A combination of morphology and 28S rRNA gene sequences provide grouping and ranking criteria to merge eight into three Ambispora species (Ambisporaceae, Glomeromycota)

Abstract

Ambispora, the only genus in Ambisporaceae and one of three deeply rooted families in Archaeosporales, Glomeromycetes, is amended. Analysis of the morphology of specimens from types and living cultures and 28S ribosomal DNA (rDNA; LSU) sequences resulted in two major changes that redefined Ambispora to include only species with the potential for spore dimorphism (acaulosporoid and glomoid). First, species described as producing only glomoid spores (Ambispora leptoticha, Ambispora fecundispora, and Ambispora callosa), only acaulosporoid spores (Ambispora jimgerdemannii), or both spore morphotypes (Ambispora appendicula) were synonymized with a redefined dimorphic species, A. leptoticha. LSU sequences and more conserved SSU gene data indicated little divergence between genotypes formerly classified as separate species. Second, Ambispora fennica was synonymized with Ambispora gerdemannii based on morphological and LSU sequence variation equivalent to that measured in the sister clade A. leptoticha. With this analysis, Ambispora was reduced to three species: A. leptoticha, A. gerdemannii, and Ambispora granatensis. Morphological and molecular characters were given equal treatment in this study, as each data set informed and clarified grouping and ranking decisions. The two inner layers of the acaulosporoid spore wall were the only structural characters uniquely defining each of these three species; all other characters were shared. Phenotypes of glomoid spores were indistinguishable between species, and thus were informative only at the genus level. Distinct subclade structure of the LSU gene tree suggests fixation of discrete variants typical of clonal reproduction and possible retention of polymorphisms in rDNA repeats, so that not all discrete genetic variants are indicative of speciation.

Experimental assessment of forest floor geophyte and hemicryptophyte impact on arbuscular mycorrhizal fungi communities

“…This is the first report of Glomus multiforum occurrence in forest soil, as this species is known so far only from grasslands and dunes (Błaszkowski 2012). Although literature data show that Ambispora leptoticha spores are rather rarely found in the world, results of molecular environmental analyses (Bills and Morton 2015;Marinho et al 2018) suggest that the species also has a wide distribution and occurs in different habitats of the world.…”

Arbuscular mycorrhizal colonization of a Cd hyperaccumulator Viola baoshanensis at Baoshan Pb/Zn Mine

“…Spore identi cation was based mainly on morphological characteristics such as spore colour, wall structures, and subtending hyphae (Aguilera et al 2014). Classi cation and taxonomic identi cation of AMF is according to identi cation reports (Redecker et al 2013;Bills et al 2015)…”

New taxa in Glomeromycota: Polonosporaceae fam. nov., Polonospora gen. nov., and P. polonica comb. nov.

“…leptoticha and Ar. trappei, originally described as A. gerdemannii and A. trappei, respectively (Nicolson and Schenck 1979;Morton and Redecker 2001;Sieverding and Oehl 2006;Bills and Morton 2015).…”