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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Paratetramitus

Family Vahlkampfiidae (ref. ID; 7755)

[ref. ID; 7755]
Uninucleate vahlkampfiids lacking a known flagellate stage have been attributed to either Vahlkampfia Chatton and Lalung-Bonnaire, 1912, or Schizopyrenus Singh, 1952, names which Page (1967) regarded as synonyms. Before discovery of its flagellate stage (Darbyshire et al. 1976), P. jugosus had been designated in the original description (Page 1967) as Vahlkampfia jugosa. The similarity to Schizopyrenus russelli Singh, 1952, was noticed, but the two species were distinguished chiefly on the basis of cyst structure and the excystment process. (Further observations on many strains have negated the statement in the original description that V. jugosa lacked uroidal filaments). The discovery of a flagellate stage would seem to confirm it distinctiveness from S. russelli, but the present study of P. jugosus, considered in the light of earlier reports, raises a serious question about that distinctiveness. Although cysts with 'wavy' exocysts like those of V. jugosa were not reported by Singh (1952), Singh and Das (1970) stated that the majority of cysts 'in recent cultures' of S. russelli had that appearance. They distinguished 'Schizopyrenus jugosa' from S. russelli by size. A comparsion of the ultrastructural study of encystment in S. russelli by Maitra et al. (1974) with the figures and descriptions of P. jugosus in the present paper shows great similiaties. The possibility that S. russelli and P. jugosus may be a single species thus appears greater than before. It must be emphasised that (1) no flagellate stage was initially found in Vahlkampfia jugosa (Page 1967); (2) many strains of P. jugosus, including the strain originally described by Page (1967) have produced only a few flagellates (Darbyshire et al. 1976); (3) attempts to obtain flagellates from some strains of P. jugosus failed completely (Darbsire et al. 1976); and (4) the capability to transform has been lost by other strains since the investigation reported in 1976. This possible synonymy presents serious nomenclatural problems. S. russelli is the type species of Schizopyrenus (Singh 1952). Schizopyrenus predates Paratetramitus, and russelli predates jugosus(-a). Therefore, if these are indeed the same species and S. russelli has heterofore been known only by a strain which does not produce flagellates under laboratory conditions, as is true of some strains of P. jugosus, then the name Paratetramitus jugosus is a junior synonym of Schizopyrenus russelli and must be discarded. The name Schizopyrenus would then no longer designate amoebae without a flagellate stage but amoebae with a flagellate stage like that of P. jugosus (Darbyshire et al. 1976). It is not permissible to transfer S. russelli to the genus Paratetramitus and leave the name Schizopyrenus for the other species which Singh (1952) assigned to that genus, since S. russelli is the type species. Nor is it possible simply to assign all strains producing flagellates to Paratetramitus jugosus and all which do not produce flagellates to Schizopyrenus (or Vahlkampfia) russelli, since the same clone cannot change genus and species by losing the capability to enflagellate. A decision on this difficult problem need not and cannot be proposed immediately, but workers using S. russelli in experimental work should be aware of it and attempt to obtain flagellates from their strains. (ref. ID; 7755)
  1. Paratetramitus jugosus (Page, 1967) (ref. ID; 7755) reported year? (ref. ID; 1543, 4060) reported author and year? (ref. ID; 5753, 7289)

Paratetramitus jugosus (Page, 1967) (ref. ID; 7755) reported year? (ref. ID; 1543, 4060) reported author and year? (ref. ID; 5753, 7289)

Descriptions

The 16S-like ribosomal RNA sequences, length and % G+C content. (ATCC#30703, GenBank M98050). (ref. ID; 7289)

Notes

The fine structure of these cysts is of special interest because the occurrence of cysts with and without raised outer wall has been demonstrated in clones of this species by re-cloning (Darbyshire et al. 1976). Observations on other species of vahlkampfiids and hartmannellids, also in clonal cultures, have demonstrated the possibility of such variation and suggested that separation or non-separation of wall layers explains it. Fig.93 almost certainly represents an early stage of wall secretion, before dehydration and hardening of the wall had progressed far. This interpretation is suggested by the better preservation of cytoplasmic components compared with those in more mature cysts whose walls had hardened. Fig.94 shows a mature cyst with separation of the wall layers and a consequent wavy appearance at some points but not around the entire periphery. Such an appearance must involve both continued dehydration of the cell and continued secretion of wall material after the outer layer had hardened. (ref. ID; 7755)