Squatinella rostrum (Schmarda, 1846)
Most likely ID: n.a.
Synonym: n.a.
Sampling location: Simmelried
Phylogenetic tree: Squatinella rostrum
Diagnosis:
- lorica oval with three distinct dorsal spines
- head shield smmoth and circular
- length 150–217 µm
- ventral shield present
- foot with three segments
- a spine on the third foot segment, directed dorsally
- equal pair of slender, pointed toes
So far I have only found Squatinella rostrum in the Simmelried, mainly between floating and decomposing plant masses. The species is easy to recognize in the samples due to the typical three spines on the dorsal side (s. figs. 1 d and 2). Specimens are also frequently found on the floating coverslip, which can then be observed from the ventral side.
Squatinella rostrum can be confused with the similar species Squatinella tridentata. Squatinella tridentata, however, has no spine on the third segment of the foot (s. fig. 3).
Further images and information on Squatinella rostrum: Michael Plewka-Freshwater life-Squatinella rostrum
Fig. 1 a-d: Squatinella rostrum. L = 190 µm. Different focal planes of a freely swimming specimen from dorsal. Obj. 40 X.
Fig. 2: Squatinella rostrum. L = 190 µm. The slightly squashed specimen as shown in fig. 1 a-d. Note the three distinct dorsal spines (DS). ES = eyespot with lense, TO = toes, TR = trophi. Obj. 60 X
Fig. 3: Squatinella rostrum. L = 206 µm. Lateral viel of a freely swimming specimen. Note the spine (FS) on the third segment of the tripartite foot (1–3). DS = dorsal spines, HS = head shield, TO = toes, VS = ventral shield. Obj. 40 X.
Fig. 4: Squatinella rostrum. L = 182 µm. Ventral view of a slightly squashed specimen. Obj. 100 X.
Fig. 5: Squatinella rostrum. Focal plane on the eyespots (ES) with lenses (LE) from ventral. Obj. 100 X.
Fig. 6: Squatinella rostrum. Two focal planes of the trophi in a strongly squashed specimen. Obj. 100 X.