Trichotria tetractis (Ehrenberg, 1830)

Most likely ID: n.a.


Synonym: n.a.


Sampling location: Simmelried


Phylogenetic tree: Trichotria tetractis



  • lorica is one piece, no lateral cleft
  • length 256–295 µm (with toes)
  • dorsal and ventral side of lorica with large facets and ornamentation
  • lateral sides of lorica without spines
  • foot of three segments
  • first segment of foot with two spines pointing dorsally
  • two long, ventrally curved toes with pointed ends
Trichotria tetractis

So far I have found Trichotria tetractis exclusively in the Simmelried between floating plants, where the species only occurs sporadically. The shape of Trichotria tetractis with its faceted lorica and long toes is very characteristic, making it easy to identify the species. An important feature to distinguish it from the similar species Trichotria pocillum is the absence of a spine between the toes (ss fig. 1 b). In addition, Trichotria pocillum has much longer dorsal spines on the first segment of the foot. In Trichotria tetractis they are short and triangular (s. fig. 1 a).


More images and information on Trichotria tetractis: Michael Plewka-Freshwater life-Trichotria tetractis


Fig. 1 a-d: Trichotria tetractis. L = 266 µm (with toes). Lateral view from right (a) and ventral view (b, c, d) of a freely swimming specimen. Note the absence of a spine (arrow) between the toes (TO) and the short dorsal spines (DS) of the first foot segement. ES = eyespot, St = stomach. Obj. 40 X.


Fig. 2 a-b: Trichotria tetractis. The ventral side of the lorica with two large facets and a distinct ornamentation. Obj. 60 X.


Fig. 3: Trichotria tetractis. L = 272 µm (with toes). Lateral view from right of the transparent lorica with ornamentation. Obj. 60 X.