Entosiphon oblongum, Cavalier-Smith and Vickerman, 2016

Lee, Won Je, 2022, Three newly recorded heterotrophic euglenids (Protist), Entosiphon oblongum, Euglena longa and Keelungia pulex from South Korea, Journal of Species Research 11 (2), pp. 89-93 : 90

1. Entosiphon oblongum Cavalier-Smith and

Vickerman, 2016 (Figs. A -D)

Material examined. Korea, Incheon, Seo-gu, Yeonhuidong, Shimgok-chun, 37°31′37.10″N, 126°39′36.81″E, 25 November 2019, collected by Won Je Lee. Type strain, live cells are kept with the Korean Culture Collection of Protists , Kyungnam University, Korea, reference ‘KF030 ’.

Description. Phagotrophs and gliding euglenid. Cells are oblong and 23.1-29.3 μm (Avg. 26.5 μm, n = 30) long. The cells are usually slightly dorso-ventrally flattened and not metabolic or plastic. Two unequal heterodynamic flagella. The anterior flagellum is about the cell length and beats actively with a sweeping motion. The thicker posterior flagellum is 1-1.5 times the cell length, is deflected posteriorly and trails along the substrate. The chiselshaped feeding siphon with two rods is moved in and out. Pellicle with several deep grooves. The cells may detach and swim with a trembling motion. The nucleus is located near the equator and to the right and is granular.

The closest sequence retrieved by NCBI BLASTN search was that of 18S rDNA sequence of E. oblongum CCAP 1220 /2 (accession number; KP306754) with a high identity of 99.83%. The 18S rDNA sequence of the stain is 1,761 bp in length.

Remarks. The most similar genera are Ploeotia and Serpenomonas , but Entosiphon can be distinguished because its siphon is extensible, and because of ultrastructural differences in the construction of the feeding siphon (apparatus) and pellicle (Triemer, 1986; Triemer and Farmer, 1991). Among the genus, E. oblongum is closely related to E. sulcatum , but differing in shape and RNA and Hsp90 sequences (see Cavalier-Smith et al., 2016).

Habitat. Soil, Freshwater sediment.

World distribution. UK, Korea.

Deposition. NIBREG0000000195.

NCBI GenBank Accession Number. OM177657.

Identifiers. Won Je Lee.