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Peterson, Walter F. (ed.) / Transactions of the Wisconsin Academy of Sciences, Arts and Letters
volume LX (1972)

Browning, Robert F.
A record of the freshwater nemertean, Prostoma rubrum, in Wisconsin,   pp. 179-180 PDF (585.6 KB)

Page 179

Robert F. Browning 
 Prostoma rubrum is the only freshwater species of the acoeiomate phylum,
Nemertea (Rhynchocoela), which is known to occur in North America. Although
Coe (1943) implies they are widely distributed throughout the United States,
the only actual sites of occurrence he mentions are some freshwater ponds
in the Woods Hole area. Poluhowich (1968) reviewed various aspects of the
biology of P. rubrum in an attempt to stimulate new collections of this worm
and extend the distribution records. In his review he provides references
to their occurrence in the Chicago area and in Pennsylvania. He also reported
that he collected numerous specimens from a small brook in Stratford, Connecticut.
In a recent letter to me, he indicated that he had received word of a few
additional reports in response to his publication but not enough to substantiate
Coe's claim of nation-wide distribution. The present report appears to be
the first record of P. rubrurn in Wisconsin. 
 A population of P. rubrum was discovered in Silver Creek, in the city of
Ripon (Fond du Lac County) from samples brought into the laboratory from
a class field trip in early September 1970. The first specimen was isolated
by two students, Joan Strewler and Kathleen Spence, and from its general
morphology, I tentatively identified it as P. rubrum. The identification
was confirmed later ' by observing the involvement of its probocsis in feeding
and the deposition of eggs in peculiar mucous tubes secreted by sexually
mature worms. 
 Using the collection method devised by Polohouwich (1968), I isolated as
many as 35—40 specimens from a liter of substrate on several occasions
during the Fail of 1970. The most productive substrate consisted of a mixture
of mud detritus, and fliamentous algae. In mid-February only two specimens
were obtained from substrate samples obtained under snow and ice cover. In
early April I found no specimens but this was probably due to the extended
period of high water associated with the spring thaw. Although the high Water
undoubtedly flushed a great deal of the preferred substrate downstream, it
is likely that many of the worms migrated deeper in the stream bed. I have
not investigated this possibility fully at the present time. 

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