body rather short, laterally compressed, slightly gibbous dorsally
length 135–152 µm
head relatively short and convex anteriorly
neck is well marked
lorica is thin and flexible, lateral clefts narrow
corona is oblique and strongly convex without projecting lips
toes short, slender, slightly recurved and taper gradually
eyespot frontal
retrocerebral organ absent
vitellarium with 4 nuclei, rarely with six nuclei
Cephalodella gracilis
I have found Cephalodella gracilis so far only in the Mainau pond and in the Purren pond in the upper mud layer. The species is mostly smaller than 150 µm and is first noticed by this small size. Important feature for classification is the apical eyespot, the dagger-shaped toes and the vitellarium with only 4 nuclei (s. figs. 2a and 3). The latter is a very characteristic feature, since most Cephalodella species have 8 or 12 nuclei in the vitellarium.
Fig. 1 a-c:Cephalodella gracilis. L = 110 µm. A freely swimming specimen from left. Obj. 100 X.
Fig. 2 a-c:Cephalodella gracilis. L = 138 µm. A slightly squashed specimen from right. Note the 4 nuclei of the vitellarium (NV). Obj. 100 X.
Fig. 3:Cephalodella gracilis. A strongly squashed specimen from right. The 4 nuclei of the vitellarium are visible (1-4). ES = apical eyespot, DA = dorsal antenna, TR = trophi. Obj. 100 X.
Fig. 4:Cephalodella gracilis. The trophi in a strongly squashed specimen. Obj. 100 X.