Posted: Jan 13 2010

 Boonea seminuda (C. B. Adams, 1839), Half-smooth Odostome

The little white pyramid shells (Pyramidellidae) found in Florida generally grouped under Odostomia in older books (Abbott 1974) has been a difficult group to distinguish. Since Abbott there has been more and more treatment of these shells resulting in new generic assignments, greater distinction between species, and some helpful descriptions. However, differences in opinion remain due to the voluminous number of shells in this group, the difficulties of working with such small material, and the lack of much interest and research until late last century. Boonea seminuda (C. B. Adams, 1839) is one of these shells that held somewhat of a prominent place early and under which many similar shells may have been grouped (esp. utilizing the nomenclature “sp aff.” or “cf.”). As observational techniques and technology have improved, better distinctions have occurred making previous presentations of shells as B. seminuda obsolete. I am presenting here the shells I believe are valid specimens of B. seminuda. B. seminuda and similar species are so close in “gross” characters that distinction may not be possible in photos that do not portray microscopic details.

Note that controversy remains as to whether the proper generic placement of B. seminuda is Boonea or Chrysallida. I follow the placement in Malacolog.

Additional Comments:

Lee (2009) points out that Abbott (1974, #3487) appears to have made a mistake and included the illustration and description of O. toyatani Henderson and Bartsch, 1914 for B. seminuda. Since Abbott's description does not fit, I believe Harry is correct. Note that Abbott also indicates an erroneous date of 1837 for B. seminuda, which should be 1839. I would suggest not utilizing Abbott when working with this shell.

The photo of B. seminuda in Rehder (1981) does look accurate on a “gross characteristics basis,” but the lack of protoconch detail creates uncertainty.

The best detailed images of B. seminuda are in: Wise, John B. 1996. Morphology and Phylogenetic Relationships of Certain Pyramidellid Taxa (Heterobranchia). Malacologia, 37(2): 443-511.

The photo and identification of B. seminuda appears accurate in: Gundersen, Ross W. The Seashells of Sanibel and Captiva Islands. TMS Inc., Racine, WI.

In preparation for this presentation I discussed B. seminuda and its proximity, but difference from Chrysallida nioba, with Harry Lee, and he, in turn, involved Colin Redfern, who presented these shells in his 2001 book of Bahamian seashells. They had the following comments regarding the shells presented in their books.


Harry Lee: “I think I must abandon the basis for splitting Chrysallida nioba of Lee (sp. 671) [not of Dall and Bartsch] from Chrysallida sp. aff. seminuda of Lee (no. 672). The teleoconch morphology seems to form a continuum from slender with delicate beading to stout with larger, flatter beads. What unites them is the not-so-immerse heteroaxial hyperstrophic protoconch - the likes of which is seen in no other close relative in the western Atlantic except C. jadisi (Olsson and McGinty, 1958). These protoconchs actually show a little more than one whorl above the teleoconch and look more like they belong on a Turbonilla (Pyrgiscus) than the Chrysallida/Boonea/Fargoa group.” “Anyhow, I have 15 lots of this latter entity, which I am willing to at least temporarily concede to be Boonea seminuda (type locality Dartmouth Harbor, MA; lectotype without protoconch), all but one (NJ; protoconch eroded off) from FL, and from all around its coast.” Harry, at this moment (1/10/10) “In the interest of conformity and expediency” agrees that his shells 671, 672, the shell presented by Gundersen, all his shells from Florida, and the shells presented here “to be Boonea seminuda." "This is based on two concepts: (1) The primacy of protoconch morphology, (2) The paradigm of variable teleoconch morphology.”

Colin Redfern: It was Harry’s belief that “Colin's B. seminuda is probably un-named” and not Adams’ shell. So he involved Colin in this issue. In consideration of Harry’s comments Colin indicated “I agree that it's a distinct species, probably un-named.”

References

Abbott, R. Tucker. 1974 American Seashells, Second Edition, Van Nostrand Reinhold Company.

Lee, Harry G. 2009 Marine Shells of Northeast Florida. Jacksonville Shell Club, Jacksonville, Florida.

Redfern, Colin. 2001. Bahamian Seashells: A Thousand Species from Abaco, Bahamas. Bahamianseashells.com, Inc: Boca Raton, Florida.

Rehder, Harald A. 1981. The Audubon Society Field Guide to North American Seashells. Alfred A. Knopf, New York.

Rosenberg, G. 2005. Malacolog 4.1.0: A Database of Western Atlantic Marine Mollusca.

So, here’s Boonea seminuda (C. B. Adams, 1839) from Florida:

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