The Helvella corium species aggregate in Nordic countries – phylogeny and species delimitation

Abstract

Mycologists have always been curious about the elaborate morphotypes and shapes of species of the genus Helvella. The small, black, cupulate Helvella specimens have mostly been assigned to Helvella corium, a broadly defined morpho-species. Recent phylogenetic analyses, however, have revealed an aggregate of species hidden under this name. We performed a multispecies coalescent analysis to re-assess species limits and evolutionary relationships of the Helvella corium species aggregate in the Nordic countries. To achieve this, we used morphology and phylogenetic evidence from five loci – heat shock protein 90 (hsp), translation elongation factor 1-alpha (tef), RNA polymerase II (rpb2), and the 5.8S and large subunit (LSU) of the nuclear ribosomal DNA. All specimens under the name Helvella corium in the larger university fungaria of Norway, Sweden and Denmark were examined and barcoded, using partial hsp and/or rpb2 as the preferential secondary barcodes in Helvella. Additional fresh specimens were collected in three years (2015–2018) to obtain in vivo morphological data to aid in species discrimination. The H. corium species aggregate consists of seven phylogenetically distinct species, nested in three divergent lineages, i.e. H. corium, H. alpina and H. pseudoalpina sp. nov. in the /alpina-corium lineage, H. alpestris, H. macrosperma and H. nannfeldtii in the /alpestris-nannfeldtii lineage, and H. alpicola as a weakly supported sister to the /alpestris-nannfeldtii lineage. Among the seven species, the ribosomal loci expressed substantial variation in evolutionary rates, suggesting care in the use of these regions alone in delimitation of Helvella species. Altogether, 469 out of 496 available fungarium specimens were successfully barcoded.

Additions to the knowledge of the genus Helvella in Europe. New records and de novo description of five species from the Nordic region

“…). Løken et al . (2020) published a taxonomic review of the Helvella corium species aggregate, including one newly described species, i.e.…”

“…As we observed for the Helvella corium species aggregate, where we have done detailed morphological and molecular examinations of all material in the larger extant Nordic fungaria supplemented with additional field collection efforts from unexplored areas ( Skrede et al . 2017 , Løken et al . 2020 ), the discerned species have highly variable distribution patterns.…”

“…In order to understand the biogeographical pattern of a well-resolved species complex we made detailed maps of all collections of the Helvella corium species aggregate, including the species H. corium, H. alpina, H. pseudoalpina, H. nannfeldtii, H. alpestris, H. macrosperma and H. alpicola ( Løken et al . 2020 ).…”

“…2017 , Hansen et al . 2019 , Løken et al . 2020 ), with emphasis on collections from Denmark, Norway and Sweden.…”

The genera Helvella and Dissingia (Ascomycota: Pezizomycetes) in Europe – Notes on species from Spain

“…The Spanish samples amount to 31 species of Dissingia (1) and Helvella (30) and in total we add 11 species to the list of European helvellas, of which nine are described as new. Altogether, 67 species are now re-evaluated and molecularly characterized from Europe ( Skrede et al 2017 , Løken et al . 2019 ).…”