"americamysis almyra" was first described from lake pontchartrain from specimens collected in 1953. it was identified as being present in st. johns river florida in 1977 and was first detected in the patapsco river flowing into chesapeake bay in 1980. it is unclear whether it had invaded these areas, perhaps in the ballast water of ships, or whether it had been there previously but had been misidentified as "americamysis bigelowi".