Novel Laccaria Species From Juglandaceae Forest in Panama With Notes on Their Ecology.

Adriana Corrales,Andrew W Wilson,Gregory M Mueller,Clark Ovrebo

doi:10.3389/fmicb.2020.01597

Abstract

Since 2013 there have been 22 new species of Laccaria described worldwide. Only three of these represent species from the neotropics. In Panama, Laccaria is abundant in monodominant Oreomunnea mexicana (Juglandaceae) forests based on sporocarps and environmental sequencing of roots. This study uses a combination of morphological and phylogenetic evidence to document up to seven species of Laccaria from these forests, one previously described, three described as new, and three requiring more data before being formally described. Molecular data used for phylogenetic analysis include the nuclear ribosomal ITS and 28S regions, along with TEF1 and RPB2. Laccaria stellata, has previously been reported from O. mexicana cloud forests of Panama. Laccaria dallingii sp. nov., L. nitrophila sp. nov., and L. fortunensis sp. nov. are described as new based on morphology and phylogenetic analysis of multiple collections. A taxon referred to as “PAN sp3” is resolved sister to L. stellata. Phylogenetic analysis also resolved two separate clades of Panamanian Laccaria as sister to L. roseoalbescens, a species previously described from Mexico. These three taxa are not described in this paper as there is too little material from which to make effective morphological descriptions even though their placement in phylogenetic analysis identify them as being unique. Ecologically, all described species except for L. fortunensis were amplified from O. mexicana ectomycorrhizal root tips. L. nitrophila was one of the most recovered species from the roots of O. mexicana in a previous study, and it has been shown to respond positively to long term nitrogen addition. Our results expand the knowledge of Laccaria diversity for Central America and highlight that at least some species of Laccaria are nitrophilic in neotropical Juglandaceae forests as well as in temperate forests.

Highlights

Laccaria (Agaricales) is considered a model genus for understanding ectomycorrhizal (ECM) ecology and evolution (Martin et al, 2008; Wilson et al, 2017a)
Phylogenetic analysis of combined and individual internal transcribed spacer region (ITS), 28S, RPB2, and EF1α dataset identify and lend support for multiple species of Laccaria occurring in Panama, Costa Rica, and tropical Mexico
The supermatrix dataset used to phylogenetically delimit species of Laccaria from Panama consisted of sequence data from 152 specimens (Figure 1A)

Summary

Introduction

Laccaria (Agaricales) is considered a model genus for understanding ectomycorrhizal (ECM) ecology and evolution (Martin et al, 2008; Wilson et al, 2017a). In a little more than a decade, studies incorporating morphological and molecular data have described 22 Laccaria species worldwide: one from New Zealand (Wilson et al, 2017a), 18 from Asia (Wilson et al, 2013; Popa et al, 2014; Vincenot et al, 2017; Cho et al, 2018; Latha et al, 2019; Li, 2020), and three from subtropical and tropical North and Central America (Montoya et al, 2015; Popa et al, 2016; Ramos et al, 2017). Montoya et al (2015) described L. roseoalbescens from Quercus dominated forest in Mexico using a combination of morphological data and nuclear ribosomal internal transcribed spacer region (ITS) and the 5 end of the nuclear ribosomal large subunit (28S). Ramos et al (2017) combined morphology and ITS and 28S sequence data to identify and describe L. squarrosa from forests of endangered Fagus grandifolia var. mexicana in Mexico

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