Penetrative and non-penetrative interaction between Laboulbeniales fungi and their arthropod hosts.

Laboulbeniales are a highly specialized group of fungi living only on arthropods. They have high host specificity and spend their entire life-cycle on an arthropod host. Taxonomic characters of Laboulbeniales are based on the architecture of the cells of the parenchymal thallus, i.e. the visible part of the fungus outside the host. The extent of the fungus spreading inside the host-the haustorium-remains largely unknown. The attachment to the arthropod host is fundamental to understand the fungus-animal interaction, but how this truly occurs is unclear. Recent evidences question the strictly parasitic life-style of Laboulbeniales. We used micro-computed tomography (µCT) and 3D reconstructions to visualize, for the first time, the complete structure of Laboulbeniales species in situ on their hosts. We compared the haustoriate species, Arthrorhynchus nycteribiae on an insect host to the non-haustoriate species, Rickia gigas on a millipede host. Our results confirm that some Laboulbeniales species are ectoparasitic and have a haustorial structure that penetrates the host's cuticle, while others are ectobionts and are only firmly attached to the host's cuticle without penetrating it. The presence and the morphology of the haustorium are important traits for Laboulbeniales evolution, and key factors for future understanding of host dependence and specificity.

The first Laboulbeniales (Ascomycota, Laboulbeniomycetes) from an American millipede, discovered through social media.

Laboulbeniales are highly specialized arthropod-associated fungi. The majority of the almost 2200 known species live on insects, although they also occur on other arthropod hosts. Recently, the number of Laboulbeniales associated with millipedes has increased considerably. Here we describe the first species of a Laboulbeniales fungus, Troglomyces twitteri sp. nov., from an American millipede. The new species was initially discovered on a photo of Cambala annulata (Say, 1821) from Ohio, USA, which had been shared on Twitter. A subsequent microscopic study of Cambala millipedes in museum collections in Denmark and France confirmed the discovery.

Hyperparasitism in caves: Bats, bat flies and ectoparasitic fungus interaction.

Bat flies (Diptera: Nycteribiinae) are highly specialized bloodsucking bat ectoparasites. Some of the ectoparasitic bat flies are themselves parasitized with an ectoparasitic fungus of the genus Arthrorhynchus (Laboulbeniales). Ascospores of the fungus attach to the cuticle of a bat fly and develop a haustorium that penetrates the host cuticle. This interaction defines the fungus as a hyperparasite. Both the fly and the fungus are obligate parasites and this peculiar case of hyperparasitism has remained largely unstudied. We studied the prevalence of Laboulbeniales, genus Arthrorhynchus, in natural populations of bat flies infesting the bat species Miniopterus schreibersii, Myotis bechsteinii, My. blythii, My. daubentonii, My. escalerai and My. myotis in Portuguese caves. Laboulbeniales were found infecting 10 of the 428 screened bat flies (2.3%) in natural populations, with fewer infections in winter. Images obtained with transmission electron microscopy show the fungal haustorium within the bat fly host tissue, from where it extracts nutrition.

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

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.

Laboulbeniales on millipedes: the genera Diplopodomyces and Troglomyces.

The genera Diplopodomyces and Troglomyces (Laboulbeniales, Ascomycota) parasitizing millipedes (Diplopoda) are reviewed. We describe four new species: D. lusitanipodos parasitic on Lusitanipus from Portugal and on Cyphocallipus from Spain, D. veneris on Lusitanipus from Portugal, T. botryandrus on Leptoiulus from Italy and T. rossii on Ophyiulus, Leptoiulus and Typhloiulus from Italy. Diplopodomyces veneris is a dimorphic species, with different morphotypes growing on the male copulatory organs and on the surroundings of the female gonopore respectively. The type species of both genera also have been studied, their descriptions are revised and a neotype for T. manfrediae is designated. New records from Italy are given for D. callipodos and T. manfrediae.

Orphella intropus (Kickxellomycotina), a new insect endosymbiont with an unusual perforating holdfast system and other trichomycetes from Italy.

New data about trichomycetes (arthropod gut endosymbionts) from northern Italy (Piedmont [Piemonte] region) are reported, including the description of two new species of Harpellales: Glotzia distorta from mayfly nymphs and Orphella intropus from stonefly nymphs. The latter species is characterized by a cellular bulbous holdfast that perforates the gut lining of its host. Sixteen additional geographical records for Italy are provided, including from the Harpellales, Harpellomyces eccentricus, Graminella bulbosa, Orphella catalaunica, Pennella grassei, Smittium perforatum, Sm. elongatum, Stachylina nana, St. jujuyensis, St penetralis and Tectimyces leptophlebiidarum, and from the Amoebidiales, Paramoebidium chattoni, P. corpulentum, P. curvum, P. ecdyonuridae, P. hamatum and P. inflexum. We provide an emendation of Pennella grassei, a rare, incompletely described and poorly illustrated species that was recovered from Italy nearly 50 y after its last citation from France.

