RESUMEN
This paper continues a discussion on the number of pearl mussel species of the genus Margaritifera in northern Europe. A biometric study of 1711 pearl mussel Margaritifera margaritifera shells from 15 rivers in Russia and Latvia (basins of the White and Baltic seas) has been conducted. All the examined samples fall into two groups: the northern group (with the shells more flattened on average, f. margaritifera) and the southern one (with more convex shells, f. elongata); the boundary between these groups is at 63 degrees N. Analysis of intrapopulation variation has shown that the samples contain individuals that correspond to f. margaritifera, f. elongata, and f. borealis. However, any hiatus between these forms is absent in all the samples, and individuals belonging to two intermediate forms are rather frequent. The hypothesis on the species specificity of the shell valve frontal section has not been confirmed based on examination of large shell samples. The pearl mussels inhabiting rivers of Northern Europe belong to a single species, M. margaritifera.
Asunto(s)
Bivalvos/anatomía & histología , Bivalvos/clasificación , Especificidad de la Especie , Exoesqueleto/anatomía & histología , Animales , Bivalvos/genética , Agua Dulce , Letonia , Océanos y Mares , Ríos , Federación de RusiaRESUMEN
Basic therapy of peripheral cochleovestibular disorders of vascular origin consists of the rational combination of medicamentous and non-medicamentous treatments that collectively ensure positive clinical results. The use of hirudotherapy for the management of peripheral cochleovestibular disorders resulted in the substantial decrease of ear noise and the maintenance of the tendency toward further improvement of cochlear and vestibular functions.