[Annelida] Distribution of Mediomastus ambiseta and M. setosus

Doug Strom via annelida%40net.bio.net (by dstrom from waterandair.com)
Thu May 3 16:44:22 EST 2012

We are finding two apparent forms of Mediomastus similar to *Mediomastus
ambiseta* in the northern Gulf of Mexico off of Mississippi - one in which
the posterior elongate setae are accumulate (with a pointed tip) and one
with what looks like long, drawn out hooks in the same position, with
minute but discernible knobs on the distal ends. Otherwise these worms seem
externally indistinguishable.

Using the 2009 key "Poliquetos de Mexico y America Tropical" [Tomo 1], Two
species have "Setas capilares presentes en notopodios abdominales
posteriores" including *Mediomastus ambiseta* and *M. setosus*. *M. ambiseta
* has the distribution code "P" for the Pacific Ocean, while for M. setosus
the distribution code is "G, P" for the Pacific and the Gulf of Mexico.

The information I can find on *M. setosus* indicates it was described from
the Pacific coast of El Salvador.

Is *M. setosus* found in the Gulf of Mexico? Ditto for *Mediomastus ambiseta
*? If so, how are they best separated?

Can someone tell me what is the current understanding of the distribution
of these species?

Thanks much in advance for your input.

Doug Strom


Doug Strom
Project Scientist - Aquatic Ecologist
Water & Air Research Inc.
6821 SW Archer Road
Gainesville, Florida 32608
Toll Free: 800.242.4927
Local: 352.372.1500
Fax: 352.378.1500
dstrom from waterandair.com <http://www.waterandair.com/>
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