This species appeared in both the Patuxent River samples and the Potomac River samples during summer and early fall of 2002. Size 33um wide, 63.4um
long, total volume 27483.6. It can be confused with P. oceanicum among others. It is considered to be oceanic and neritic in distribution in cold temperate to ropical waters. The summer of 2002 had extremely high salinities for the Chesapeake Bay.