This species was reported in the early literature for Utah as Margaritana margaritifera and was referred to by the common name, the river pearl mussel (e.g., Chamberlin and Jones 1929).
No subspecies are currently recognized.
Status in Utah
Formerly at least 11 localities (representing perhaps 9 populations) were known in Utah. Current opinion is that all populations in Utah have been extirpated (see Clarke 1993), though there is the possibility that small populations still exist at known historical localities or that some populations remain to be discovered. Formerly, this species occurred in the northern third of Utah (Call 1884, Henderson 1924, Chamberlin and Jones 1929, Woolstenhulme 1942a, 1942b).
The size and extent of historical populations was not reported.
Clarke (1993) asserted that "overutilization of water resources by man" is responsible for the extirpation of this species. Despite the fact that no populations have been found at historical localities recently (viz. Clarke 1993), discovery of an extant population is still a possibility. Individuals of this species can be quite long-lived; populations could exist undetected at low levels for many years. Continued efforts to relocate populations are needed throughout northern Utah.
The possibility that some of the historical localities were, in fact, based on introduced individuals may have lead to a misinterpretation of the historical range of this mussel in Utah. As Clarke (1993) stated: "It is probable, however, that at least some of the historical records for this species resulted from glochidia which were shed from imported trout used for stocking purposes, and that those finds did not represent reproducing populations in Utah."
Habitats Utilized in Utah
Nearly all Utah localities are small streams, but detailed Utah habitat data are unavailable.