L. Forró szerk.: Miscellanea Zoologica Hungarica 12. 1998 (Budapest, 1998)

Farkas, S.: The terrestrial isopod fauna of the Rinya region II. Péterhida

MISCELLANEA ZOOLOGICA HUNGARICA Tomus 12. 1998 p. 45-53 The terrestrial isopod fauna of the Rinya region II. Péterhidal by S. Farkas (Received August 17,1998) Abstract: Isopods of a dry oak forest and the surrounding ruderal vegetation were sampled along a line transect by pitfall trapping. The captured species were Armadillidium vulgare Latr. (46.16%), Porcellium collicola Verh. (33.16 %), Trachelipus rathkii Brandt (10.29 %) and Trachelipus ratzeburgi Brandt (9.47 %). Difference was not found between the spatial distribution of A. vulgare and P. collicola. T. ratzeburgi seemed to prefer the inside of the oak forest, whereas individuals of T. rathkii were trapped mainly in the ruderal vegetation. The ratio of gravid females of T. rathkii was conspicuously higher at the sampled places than that in wetland forest. This phenomenon is probably due to the effect of the less suitable habitat. The seasonal changes of surface activity and sex ratio were also examined. Keywords: Isopods, Armadillidium vulgare Latr., Porcellium collicola Verh., Trachelipus rathkii Brandt, Trachelipus ratzeburgi Brandt, pitfall trapping, spatial distribution, habitat preference, surface activity, sex ratio Introduction The systematic ecological research of the isopods living in the regions of the Dráva River and Rinya Stream (Southwest Hungary) began in 1996. One of the 32 sampling sites was located in a lowland oak forest not far from the village of Péterhida. The main questions of the study were: (1) which Isopoda species live here; (2) is there any habitat preference of the male, female and gravid female specimens of the different Isopoda species; and how does (3) the surface activity (4) sex ratio and (5) reproductive characteristics of their populations change in time. Material and methods The Danube-Dráva National Park is located in South Transdanubia in Hungary and consists of many islandlike natural reserves. One of them is the oak forest located 2 km south of the village of Péterhida. The sampling site is located at: 46°00'10" North latitude and 17°0r35" East longitude (Fig. l.)(XL 89 UTM unit) . The material was collected between 1 May 1996 and 29 November 1996. The traps were checked approximately every 18th day, ten times in all during the sampling period. (The material collected at the first check will be referred to as sample No. 1., the second as No. 2., etc.). The plastic jars used as traps had a diameter of 7 cm and height of 10 cm, and were half filled with 70 % ethyleneglycol. A Rinya-ártér Isopoda faunája I. Bakháza. (The Isopoda fauna of the Rinya region I. Bakháza)