New species and new records of trichomycetes from Italy.

We present the results obtained from a short survey in central Italy to broaden the poorly known diversity of trichomycetous gut symbionts, members of the Kickxellomycotina, in this country. Among the reported fungi, two new species of Harpellales are described: Harpellomyces aprutinus and Orphella italica, as well as 14 other species that are new for Italy. Among these, the remarkable and rare species Gauthieromyces microsporus is included, previously known only from the type locality in France. One species of Asellariales, Asellaria gramenei, also is reported. Taxonomic and biogeographic implications of these records are discussed.

New Laboulbeniales parasitic on endogean ground beetles.

Three new species of Laboulbenia occurring on endogean Carabidae are described. These are L. lucifuga, parasitic on Winklerites spp. from Greece, L. magrinii, parasitic on Typloreicheia spp. from Italy, Reicheia spp. from Italy and Corsica and L. vailatii, parasitic on Coecoparvus spp. from Greece. New characters of L. coiffatii and L. endogea are pointed out, and the genus Scalenomyces is synonymized with Laboulbenia.

Cesariella, a new genus of Laboulbeniales.

Cesariella graeca gen. sp. nov. is described to accommodate a new species of the Laboulbeniales (Fungi, Ascomycota) parasitic on the endogean ground beetles Reicheadella aetolica and R. bischoffi (Coleoptera, Carabidae) from Greece. Cesariella is distinguished from the allied genus Laboulbenia by the presence of two cells borne on the inner side of cell III, and by the presence of a conspicuous remnant of the spore apex protruding laterally near the base of the appendage.

Zygospores as evidence of sexual reproduction in the genus Orphella.

The presence of zygospores in the genus Orphella is newly described. We found zygospores in three species of the genus, O. catalaunica, O. coronata and O. helicospora, which are all the species of the genus known from the Iberian territory. Zygospores are associated with a heterothallic conjugating sexual process in O. coronata, whereas in O. catalaunica and O. helicospora, they form homothallically. In all instances, zygospores are consistently associated with an organized pattern of sterile cells, forming structures comparable to those present with asexual trichospores. We compare the ontogeny of Orphella zygospores with that found in the harpellid Genistellospora homothallica and discuss the possible close relationship of Orphella with Kickxellales (Zygomycetes). We report O. coronata in Spain for the first time, replacing all previous records of O. haysii. Results are supported with line drawings and photographs.

The genus Smittium (Trichomycetes, Harpellales) in the Iberian Peninsula.

A study of larval Diptera (Chironomidae, Culicidae and Simuliidae) from Spain has been carried out to fulfill a catalogue of species of the genus Smittium (Harpellales: Legeriomycetaceae) present within these hosts. Among the reported taxa, eight are new species: Smittium brevisporum, S. bulbosporo-phorus, S. gracilis, S. hecatei, S. heterosporum, S. inex-pectans, S. prostratum and S. pseudodimorphum. We also report six previously described species, which are new for the Iberian Peninsula: S. alpinum, S. dipterorum, S. megazygosporum, S. pusillum, S. typhellum and S. fecundum. Three other species (S. simulii, S. culicis and S. culisetae) previously were reported from Spain. In two of them (S. fecundum and S. culicis), we describe for the first time the presence of zygospores. Some of the included species have been artificially cultured as well as ultrastructurally studied using scanning electron microscopy (SEM), with the purpose of observing the surface of both trichospores and the trichospore collar and the morphology of the trichospore appendage.

Two new genera of Laboulbeniales allied to Zodiomyces.

Two new genera of Laboulbeniales (Ascomycota) allied to Zodiomyces (Zodiomycetoideae) are described. These are Capillistichus with the single species C. tenellus, parasitic on Laccobius spp. (Coleoptera, Hydrophilidae), and Scepastocarpus with the single species S. peritheciiformis, parasitic on Hydrochus spp. (Coleoptera, Hydrophilidae). Both genera and species are from Spanish collections. Perithecial characters appear to be similar in the two new genera and in the related Zodiomyces, becoming a diagnostic character of the group (subfamily Zodiomycetoideae). Receptacular characters form the basis of separation into genera. To complete the study of all the taxa included in the subfamily, specimens and type slides of all three species of Zodiomyces have been reviewed.

Bojamyces transfuga sp. nov. and new records of Trichomycetes from mayfly larvae in Spain.

The new species Bojamyces transfuga is described. It was found growing in the hindgut of mayfly nymphs and in their shed abdominal exoskeleton lumen. Bojamyces transfuga shows single appendaged trichospores and zygospores of type I, unlike Bojamyces repens, where appendages and zygospores are unknown. The generic description of Bojamyces is emended to accommodate this new taxon. Bojamyces repens, known only from the United States, has been found for the first time in the Iberian Peninsula on mayfly molts. We also note the presence of Legeriomyces rarus in Europe, on the Iberian Peninsula and Balearic Islands. Previously it was known only in Western Australia.