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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Reckertia

Reckertia Conrad, 1920 (ref. ID; 7130)

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

[ref. ID; 7130 redescribed paper]
Revised diagnosis; Thaumatomonads with triangular, basket, or irregular two-tier siliceous body scales; separate spine scales absent; PF longer than body, lacks scales; AF much shorter than body, covered in smaller round or oval scales with pointed or rounded ends (AF possibly sometimes absent); pseudopodia in at least two species (R. sagittifera and filosa); marine except for R. nigeriensis (Wujek et al., 2008). (ref. ID; 7130)
Comments; Wujek et al. (2008) called Thaumatomastix 'an unwieldly, artifical conglomeration of forms that produce scales of two morphologies'. When they synonymised Reckertia with Thaumatomastix, Beech and Moestrup (1986) apparently overlooked that Thaumatomastix setifera of Lauterborn (1896, 1899) had spines and no pseudopodia (though Tx. setifera of Skuja (1939) did have extensive branched ventral pseudopods), whereas Reckertia had pseudopodia but no spines (Conrad 1920). Though Tx. salina and Reckertia sagittifera both have scales on the anterior flagellum (Beech and Moestrup 1986; Moestrup 1982) that is insufficient reason to group them together. Because of the absence of spine scales in Reckertia sagittifera and filosa and because a spiny Thaumatomastix sp. does not group with the non-spiny R. filosa on our 18S rRNA tree we treat Thaumatomastix and Reckertia as distinct genera, thus solving the problem noted by Wujek et al. (2008). Nine nominal species of Thaumatomastix lack separate spine scales and are here segregated in the genus Reckertia, which is easier to confuse in the light microscope with Allas or Thaumatomonas than are Thaumatomastix sensu stricto, whose spine scales would usually distinguish them. Most Thaumatomastix and Reckertia have a relatively short anterior flagellum as in Allas/Thaumatomonas (or apparently none: Mikrjukov 2002; Thomsen et al. 1993). In all Reckertia species listed below the anterior flagellum bears small scales (Thomsen et al. 1993, 1995, 1997), except that no anterior flagellum was observed in R. nigeriensis (Wujek et al. 2008). We transfer all nine named Thaumatomastix that lack separate pointed/spined body scales (the key defining character of the type species Tx. setifera) in addition to two-tiered plate scale to Reckertia. As the single type of body scale of Tx. splendida, despite having a long central spine, seems not to be homologous with those of Thaumatomastix but an independent secondary modification of triangular two-tier plate scales like those of R. fusiformis, we include it in the transfers to Reckertia. (ref. ID; 7130)
Type species; Reckertia sagittifera Conrad 1920 (ref. ID; 7130)
  1. Reckertia dybsoena Cavalier-Smith, 2011 (ref. ID; 7130 redescribed paper)
    Basionym; Thaumatomastix dybsoena Thomsen et al., 1993 (ref. ID; 7130)
  2. Reckertia filosa Howe, Scoble, & Cavalier-Smith, 2011 (ref. ID; 7130 oiginal paper)
  3. Reckertia formosa Cavalier-Smith, 2011 (ref. ID; 7130 redescribed paper)
    Basionym; Thaumatomastix formosa Thomsen et al., 1993 (ref. ID; 7130)
  4. Reckertia fragilis Cavalier-Smith, 2011 (ref. ID; 7130 redescribed paper)
    Basionym; Thaumatomastix fragilis Thomsen et al., 1995 (ref. ID; 7130)
  5. Reckertia fusiformis Cavalier-Smith, 2011 (ref. ID; 7130 redescribed paper)
    Basionym; Thaumatomastix fusiformis Thomsen et al., 1995 (ref. ID; 7130)
  6. Reckertia groenlandica Cavalier-Smith, 2011 (ref. ID; 7130 redescribed paper)
    Basionym; Thaumatomastix groenlandica Thomsen & Ikavalko, 1995 (ref. ID; 7130)
  7. Reckertia igloolika Cavalier-Smith, 2011 (ref. ID; 7130 redescribed paper)
    Basionym; Thaumatomastix igloolika Thomsen & Ikavalko, 1995 (ref. ID; 7130)
  8. Reckertia nigeriensis Cavalier-Smith, 2011 (ref. ID; 7130 redescribed paper)
    Basionym; Thaumatomastix nigeriensis Wujek, Pershon & Kadiri, 2008 (ref. ID; 7130)
  9. Reckertia sagittifera Conrad, 1920 (ref. ID; 7130)
  10. Reckertia spinosa Cavalier-Smith, 2011 (ref. ID; 7130 redescribed paper)
    Basionym; Thaumatomastix spinosa Thomsen et al., 1993 (ref. ID; 7130)
  11. Reckertia splendida Cavalier-Smith, 2011 (ref. ID; 7130 redescribed paper)
    Basionym; Thaumatomastix splendida Thomsen et al., 1995 (ref. ID; 7130)

Reckertia filosa Howe, Scoble, & Cavalier-Smith, 2011 (ref. ID; 7130 oiginal paper)

Diagnosis

Type 18S rDNA sequence, GenBank AY268040 (JJP-2003); ITS2 rDNA GenBank HQ176330; cell size 11.4 um (11-12.5 um). PF gliding, 17.8 um (17-20 um), 1.75-2X BL, trails; AF stubby, 2.5 um (2-3.5 um), constantly beats. Cell rigid; oval, flattened, disc-like; usually slightly wider at a posterior than anterior. Long, banching filose and lamellar pseudopodia (contrasting with the broad finger-like pseudopods of R. sagittifera: Conrad 1920) emerge beneath stationary cells, project in all directions. Two-tiered triangular scales cover cell surface; these body scales (at their broadest 0.50-0.59 um) have prominent oval holes set back from each corner, not circular holes as in R. formosa (Thomsen et al. 1993), unlike any other named species; unlike in formosa, the denser rim of each hole is supported by three dense outward-projecting struts; also unlike in formosa, the edge of the scale is homogeneously thin and has elongated bean- to oval-shaped hole in the upper tier between each corner hole. PF naked; anterior flagellar scales rounded ovals (0.33-0.37x0.20-0.22 um), not circular as in R. formosa, dysboena and spinosa; unlike in R. sagittifera the central linear density of flagellar scales is straight not sinuous. Unlike Al. aff. diplophysa, and Ts. oxoniensis and vancouveri, has multinucleate phase and thrives in saltwater. Cell movement swift, smooth gliding, slight vibrations caused by movement of AF, as in Sandon's Al. diplophysa. Changes of direction fairly frequent. Cultured in artificial seawater with grain; bacterivorous. Anterior cv. Cysts not observed. (ref. ID; 7130)

Comments

The new amoeboflagellate Reckertia filosa is the first cultured members of the genus and first genuie Reckertia of known sequence. (ref. ID; 7130)

Etymology

filum L. thread, for its filopodia. (ref. ID; 7130)

Type strain

CCAP 1903/1 (isolation date unknown; Russia; A.P. Mylnikov; originally identified as Allas sp.). (ref. ID; 7130)