How many species of loess mollusks were there in Serbia from MIS 24 to MIS 2?

Abstract

There were multiple attempts to investigate mollusks from loess sediment in Serbia, as this natural archive covers a great part of the northern territory of Serbia. However, these approaches did not have a large temporal coverage, as usually only the loess from the last glacial cycle was studied, rarely reaching the Middle Pleistocene. In recent years this research was extended until the MIS 24, according to the Danube loess stratigraphy (Marković et al., 2015). Here we present the latest information about snail species that lived in glacial conditions over the northern province of Serbia, Vojvodina. We enriched the list of found mollusks from earlier studies, by exploring the two oldest loess-palaeosol sections in Serbia, which when compiled into a composite profile cover almost one million years (Veliki Surduk – Stari Slankamen). Some problems exist when compiling all the findings of snail species in other loess sections in Serbia, such as the lack of stratigraphic interpretation in the early studies. This is why found shells from such locations can not be included in this list. We found that Chondrula tridens, Granaria frumentum, Helicopsis striata, Pupilla muscorum, Pupilla triplicata, Vallonia costata, Clausilia dubia, as well as Milacidae, Limacidae and Agriolimacidae were present from the earliest periods of loess accumulation in Serbia. The prevalent malacological assemblage of loess observed in Serbia during glacial periods suggests a predominance of mild climatic conditions characterized by a steppe environment. Conversely, less prevalent species indicate more rigorous environmental conditions, persisting during the coldest phases of certain glacials. Originally, the list of mollusks from Veliki Surduk – Stari Slankamen section included 41 species, but after adding the mollusks found in other profiles in Serbia, the list now has 62 species. The lowest diversity of mollusks was found in MIS 8. On the other hand, there were 55 species in the period MIS 2-4, but they are very diverse in their environmental preferences. Refinements and updates to this dataset require subsequent malacological investigations, which may yield the discovery of hitherto unrecorded species or the incorporation of newly identified taxa of the nine loess units formed during glacial conditions in Serbia.