Species inventory and distribution patterns of freshwater amphipods in Moldova

Amphipod fauna of Moldova remains one of the least known in Europe with the most recent data upon species distribution being already almost 50 years old. In this paper, we summarize the knowledge upon the distribution of amphipods in Moldovan inland waters based on literature survey combined with our new original data and present a comprehensive checklist of recorded amphipod species. The new original data come from samples collected in 2012 at 25 sites across Moldova from a variety of freshwater habitats, ranging from springs and streams to rivers and artificial lakes. In the collected material, we identified only 4 species of gammarids – one, Gammarus kischineffensis, belonging to family Gammaridae and three species of Pontogammaridae: Pontogammarus robustoides, Obesogammarus crassus and Dikerogammarus haemobaphes. Presence of all these species has already been reported from Moldova. This number is surprisingly low if compared to the total number of amphipod species known to occur in the country, which is 18. However, 14 of these species are Ponto-Caspian elements and were reported only from the largest Moldovan rivers, Dniester and Prut. Further 12 Ponto-Caspian amphipod species may likely occur in the Moldovan section of the Dniester as they were found before in the lowest run of the river, already on the Ukrainian territory. Leaving out the Ponto-Caspian fauna, only five typically freshwater species were reported from Moldova so far: G. kischineffensis, G. balcanicus, Synurella ambulans, Niphargus birsteini and N. yaroshenkoi. This poverty is striking if compared to surrounding countries. Interpreting these results within a geological and palaeogeographical framework, we may suppose that it is due to the low landscape complexity combined with the relatively young age of the Moldavian Plateau and its hydrological network.