Musculium partumeium (Say, 1822) Swamp Fingernailclam

Musculium partumeium (Say, 1822) Swamp Fingernailclam

Musculium partumeium (Say, 1822) Swamp Fingernailclam

Musculium partumeium (Say, 1822) Swamp Fingernailclam
    Two empty shells found in mud beneath small log in the roadside swale on the east side of US-1 about 3.3 miles northwest of International Golf Parkway, St. Johns County, Florida, 5/22/2021. The specimens were found adjacent to normally swampy area (upper reaches of the Twelve Mile Swamp) which was mostly dry when the shells were found. The specimen pictured in the top two images measures 10 mm.
    Williams et al. (2014: 411) wrote of the species: "It may be associated with ephemeral habitats (Heard 1979a) and is relatively tolerant of anoxic conditions (Mackie 2007)." He gave a max size of 8 mm. Mackie (2007: 251) remarked "Ordinarily this species does not exceed 9 mm in shell length, but specimens up to 12 mm long have been collected on occasion." He went on to say "In temporary ponds this species aestivates in both newborn and adult length classes (M. securis aestivates only as newborn). The major birth period is in the spring, before the pond dries up. In temporary ponds , a second birth period may also occur during the fall, after the pond fills with water ..."

All the authorities below acknowledge a extensive range in North America, including Northeast Florida.

Burch, J.B., 1972. Freshwater Sphaeriacean Clams (Mollusca: Pelecypoda) of North America. Biota of Freshwater Ecosystems Identification Manual No. 3. U.S.E.P.A., Washington, DC. [i]-viii + 1-[32] [iv, vi, 24, 26, 30 blank pages]. March.

Herrington, H.B., 1962. A Revision of the Sphaeriidae of North America (Mollusca: Pelecypoda). Miscellaneous Publications of the Museum of Zoology, University of Michigan 118: [1]-74. 26 April. <http://deepblue.lib.umich.edu/bitstream/handle/2027.42/56362/MP118.pdf>

Mackie, G.L., 2007. Biology of freshwater corbiculid and sphaeriid clams of North America. Ohio Biological Survey (new series) 15(3): 438 pp. + ix.

Williams, J.D., R.S. Butler, G.L. Warren, N.A. Johnson, 2014. Freshwater Mussels of Florida. University of Alabama Press, Tuscaloosa, AL. [i]-xv + 1-498.