Sphenomonas angusta Skuja 1956

Aydin, Esra Elif & Lee, Won Je, 2012, Free-living Heterotrophic Flagellates from Intertidal Sediments of Saros Bay, Aegean Sea (Turkey), Acta Protozoologica 51 (2), pp. 119-137 : 134

Sphenomonas angusta Skuja 1956 ( Figs 3g , 4s)

Observation: Cell is about 10 μm long, not flattened and with a dorsal groove. The cell is anteriorly truncated and posteriorly rounded. The cell body is slightly curved: the right margin of the cell is straighter than the left one. The cell has two flagella of unequal length; the anterior flagellum is about 1.5 times the cell length and the trailing posterior flagellum is about 0.2 times the cell length. One large refractile inclusion occupies the posterior part of the cell. Description based on observation of one cell.

Remarks: Sphenomonas angusta was first described by Skuja (1956) with cell length of 13–21 μm. He described a smooth cell, but his illustrations show a single groove. This genus consists of 14 nominal species ( Christen 1959, Huber-Pestalozzi 1955, Playfair 1921, Skuja 1956, Schroeckh et al. 2003). Most of the species were reported from freshwater sites, but 3 species have been found in marine sites. Sphenomonas angusta is distinguished from other species of the genus by having one dorsal groove. This species is similar to S. e longata, but the reported cell length range of S. elongata is 30–70 µm. Generally Sphenomonas is similar to Notosolenus , but Sphenomonas is not flattened and with a hyaline inclusion which often largely fills the cell. This species is reported from Australia and Korea with the range of 10–14 µm cell length ( Lee and Patterson 2000; Lee 2002b, 2008, 2012).

Unidentified organism

One cell was observed at one occasion. It was difficult to establish the identity of the cell due to not enough information, but its presence is recorded to establish its occurrence in a marine bottom sediment.

‘Aegoni’ ( Figs 3n–p , 4a–c)

Observation: Cell is cap-shaped, like a jellyfish, about 5 µm long and 7 µm wide. Many flagella emerging from the posterior part of the cell are unequal in length. The shorter flagella with the varying lengths (mostly between 7–10 µm) are located on the lateral sides and surrounding the longer flagella beat actively, whereas the longer and numerous flagella in the middle are about 4 times the cell legth, wave sligthly and resemble a pony tail. The cell with a lateral protrusion at the one side of the cell close to posterior region. The protrusion can be seen as a separate beak – like structure from lateral view. In fact, it is an extension of the surrounding plate caused by the posterior depression where flagella emerge and the mouth is located – which is wider and/or larger on one lateral side. Bacteria that contact the flagella moved to the mouth by the flagellar movement. Description based on observation of one cell.

Remarks: The cell observed here is reported as an unidentified taxon because of not enough information. This species is similar to Multicilia marina Cienkowski 1881 in having many flagella, but can be easily distingushed by their movement patterns; ‘Aegoni’ swims, while Multicilia glides or rolls. Multicilia marina has been studied well by Mikrjukov and Mylnikov (1998). This species differs from Stephanomonas locellus (Fromentel) Kent 1880 because S. locellus has only one flagellum and many cilia around the body. Also S. locellus (32 µm) is bigger than the cell observed here. Further studies are needed to establish the identity of this organism.

Figures

Fig. 3. a – Petalomonas marginalis; b – Petalomonas minuta; c – Petalomonas ornata; d – Petalomonas poosilla; e–f – Ploeotia corrugata; e – general appearance of the cell from ventral and (f) dorsal view showing the ridges; g – Sphenomonas angusta; h – Ploeotia vitrea; i – Polyoeca dichotoma; j – Protaspis obliqua; k – Protaspis tegere; l – Salpingoeca marina; m – Pseudophyllomitus granulatus; n–p – ‘Aegoni’, n – postero-lateral view of the cell showing the beak – like structure; o – posterior view of the cell showing the flagellar insertions; p – general view of the cell. Scale bar: 5 μm for all figures.