Sorastrum spinulosum Nägeli, 1849
Most likely ID: n.a.
Synonym: n.a.
Sampling location: Mühlweiher Litzelstetten
Phylogenetic tree: Sorastrum spinulosum
Diagnosis:
- coenobia spherical, free floating
- coenobia of 4-8-16-32 cells
- cells rhomboidal or reniform
- cells with 1–4 outward directed spines
- cells connected in center of coenobia via gelatinous stalks
- diameter (of coenobia) 25–60 µm
- cells 6–18 µm long, 8–20 µm wide
- one parietal chloroplast with one pyrenoid
Sorastrum spinulosum is said to be a widespread alga with a characteristic appearance, but so far I have only found one specimen, which comes from the Mühlweiher Litzelstetten.
The coenobia of Sorastrum spinulosum are spherical and often drift in the plankton. I found my specimen among floating plants. The cells are more or less kidney-shaped and have a concave indentation on the outward-facing side and 1–4 spines at the apical ends. In my specimen, there were mostly two spines. At the inward-facing end, the cells have a short gelatinous stalk, with which they are connected to the other cells. However, this can only be seen in strongly squashed specimens (s. fig. 2 b). With a diameter of 33 µm, my specimen was at the lower end of the range of 25–60 µm given by Streble & Krauter.
Fig. 1 a-b: Sorastrum spinulosum. D = 33 µm (of coenobium). Two focal planes of a slightly squashed specimen. Obj. 100 X.
Fig. 2 a-b: Sorastrum spinulosum. D = 33 µm (of coenobium). The same coenobium as shown in fig. a-b but stronger squashed. Note the center of the coenobium, where the gelatinous stalks of the cells are connected (arrow). Obj. 100 X.