Acroloxus

Abstract: Using published records and original data from recent field work and revision of Iranian material of certain species deposited in the collections of the Natural History Museum Basel, the Zoological Museum Berlin, and Natural History Museum Vienna, a checklist of the freshwater gastropod fauna of Iran was compiled. This checklist contains 73 species from 34 genera and 14 families of freshwater snails; 27 of these species (37%) are endemic to Iran. Two new genera, Kaskakia and Sarkhia, and eight species, i.e., Bithynia forcarti, Bithynia starmuehlneri, Bithynia mazandaranensis, Pseudamnicola georgievi, Kaskakia khorrasanensis, Sarkhia sarabensis, Valvata nowsharensis and Acroloxus pseudolacustris are described as new to science; Ecrobia grimmi (Clessin & Dybowski, 1888), Heleobia dalmatica (Radoman, 1974) and Hippeutis complanatus (Linnaeus, 1758) are reported for the first time from Iran. Additional field work is highly desirable for a more appropriate evaluation of the extant freshwater snail biodiversity in Iran.

Abstract: There are two British freshwater limpets: Ancylus (Ancylastrum) fluviatilis Muller and Acroloxus (Ancylus) lacustris (Linnaeus.). The names have undergone the same bewildering changes as those of most other freshwater gastropods; here the nomenclature of the Conchological Society's recent census is used (Conch. Soc. 1951). The distribution throughout the British Isles (Conch. Soc. 1951) and the ecology of both species (Boycott 1936) have been studied, but not much is known about the natural history or about the detailed distribution in a small area. The present study aims to supply some information on these topics. Unfortunately I did not know about Hunter's (1953) studies of the same animal until after the present work was complete. The investigation was carried out during a year's residence at the Windermere Laboratory of the Freshwater Biological Association, and this report on it describes first, the general distribution in the Lake District, including observations on how deep Ancylus goes in Windermere. Then there is an account of mating and egg-laying habits, and of an attempt to find out how many eggs an individual lays. Extensive observations were made on the course of growth and time of reproduction at two stations in Windermere and one in a small stony stream, or beck to use the local word. This leads on to a consideration of the fluctuation in numbers with the passing of the seasons and the total populations at different stations at comparable times. Finally, some observations on food and on commensals are recorded.

Abstract: To date, based on the studies of foreign and Turkish malacologists, 28 basommatophoran snail species belonging to 16 genera from 5 families (Physidae, Lymnaeidae, Planorbidae, Ancylidae, and Acroloxidae) have been found in freshwaters of Turkey. In Turkey, the genera Acroloxus (1 species), Galba (1), Stagnicola (1), Radix (2), Lymnaea (1), Physa (1), Physella (1), Planorbarius (1), Ferrissia (1), Planorbis (2), Anisus (4), Bathyomphalus (1), Gyraulus (8), Hippeutis (1), Ancylus (1) and Bulinus (1) are recognized. Also, 16 species (including 8 recent) and 5 subspecies are known from Quaternary fossil deposits of Turkey.

Abstract: Ancient Lake Ohrid, located on the Albania-Macedonia border, is the most biodiverse freshwater lake in Europe. However, the processes that gave rise to its extraordinary endemic biodiversity, particularly in the species-rich gastropods, are still poorly understood. A suitable model taxon to study speciation processes in Lake Ohrid is the pulmonate snail genus Acroloxus, which comprises two morphologically distinct and ecologically (vertically) separated endemic species. Using a multilocus phylogenetic framework of Acroloxus limpets from the Euro-Mediterranean subregion, together with molecular-clock and phylogeographic analyses of Ohrid taxa, we aimed to infer their geographic origin and the timing of colonization as well as the role of geography and ecology in intra-lacustrine diversification. In contrast to most other endemic invertebrate groups in Lake Ohrid, the phylogenetic relationships of the endemic Ohrid Acroloxus species indicate that the Balkan region probably did not serve as their ancestral area. The inferred monophyly and estimated divergence times further suggest that these freshwater limpets colonized the lake only once and that the onset of intra-lacustrine diversification coincides with the time when the lake reached deep-water conditions ca 1.3 Mya. However, the difference in vertical distribution of these two ecologically distinct species is not reflected in the phylogeographic pattern observed. Instead, western and eastern populations are genetically more distinct, suggesting a horizontal structure. We conclude that both geography and ecology have played a role in the intra-lacustrine speciation process. Given the distinct morphology (sculptured vs. smooth shell) and ecology (littoral vs. sublittoral), and the timing of intra-lacustrine diversification inferred, we propose that the onset of deep-water conditions initially triggered ecological speciation. Subsequent geographic processes then gave rise to the phylogeographic patterns observed today. However, the generally weak genetic differentiation observed suggests incipient speciation, which might be explained by the comparatively young age of the lake system and thus the relatively recent onset of intra-lacustrine diversification.