New species of Tulasnella associated with terrestrial orchids in Australia

Abstract

Recent studies using sequence data from eight sequence loci and coalescent-based species delimitation methods have revealed several species-level lineages of Tulasnella associated with the orchid genera Arthrochilus, Caleana, Chiloglottis, and Drakaea in Australia. Here we formally describe three of those species, Tulasnella prima, T. secunda, and T. warcupii spp. nov., as well as an additional Tulasnella species associated with Chiloglottis growing in Sphagnum, T. sphagneti sp. nov. Species were identified by phylogenetic analyses of the ITS with up to 1.3 % sequence divergence within taxa and a minimum of 7.6 % intraspecific divergence. These new Tulasnella (Tulasnellaceae, Cantharellales) species are currently only known from orchid hosts, with each fungal species showing a strong relationship with an orchid genus. In this study, T. prima and T. sphagneti associate with Chiloglottis, while T. secunda associates with Drakaea and Caleana, and T. warcupii associates with Arthrochilus oreophilus.

Diversity of mycorrhizal Tulasnella associated with epiphytic and rupicolous orchids from the Brazilian Atlantic Forest, including four new species

“…COAD 2885 showed high percentage sequence divergence between clades (7.5%). This value is higher than the 3% sequence divergence cut-off value proposed for species delimitation 50 or 3-5% divergence used for Tulasnella species 38 . Regarding the other new species described here, the interspecific nucleotide divergence ranged from 5.4 to 41.6%.…”

“…as the type species, and nowadays there are 73 accepted species in Index Fungorum 40 . Due to the lack of molecular data from the type specimen, many Tulasnella species are described only by morphological-based approaches 38 . Morphological characters, such as size and shape of hyphae, basidia, sterigmata and basidiospore, when used alone, may lead to incorrect species identification 34 , e.g.…”

“…because they are affected by cultural conditions. For species delimitation, we have combined both molecular and morphological data as recommended by Cruz et al 34,36 , using ITS as suggested by Linde et al 38 .…”

“…Tulasnella species have complex morphological characteristics, but rarely form fruitbodies in situ or sexual structures in vitro [29][30][31][32][33] . As morphological characteristics are not sufficient to describe Tulasnella species 34 , molecular approaches have been used too 32,33,[35][36][37][38] . Species identification is mostly based on phylogenetic concordance of multiple unrelated genes/regions, but for this complex genus, the internal transcribed spacer (ITS) of the nuclear ribosomal DNA was shown to be highly suitable for species delimitation in Tulasnella 31,38 .…”

Population structure of an orchid mycorrhizal fungus with genus-wide specificity

“…A second and recently discovered Tulasnella species, T . sphagneti 15 , was found associated with orchids that grow in subalpine sphagnum hammocks. ITS sequence divergence between T .…”