Entosiphon sulcatum (Stein, 1878)

Most likely ID: n.a.


Synonym: n.a.


Sampling location: Simmelried, Purren pond, Mainau pond, Bussenried, Bündtlisried, Ulmisried, Mühlhalden pond, Mühlweiher Litzelstetten


Phylogenetic tree: Entosiphon sulcatum



  • body oval with 4–8 longitudinal grooves
  • length 20–25 µm, width 10–15 µm
  • trailing flagellum about twice of body length
  • leading flagellum about body length
  • cytopharynx with a tube-shaped ingestion apparatus (siphon)
  • siphon reach almost the posterior end
  • nucleus lateral, about mid-body
  • one contractile vacuole lateral in anterior third
Entosiphon sulcatum

Entosiphon sulcatum is one of the most common colorless, eugenid flagellates. It occurs in almost all of my sampling sites. The species is easily identified by the tubular siphon and the distinct longitudinal grooves of the pellicle. I find Entospihon sulcatum especially common in floating detritusl flakes in old specimens. Entosiphon also likes to settle on the floating coverslip.


Fig. 1 a-b: Entosiphon sulcatum. L = 24 µm. Two focal planes of a slightly squashed specimen. Note the tube-shaped siphon (Si) and the longitudinal grooves (Lg) of the pellicle. CV = contractile vacuole, LF = leading flagellum, Nu = nucleus, TF = trailing flagellum. Obj. 100 X.


Fig. 2 a-b: Entosiphon sulcatum. L = 27 µm. Two focal planes of a second specimen. Note that the siphon (Si) is reaching almost up to the posterior end (arrow). LF = leading flagellum, Nu = nucleus. Obj. 100 X.


Fig. 3 a-c: Entosiphon sulcatum. L = 28 µm. Three focal planes a slightly squashed specimen in the process of cell division. Note the doubled siphons (Si 1, Si 2). The specimen appears pink by ingested rhodobacteria (IR). LG = longitudinal grooves of the pellicle. Obj. 60 X.