Keelungia pulex Chan and Moestrup, 2013

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 : 91-92

3. Keelungia pulex Chan and Moestrup, 2013

(Figs. H -J)

Material examined. Korea, Chunnam, Yeosu-si, Samsan-myeon, Seodo-ri, Seodo Port, 34°3′18.26″N, 127°17′ 54.33″E, 6 May 2021, collected by Miran Kim. Type strain, live cells are kept with the Korean Culture Collection of Protists , Kyungnam University , Korea, reference ‘ KM080 ’.

Description. Phagotrophs and gliding euglenid with two emergent flagella. Cells are oblong to ovoid and 13.5- 19.7 μm (Avg. 16.4 μm, n = 97) long with two flagella. The anterior flagellum is directed forward and about the cell length, and the posterior flagellum is 2-4 times the cell length. The anterior flagellum commonly keeps in an S-shape and beats rapidly and is used for change of direction. The posterior flagellum is trailing. The hook-shaped ingestion apparatus with two rods is visible by light microscopy and reach almost to the posterior end of the cell. The flagellar reservoir extended for about half the cell length. The cells have several longitudinal ridges, which are generally difficult to see in the light microscope.

The closest sequence retrieved by NCBI BLASTN search was that of 18S rDNA sequence of K. pulex (accession number; HM044218) with a high identity of 100%. The 18S rDNA sequence of the stain is 1,576 bp in length.

Remarks. Present observations are in agreement with the previous observation ( Chan et al., 2013), although the cell length ranges do not overlap (this population, 13.5-19.7 μm long; Chan and Moestrup’s population, 8-11 μm). Keelungia pulex shows a high similarity in morphological characters with K. nitschei Arndt et al., 2019 (8.3- 11.6 μm), but the anterior end of K. nitscheri is truncated. This is the main morphological character distinguishing K. pulex from K. nitschei ( Schoenle et al., 2019) . Keelungia pulex can be distinguished from a small ploeotid species, Ploeotia azurina (10-16 μm), because P. azurina is ovate with pointed posterior end. It resembles P. longifilum (12- 20 μm) and Keelungia sp. (KM082) (9.3-13 μm) reported by Lax et al. (2019) in cell shape, cell length and long posterior flagellum. Further studies are needed to establish the identities of these species.

Habitat. Marine water column.

World distribution. Taiwan, Korea.

Deposition. HnibrEG000001-EG000005.

NCBI GenBank Accession Number. OM177658.

Identifiers. Won Je Lee.