New discoveries of introduced and cryptogenic fresh and brackish water gastropods (Caenogastropoda: Cochliopidae) in the western United States

We report the discovery of a second western Atlantic brackish-coastal cochliopid gastropod in San Francisco Bay [Spurwinkia salsa (Pilsbry, 1905)], and detail the first records for a widely distributed member of the family, Tryonia porrecta (Mighels, 1845), from artificial lakes (in the Phoenix metropolitan area). These identifications were based on morphological criteria and supported by mitochondrial DNA sequence data that also indicates little or no divergence of the newly reported populations, which is consistent with evolutionarily recent spread or separation. Spurwinkia salsa was most likely introduced to San Francisco Bay either in recent decades in bait worm packing or ships’ ballast or in the 19^th or early 20^th century in solid ballast or with oyster imports. The discovery of T. porrecta in artificial lakes in the Phoenix area in 1984 and 2014 may be due to either recent arrival in the area or to dispersal into a newly available habitat from a population long present in the area. In either case, the occurrence of T. porrecta in the Phoenix area is likely due to transport on birds along an eastern branch of the Pacific Flyway. The discovery of T. porrecta in artificial lakes suggests that this species (which is typically distributed in thermal springs) is more broadly tolerant than previously thought. Additional spread of this unusual snail within the highly modified aquatic ecosystem of the Phoenix metropolitan area (which includes more than 900 artificial lakes) would appear likely.