The Dinaride Lake System, as one of the largest freshwater systems in the Neogene of Europe, is widely known for its exceptional mollusc fauna. During the Early and Middle Miocene, it displayed a major evolutionary hotspot resulting in a high level of endemicity. Despite advanced investigations in that region, comprehensive knowledge on the mollusc fauna of the Kupres basin is largely lacking. The herein presented results give insight into this outstandingly preserved fauna and are the base for a systematic revision of several supraspecific taxa among the Hydrobiidae. Because their phylogeny is poorly known, this study may serve as starting point for an overall systematic revision of this highly diverse family. Moreover, the faunal composition allows inferences on palaeobiogeography and hydrological connections within the Dinaride Lake System during the early Middle Miocene. About one-third of the described taxa are restricted to the Kupres basin. The other taxa document faunistic relations to the coeval faunas of the Sinj, Drniš and Džepi basins. Phases of hydrological isolation, indicated by carbonate dominated lithology, coincide with a high frequency of sculptured morphologies within the gastropods. Phases of increased aridity led to high evaporation, a lowered lake level and enhanced carbonate production which seem to have promoted strongly calcified shells. The stratigraphic ranges of the species imply a depositional age of 15.5 ± 0.2 Ma (earliest Middle Miocene; Langhian). Among the Hydrobiidae Cyclothyrella gen. nov. and Pseudodianella gen. nov. are introduced as new genera. Bania obliquaecostata sp. nov., Melanopsis corici sp. nov., Nematurella vrabaci sp. nov., Prososthenia diaphoros sp. nov. and Prososthenia undocostata sp. nov. are described as new species. For the secondary homonym Melanopsis bittneri (Neumayr, 1880), the new name Melanopsis medinae nom. nov. is proposed.
Aim Elevated biodiversity is the result of the cradle, museum or sink functions. The contributions of these three functions to species accumulation and their changes through time remain unknown for glacial refugia. Additionally, our understanding of the role these functions played during pre‐glacial periods is limited. We test for changes in contributions of functions through time leading to the current diversity patterns using a model refugium and taxon. Location Anatolia, Western Palaearctic. Taxon Freshwater neritid snails (genus Theodoxus). Methods Assessments were made to define molecular operational taxonomic units (MOTUs) for Theodoxus and reaffirm the genus as a suitable model taxon with elevated interspecific diversity in noted glacial refugia. Thereafter, we constructed a time‐calibrated multilocus Bayesian phylogeny of mtDNA and nDNA by using both fossil data and published substitution rates. Ancestral area estimation was performed on the phylogeny to define the contribution of the functions through time. Results Accumulation of Theodoxus diversity in Anatolia over the Miocene–Pliocene transition is attributed to the museum function, but its contribution was small as only few divergence events occurred. The cradle function dominated during the Pliocene and Early Pleistocene, when most interspecific diversity built up and extant lineages in Anatolia were established. The sink function acted from the Middle Pleistocene to present‐day, but with only a small contribution to the total extant Anatolian interspecific diversity. Main conclusion Our results do not entirely mitigate the role glacial cycles played in species accumulation, but highlight Ice Ages may have been less effective in forcing temperate aquatic interspecific diversity into more opportune areas. The elevated diversity in refugia may rather be the result of earlier in situ diversification. Elevated interspecific diversity attributed to the legacy of glacially forced retreats may need to be re‐evaluated in cases where refugia have long and complex geological histories such as Anatolia. These results highlight the importance of considering species accumulation through a temporal perspective to adequately explain present‐day biodiversity patterns.
For the first time a palaeobiogeographic framework is proposed for European Neogene freshwater systems. The distribution of 2226 species-group taxa of freshwater gastropods from over 2700 Miocene and Pliocene localities was evaluated. The localities were grouped into palaeo-freshwater systems based on latest palaeogeographic reconstructions. Cluster analyses were computed for four time slices, i.e., Early Miocene, Middle Miocene, Late Miocene, and Pliocene. The analyses demonstrate a generally high degree of provincialism for the Neogene freshwater systems and allow the definition of biogeographic units. The delimitations are based on the cluster analyses, the degree of endemicity, and geographical coherence. The Early Miocene is characterised by a relatively low degree of provincialism suggesting the distinction of three regions. Coinciding with the development of many endemic systems on the Dinarian-Anatolian Island and in central Europe, the Middle Miocene demonstrates a higher degree of provincialism, allowing the definition of six biogeographic regions. With the onset of the Late Miocene the retreat of the Central Paratethys and development of the huge Lake Pannon massively shaped faunal evolution and palaeobiogeography in general. The formation of the 'Lago-mare' environment fringing the Mediterranean Basin as well as the development of several restricted freshwater systems in western Europe additionally promoted biogeographic division. The increasing provincialism allowed the delimitation of six biogeographic regions, three of which could be subdivided into seven dominions. With the disappearance of Lake Pannon and the decline of western European and Mediterranean faunas at the Miocene-Pliocene boundary, biodiversity hotspots shifted towards eastern and southeastern Europe. For the Pliocene, four biogeographic regions, five dominions, and four provinces were defined. Most of the here proposed biogeographic units and faunal differences are governed by the varied existence of large, long-lived systems. Because of their prolonged duration they immensely influenced the community composition on the family level, differences of the relative species richnesses per biogeographic region, and the rising rate of endemicity. The underlying mechanism for this pattern is the ongoing continentalization of Europe triggered by the Alpidic orogenesis and the simultaneous retreat of the Paratethys Sea. The continuing restriction of this huge intracontinental sea from the Mediterranean promoted the evolution of endemic freshwater faunas. The arising long-lived systems like Lake Pannon, Lake Dacia or Lake Slavonia persisted over several millions of years and stimulated the evolution of highly diverse and endemic faunas.
Defining and recording the loss of species diversity is a daunting task, especially if identities of species under threat are not fully resolved. An example is the Pontocaspian biota. The mostly endemic invertebrate faunas that evolved in the Black Sea – Caspian Sea – Aral Sea region and live under variable salinity conditions are undergoing strong change, yet within several groups species boundaries are not well established. Collection efforts in the past decade have failed to produce living material of various species groups whose taxonomic status is unclear. This lack of data precludes an integrated taxonomic assessment to clarify species identities and estimate species richness of Pontocaspian biota combining morphological, ecological, genetic, and distribution data. In this paper, we present an expert-working list of Pontocaspian and invasive mollusc species associated to Pontocaspian habitats. This list is based on published and unpublished data on morphology, ecology, anatomy, and molecular biology. It allows us to (1) document Pontocaspian mollusc species, (2) make species richness estimates, and (3) identify and discuss taxonomic uncertainties. The endemic Pontocaspian mollusc species richness is estimated between 55 and 99 species, but there are several groups that may harbour cryptic species. Even though the conservation status of most of the species is not assessed or data deficient, our observations point to deterioration for many of the Pontocaspian species.
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