Ref ID : 7755
Frederick C. Page; The Limax Amoebae: Comparative Fine Structure of the Hartmannellidae (Lobosea) and Further Comparisons with the Vahlkampfiidae (Heterolobosea). Protistologica XXI(3):361-383, 1985
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The amoeboid and, in species producing them, encysted stages of seven species (four genera) of Hartmannellidae were examined with the electron microscope. Further information is also presented on the ulrastructure of nine species (five genera) of Vahlkampfiidae, including cysts. Both the integrity of the present family Hartmannellidae and the generic distinctions proposed earlier are supported by these results. All species of Hartmannellidae had sucker-like or cup-like surface structures, which were lacking from all Vahlkampfiidae. All had mitochondria with tubular cristae, unlike the Vahlkampfiidae. Cashia had distinctive mitochondrial cristae of a helical pattern otherwise unknown in gymnamoebae. All strains of Saccamoeba contained endocytic bacteria, not found in any other hartmannellids or in vahlkampfiids. In all the Hartmannellidae the Golgi system was organised as distinct dictyosomes of the classical pattern, unlike most vahlkampfiids. Taxonomically useful characters included cell surface, aspects of nuclear structure, mitochondria, and rough endoplasmic reticulum. The cyst wall was useful at the species level, but its usefulness at higher levels has not been demonstrated, except the presence or absence of pores. Observations of cyst structure provided an explanation of the variations observed with the light microscope in wall structure and consequently in the process of excystment. The taxonomic validity of ultrastructural characters was further demonstrated by comparisons of pairs of conspecific strains from Britain and North America. This study strengthens the suspicion that Schizopyrenus russelli Singh, 1952, and Paratetramitus jugosus (Page, 1967) are synonyms, although flagellate cells have not yet been reported in S. russelli.