Mytilina crassipes Lucks, 1912
Most likely ID: n.a.
Synonym: n.a.
Sampling location: Suploch (Hiddensee), Simmelried
Phylogenetic tree: Mytilina crassipes
Diagnosis:
- lorica long, laterally compressed, without spines
- lorica dorsally double-keeled
- length to high ratio of lorica >= 2
- length (with toes) 220–280 µm
- eyespot absent
- toes long, slightly ventrally curved with pointed tips
- double-jointed foot
I find Mytilina crassipes frequently and regularly in the Simmelried. The specimens are usually found in the uppermost mud layer.
Mytilina crassipes has no spines or appendages. The long toes, which end in sharp tips, are striking. The double-joined foot is usually angled, which can be seen clearly even at low magnification.
Mytilina crassipes can easily be confused with Mytilina bisulcata. The two species differ only in the body length and the length to height ratio of the lorica. While Mytilina crassipes is longer than 200 µm (with toes) and has a lorica length to height ratio of 2 or greater, Mytilina bisulcata is much stockier and with a total length of 130-180 µm also smaller. The lorica length to height ratio of Mytilina bisulcata is always less than 2 (usually about 1.8)
More images and information on Mytilina crassipes: Michael Plewka-Freshwater life-Mytilina crassipes
Fig. 1 a-d: Mytilina crassipes. L = 230 µm (with toes). A freely swimming specimen from the left side. The length to high ratio of the lorica of this specimen is 2.1. Obj. 60 X.
Fig. 2 a-c: Mytilina crassipes. L = 236 µm (with toes). A freely swimming second specimen from the right. The length to high ratio of the lorica of this specimen is 2.1. Obj. 40 X.
Fig. 3: Mytilina crassipes. Detail of the head and the anterior margin of the lorica of a slightly squashed specimen. Obj. 100 X.
Fig. 4: Mytilina crassipes. Detail of the angled foot (FT) and the slightly curved toes (TO). Obj. 100 X.