Thaumatomonadidae

Lee, Won Je, 2019, Small Free-Living Heterotrophic Flagellates from Marine Intertidal Sediments of the Sydney Region, Australia, Acta Protozoologica 58 (4), pp. 167-189 : 183

Thaumatomonadidae Hollande, 1952 Thaumatomastix sp.

Figs 3f , 5b

Description: Cells are spindle-shaped, anteriorly and posteriorly pointed. The cells are 8–15 µm long, flattened and rigid, and appear to be covered by a layer of body scales. The spines on the scales are present, but are only visible when the cells become stressed. Two thickened flagella emerge from the widely opened flagellar canal or the anterior end of the cell. The anterior flagellum is about the cell length and beats slowly from side to side. The posterior flagellum is about 2 times longer than the cell, is non-acronematic and trails. The nucleus is located subapically with caps, which are easy to overlook. Some extrusomes are symmetrically distributed around the margin of the cell. The cells glide slowly and may have a slow jerking movement. When the cell is gliding, the anterior part of the cell is adpressed to the substrate and the posterior end is directed away from it. Food materials are seen throughout the cell. Relatively common.

Remarks: This species is assigned to Thaumatomastix because it is a gliding flagellate, with two flagella inserting into a subapical depression and has scales. It could not be identified because ultrastructural features of the silicified scales were not recorded. There are about 13 nominal species in Thaumatomastix ; T. bipartita Beech et Moestrup, 1986 , T. dybsoeana Thomsen et al., 1993 , T. formosa Thomsen et al., 1993 , T. fragilis Thomsen et al., 1995 , T. fugiformis Thomsen et al., 1995 ; T. patelliformis (Takahashi et Hara, 1984) Beech et Moestrup, 1986 , T. salina (Birch-Andersen, 1973) Beech et Moestrup, 1986 , T. sagittifera (Conrad, 1920) Beech et Moestrup, 1986 , T. setifera Lauterborn, 1899 , T. spinosa Thomsen et al., 1993 , T. splendida Thomsen et al., 1995 , T. triangulata (Balonov, 1980) Beech et Moestrup, 1986 , T. tripus (Takahashi et Hara, 1984) Beech et Moestrup, 1986 . Of the 13 species, plate scales, spine scales and flagellar scales of 9 species were summarised by Thomsen and co-workers ( Thomsen et al. 1993). Thaumatomastix Lauterborn, 1899 , Thaumatomonas de Saedeleer, 1931 and Protaspa Cavalier-Smith, 2011 (= Protaspis Skuja, 1939 ) have similar characters; a similar shape, a ventral groove, anteriorly located nucleus, they glide, produce pseudopodia and have two flagella. Thaumatomastix and Thaumatomonas have been known to have scales visible by electron microscopy or light microscopy, but Protaspa has not been known whether it has scales or not. Further studies are needed to establish the identity of these genera.

Figures

Fig. 3. Apusomonadida, Cercomonadida, Protaspidae, Thaumatomonadidae and Protista incertae sedis. (a) Apusomonas proboscidea, (b) Cercomonas parva, (c) Cercomonas sp.1, (d) Cercomonas sp.2, (e) Protaspa flexibilis sp. nov., (f) Thaumatomastix sp., (g) Eoramonas jungensis sp. nov., (h) Gweamonas unicus, (i) Phyllomitus undulans (from Lee 2002a), (j) Protist 1, (k) Protist 2. Scale bar = 10 μm for all figures.

Fig. 5. (a) Protaspa verrucosa, note ventral groove. (b) Thaumatomastix sp., general appearance of cell and showing a layer of body scales. (c)–(d) Clautriavia cavus, general appearance of different cells, (c) cell from Lee and Patterson (2000). (e) Gweamonas unicus, note coiled flagellum and flagellar insertion. (f)–(h) Eoramonas jungensis sp. nov., showing general appearance of different cells, note flagellar insertion and beating pattern of anterior flagellum. (i)–(j) Glissandra similis, showing general appearance of different cells, note the ventral groove. (k) Phyllomitus undulans, note two flagella adhering each other, from Lee (2002a). (l)–(m) Protist 1, showing general appearance, note flagellar insertion. (n) Protist 2, showing general appearance, note collar and two emergent flagella.All micrographs are DIC images. Scale bar in (h) = 5 μm for (e)–(h) and in (n) = 10 μm for other figures.