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Order Leptomyxida Pussard et Pons, 1976, sensu Smirnov et al. 2017

Diagnosis: Naked with locomotive form altering from a flattened expanded or reticulate one, when slowly moving, to a subcylindrical monopodial one when in rapid movement or under specific conditions; adhesive uroid; uninucleate with tendency to have more and with Leptomyxa always multinucleate; glycocalyx amorphous; Rhizamoeba saxonica has collosomes under cell membrane. Leptomyxid amoebae have a tendency to form multinucleate plasmodia which can be flabellate, multilobed, or highly branched and reticulate. Amoebae never have anterior subpseudopodia.

The diagrams below show three typical forms of Leptomyxida:

Leptomyxa
Rhizomonotactic morphotype: locomotive form of Rhizamoeba spec.
Leptomyxa
Stationary flattened form of the same amoeba as above, covered by debris as usual
Leptomyxa
Leptomyxa spec., branched morphotype – from Valamo Island, Russia (Photomicrograph courtesy Alexey Smirnov)
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