Crayfish are key organisms in freshwater ecosystems across the United States (USA) and Canada, yet are among their most highly imperiled taxonomic groups. In 1996, a committee of prominent USA crayfish biologists warned of a crayfish imperilment plight and neglect of the fauna by natural resources agencies. It is unclear whether crayfish conservation has been prioritized by those agencies in the intervening decades. Our objective was to evaluate the status of crayfish conservation and management in 50 USA and 13 Canadian fish and wildlife agencies through a telephone survey. Fifty-one percent of agencies employed biologists to conduct crayfish work, mostly in the southern USA, and focused on threats (e.g., invasive species) or species’ distributions and conservation status. Of the 32 agencies working on crayfish, 59% considered them a priority, but 53% acknowledged insufficient funding. The most commonly cited information needs were threats, species compositions (native and introduced), distributions, conservation status assessments, and ecology. We report an encouraging but limited increase in agencies working on crayfish over the past two decades.

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Crayfish are common hosts of microsporidian parasites, prominently from the genus Thelohania. Thelohania is a polyphyletic genus, with multiple genetically distinct lineages found from freshwater and marine environments. Researchers have been calling for a revision of this group for over a decade. We provide evidence that crayfish-infecting freshwater Thelohania are genetically and phylogenetically distinct from the marine Thelohania (Clade V/Glugeida), whilst also describing two new species that give further support to the taxonomic revision. We propose that the freshwater Thelohania should be transferred to their own genus, Astathelohania gen. et comb. nov., in a new family (Astathelohaniidae n. fam.). This results in the revision of Thelohania contejeani (Astathelohania contejeani), Thelohania montirivulorum (Astathelohania montirivulorum), and Thelohania parastaci (Astathelohania parastaci). We also describe two novel muscle-infecting Astathelohania species, A. virili n. sp. and A. rusti n. sp., from North American crayfishes (Faxonius sp.). We used histological, molecular, and ultrastructural data to formally describe the novel isolates. Our data suggest that the Astathelohania are genetically distinct from other known microsporidian genera, outside any described family, and that their SSU rRNA gene sequence diversity follows their host species and native geographic location. The range of this genus currently includes North America, Europe, and Australia.

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