Aciculae and Orbiniids

[Geoff Read]

Annelida folk,

It occurs to me that the embedded aciculae found as  parapodial lobe
supports in Orbiniidae are an interesting feature perhaps  unique outside
of the Eunicida and Phyllodocida where similar supports are at their most
noticeable. True or false? Do the embedded setae of chaetopterids
also qualify? Are there any other families outside those orders which also have
aciculae? Are they also absent in Amphinomida? I imagine the orbiniid aciculae
are no more than  coincidental not-very-near-parallel developments in this
particular family.  Is it thus possible for  (say) cladistic convenience
to define phyllodocida-type acicula(e) that excludes the orbiniid
lookalike? (Perhaps - internal aciculae on both rami, all setigers?)

Opinions & observations are welcome.

--
Geoff Read             <g.read at niwa.cri.nz>
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