Entosiphon

This article is about a genus of flagellates. For the plant alternatively known as Entosiphon, see Atuna (plant).

Entosiphon is a genus of euglenids. It was described by Friedrich Stein in 1878.

Entosiphon
Differencial interference contrast micrograph of Entosiphon oblongum. Scale bar: 10 μm.
Scientific classification
Domain:	Eukaryota
Clade:	Discoba
Phylum:	Euglenozoa
Class:	Euglenida
Family:	Entosiphonidae Cavalier-Smith 2016[1]
Genus:	Entosiphon Stein 1878[2]
Type species
Entosiphon sulcatum (Dujardin 1841) Stein 1878
Other species
Entosiphon oblongum

Description

Entosiphon is a genus of phagotrophic euglenids, single-celled flagellates with two flagella characterized by a protein pellicle present beneath the cell membrane. In particular, Entosiphon cells are distinguished by a protrusible ingestion apparatus. Their pellicle is composed of twelve protein strips.^[3]

Classification

The genus Entosiphon was described by Friedrich Stein in 1878. It was established to transfer a species of Anisonema, A. sulcata, to a separate genus, which changed the original spelling of this species to E. sulcatum.^[2] A second species, E. oblongum, was described in 2016.^[4] The genus was placed in a separate family Entosiphonidae the same year.^[1]

The evolutionary position of Entosiphon among euglenids is unstable, either branching with Hemiolia and Liburna or forming a separate branch, depending on the methods and datasets used. In all cases, it consistently branches among basal, non-flexible euglenids, outside of any major euglenid group.^[3][5]