The Collaborative International Dictionary of English v.0.48:

Phaeospore \Ph[ae]"o*spore\, n. [Gr. faio`s dusky + E. spore.]
   (Bot.)
   A brownish zoospore, characteristic of an order
   (Ph[ae]ospore[ae]) of dark green or olive-colored alg[ae].
   -- Ph[ae]`o*spor"ic, a.
   [1913 Webster]