New species of Smittium and Stachylina and other trichomycetes in larval Diptera from streams in Nova Scotia, Canada 1This paper is dedicated to Jo-Ann Frost, one of the first students of these fungi in Nova Scotia, and to the numerous other undergraduates who have engaged with us in our studies of gut fungi, not only in the province, but wherever our studies have taken us.

The guts of non-predaceous invertebrates in aquatic and moist terrestrial habitats are often colonized by an ecological group of microorganisms called trichomycetes. Taxonomically, these endobionts are currently a diverse, polyphyletic assemblage including both zygomycetous fungi as well as protistan species. Trichomycetes are worldwide in distribution and are from varied habitats, but the species inventory of gut fungi from hosts in Canada is far from complete. We summarize the findings from our earliest surveys (from 1997 to 2005) and collections of candidate dipteran hosts in Nova Scotia. Nine new species of gut fungi are added to the inventory list, including the following seven Smittium spp.: Smittium aggregatum, Smittium gronthidium, Smittium papillum, Smittium pavocaudatum, Smittium radiculans, Smittium sparsum, and Smittium verticillatum, and the following two Stachylina spp.: Stachylina brevicellaris and Stachylina subgrandis. Four of the other 13 Harpellales, Pennella digitata, Smittium megazygosporum, Stachylina penetralis, and Zancudomyces culisetae are reported for the first time in Atlantic Canada. Also recorded is Paramoebidium curvum, with many more specimens of this genus from various locations and hosts included as Paramoebidium spp. only. We suggest that future collections of Diptera, to further document and discover trichomycetes, are warranted across the varied host habitats that abound not only in eastern Canada but the rest of the country as well.

Defining DNA-Based Operational Taxonomic Units for Microbial-Eukaryote Ecology

ABSTRACT DNA sequence information has increasingly been used in ecological research on microbial eukaryotes. Sequence-based approaches have included studies of the total diversity of selected ecosystems, studies of the autecology of ecologically relevant species, and identification and enumeration of species of interest for human health. It is still uncommon, however, to delineate protistan species based on their genetic signatures. The reluctance to assign species-level designations based on DNA sequences is in part a consequence of the limited amount of sequence information presently available for many free-living microbial eukaryotes and in part a consequence of the problematic nature of and debate surrounding the microbial species concept. Despite the difficulties inherent in assigning species names to DNA sequences, there is a growing need to attach meaning to the burgeoning amount of sequence information entering the literature, and there is a growing desire to apply this information in ecological studies. We describe a computer-based tool that assigns DNA sequences from environmental databases to operational taxonomic units at approximately species-level distinctions. This approach provides a practical method for ecological studies of microbial eukaryotes (primarily protists) by enabling semiautomated analysis of large numbers of samples spanning great taxonomic breadth. Derivation of the algorithm was based on an analysis of complete small-subunit (18S) rRNA gene sequences and partial gene sequences obtained from the GenBank database for morphologically described protistan species. The program was tested using environmental 18S rRNA data sets for two oceanic ecosystems. A total of 388 operational taxonomic units were observed for 2,207 sequences obtained from samples collected in the western North Atlantic and eastern North Pacific oceans.

New species of Lancisporomyces, Orphella, and Paramoebidium, endosymbionts of stonefly nymphs from streams in Nova Scotia, Canada

Trichomycetes are endobionts that include both fungal and protistan species living in the guts of aquatic insects. Although widely distributed around the world, the biodiversity of these fungi in Canada is virtually unknown. We report the occurrence of 13 species of trichomycetes associated with stonefly nymphs in the families Capniidae, Leuctridae, Nemouridae, and Taeniopterygidae from collections spanning 8 years. This paper extends the geographical range for a number of known fungal species. We describe four new species of Harpellales, Lancisporomyces anguilliformis, Lancisporomyces falcatus, Lancisporomyces nemouridarum, and Orphella dalhousiensis, including both asexual and sexual features for each, as well as two new species of Paramoebidium (Amoebidiales), Paramoebidium cassidula and Paramoebidium stipula. The observations on zygospore morphology in Lancisporomyces and ontogeny of sexual spores in Orphella broaden our perspective on sexual reproduction in the Harpellales. Also highlighted are data on temporal aspects of species occurrence, asexual and sexual sporulation for some species that show host specificity as well as synchrony in maturation of the endobionts with their stonefly hosts.