Sareomycetes cl. nov.: A new proposal for placement of the resinicolous genus Sarea (Ascomycota, Pezizomycotina)

Abstract

Resinicolous fungi constitute a heterogeneous assemblage of fungi that live on fresh and solidified plant resins. The genus Sarea includes, according to current knowledge, two species, S. resinae and S. difformis. In contrast to other resinicolous discomycetes, which are placed in genera also including non-resinicolous species, Sarea species only ever fruit on resin. The taxonomic classification of Sarea has proven to be difficult and currently the genus, provisionally and based only on morphological features, has been assigned to the Trapeliales (Lecanoromycetes). In contrast, molecular studies have noted a possible affinity to the Leotiomycetes. Here we review the taxonomic placement of Sarea using sequence data from seven phylogenetically informative DNA regions including ribosomal (ITS, nucSSU, mtSSU, nucLSU) and protein-coding (rpb1, rpb2, mcm7) regions. We combined available and new sequence data with sequences from major Pezizomycotina classes, especially Lecanoromycetes and Leotiomycetes, and assembled three different taxon samplings in order to place the genus Sarea within the Pezizomycotina. Based on our data, none of the applied phylogenetic approaches (Bayesian Inference, Maximum Likelihood and Maximum Parsimony) supported the placement of Sarea in the Trapeliales or any other order in the Lecanoromycetes. A placement of Sarea within the Leotiomycetes is similarly unsupported. Based on our data, Sarea forms an isolated and highly supported phylogenetic lineage within the "Leotiomyceta". From the results of our multilocus phylogenetic analyses we propose here a new class, order, and family, Sareomycetes, Sareales and Sareaceae in the Ascomycota to accommodate the genus Sarea. The genetic variability within the newly proposed class suggests that it is a larger group that requires further infrageneric classification.

Sareomycetes: more diverse than meets the eye

“…In addition to frequent reports, the two Sarea species have also been a subject of some interest regarding their systematic placement, which has been unclear (Reeb et al 2004 ; Miadlikowska et al 2014 ). A recent study resolved the uncertainty and has supported the erection of a new class in Pezizomycotina , Sareomycetes (Beimforde et al 2020 ). This study, as well as a recent study that yielded 31 endolichenic isolates of Sarea species (Masumoto and Degawa 2019 ), have illustrated that both Sarea species are genetically diverse.…”

Sareomycetes: More Diversity than Meets the Eye

“…The reports of Zythia resinae from New Zealand almost certainly represent a third instance of anthropogenic introduction. Pinaceae and Cupressaceae are, the only families known to host fungi in Sareomycetes; of these families, only two species in Cupressaceae are native to New Zealand (De Lange and Rolfe 2010), but all reports of Zythia are from Abies, Pinus, and Pseudotsuga, in Pinaceae (Gadgil and Dick 1999;Beimforde et al 2020). A nal apparent indicator of ease of transmission through wood projects are a series of seven nuITS sequences uploaded to Genbank and misidenti ed as "Hormococcus conorum" and "Zythia pinastri" (NCBI, NLM, Bethesda (MD) 2020a, b, c, d, e, f, g).…”

“…Additional studies to determine the causal agent of the resinous stem canker of Chamaecyparis obtusa determined that Z. resinae did not cause symptoms on hosts in Pinaceae or Cupressaceae, and identi ed the causal agent as Cistella japonica (Hayashi and Kobayashi 1985;Yokozawa et al 1986Yokozawa et al , 1989Suto 1987Suto , 1992Suto , 1997Suto , 1998Kobayashi et al 1990). The varying results and generality of these tests leave unresolved the question of pathogenicity of species in Sareomycetes; some authors assume pathogenicity and others accept a saprobic lifestyle, as summarized by Beimforde et al (2020).…”

“…The history of the multiple publications attempting to elucidate the taxonomic position of these fungi using molecular data is outlined by Beimforde, et al (2020). Reliance on these publications is likely the reason for uncertain placements or placements in Leotiomycetes by several subsequent authors (Lumbsch et al 2007;Kirk et al 2008 Recently, use of information from six genes and sampling taxa throughout Pezizomycotina resulted in the erection of a new class, Sareomycetes, to accomodate Sarea and Zythia (Beimforde et al 2020). This placement explains over two centuries of confusion and uncertainty.…”

“…In addition to frequent reports, the two Sarea species have also been a subject of some interest regarding their systematic placement, which has been unclear (Reeb et al 2004;Miadlikowska et al 2014). A recent study resolved the uncertainty and has supported the erection of a new class in Pezizomycotina, Sareomycetes (Beimforde et al 2020). This study, as well as a recent study that yielded 31 endolichenic isolates of Sarea species (Masumoto and Degawa 2019), have illustrated that both Sarea species are genetically diverse.…”