>From:    David Campbell <[log in to unmask]>
>Subject: Classification and Southern Synthesis
>
>For Paleoheterodonta, Hyriidae should be with Muteloidea rather than
>Unionoidea.  The proper name for Muteloidea is not entirely clear, as
>different
>references cite different dates and authors for family-level names, and I have
>not been able to track down the original references from the first half of the
>1800's.  Etheridae is polyphyletic.
>
>From:    G Thomas Watters <[log in to unmask]>
>Subject: Re: Classification and Southern Synthesis
>
>This can't be right. The Hyriidae, Margaritiferidae, and Unionidae all
>share the same larval type, a glochidium, which is vastly different from
>the alien-esque haustorial and lasidium larvae of the Mutelidae and
>Mycetopodidae, which are clearly related.
>
>From:    David Campbell <[log in to unmask]>
>Subject: Re: Classification and Southern Synthesis
>
>I believe the glochidium is considered paraphyletic relative to the
>haustorial and lasidium larvae.  I.e., glochidial larvae are primitive for
>the Unionoida.  After the evolution of glochidia, the group split.  Within
>one branch, the other larval type developed.  I will check the relevant
>references, however.
>
>David Campbell

Tom and David,

According to an analysis of the data from 630 base pairs of DNA sequence
for the cytochrome oxidase I (COI) gene that is close.  The Unionoidea and
Unionidae are paraphyletic and it is hypothesized that the glochidium is
the ancestral unionoid larval type (the glochidium is not necessarily
paraphyletic however).  The Margaritiferidae, Mycetopodidae, Mutelidae, and
Hyriidae were all supported as monophyletic.  The topology of the tree is
thus: ((((Unionidae [excluding Coelatura], Margaritiferidae), Coelatura),
(Mutelidae, Mycetopodidae)), Hyriidae).  Neotrigonia was used as the
outgroup.

David, where do you get your reference(s) to support your statement that
the "Etheridae is polyphyletic"?

Cladisticly,

Kevin

Kevin S. Cummings
Research Scientist
Illinois Natural History Survey
607 E. Peabody Drive
Champaign, IL 61820
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http://www.inhs.uiuc.edu/cbd/collections/mollusk.html