Posted: Oct 14 2013
Seila aff. adamsii PW4.5 of Krisberg
As many, many others have, I have had difficulty with the apparent presence of several variations in Florida of the taxon presented by most authors under the label of Seila adamsii (H.C. Lea, 1845). I have been unsuccessful in identifying type material or illustrations for this taxon. Although I've found works presenting a taxon as Seila adamsii , none have information supporting confirmation of coincidence morphology with Lea's taxon. The key distinguishing character differentiating Seila is the protoconch, and I have yet to find any information regarding the protoconch of Lea's taxon. I have also been unsuccessful in obtaining any material from the locale of Lea's type with complete protoconchs that might allow for an informed extrapolation.
Among the Port Canaveral micros Phil and I collected and are posting in our field report A Day Shelling Cocoa Beach Florida Area 2013 was one of the forms of Seila adamsii. I created the first two slides below to present the specimen and note the problem with identifying a specific form as Lea's taxon. I'm adding more as more information comes to my attention.
After posting the above two slides I became aware that the following paper [Thiriot-Quiévreux C. (1980)] links Lea's taxon to the form having 4.5 protoconch whorls.
However, soon afterward I became aware that the following paper which links Lea's taxon to the form having 2 - 2.5 protoconch whorls
As indicated above, for purposes of discussing and distinguishing the various forms, I have arbitrarily designated the form with 2.75 conic protoconch whorls to be Lea's S. adamsii. See presentation of Seila adamsii (H. C. Lea, 1845) , particularly slide 6 for more detailed discussion.
However, based upon the specimen provided by Prof. Carlton in the slide below and Thiriot-Quiévreux's North Carolina shell with 4.5 protoconch whorls, I suspect the form with 4.5 protoconch whorls may more likely be Lea's S. adamsii. We are continually trying to obtain specimens with intact protoconchs from locations proximate to Adams' type locale (New Bedford, CT). Prof. Carlton's partially decollate specimen is the closest we've come. Until specimens with intact protoconchs are obtained I have left my presentations using the 2.75 protoconch whorled form as Lea's S. adamsii unchanged.
