Petalomonas platyrhyncha (Skuja, 1948)

Most likely ID: n.a.


Synonym: n.a.


Sampling location: Simmelried


Phylogenetic tree: Petalomonas platyrhyncha



  • length 35 – 48 µm, width 19 – 26 µm, thickness 10-20 µm
  • body broadly ovoid
  • tapered posteriorly end
  • anteriorly a round, snout-shaped apex
  • dorso-ventrally flattened
  • one flagellum
  • three dorsal keels
  • the keels converge anteriorly and posteriorly
  • ventrally no keels, flat or concave shaped
Petalomonas platyrhyncha

Petalomonas platyrhyncha is a very common species in the Simmelried. Almost every sample contains specimens. The population in Simmelried seems to be larger than the one described by Skuja from Swedish Lapland. He gives a maximum length of 48 µm. However, I could also find specimens with more than 80 µm length. Thus, Petalomonas platyrhyncha belongs to one of the largest Petalomonas species. The cells are mostly filled with colorless, highly refractive spheres. The nucleus is large and centrally located. The species has a round, snout-shaped apex, which reliably distinguishes it from the similar species Petalomonas praegnans, which is symmetrically pointed at the anterior end.


Fig. 1: Petalomonas platyrhyncha. L = 85 µm. a) dorsal view. b, c) lateral view from left. AP = apex, F = flagellum, K1 -K3 = dorsal keels. Obj. 100 X.


Fig. 2: Petalomonas platyrhyncha. L = 52 µm. Lateral view of a specimen during cell division. Obj. 40 X.