Mechanisms of Movement in Taxonomy of Sarcodina. II. The Organization of Subclasses and Orders in Relationship to the Classes Autotractea and Hydraulea

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Abstract
Because a logical division of the Sarcodina into two classes (Autotractea and Hydraulea) based on mechanisms of movement cuts across the previous systematic categories, a revision of the suprafamilial groups is necessary. Suggestions have repeatedly been made in the past for ordinal arrangement of the Sarcodina based on their protoplasmic movements which result in the characteristic morphologies of their pseudopods. A logical revision of those proposals in relation to the Autotractea and Hydraulea is suggested as follows: The class Autotractea to include two major groups; 1) the subclass Actinopodia, with axopods, containing the orders a) Heliozoida, with axopods extended from a central granule and b) Acantharida, with axopods extended from the center of the body, penetrating an internal membrane; and 2) the subclass Filoreticulosia, with filoreticulopods, but no axopods, containing the orders a) Hypo-radiolarida, with radiating rarely anastomosing filoreticulopods, b) Radiolarida, with peripherally radiating basally anastomosing distinctly granular filoreticulopods, c) Granuloreticulida, with filoreticulopods as a mobile anastomosing network around the body, and d) Filida, with finely granular filoreticulopods which rarely branch and anastomose. The class Hydraulea includes two major groups; 1) the subclass Cyclia, with ameboid generally unidirectional cyclic flow in steady locomotion, containing the orders a) Lobida, with pseudopods digitate or as hemispherical eruptive waves, or as a clear border formed by protoplasmic flow, and b) Acrasida, with amebulas which aggregate to form a slug-like pseudoplasmode; and 2) the subclass Alternatia, with polytubular plasmodial body in which the cytoplasm moves by shuttleflow with a net unidirectional advance, containing the orders a) Mycetozoida, with amebulas which grow to become the plasmode of interconnected gel tubes, and b) Xenophyophorida, poorly understood marine organisms with polytubular chitinoid structure and granular internal cytoplasm. This scheme ignores previous systems based on some kind of shell, form of cyst, or mitotic nuclear events, or radiate or nonradiate deployment of pseudopods. In the system herein presented, the so-called radiolarians, heliozoans, testaceans, and proteomyxans are redistributed among the classes and orders named; and the kinship of foramini-fers and radiolarians (evident in functional morphologies of their pseudopods) is recognized.

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