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Sphaeroma papillae

Sphaeroma papillae
Manorhaven Town Park, Port Washington, Nassau County, New York, USA
January 4, 2021
Common to abundant under dark rocks in areas of the intertidal zone innudated by fresh water at low tide (usually by freshwater seeps or creek outlets). I generally found these in areas where the salinity at low tide was around 6ppt with the nearby bay being much saltier (20-32ppt) but there were occasional breaks in that rule. Easily identified by the non-serrated uropod exopod margin (serrated in S. quadridentatum), the telson having two bumps (smooth in S. quadridentatum) and by having the uropod rami the same length as each other (the exopod much shorter than the endopod in Cassidinidea, the only other genus this far north)