Cosmarium neodepressum

Ramos & Moura, 2020

Most likely ID: n.a.

 

Synonym: Cosmarium depressum

 

Sampling location: Simmelried

 

Phylogenetic tree: Cosmarium neodepressum

 

Diagnosis: 

  • semi-cells elliptic, slightly depressed
  • length 36–56 µm, width 36–60 µm
  • sinus narrow, linear
  • isthmus narrow
  • cell wall covered with fine pores
  • one pyrenoid per semi-cell
Cosmarium-neodepressum
Cosmarium neodepressum

So far I have only found Cosmarium neodepressum in the Simmelried, where this desmid alga can be found regularly, but never frequently.

 

Cosmarium neodepressum has unfolded, flat chloroplasts, which makes the specimens appear very transparent and bright. The semi-cells are broadly elliptical with a typical shape. The cell wall is granulated. These are pores through which the often visible gelatinuous sheath is excreted. Bacteria often colonize the surface of this sheath.

Cosmarium-neodepressum

Fig. 1 a-b: Cosmarium neodepressum. L = 40 µm.  Two focal planes of a young specimen. Note the granulated surface of the cell wall (b). Obj. 100 X.

Cosmarium-neodepressum

Fig. 2: Cosmarium neodepressum. L = 38 µm.  A specimen in brightfield illumination. Obj. 100 X.

Cosmarium-neodepressum

Fig. 3: Cosmarium neodepressum. L = 44 µm. A specimen with a clearly visible gelatinuous sheath (GS). Obj. 40 X.

Cosmarium-neodepressum

Fig. 4: Cosmarium neodepressum. A specimen in cell division. Nu = nucleus. Obj. 100 X.

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