149. Jamieson, B.G.M. and Guinot, D. 1996b. Ultrastructure of the spermatozoon of Australocarcinus riparius (Crustacea: Brachyura: Gonoplacidae: Trogloplacinae). Memoirs of the Queensland Museum 39, 289-296.

The spermatozoon of the freshwater crab Australocarcinus riparius is
  heterotreme. However, absence of a recognizable acrosome ray zone is not a
  general heterotreme feature, though constant for thoracotremes. This zone
  is also unrecognizable in potamoids and in corystoids. The convex ring at
  the posterior end of the inner acrosome zone is similar to the xanthid
  ring, characteristic of the Xanthidae and Panopeidae, but homology is
  doubtful. Other xanthid features such as the accessory opercular ring and
  opercular overhang are absent from the sperm of A. riparius and
  relationship with xanthoids is not supported spermatologically. In its
  pointed shape, the perforatorium resembles that of corystoids but there
  the operculum is perforate. No special similarities to sperm of potamoids,
  which similarly have an obligatory freshwater existence at all stages of
  the life cycle, are apparent. The sperm of A. riparius shows no clear
  affinity with those of any other Heterotremata although confirming its
  inclusion in that group. In producing more than one spermatozoon per
  spermatophore, A. riparius, having marine relatives, may be less evolved
  along the path of lecithotrophy than are the potamoids, lacking marine