NOTE: Hover over the bold words for definitions or see the Glossary.
R. I. Johnson described this species in 1984. The shell shape of the Waccamaw fatmucket is sexually dimorphic. In males, the posterior ridge is angular (sometimes bi-angulate), while in females the posterior slope is broadly rounded to accommodate the marsupium. The periostracum is golden yellow to brown with green rays along the posterior third or more of the shell. The nacre has a pink-lavender cast. The marsupium has a dark margin. Two well developed pseudocardinal teeth are found in the left valve; one well developed pseudocardinal tooth in the right valve, one vestigial. Lateral teeth are short and straight, two in the left, one in the right. The male Waccamaw fatmucket may be confused with the Waccamaw spike; however, the spike has a much more angular posterior ridge and rarely has discernable rays on the periostracum. Genetics work by Stiven and Alderman (1992) suggests that the Waccamaw fatmucket is very closely related to the eastern lampmussel. Additional studies are recommended to confirm these findings.
Shell Anatomy
The alewife floater ranges from Nova Scotia and New Brunswick, Canada, to the Potomac River in Virginia and Maryland (Johnson 1946, 1970, Burch 1975). A disjunct population is also known from the Chowan River in North Carolina (Shelley 1983). William Adams (pers. comm.) found live individuals in the Chowan River during the Summer of 1989. This species has also been documented from the Roanoke River below the last dam at Weldon down to Washington County.
Distribution by County: Chowan River Basin: Hertford Co. (Meherrin River, Chowan River); Gates Co. (Chowan River). Roanoke River Basin: Northampton Co. (Roanoke River); Washington Co. (Roanoke River). NOTE: All headwater areas that flow into these occupied habitats should receive special management.
Johnson (1970) states that this species appears to prefer clean sand/gravel substrates in relatively fast flowing water. However, at the Chowan River, NC site the water has an almost imperceptible flow (B. Adams, personal communication).
The alewife (Alosa pseudoharengus) appears to be the alewife floater's dominant fish host (Johnson 1946). According to Ortmann (1911), all Anodonta species appear to be bradytictic (long term brooders).
General Life History For Mussels