Poster Presentation Society for Freshwater Science 2025 Annual Meeting

Genome Skimming Supports Two New Crayfish Species from the Genus Pacifastacus Bott, 1950 (Decapoda: Astacidae) (118195)

Eric R. Larson 1 , Cathryn L. Abbott 2 , Scott R. Gilmore 2 , Caren C. Helbing 3 , Mark Louie D. Lopez 3 , Hugh MacIntosh 4 , Bronwyn W. Williams 5 , Nisikawa Usio 6
  1. University of Illinois, IL, United States
  2. Pacific Biological Station, Fisheries and Oceans Canada, Nanaimo, British Columbia, Canada
  3. Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
  4. Invertebrate Zoology, Royal BC Museum, Victoria, British Columbia, Canada
  5. North Carolina Museum of Natural Sciences, Raleigh, North Carolina, United States
  6. Institute of Nature and Environmental Technology, Kanazawa University, Kanazawa, Ishikawa, Japan

Recent phylogenetic analyses have suggested that the signal crayfish Pacifastacus leniusculus (Dana, 1852) contains two highly distinct lineages that merit elevation to species status. We further investigate these lineages here using genome skimming to conduct phylogenetic analyses on mitogenomes and highly repetitive 18S, 28S, and H3 nuclear markers. We also analyze morphological characters of these putative species to identify traits that may facilitate their identification in the field. Phylogenetic trees of mitogenomes support these lineages as equivalent to other species in the family Astacidae, and phylogenetic trees on concatenated nuclear markers return comparable topologies. We propose these crayfishes as the Misfortunate Crayfish Pacifastacus malheurensis sp. nov., which occurs in central and eastern Oregon, United States, and the Okanagan Crayfish Pacifastacus okanaganensis sp. nov., which occurs in south central British Columbia, Canada and north central Washington, United States. Both of these Pacifastacus species face conservation risks from displacement by non-native invasive crayfishes, but P. malheurensis sp. nov. is especially vulnerable to rapidly spreading Rusty Crayfish Faxonius rusticus (Girard, 1852) in central Oregon.