Penium spirostriolatum (Barker, 1869)

Most likely ID: n.a.


Synonym: n.a.


Sampling location: Ibmer Moor (Austria)


Phylogenetic tree: Penium spirostriolatum



  • cells cylindrically, attenuating gradualley to truncate or rounded apices
  • length 80–400 µm
  • cell wall with spiralized ridges
  • 2–4 chlorplasts per cell
  • chloroplasts with 6–7 longitudinal ridges and 1–3 pyrenoids
  • pyrenoids somtimes elongated
  • girdle bands present
  • nucleus central
  • terminal vacuoles in the apices absent
Penium spirostriolatum

I found Penium spirostriolatum in June 1995 in the Ibmer Moor (Austria). The alga is not present in my local sites.


Penium spirostriolatum can easily be recognized by the 4 chloroplasts per cell, which are separated from each other by transverse gaps (s. fig. 1 b). The chloroplasts have 6-7 longitudinal ridgess, making them appear star-shaped in cross-section. The pyrenoids in the chloroplasts can sometimes have an elongated, stretched shape.


The similar species Closterium closteroides var. intermedium can also have 4 chloroplasts, which are separated by transverse gaps. However, this species has clear teminal vacuoles at the apices, in which crystals are visible, as is typical for the genus Closterium.


Fig. 1 a-b: Penium spirostriolatum. L = 160 µm. Two focal planes of a specimen frim the Ibmer Moor (Austria). Note the gaps between the 4 chloroplasts (arrows). Nu = nucleus. Obj. 40 X.