Entomologica Romanica Vol. 18 / 2013


Table. 1. The distribution and the frequency of terrestrial isopod species from Oas Mountains (Lg-L. germanicum, Lh-Z. hypnorum, Hr-//. riparius, Ht-ZÍ transsilvanicus, V-Trichoniscus sp., Cc-C. convexus, Ppo-Z politus, Pc-P collicola, Pcm-P conspersum, Td-Z difficilis, Ta-Z arcuatus, Tn-Z nodulosus, Trk-Z rathkii, Ps-P scaber, Avu-A vulgare, Ave-A. versicolor, N- number of species, N loc- number of localities, F-frequency of occurrence, SM-Satu Mare county, MM-Maramures county). seven groups: fallen logs, barks, stones, humid soil and vegetation neighbouring wetlands, debris, trash cardboards or clothes. The collecting method was the direct one, with tweezers. In the case of small sized isopods we used blade of grass for not destroying them. In some cases, especially in forests, we used the litter sieve. The collected isopods were stored in alcohol, and the species were determined in laboratory using the specialty literature (e.g. Radu 1983, 1985). Results After investigating 26 localities from Oas Mountains, we identified 16 terrestrial isopod species: Ligidium germanicum. L. hypnorum, Hyloniscus riparius, H. transsilvanicus, Trichoniscus sp., Cylisticus convexus, Protracheoniscus politus, Porcellium collicola, P conspersum, Trachelipus difficilis, T. arcuatus, T. nodulosus, T. rathkii, Porcellio scaber, Armadillidum vulgare and A. versicolor. We collected 751 terrestrial isopods individuals from 55 samples, so the average number of individuals / sample was 13.47. By their frequency (Table 1), the terrestrial isopod species can be classified into three groups: frequent species, common species and rare species. Thus, H. transsilvanicus is the most frequent species in the area, being identified in 18 localities from 26. This species is followed by L. germanicum, H. riparius, P. politus, P. collicola, A. vulgare. etc., which were identified in approximately 10-11 localities from the total of 26. The species richness is different by the localities, and it is influenced by the number of microhabitats that could be investigated in each of the localities. Thus this value varies between 1 and 12 (Table 1), the average number of the species / locality being 4.42. Most of the species were identified in areas neighboring natural and semi natural wetlands or streams, without or with forest (Table 2). In this case it is evident that the most common species were the typical ones for wetlands, like H. riparius, 3 5 6 Locality Lg Lh Hr Ht Tc Cc Ppo Pc Pcm Td Ta Tn Trk Ps Avu AveN Handalu Ilbei (MM)X X X X 4 Sabisa (MM)X X X X 4 Seini (MM)X X 2 Viile Apei (MM)X X 2 Aliceni (SM)X X X 3 Babesti (SM)X X X Băile Puturoasa (SM)X Batarci (SM)X Vama (SM)X 3 4 2 3 6 6 3 6