Biddulphia sinensis syn. Odontella sinensis
One of the largest diatoms found in the Chesapeake Bay averaging 300u long by 210u wide with a total volume of over 106 cubic microns. Usually found in more saline lower bay waters, this example came from a plankton tow in the mid-bay area off Bloody Point in September.
The salinity was 16ppt, the temperature was 17C.
This is considered an invasive species. It was first described by Greville in 1866 in Hong Kong Harbor. Earliest report of it in the Chesapeake Bay was in 1960-62 by Mulford, Patten et al.