Water flea ID please

Olympusman · Post by **Olympusman** » Sat Jun 14, 2014 12:10 pm

My references don't provide an ID for this water flea. It is notable for the fairly flat dorsal aspect wherein most Daphnia are more rounded.

Three stacks combined in Microsoft Picture Editor

merrimoles · Post by **merrimoles** » Sun Jul 27, 2014 4:38 pm

This is definitely Simocephalus sp, as indicated by the ventral margin of the head. Older texts will give you S. vetulus, but there seems to be a consensus that this species doesn't actually occur in N America (which is where I assume you found this). There isn't full agreement as to what to call this taxon in N America, but S. mixtus seems to be the most popular.

Olympusman · Post by **Olympusman** » Mon Jul 28, 2014 7:13 am

Merrimoles,
Thanks for the ID.

Mike

Clado · Post by **Clado** » Tue Jul 29, 2014 3:13 am

Hello Olympusman and merrimoles,

May be there is another possibility, Simocephalus expinoses lives in North America too. The posterior margin of the carapace is rather straight and S. mixtus is more convex. A claer image of the postabdomen would solve this problem because S. expinoses has a comb of spines on the base of the furca.