Genus Lasmigona main content.

Genus Lasmigona

Family Unionidae



Lasmigona subviridis, the green floater, ranges from the Carolinas to the Hudson River basin and the St. Lawrence in New York. In New Jersey, the species once occurred in the Delaware-Raritan Canal and the Passaic, Raritan, Delaware and Pequest rivers. In 1996, a single live individual was found in Stony Brook, Mercer County. The Stony Brook occurrence represents the only reported sighting of a live green floater in the state since the early 1900's. The green floater is listed as endangered in NJ.

Species Summary

Species summary

Lasmigona subviridis (Conrad, 1835)
green floater



size: adult less than 65 mm, typically 55 mm
beak: projecting only slightly above hinge line, may be double looped, cavity shallow
color patterns: numerous dark green rays of varying width; periostracum dull yellow to brownish-green; nacre dull bluish-white
shape: subovate, ovate, triangle-ovate, or trapezoid
shell features: fragile, thin shell; small, rounded posterior ridge;
teeth: moderately developed but delicate, laterals vestigial; left valve with an interdental tooth, two pseudocardinal teeth and two lateral teeth; right valve with one pseudocardinal tooth and one lateral tooth


abundance: NJ: rare
status: US: not legally protected; NY: threatened; NJ: endangered; CT: does not occur
conservation challenges: this species should be sought in its former localities and in any ecologically compatible habitat in New Jersey
As an endangered species, L. subviridis may not be collected without a permit from the New Jersey Department of Environmental Protection. For details of restrictions and permits for collecting fresh water mussels and other invertebrates in the states of the metro area, please go to the Permits page.


N.A. distribution: South Carolina and Cape Fear River Basin, North Carolina to the Hudson River Basin and westward to St. Lawrence River Basin, NY
present metro distribution: NY: Susquehanna River watershed; NJ: Stony Brook, Mercer County (lower Hudson River watershed): CT: does not occur
other regional localities: none
historical localities: NY: Lake Ontario watershed, Oswego River watershed, southwestern Lake Ontario watershed, upper Hudson River watershed; NJ: Passaic and Raritan rivers (lower Hudson River watershed, Delaware and Pequest rivers; CT: did not occur


Life History:

habitat: quiet, meandering parts of hydrologically stable small rivers and smaller streams, most often in slow water or pools and eddies, substrate gravelly or sandy prefers slower currents Habitat Photo
hosts: not known, may not require host fish; direct development has been documented


L. subviridis

Left view
left view
Right view
right view
Profile view yellowish
profile view- yellowish brown form
Profile view greenish
profile view: greenish with rays form
Lasmigona subviridis, a green floater mussel. Dorsal view with closed shell shows beak facing camera.
dorsal view
Profile view brown
profile view: brown form
beak projects slightly above hinge line
Beak sculpture
beak sculpture may be double-looped; note two pseudocardinal and two interdental teeth (left valve)
Interior view
interior view
Interior view note
interior view note two pseudocardinals left, one right; two laterals left, one right