Thaumatomastigid with flagella inserting subapically on ventral side, no flagellar pocket, flagella equal or subequal. Ventral surface usually grooved, and nuclei often with nuclear caps (= dictyosomes?). May be dorso-ventrally flattened. Appear naked by light microscopy, no ultrastructural studies have been carried out. Type species P. glans, Skuja, 1939.

Depth range based on 3 specimens in 8 taxa.

Environmental ranges
  Depth range (m): 0.75 - 0.75
 
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