Novelty upon novelty visualized by rotational scanning electron micrographs (rSEM): Laboulbeniales on the millipede order Chordeumatida.

Ana Sofia P S Reboleira,Henrik Enghoff,Sergi Santamaria

doi:10.1371/journal.pone.0206900

Ana Sofia P S Reboleira, Henrik Enghoff + Show 1 more

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https://doi.org/10.1371/journal.pone.0206900

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Abstract

Laboulbeniales are highly specific ectoparasitic fungi of arthropods (insects, millipedes, and arachnids). The first Laboulbeniales parasitizing the millipede order Chordeumatida (Diplopoda) were discovered and described as a new dioecious genus of Laboulbeniales, Thaxterimyces, to accommodate the new species T. baliensis. Also the millipede host is a new species and is described as Metopidiothrix sheari. This is the first time Laboulbeniales fungus and its millipede host are described as new together. Males of Metopidiothrix have the most extensive secondary sexual modifications in the entire class Diplopoda. Although nothing is known about the function of these modifications, the unique pattern of Laboulbeniales infection in the new millipede species is obviously related to host sexual behavior. Rotational Scanning Electron Micrographs (rSEM) are used to create a 3D comprehensive model to examine the fungal-host interaction, a more advanced visualization of the ectoparasitic fungus on its host. Laboulbeniales diversity on millipedes is still understudied, and a consistent effort is needed to unveil and understand the extent and diversity of this biological interaction. Due to their minute size and apparently non-detrimental effect on their hosts, Laboulbeniales in general have been largely ignored by mycologists and neglected by generations of entomologists. As a result a significant component of global biodiversity has been strongly underestimated, and a wealth of new discoveries is still to be made both in the field and in existing museum collections.

Highlights

Laboulbeniales constitute an exceptional order of ascomycetous fungi
Photomicrographs of the fungus were made with a Jenoptik ProgRes 10 Plus digital camera on a Leica DMR microscope equipped with differential interference contrast optics (DIC)
Apart from the genus Rickia, which is present on insects and mites [9,10,11], the other four genera of Laboulbeniales on millipedes are known to be specific to this class: Troglomyces Colla, 1932; Diplopodomyces W

Summary

Introduction

Laboulbeniales constitute an exceptional order of ascomycetous fungi. All are known to be obligate ectoparasites growing only on the surface of living arthropods [1]. Known from arachnids, millipedes and insects, these fungi are characterized by a reduced and compact hyphal system, called thallus, comprising a receptacle bearing one or more perithecia and/or sterile and male appendages [2]. Laboulbeniales have no known anamorphic phase, i.e., the thalli. Laboulbeniales on Chordeumatida order of millipedes sciences-february-2014. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

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