Postabdominal
claw with middle pecten larger but not more than twice as long
as distal pecten
Anterior
margin of head with small to large helmet
“Retrocurved” means to come to a point at a position
dorsal to the midline of the body (1). Helmets are elongated or
expanded heads often in conjunction with longer shell spines and
shorter, narrow carapaces (1).
Ecology
Additional
Notes
Additional
Pictures
Quicktime
Movies
References
(1) Riessen, H. P. (1984). The
other side of Cyclomorphosis: Why Daphnia lose their helmets. Limnol.
Oceanogr. 29 (5): 1123-1127.