02 June 2010

Helix cornea and other taxonomic headaches from 111 years ago

I spent about an hour today synonymizing 2 lists of land snail species that had been collected in western Turkey in 1899. I didn't actually attempt to come up with a synonymy for each species; I only wanted to know what species the author of the paper had collected. The problem was that the author apparently didn't have much experience with the species of his study area. So his lists are peculiar mixtures of those species expected from the area and those that are not.

For example, one recorded species was Vitrea koutaisiana Mousson, now called Oxychilus koutaisianus and known only from northeast Turkey. It is possible that the range of the species was wider 100 years ago. But the more likely explanation is that a similar species common in the author's study area in western Turkey, possibly O. cyprius, was misidentified.

Another example was Clausilia messenica now known as Albinaria nivea. According to AnimalBase, A. nivea lives in the Pelopónisos region of Greece, but not in Turkey. There are 3 Albinaria species that are presently known from the study area. Which of those did the author find? The only way to find out is to go the same location and search for snails, which is something I intend to do this summer.

Sometimes taxa that were thought to be separate species in the past are now lumped under one name. For example, among the species listed by the author were H. virgata and H. variabilis, which are now considered to be synonyms with the former being the primary one.

As taxonomists continuously refine their understanding of the evolutionary relationships between different taxa, species get shuffled around between genera and consequently, their accepted names change. Only a small fraction of the names given to newly described species in the 18th and 19th centuries still remain in use. The only 2 examples from the lists I was working with are the snail species Linnaeus called Helix lucorum and Helix pomatia in 1758. They still go by those names, although the latter does not live in Turkey. Another case of geographically misplaced misidentification. But what was the 2nd Helix species the author had?

One troublesome name in one of the lists is Helix cornea. Again, according to AnimalBase, there have been 2 taxa by that name. One is a terrestrial species Draparnaud described from France in 1801 and which is currently not referrable to a known species. The other is the freshwater species now known as Planorbarius corneus (Linnæus, 1758). Which one did the author find? He provides a clue: the snails were attached to the plants growing in the fields. Therefore, they were land snails. But what on earth was the terrestrial Helix cornea?

2 comments:

Anonymous said...

Aydin,

Along with going into the field and recollecting, it would have been nice if the author had placed some voucher specimens in a museum. Then you could have studied his taxa in the museum and confirm identifications. The you could go into the field to see what changes have occurred over the past hundred years.

Charlie

AYDIN ÖRSTAN said...

Charlie, yes the idea is to compare now & then, but all I have for 1899 are the confusing names in the paper.