A rapid expansion of tubenose goby (Proterorhinus marmoratus) in a system of lowland reservoirs and adjacent rivers in the south-east of the Czech Republic (Danube basin) is reported. Spontaneous expansion of distributional range resulted in this species becaming a dominant fish in littoral zones with up to 100% relative abundance of the reservoirs and rivers.
After Neogobius kessleri, Neogobius gymnotrachelus, and Neogobius fluviatilis, Neogobius melanostomus is the fourth species of Gobiidae to find its way up the River Danube to Slovakia, occurring in our samples near Štúrovo (river km 1720) and in the River Hron (river km 0.82). The fish (male, females, juvenile) were captured along weakly sloped sandy riverbanks with large stones. The mensural and meristic characters of the specimens were similar to those reported elsewhere for the species.
Two sedentary gobiids (the cryptic species Pomatoschistus microps and P. marmoratus) have been analysed in several Mediterranean lagoons of southern France and in Corsica. In order to determine the level of population isolation between neighbouring lagoons, mtDNA was screened using RFLP (7 endonucleases) of an amplified 2 kb region (including the D-loop and Cyt b). The mtDNA diversity of the genus is high (42 haplotypes for 125 individuals) so that a detailed haplotype tree has been constructed using two additional outgroup species. The main result is that almost no common haplotypes are shared between populations of the same species inhabiting neighbouring lagoons. A high level of isolation between neighbouring lagoons during several centuries is deduced, at least for P. microps populations.
The postcranial skeleton of the Ponto-Caspian endemic benthophilines Anatirostrum and Benthophilus show unique specializations within gobioid fishes. Precaudal and caudal vertebrae are reduced in numbers and the dorsal pterygiophore insertion pattern is modified. Pterygiophores, which support no spine or segmented fin ray, are present in the skeletons at the rear of the first dorsal fin and at the second dorsal fin origin. Because of the low number of vertebrae the second dorsal and anal fin pterygiophores of Anatirostrum and Benthophilus are displaced anteriorly. The pterygiophores that support the first spine of these two median fins are positioned opposite to each other.