14 October 2005

Papers read this week

Baur, A. & Baur, B. 2005. Interpopulation variation in the prevalence and intensity of parasitic mite infection in the land snail Arianta arbustorum. Invertebrate Biology 124:265-272.
The parasitic mite Riccardoella limacum lives in the lungs of land snails where it sucks its host's blood. The authors examined the prevalence of mite infection in 997 adults of Arianta arbustorum from 11 natural populations distributed over an altitudinal gradient ranging 335-2360 m in Switzerland. No infected snails were found in 7 populations, while in the remaining 4 populations the prevalence of mite infection ranged 45.8-77.8%. Interestingly, parasitic mites did not occur in snail populations situated at elevations of 1290 m or higher. The authors speculate that the snails' hibernation period may be too long at high elevations for mites and their eggs to survive.

Brodie, R.J. 2005. Desiccation resistance in megalopae of the terrestrial hermit crab Coenobita compressus: water loss and the role of the shell. Invertebrate Biology 124:194-201.
The hermit crab Coenobita compressus undergoes larval development in the sea and then moves to land as a megalopa (a juvenile resembling an adult), where it metamorphoses and remains for the rest of its life. Among other things, the author demonstrated that megalopae with shells survived desiccation much better than those without shells. In marine hermit crabs, the shell protects against predators. And because shell-wearing behavior predates land invasion, the author considers shell-wearing a pre-adaptation to terrestrial life, where the shell also protects against desiccation.

I will post more about this interesting paper in the near future.

Parmakelis, A., Pfenninger, M., Spanos, L., Papagiannakis, G., Louis, C. & Mylonas, M. 2005. Inference of a radiation in Mastus (Gastropoda, Pulmonata, Enidae) on the island of Crete. Evolution 59:991–1005.
I have written about the land snail genus Mastus before. In this study, the authors present a molecular, conchological and anatomical study of what seems to be a radiation (a rapid increase in species number) in Mastus in the Aegean archipelago, especially on the Island of Crete where there are 16 endemic species of Mastus. To explain the diversity of the Cretan Mastus species, they propose an allopatric nonecological radiation process that took place about 7 to 9 million years ago soon after the formation of the so-called mid-Aegean trench that separates the Turkish mainland (and the nearby islands) from the Aegean archipelago.

One puzzle that remains to be solved is the presence of 2 of the species (M. carneolus and M. etuberculatus) both on the Aegean archipelago and on the Turkish mainland across the mid-Aegean trench.

I will also post more about Mastus in the future.

Triantis, K.A., Pokryszko, B.M., Vardinoyannis, K. & Mylonas, M. 2004. A new species of Truncatellina (Gastropoda: Vertiginidae) from Mount Ossa (=Kissavos) (Greece). Journal of Conchology 38:393-397.
The description of Truncatellina cameroni, new species, from Mt. Ossa in Greece is given. It is the largest known species in the genus (holotype shell height: 3.17 mm).

Taylor, E.W., Sweeney, M.P. & Counts, C.L. 1977. Use of empty gastropod shells (Polygyridae) by pseudoscorpions. Nautilus 91:115.
I have written about pseudoscorpions. I frequently find them among recently collected empty snail shells. In this half-page paper, the authors reported collecting 2 species of pseudoscorpions from empty shells of Neohelix albolabris and Mesodon thyroidus in West Virginia. The authors speculated that the snail shells may offer protection to pseudoscorpions from weather extremes and predators.

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