The Collaborative International Dictionary of English v.0.48:

Phasmidia \Phasmidia\ prop. n.
   One of two subgroups of Nematoda used in some classification
   systems.

   Syn: class Phasmidia.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

Phasmidia
    n 1: one of two subgroups of Nematoda used in some
         classification systems [syn: Phasmidia, class
         Phasmidia]