both Nesolechia and Punctelia, the reclassification of Nesolechia oxyspora into Punctelia, a genus with distinct phenotypic traits, based solely on genetic data, remains questionable. There is even concern that the phylogenetic analysis may have utilized sequences from a lichen rather than the correct sequences for N. oxyspora. As the type species, Nesolechia oxyspora embodies the key diagnostic traits of its genus. Therefore, a combined approach incorporating both phylogenetic and morphological analyses based on the type specimen would provide a more robust basis for taxonomic conclusions.
To date, Nesolechia comprises 22 recognized species, majority of which are lichenicolous, with the exception of N. imponens Leight. ex Zopf, which may represent a lichen rather than a lichenicolous fungus. Nesolechia is a historically significant yet under-studied genus, with many of its species originating from transfers out of other genera. The most recent addition to this group dates to the early 20th century, highlighting the critical need for modern taxonomic revision combining morphological and molecular analyses.
Type species: Nesolechia oxyspora (Tul.) A. Massal.
= Abrothallus oxysporus Tul. Current name: Punctelia oxyspora (Tul.) Divakar, A. Crespo & Lumbsch.
Neotype species: Nesolechia oxysporella (Nyl.) Rehm, Massalongo’s Lich. exs. 153.
= Lecidea oxysporella Nyl.
Other accepted species: Species Fungorum – search Nesolechia.
Figure 1 – Nesolechia oxysporella redrawn from description of Nylander (1858b)). a Asci. b Ascospores. Scale bars: a = 10 μm, b = 5 μm.
References
Massalongo ADB 1856 – Miscellanea lichenologic. 1–46.
Entry by
Meng QF, Center of Excellence in Fungal Research, Mae Fah Luang University, Chiang Rai, 57100, Thailand and School of Public Health, Zunyi Medical University, Guizhou 563000, China.
Published online 1 July 2026