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Posted: Nov 29 2006

Zafrona dicomata (Dall, 1889) vs Zafrona idalina (Duclos, 1840)

The following is copied from another topic (Florida Keys Micros) and is presented here for easy future access.

On May 18 2006, dteven wrote: And now for

some pix. Here are the two shells I'm calling

Zafrona sp. because I don't think they're

Z. dicomata. The two shells from Key Largo

that I had called Zafrona sp. seem to be

Zafrona idalina (Duclos, 1840) based on

resemblance to some specimens on the

Femorale website.

Marlo commented: Comparing the two images side-by-side, I don't think they're the same. The Key Largo specimen is smooth and more bulbose on all whorls. Idalina appears to have axial ribbing, esp. on the early whorls. I also get doubtful when several dozen specimens from the same material are clearly a particular species and 2-3 look a little different. My first reaction is "population variability."

dteven replied that: Z. idalina is clearly a variable species, apparently much more so than Z. dicomata. Look at the gallery of Z. idalina images at:

The last image (8.6 mm Curacao) is nearly white and the whorls are bulbous, like my specimens. Three images above that (6.8 mm Venezuela) is another white shell, more slender, but with a trace of the brown-and-white checkered band that runs around the periphery. And three images above that (6 mm up Colombia) is a red shell with an even clearer example of that band. I don't see this band in any of my Z. dicomata specimens from Key Largo, nor in pictures I've been able to find online.

There is ample room for opinion, but it's much easier for me to see these specimens fitting into a series of Z. idalina than into a series of Z. dicomata. (My opinion is only as good as Femorale's identifications.) I'll send them back to Marlo for reexamination.










Marlo later posted: Well, I received

Dan's shells. Here's some images 

I made. Pictured are Dan's two

specimens and one "classic reddish

-brown" Z. dicomata, all from the

same lot.








Unfortunately, I have no Z. idalina for direct comparison. However, we do have Redfern's descriptions of the two species. Both species are variable, and such characters as color, size and general body shape, when considering only one or two together, cannot be taken as conclusive. Individual specimens in a population may vary widely and extreme distortions do occur. The best way to draw a conclusion is to look at as much evidence as possible and go with the most apparent conclusion. Dan's two specimens differ from the more usual color for F. dicomata and the less mature one (thin lip) certainly has distinctly more convex whorls than the other two. However, I don't think this alone is enough to require they are a separate species. I believe the preponderance of evidence listed below indicates Dan's two specimens should be identified as Z. dicomata:


1. Comparing all three, they all have the same smooth, 1.5 whorled protoconch atop a straight-sided, not much larger first teleoconch whorl. According to Redfern, Z. idalina also has a 1.5 whorled protoconch, but atop a large, more convex first teleoconch whorl. Note also in the below image that Dan's specimens exhibit the same degree of convexity for the first three teleoconch whorls as the classic and do not begin to display  an unusual degree of

convexity until the forth.













2. Comparing the one of Dan's specimens with a thickened lip to the classic specimen of Z. dicomata, neither reflect the "about 8 teeth in outer lip, strengthening  posteriorly," which Redfern describes as characteristic of Z. idalina.




3. My collection includes these shells from throughout the Keys, including 100's from this Key Largo locale. All have been ID'd as Z. dicomata. Many have been examined and confirmed as Z. dicomata by other experienced Florida experts, including three lots from this Key Largo area. It's highly unlikly that a living population of Z. idalina exists intermixed with Z. dicomata and would not have been previously noticed.

4. I asked Harry Lee to examine Dan's shells. His ID was "Z. dicomata" and commented, "Really chubby. The fatter one is clearly abberant. Not another species." He also commented that he had no confirmed Z. idalina from Florida.

Dan, in my mind the evidence says these are Z. dicomata.

On Nov. 21
dteven wrote: Marlo, thanks so much for taking the time to look closely at these. Now that you've sent them back and I've borrowed a copy of Redfern, I agree with you: they don't match his description of idalina, and the color and form differences do not conclusively separate them from dicomata.

2/13/08  Marlo:

I have the pleasure to report that Let's Talk Seashells appears to be getting more visitors, including some that are reviewing the older subjects.

Today I heard from
Phil Poland of Clearwater, Florida, a long time Florida collector who spent many years collecting Florida micros and generously providing material to researchers and serious collectors around the world.




Upon reviewing this discussion Phil wrote me with the following

interesting information. "The Z. idalina on the front of Sally Kaicher's

card pack was collected by me in about 20' of water, in rubble, off Looe

Key." Looe Key is a reef about six miles offshore of the lower Florida Keys.

Phil's find was made in the 1970's. Upon hearing the news Harry Lee

commented, " This is the first reliable report of Zafrona idalina from FL of

which I am aware. Gary R. doesn't have it either."

Dan, I don't think this changes our conclusions, but it means we may

find Z. idalina in the Keys yet.


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