04 August 2006

Land snails of Turkey: Xeropicta smyrnocretica

An e-mail that came a couple of days ago from the editor of a well-known malacological journal brought good news. A manuscript we had submitted had been accepted for publication. However, a reviewer recommended some revisions, one of which concerned the identity of a snail that we were calling Xeropicta smyrnocretica. The snails in the family Hygromiidae are notoriously difficult to identify. So the questioning of the reviewer led me to reconsider the suspect identification.

Here is a brief summary of the existing literature on this species. Germain1 described Helicella (Xerocrassa) cretica var. smyrnocretica in 1933. The type location was specified only as "Environs de Smyrne [= Izmir]). Thirty years later, Forcart2 dissected a specimen and determined that the snail in question was not in Xerocrassa (which he considered a subgenus of Helicopsis), but instead was in Xeropicta (another subgenus). Another 10 years later, Hudec3 examined some specimens that had also been collected in Turkey, which he called, following Forcart, Helicopsis (Xeropicta) smyrnocretica, and emphasized the characteristic sculpture of the shell surface.

There are 3 widespread hygromiids that may be confused with X. smyrnocretica: Cernuella virgata, Xeropicta krynickii and Xerocrassa cretica. However, each has a characteristic that makes it easy to distinguish them from each other. The shell below is one of the specimens that we are identifying as X. smyrnocretica from southeast of Izmir, north of Aydin. It has some irregular and indistinct growth rings.


The photo below shows the microsculpture of the same shell, which consists of very fine regular spiral lines. I believe this is the microsculpture Hudec noted.


Xeropicta krynickii also has a microsculpture somewhat similar to that of X. smyrnocretica, but the former has an eccentric umbilicus unlike that of the latter. So, that rules out X. krynickii. Cernuella virgata can also be eliminated, because it does not have a microsculpture of regular spiral lines. We are left with X. cretica. Luckily, I have on loan some specimens of that species from the Field Museum in Chicago.


Here is a larger picture of X. cretica. Every shell in this lot (and also in another lot) has densely stacked radial ribs as you can see in the photo. That characteristic and also the lack of a distinct microsculpture distinguish this species from X. smyrnocretica.


Having gone thru the specimens and the available literature one more time, I am once again confident of my identification.

1. Germain, L. 1933. Bull. Mus. Nat. Hist. Nat. Paris 5:389-392.
2. Forcart, L. 1963. Arch. Moll. 92:78-79.
3. Hudec, V. 1973. Zoologische Mededelingen 46:231.


Anonymous said...

In the picture with 4 cretica, the one at the bottom seems like krynickii, seemingly an introduced species (as with cretica itself), and i think there is a little more studies are needed in anatomy and morphology of smyrnocretica.


Tim Pearce said...

And assuming that the FMNH specimens are identified correctly!