Menoidium pellucidum (Perty, 1852)
Most likely ID: n.a.
Synonym: n.a.
Sampling location: Purren pond, Mainau pond, Ulmisried, Simmelried
Phylogenetic tree: Menoidium pellucidum
Diagnosis:
- cells curved, rigid, laterally strongly compressed
- length 36–69 µm
- anterior end snout-shaped and elongated with two lips
- ventral lip longer than dorsal lip
- pellicle longitudinally striated
- posterior end slightly tapered and rounded
- one flagellum, half of body length
- nucleus globular below mid-body with central nucleolus
- large paramylon grains in anterior half of cell
- aggregation of small paramylon granules in posterior half of cell
I find Menoidium pellucidum frequently and regularly in different sampling sites. The species is very common. This representative of the genus Menoidium is easily identifiable by its size (usually longer than 50 µm) and by the snout-shaped extension of the anterior end. This is formed by two lips. The ventral lip is always longer and protruding (s. fig. 2 a). The pellicle is longitudinally striated (s. fig. 2 b), but in my experience this is not clearly seen in all specimens. As in other species of Menoidium, an aggregation of small paramylon granules is often found in the posterior half of the body, while large paramylon granules are found in the anterior half. However, their number and size is variable and depends on the nutritional status.
Fig. 1 a-b: Menoidium pellucidum. L = 63 µm. Two focal planes of a slightly squashed specimen. Note the nucleus (Nu) with a start shaped nucleolus. Mit? = probably mitochondria beneath the pellicle. Obj. 100 X.
Fig. 2 a-b: Menoidium pellucidum. L = 56 µm. Two focal planes of a second specimen. Note the elongated ventral lip (VL) at the anterior end and the longitudinal striation (LS) of the pellicle. APG = aggregation of small paramylon grains, F = flagellum, Nu = nucleus, PG = paramylon grains. Obj. 100 X.
Fig. 3 a-b: Menoidium pellucidum. L = 66 µm. Two focal planes of a third, slightly squashed specimen. CV = contractile vacuole, Nu = nucleus. Obj. 100 X.