>> Dr. Campbell did mention a few: Sphaeridae (Bivalvia)
are parthenogenetic, and I once read [have to look up the
reference] a paper on a fresh water gastropod where
males are extremely rare, and parthenogenesis is very
likely [if not a rule]<<

Potamopyrgus antipodarum, aka New Zealand mudsnail,
is a parthenogenetic hydrobiid that has invaded most of the
rest of the world.  Thiarids such as Melanoides
tuberculatus and Thiara granifera are mostly
parthenogenetic, but males have been found in at least
some species, and there is evidence for occasional sexual
reproduction.

>> But what I was looking for was a hybrid population of
males and females which was self sustaining, i.e. after
mating, fertilisation etc. for some generations.<<

This is very common in plants; wheat is one of the most
familiar examples (though I do not know if it has separate
sexes, it does reproduce sexually).

Corbicula sort of does this.  The invasive semi-clonal
lineages are triploid and probably hybrid in origin.  Males
produce diploid biflagellate sperm, and the paternal DNA is
what is actively used by the animal.  There has been some
crossing between lineages.

    Dr. David Campbell
    Old Seashells
    University of Alabama
    Biodiversity & Systematics
    Dept. Biological Sciences
    Box 870345
    Tuscaloosa, AL  35487-0345 USA
    [log in to unmask]

That is Uncle Joe, taken in the masonic regalia of a Grand
Exalted Periwinkle of the Mystic Order of Whelks-P.G.
Wodehouse, Romance at Droitgate Spa

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