Helkesimastix faecicola Woodcock and Lapage 1914

Lee, Won Je, 2015, Small Free-Living Heterotrophic Flagellates from Marine Sediments of Gippsland Basin, South-Eastern Australia, Acta Protozoologica 54 (1), pp. 53-76 : 66

Helkesimastix faecicola Woodcock and Lapage 1914 ( Figs 1k , 4h )

Observation: Cells are elliptical, 4 to 8 µm long, flexible, not flattened and with two flagella. The short flagellum (arrow, Fig. 4h ) emerging subapically (almost apically) from a shallow depression directs posteriorly and is easy to overlook. The long flagellum is 1.5 to 2.5 times longer than the cell, attaches to the cell body and is acronematic. The cells glide closely contact to the substrate. Observed abundantly at one sampling station in Gippsland Basin.

Remarks: The cells described here are assigned to Helkesimastix faecicola Woodcock and Lapage, 1914 (6–7 µm) although H. faecicola had only one flagellum. The tiny flagellum in the cells described might be over- looked. This species was found at a marine site in England ( Lackey and Lackey 1963). It appears to be slightly different from H. faecicola described by Zhukov (1971), Zhukov and Mylnikov (1983), and Tong et al. (1997). The cells described by Tong et al. (1997) have only one flagellum, and the cells by Zhukov (1971) and Zhukov and Mylnikov (1983) are more similar to Bodo platyrhynchus ( Larsen and Patterson 1990) . Helkesimastix faecicola is similar to Prismatomonas limax Massart 1920 in cell shape and cell size, and in having an acronematic fla- gellum attaching to the cell body. Prismatomonas limax may be a junior synonym of H. faecicola . Helkesimastix faecicola is distinguished from Allantion by having two flagella and by the long flagellum attached to cell body. This species is similar to Bodo platyrhynchus in cell length and having two flagella, but is distinguished by the beating of the short flagellum in B. platyrhynchus . The anterior flagellum of B. platyrhynchus beats forwardly while that of H. faecicola directing posteriorly does not beat. Recently, another species ( H. marina , 4.5– 7 µm) has been reported from marine sediment in Belize by Cavalier-Smith et al. (2009). According to Cavalier-Smith et al. (2009), there are two major differences from H. faecicola ; the presence of a contractile vacuole and the shape of the cysts (~ 4 µm) which are non-spherical and dish-shaped ( Cavalier-Smith et al. 2009, p. 455; Figs 1r, s ). However, Woodcock and Lapage (1914) also mentioned that it has a contractile vacuole (p. 357), and its cysts are 3 to 3.5 µm and spherical or ovate (Plate 13: 1–3). When looking at the cysts in Figs 1r and 1s of Cavalier-Smith et al. (2009), they are almost spherical. In addition, these species overlap in cell length. Thus, these two species are indistingushiable from each other and here H. marina is regarded as a junior synonym of H. faecicola .

Figures

Fig. 1. a – Chilomastix cuspidata, b – Rhynchopus amitus, c – Spironema multiciliatum, d – Psammosa unguis nov. comb., e – Apusomonas sp., f – Rhynchobodo formica, g – Mantamonas plastica, h – Roombia truncata, i – Thaumatomastix setifera, j – Ancyromonas impluvium nov. spec., k – Helkesimastix faecicola, l – Kurnaimonas celerisnov. spec., m – Sinistermonas sinistrorsus nov. spec., n – Kiitoksia kaloista, o – Protist ‘1’. Scale bar: 10 µm for all figures.

Fig. 4. a – Carpediemonas membranifera; b – Kipferlia bialata; c – Discocelis saleuta, note a short flagellum; d – Metopion fluens, showing general appearance of cell, note shorter flagellum (arrow); e–f – Kurnaimonas celeris nov. spec., showing general appearance of cell; g – Pseudophyllomitus granulatus; h – Helkesimastix faecicola, showing general appearance and note short flagellum (arrow); i – Metromonas grandis, showing general appearance of cell and note the folded margin on the left side and short flagellum (arrow); j – Metromonas simplex, showing general appearance of cell and note short flagellum (arrow); k – Kiitoksia kaloista, showing two flagella and note short flagellum (arrow); l – Sinistermonas sinistrorsus nov. spec., showing general appearance of cell, and note flagellar insertion and beating pattern of anterior flagellum; m – Telonema subtilis, showing general appearance; n – Protist ‘1’. All micrographs are DIC images. Scale bar: 5 µm for all figures.