Abstract Detail

Mycological Section

Haelewaters, Danny [1], Pfister, Donald H. [2].

Cryptic diversity in the Hesperomyces virescens species complex (Ascomycota, Laboulbeniomycetes, Laboulbeniales).

To date, most fungi remain unknown and undescribed. One group is among the least studied, the Laboulbeniales. They are obligate biotrophic parasites and live attached to the exterior of mainly beetles. As of 2015, about 2,100 species have been described, but it has been estimated that 15,000 to 75,000 species will be found on arthropod hosts. Although many new records and species are being published, larger biological questions in this unusual group of fungi remain unanswered. One question is the degree to which speciation has occurred on particular host insects. Hesperomyces virescens is known from all continents except Antarctica. It occurs on species from 13 lady beetle genera (Coleoptera, Coccinellidae). The taxonomy in the Laboulbeniales is largely based on morphological characters; the apparent global distribution of H. virescens might be an artifact due to the morphological species concept. Previous studies, based on intra- and interspecific transmission experiments, suggested that different lineages of H. virescens exist and that each of these lineages has a high degree of host specificity. In our study, two lady beetle species, Harmonia axyridis and Olla v-nigrum, were collected and screened for the presence of H. virescens. DNA was extracted from thalli from these two hosts and PCR amplification was performed to obtain SSU, ITS, and LSU rDNA sequences. Phylogenetic inferences of the combined ITS+LSU dataset were estimated under maximum parsimony and maximum likelihood methods. Our phylogenetic results confirm that H. virescens consists of genetically divergent lineages, perhaps driven by adaptation to host species. Analysis of the LSU dataset, which includes one sequence of H. virescens from a dried Cycloneda sanguinea lady beetle, gives additional support for this view since it shows three lineages, segregating by host species. The morphological stasis seems to be the result of morphological changes lagging behind genotypic changes. Future analysis will include more host species along with a consideration of the geographical origins of the beetles. We are also testing the same hypothesis on Polyandromyces coptosomalis, another species in the Laboulbeniales. This parasite has been found on members of the families Pentatomidae and Plataspidae (Hemiptera) in the Canary Islands, Ecuador, Fiji, Madagascar, and the Solomon Islands. Although no morphological changes are observable, analysis of the SSU rDNA region suggests that P. coptosomalis is also a species complex. Our discovery that cryptic diversity is present in the Laboulbeniales shows that this group of fungi may be even more diverse than previously thought.

1 - Harvard University, Organismic and Evolutionary Biology, Farlow Herbarium, 22 Divinity Avenue, Cambridge, MA, 02138, USA
2 - Harvard University, Organismic and Evolutionary Biology, Farlow Herbarium, 22 Di, Cambridge, MA, 02138, United States

Keywords:
Laboulbeniales
Ascomycota
Fungi
Hesperomyces virescens
cryptic diversity
lady beetle
ribosomal DNA
species-level phylogeny
taxonomy.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Hall D/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 5:30 PM
Number: PMY021
Abstract ID:1045
Candidate for Awards:MSA Best Poster Presentation Award by a Graduate Student