L. Forró - É. Murai szerk.: Miscellanea Zoologica Hungarica 6. 1991 (Budapest, 1991)

Szlávecz, K.: The terrestrial isopod fauna of the Hortobágy National Park

RESULTS AND DISCUSSION Species composition and distribution A total of 2932 specimens were examined. They belong to five species, Armadillidium vulgare Latr., Porcellium collicola Verh., Porcellio scaber Latr., Trachelipus rathkü Brdt. and Cylisticus convexus de Geer. Porcellio scaber was found around a building, and Cylisticus convexus is represented by only one specimen. Both species commonly occur around human settlements. The occurrence of the other three species are shown in Table 1. Unfortunately not all the labels contain information about the habitats of the animals. Nonetheless they seem to be widely distributed throughout the National Park since these localities cover a large part of it. Table 1. Occurrence of the three most abundant terrestrial isopod species in the Hortobágy National Park and the adjoining nature conservation area. Locality A. vulgare P. collicola T. rathkii Újszentmargita forest X X X forest edge X X X meadow X X X reeds X X X Óhat • forest X X X Darassa X X Vajdalapos forest X X X Görbehát ? X X Ku nmadaras-Döghalom ? X Ágotapuszta forest X Out of the three species two - Armadillidium vulgare and Trächelipus rathkii are widely distributed throughout the world. Trächelipus rathkü is one of the most expanding species in North America (GRUNER 1965). Porcellmm collicola had been considered a Central European species until recently, when SCHMALFUSS (1985) reported the species from Greece. Its occurrence here, in the saline Hortobágy was so unexpected, that LOKS A (1973), who regularly sampled the soil fauna of Újszentmargita from 1969 to 1970, found it necessary to give a detailed description of the species. Population characteristics The collecting method, being qualitative, allows only qualitative evaluation of the populations. Nonetheless some remarks still could be made especially based upon the Újszentmargita material that yielded the largest number of individuals (Table 2.). Sex ratio seems to be close to one for both T. rathkü and P. collicola, whereas females are in majority in the A. vulgare population. However, while this