GENERIC CRITERIA FOR FLABELLULA RUGIPES AND HYALODISCUS WITH DESCRIPTIONS OF SPECIES

SYNOPSIS. Six strains of amoebae isolated from freshwater habitats and having broad, flattened locomotive forms were studied in clonal cultures, with attention to trophic structure, nuclear division, cyst structure in those strains which formed cysts, some aspects of cytochemistry, and other characteristics. Three strains were found to belong to the genus Flabellula, one being identified as F. platypodia (Gläser, 1912) and the other 2 as F. mira Schaeffer, 1926. The new species Rugipes placidus is described. One strain, identified as belonging to the species originally called Amoeba actinophora Auerbach, 1855, is re‐described as Hyalodiscus actinophorus, and a similar strain is described as H. actinophorus var. minor n. var. All 3 strains of Flabellula had the unusual type of mitotic figure reported by Gläser for F. platypodia but not previously studied with the Feulgen technic. The genus Rugipes has the mitotic pattern more common to small amoebae and is distinguished from Flabellula partly on that basis. Both strains of Hyalodiscus have division figures of this common type. Of the strains included in this investigation, only R. placidus and H. actinophorus formed cysts in culture. The cysts of neither species were viable after one year at room temperature and humidity. The status of Rugipes as distinct from Flabellula is discussed. The genus Hyalodiscus is interpreted in a manner compatible with the original definition of Hertwig and Lesser and is included within the order Amoebida. The strains of this genus isolated have a doubly contoured, strongly PAS‐positive covering over the endoplasmic hump. Some criteria for the taxonomy of amoebae are evaluated in the light of work reported in this and 2 previous papers. Copyright © 1968, Wiley Blackwell. All rights reserved