Microworld

world of amoeboid organisms

Class Granofilosea Cavalier-Smith and Bass, 2009

Diagnosis: With very fine branching or unbranched granuloreticulopodia bearing obvious extrusomes as the granules at frequent rather regular intervals, or with radiating, sometimes branched, axopodia with similar granules; pseudopodia supported by internal microtubules and typically appressed to the substratum during feeding, in a semi-immobile state; in most species, pseudopodia do not anastomose; some with biciliated swimming or gliding stage.

  1. Order Limnofilida Cavalier-Smith and Bass, 2009
    Small freshwater heterotrophic protozoa with extremely slender, branching granular filopodia, appressed to the substratum during feeding. Phylogenetically defined as the largest clade that includes Limnofila but excludes Massisteria. It excludes the phylogenetically distant marine Nanofila which is morphologically similar but with unbranched filopodia.
    1. Family Limnofilidae Cavalier-Smith and Bass, 2009
      Trophic phase a small, often globular cell; cilia if present generally not visible in the light microscope; with branched regularly granular and very slender filopodia. Bacterivorous.
      Type genus Limnofila Cavalier-Smith and Bass, 2009
  2. Order Leucodictyida Cavalier-Smith, 1993
    Bi-ciliate marine protists with very slender branching granular filopodia that can fuse temporarily to form meroplasmodia; granules are concentric extrusomes; tubular mitochondrial cristae; large granules in the distal centriolar matrix (a synapomorphy not remarked on before); with (Massisteria) or without (Leucodictyidae: Leucodictyon, Reticulamoeba) obvious paranuclear microbody.
  3. Order Cryptofilida Cavalier-Smith and Bass, 2009
    Non-ciliate heterotrophic pro­tists with branching or unbranched granular filopodia appressed to the substratum during feeding. If filopodia branch, cells are larger than Limnofilida.
    1. Family Nanofilidae Cavalier-Smith and Bass, 2009
      Tiny non-ciliate marine hetero­trophic protists with unbranched granular filopodia appressed to the substratum during feeding.
      Type genus Nanofila Cavalier-Smith and Bass, 2009.
      Diagnosis: tiny non-ciliate marine hetero­trophic protists with unbranched granular filopodia appressed to substratum during feeding.
      Type species Nanofila marina Cavalier-Smith and Bass, 2009
    2. Family Mesofilidae Cavalier-Smith and Bass, 2009
      Biciliate amoeboflagellates with numerous extremely long branching filopodia that in contrast to Heliomorphidae (Tetradimorpha and Heliomorpha — usually known by the invalid names Dimorpha or Dimorphiella) do not radiate in three dimensions from a centrosome but are appressed to the substratum during feeding. Filopodia and long cilia can be present simultaneously or each on their own, depending on the growth phase.
      Type genus Mesofila Cavalier-Smith and Bass, 2009. Diagnosis as for family Mesofilidae.
      Type species Mesofila limnetica Cavalier-Smith and Bass, 2009
  4. Order Clathrulinidae Claus, 1874
    Extracellular capsule or lorica attached to substrate, with axopodia emerging from perforations; kinetocyst extrusomes along axopodia; tubular mitochondrial cristae; biciliated and amoeboid stages; can be colonial. Cienkowskia, Clathrulina, Hedriocystis, Actinosphaeridium.
  5. Order Heliomonadida Cavalier-Smith 1993 (=Dimorphida Siemensma 1991)
    1. Family Heliomorphidae Cavalier-Smith and Bass, 2009
      Biciliate freshwater hetero­trophic Cercozoa with axopodia radiating three dimensionally from a centrosome and supported by microtubules cross-linked in a quincunx pattern; centrioles exceptionally long; axopodia have fairly regularly spaced complex extrusomes with a concentric core. Anterior cilium bears fine hairs in at least one genus; ciliary transition region more complex than in other Granofilosea, with a second distal transverse plate well distal to the centriolar distal partition, a peripheral dense cylinder and axosome. The centrosome is embedded in a deep depression at the anterior end of the nucleus and some axopodial axonemes penetrate the nuclear cup via cytoplasmic channels.
      Type genus Helio­morpha Cavalier-Smith and Bass, 2009
    2. Family Tetradimorphidae

Class Proteomyxidea Lankester, 1885 emend. Cavalier-Smith and Bass, 2009

Naked cercozoan rhizopods with non-granular filopodia or (more usually) reticulopodia; plastids absent; cilia usually absent. Feeding stage uninucleate or multinucleate, sometimes numerous cells form a macroscopic plasmodium. Phagotrophic; feed on bacteria, fungi, algae or small animals. Marine or freshwater or in soil or among mosses or lichens.

Ferry Siemensma, created March 2, 2019; last modified April 20, 2022
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