S. Mahunka szerk.: Folia Entomologica Hungarica 46/2. (Budapest, 1985)

ponticai steppes (Dobrogea - Romania; southern Ukraine - USSR) and to distribution of Mus muscu lus spicilegus Petényi (TRAUB et al., 1983; REICHSTEIN, 1978). A lot of exact finds In the Pannonian lowland originated from house mice (

M. musculus L.) taken in urban and suburban habitats. An exception was the find of M. arvalis

. There are more reasons to consider the occurrence of N. mokrzeckyi in the Carpathian hollows as native (DUDICH, SZABÓ, 1984) than as secondary one (JURÍK, 1962). Nosopsyllus (Nosopsyllus) consimilis (Wagner, 1898) Taxonomy: Monotypic species. General distribution: Almost the same as N. mokrzeckyi. Hosts: Muridae, Microtinae, Cricetinae, Gerbillinae. Literature data from the Carpathian Basin (Fig. 3): Czechoslovakia: 4828/2204 Leles (JURIK, 1962). Romania: 4 559/2 1 50 Lovrin (TASKAYEVA, HAMAR, 1962 ex SUCIU, 1973). Discussion and conclusions We described distributional features of species of the genera Megabothris and Nosopsyllus in Hungary and neighbouring areas in the Carpathian basin, with regard to the relatively poor knowledge as to their ecology. Both species of the Megabothris genus belong to arboreal faunal components. Their recent distribution and relations between their areas of occurrence are consequences of continuous secular transformation (succession) of ecosystems during the Holocene within that exceptionally motley, orographically variable Carpathians. The influence of human activity, or transformation of ecosystems during the last few centuries was less significant from this point of view. The species of M. walkeri and M. rectangulatus are considered as relics of the oldest Holocene. The first one is related to large, open wetlands In the Pannonian lowland and the Carpathian hollows. The second one belongs to a faunal complex of the boreal taiga. They both were parapatric within the Carpathians, as It is the case in northern Scandinavia at present (SMIT, 1969; TRAUB et al. 1983 and others). An other species, M. turbidus

, appeared in the Carpathians as the last one during the earlier Holocene (boreal) due to the expansion of mixed forests and arboreal fauna. Its common distribution to most vegetation zones finalized during the climatic optimum (atlantic), when it occupied the whole area with an exception of primary forest-free parts that had separated still smaller areas of occurrence of congeneric species. M. rectangulatus was limited by this way to the higher mountains and subalpine zones of the Carpathians and the Alps. Similarly was M.wal keri limited to large relic wetlands in the Pannonian lowland and lowlands along the Baltic Sea. The mentioned species of the genus Megabothris are alio-, or parapatric in the area of the Carpathians today. The interspecific competition had contributed to a recent feature of their distribution undoubtedly (the principle of "competitive exclusion", according to GAUSE). Our own data on the relationship between M. turbidus and M. walkeri were mentioned already. These are supported by results of analysis of M. agrestis and M. arvalis in Poland (STURMOWSKI, 1972; HELLON, RAUHUT, 1967). They did not find any common occurrence of both species of fleas in approx. 500 investigated nests. As to finds in Germany (PEUS, 1970, 1972), there was registered a common occurrence of both species in the same habitat. But it should be mentioned, that the samples were cumulative (pools) in relation to certain species of host (rodent). In western Europe (PEUS, 1972; BEAUCORNU, 1976) no such rigorous separation of the above-mentioned species was registered as here, in the Carpathians. It is caused apparently by a more humid, oceanic climate. The influence of continental climate is emphasized by the artificial drainage of wetlands and regulation of watercourses in the zone of lowlands and hollows. It might also be a cause of bizonal distribution of M. turbidus in the Pannonian area and its vicinity. The species of Nosopsyllus undoubtedly belong to the steppe faunal complex, regardless to their originality within the Carpathians, or to their secondary introduction - having occupied niches in the small mammals'parasitocenoses. The data on occurrence of N. consimilis in the area of Pannónia and even to north of the Carpathians (VIGOVSKI, KHOKHLOVA, 1967) needs revision. Populations of N. mokrzeckyi live locally on house mice commensals and - perhaps also exoanthropically in large areas of the Carpathian Basin. Our aim is not to make a revision concerning the taxonomical status of Nosopsyllus paganus