Freshwater mussel records collected by the Maryland Department of ...

other infrequently encountered species were the result of incidental observations made
during other MANTA surveys.
The taxonomic uncertainty of L. cariosa and lanceolate Elliptios (Johnson 1970,
Bogan et al. 2009, Watters unpublished data) further confounds our attempts to define
their distribution and conservation needs. Live and dead specimens exhibiting
characteristics of L. cariosa, L. cardium, and potential intergrades of the two can often be
found at the same location in Potomac River basin streams (Bogan pers. comm.).
Furthermore, given the indiscrete stocking of game fish around the turn of the 20 th
century that undoubtedly resulted in the introduction of L. cardium to Maryland
(Ortmann 1912, Marshall 1917, Marshall 1918, Marshall 1920) it is possible that L. ovata
Say 1817 was also introduced. Layzer (unpublished data) found smallmouth and
largemouth bass (both stocked into the Potomac River) served as glochidial hosts. We
have observed several L. ovata like specimens and Villela (pers. comm.) acknowledged
the likelihood of our suspicion. Bogan et al. (2009) recently concluded that specimens
previously identified as E. angustata Lea 1831, E. producta, and E. fisheriana from
Virginia formed a single clade. The specimens were not related to topotypic E. producta
and thus were recognized as E. fisheriana. He also found that E. lanceolata was a valid
species, but its placement within the genus Elliptio may be incorrect. Currently, E.
producta is listed as a state rare species in need of conservation (MDNR 2007). The
status of E. lanceolata is listed as uncertain due to a lack of records, its cryptic nature,
and confusion over its taxonomic and native status (MDNR 2007). The conservation
status of lanceolate Elliptios will likely need to be addressed in light of recent
phylogenetic evidence (Bogan et al. 2009). Additional survey efforts for E. lanceolata
are warranted to determine the species distribution and conservation status in Maryland.
Examination of previously collected E. lanceolata material and comparison to specimens
analyzed in Bogan et al. (2009) may also shed light on its status. It is imperative that
these cryptic unionids are properly identified. We will collaborate with researchers
working to resolve taxonomic and phylogenetic issues to ensure that consistent, quality
data are reported. If future taxonomic revisions result in changes, we suggest that
freshwater mussel data be accordingly updated in order to ensure proper communication,
management, and conservation of these imperiled resources.
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