Polychaos Schaeffer, 1926 (ref. ID; 649, 3687, 4238)

When Schaeffer (1926) created the genus Polychaos for the species which he had described (Schaeffer 1916) as Amoeba dubia, he included Amoeba fasciculata in that genus, apparently without having seen the organism himself. Lepsi (1960) appears to have been the first author to correct the names to Polychaos dubium and P. fasciculatum, but he did not see the latter species. Polychaos Schaeffer 1926 was characterised by Page (1976) in a diagnosis somewhat abridged but not differing essentially from that of Schaeffer (1926) as follows: "Usually polypodial, with several tubular pseudopodia, more or less equal and with no one dominant, proceeding anteriorly and antero-laterally from common posterior mass; pseudopodia sometimes flattening and broadening towards ends; may be monopodial in rapid locomotion; no dorsal, ridges; nucleus granular or with other arrangements of nucleolar material reported." In the genus Page included P. dubium, the type-species, and P. fasciculatum, P. nitidubium Bovee 1970, P. timidum Bovee 1972. (ref. ID; 649)

Polychaos (Amoeba) dubium (Schaeffer, 1917) (ref. ID; 3687) reported author and year? (ref. ID; 4728, 4817, 4836, 4837)
Syn; Amoeba dubia Schaeffer, 1916 (ref. ID; 1335)
Description; Numerous pseudopodia flattened and with smooth surface; crystals, few large up to 30 um long and of various forms among which at least four types are said to be distinct; contractile vacuole one or more; fresh water. (ref. ID; 1618)
Measurements; About 400 um long. (ref. ID; 1618)
Polychaos fasciculatum (Penard, 1902) (ref. ID; 3687) or (Penard, 1902) Schaeffer, 1926 (ref. ID; 649)
Syn; Amoeba fasciculata Penard, 1902 (ref. ID; 649)
Re-diagnosis; Advancing mass varying between single, broad pseudopodium and up to five subcylindrical pseudopodia, with frequent production of new pseudopodia and lateral fusion of bases; temporary hyaline caps on pseudopodia; posterior end of amoeba narrowed, often with finely morulate or villous uroid and often trailing several digitiform pseudopodial remnants; length in locomotion approximately 65 to 180 um, with mean about 108 to 113 um; only monopodial forms reaching greatest length. Nucleus approximately 11 to 23 um in diameter; nucleolar material parietal, discernible as a single, elongate, curved body or two or more lobes, more or less homogeneous in texture to light microscope. Significant electron-microscopical characters: filamentous surface coat generally extending to 80 nm above plasma membrane with some filaments 280 nm long; nuclear envelope lacking definite internal fibrous lamella. (ref. ID; 649)
Comments; Amoeba fasciculata was described by Penard (1902) from a marsh and a pond in Switzerland. All subsequent descriptions appear to be based on Penard's, as was that of Page (1976). With no further collections of the species reported. Penard's organism had a mean size of 140 um, produced several subcylindrical pseudopodia, and often had several finger-like uroidal appendages, which were the source of the specific epithet. Its nucleus had a parental nucleolus described as consisting of two crescents on opposite sides of the nucleus, rather than the many small nucleolar bodies occurring in the well-known species of Amoebidae. (ref. ID; 649)
Habitat; Fresh water; reported from Switzerland, England, the Netherlands. (ref. ID; 649)
Polychaos nitidubium Bovee, 1970 (ref. ID; 649)
Description; This species is another large amoeba, up to 550 um, with many nucleoli and posterior projections resembling the pseudopodial remnants of P. fasiculatum and P. dubium. (ref. ID; 649)
Polychaos timidum Bovee, 1972 (ref. ID; 649)
Description; This species is a smaller amoeba with a nuclear structure unlike that of its congeners and with more pointed projections. (ref. ID; 649)