zygozoosporehttp://www.oed.com/dictionary/zygozoospore_n%3Ftab%3Dmeaning_and_usezygozoospore, n.
First published 1921; not fully revised

zygozoosporenoun

  1. 1881–
    A zoospore formed by conjugation; a motile zygospore.
    1. 1881
      Family Protococcaceæ. Genus Chlorochytrium... Each cell becomes resolved into spherical zoospores, which upon leaving the mother-cell conjugate within the gelatinous envelope. The zygozoospores before becoming surrounded with a membrane make their way..into the intercellular spaces of living plants.
      Nature 28 July 292

Originally published as part of the entry for zygo-, comb. form

zygo-, comb. form was first published in 1921; not fully revised.