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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Thaumatomonas

Thaumatomonas De Saedeleer, 1931 (ref. ID; 7130)

Family Thaumatomonadidae Hollande, 1952 (ref. ID; 7130)

See Allas
  1. Thaumatomonas coloniensis (ref. ID; 7130)
  2. Thaumatomonas lauterborni (ref. ID; 7130)
  3. Thaumatomonas oxoniensis Bass & Cavalier-Smith, 2011 (ref. ID; 7130 original paper)
  4. Thaumatomonas seravini (ref. ID; 7130)
  5. Thaumatomonas vancouveri Cavalier-Smith & Chao, 2011 (ref. ID; 7130 original paper)
  6. Thaumatomonas zhukovi (ref. ID; 7130)

Thaumatomonas oxoniensis Bass & Cavalier-Smith, 2011 (ref. ID; 7130 original paper)

Diagnosis

18S rDNA sequence, GenBank HQ121429; ITS2 rDNA GenBank HQ176328. Cell size 9.5 um (9-10.5 um) PF trailing, longer than Al. diplophysa: approximately 2X BL, 18.5 um (17-19 um); AF little more than a stub, 2 um (1.5-2.5 um), shorter than Al. aff. diplophysa, unlike R. filosa moves very little. When motile, cell shape a rigid oval, anterior and posterior ends sometimes acuminate; spherical during stationary phase. Long, branching filose and lamellar pseudopodia emerge from beneath stationary cell, project in all directions. Light sensitive: observation causes stationary cells to become motile. During the transition pseudopodia retract, PF is manipulated, cell rotates and begins gliding. Cell movement swift; glides smoothly with little or no vibration, unlike Al. diplophysa Sandon and R. filosa. Changes direction fairly frequently. Anterior cv, n in anterior half of cell. Single layer of two-tiered scales, bilaterally symmetric ovals of rather variable structure; (4-)5 terminal struts at each ends as in Ts. coloniensis and four lateral perforation each side of upper plate (not 4-6 as in Ts. coloniensis). Cysts not observed. Freshwater, bacterivorous, cultured in Volvic and grain. (ref. ID; 7130)

Etymology

oxoniensis of Oxford, the type locality. (ref. ID; 7130)

Type strain

Hinksey - CCAP 1903/2 (2002; Hinksey Park lake benthos, Oxford, UK; DB). (ref. ID; 7130)

Thaumatomonas vancouveri Cavalier-Smith & Chao, 2011 (ref. ID; 7130 original paper)

Diagnosis

18S rDNA sequence, GenBank AF411264; ITS2 rDNA GenBank HQ176329; the original strain 3108W2 (compost heap; Vancouver, Canada; isolater Ema Chao, 1996) is dead. Cell size ~8 um (measured on fixed cells, not live ones as for other species). Motile cell morphologically similar to Ts. oxoniensis, but with proportionately longer PF (1.2X BL). AF ~1 um, shorter than in A. diplophysa. Large anterior n with prominent nucleolus; centrioles long, parallel contact n at their base. No pseudopods observed in life. ITS2 sequence differs from Tx. oxoniensis in at least 16 nucleotides including two pairs of compensatory base changes and four hemicompensatory substitutions. Oval two-tier scales with broad upper plate supported by about 4 struts at each end and several lateral perforations (all different from Ts. lauterborni, seravini and zhukovi, but fairly similar to oxoniensis and coloniensis). (ref. ID; 7130)

Descriptions

Electron microscopy: A pronounced flagellar pocked over 1 um deep is supported on its sides by numerous cortical microtubules. A ventral groove contains numerous filopodia; we refer to this cavity as a 'groove' for consistency with the terminology for Thaumatomonas lauterborni (Karpov and Zhukov 1987), but our few pictures suggest that it may really be a cytopharynx with only a terminal opening rather than groove open along its length. The entire cell surface except for the flagella, flagellar pocket and ventral groove is covered with a layer of oval scales with a double structure in cross section, which resemble those of Ts. coloniensis (Wylezich et al. 2007) in having lateral perforations in the upper plate, unlike Ts. lauterborni that does not (Karpov and Zhukov 1987), but are probably at least slightly distinct from all those previously described for thaumatomonads. Scales develop in vesicles attached to the mitochondria, which have tubular cristae. The two centrioles are parallel and connected by fibrillar material. Dense fibrillar material is attached to the basal two thirds of the centriole and below their proximal end, and at some sectioning angles appears as a V-shaped base to the centriole with one arm of the V attached to opposite sides of the centriole. The flagellar transition region is long and has a dense proximal plate, which is probably a homologue of the hub-lattice structure of other Cercozoa (Cavalier-Smith et al. 2008), and a dense distal plate. No scales or hairs were seen on the flagellar membranes. (ref. ID; 7130)

Comments

Strain 3108W2 was originally identified as Allas sp. (Cavalier-Smith and Chao 2003)) as its cell shape and flagellar proportions were closer to Allas diplophysa than to Thaumatomonas lauterborni of De Saedeleer (1931) and were even less like Thaumatomonas seravini, the only two Thaumotomonas species then known, both of which also had plasmodial stages not observed in Ts. vancouveri or reported for Allas. (ref. ID; 7130)

Etymology

vancouveri from Vancouver, BC, the type locality. (ref. ID; 7130)