Anisonema acinus Dujardin, 1841 from the northernmost pond edge benthos of the spring-fed freshwater coastal pond at Ocean Dunes in the Atlantic Double Dunes reserve situated 250 meters from the edge of the Atlantic Ocean. Measures 42.5 um in length. Imaged in Nomarski DIC using Olympus BH2 under SPlan 40x objective plus variable phone cropping on Samsung Galaxy S9+.
"Anisonema acinus Dujardin, 1841 Gliding euglenid with profile similar to a barley-grain, 25-47 µm long, mostly about 30 µm, dorso-ventrally flattened. With a wedge-shaped ingestion organelle which may be difficult to observe. With two flagella, the anterior flagellum about 1.5 times as long as the cell, and beating with an undulating and sweeping motion in front of the cell. The posterior flagellum is up to twice the length of the cell, very thickened at its base and follows an almost semi-circular loop as it leaves the flagellar pocket, emerging under a ventral fold of the cell surface. The posterior flagellum can cause occasional reversals of movement. With the flagellar pocket to left of cell and with an associated contractile vacuole. Nucleus with maculate texture and to right of the cell near mid-line. About 8-10 very delicate grooves on each side of body, grooves sometimes not seen. Sometimes contain algal materials, although no ingestion organelle was observed. Common and widespread" (1).
"The genus Anisonema contains slightly metabolic gliding euglenids with the capacity for reversal movements. The confirmation of an ingestion apparatus in this genus will require a review of the composition of this and adjacent genera" (1). "All are ovoid cells that maintain a constant shape most of the time (but are capable of some deformation), and glide on their thickened, hook-shaped posterior flagellum, whereas the anterior flagellum flails freely in front of the cell. Unlike Dinema, their pellicle is not thickened, and the feeding apparatus is difficult or impossible to observe. Many of our cells have ingested algal material" (2).
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Free-living Heterotrophic Flagellates from Freshwater Sites in Tasmania (Australia), a Field Survey. Won J. LEE, Alastair G. B. SIMPSON and David J. PATTERSON. Acta Protozool. (2005) 44: 321 - 350
The Molecular Diversity of Phagotrophic Euglenids Examined Using Single-cell Methods Gordon Lax, and Alastair G.B. Simpson. Protist, Vol. 171, 125757, November 2020
