L. Forró szerk.: Miscellanea Zoologica Hungarica 10. 1995 (Budapest, 1995)

Gubányi, A.: Biometrical investigation of water frogs in the Szigetköz Landscape Protection Area

above-mentioned phenomenon was also confirmed by Terentjev (1943) and Schuster (1950). Kauri (1954, 1959) consideied the water frog forms belonging to one species and investigated their growth patterns of by different geographical regions. Berger (1964, 1966, 1970) queried the conclusions of Kauri (1954, 1959) and found sexual dimorphism and positive correlation between body length and other measurements in the cases of adult water frogs. The variability of morphometric indices (FTMMTL, TL/IMTL, BL/TL) by developmental stage has also been demonstrated. Juszczyk (1971) studied the morphometric structure of green frog populations on a large scale and confirmed the appearance of three distinct forms of green frogs. The allometric growth rate of morphometric characters was also studied in Rana ridibunda (Opatrny 1966). Günther (1968, 1973) investigated biometrical ratios of BL/TL, TL/IMTL and FTL/IMTL, respectively. According to Wijnands & Van Gelder (1976), two indices (BL/TMTL and BL/TMTW*) were found to be the most important discriminating features between the three species. Gubányi (1992) and Gubányi & Korsós (1992) published further results on multivariate analyses of selected morphological measurements based on biochemical identification of the species, and claimed the importance of two ratios BL/FTL and TL/IMTL, which were not sexually dimorphic, as possible key characters for determination of the diploid water frog forms. At the same time, the population specific variability of morphometric characters was demonstrated for diploid and triploid Rana kl. esculenta specimens (see Plötner et al. 1994 for review). The Department of Zoology of the Hungarian Natural History Museum has undertaken a long term monitoring program of animal and plant communities, including amphibians (see Gubányi & Creemers 1994), in the Szigetköz, situated on the floodplain of the River Danube. The aim of the study was to examine the morphometric characters of a mixed Rana lessonae - Rana esculenta population system and provide a practical identification function key for diploid Rana lessonae and Rana kl. esculenta individuals in the inland delta of the River Danube. Water frog populations were also studied in the Slovakian part of the floodplain of the River Danube (Csallóköz) by Lác (1959) and Kux (1975). Materials and methods The study was carried out between 1989-1993. The frogs were collected at the following localities: 1. Cikolasziget (Győr-Sopron-Moson county), a temporary pond (about 200 m

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), surrounded with poplar (Populus canadensis) in the floodplain along the dam. 2. Ásványráró (Győr-Sopron-Moson county), temporary ponds and dead arms and channels in the floodplain, close to the dam, covered by Rorippa amphibia. 3. Lipót (Győr-Sopron-Moson county): shallow, gravelled permanent channels without submerged aquatic plant vegetation in the floodplain; and Bár-Duna ér (a channel) near the village. 4. Hédervár (Győr-Sopron-Moson county), 50 m long stretch of Lipót-Hédervári channel, covered by Ceratophyllum demersum in the vicinity of the village. 5. Palkányos (Győr-Sopron-Moson county), parts of the dead arms of River Danube in the floodplain. 6. Nagybajcs: (Győr-Sopron-Moson county): temporary waters in the floodplain. * BL = body length, TB = tibia length, FTL = first toe length. IMTL = inner metatarsal tubercle length, IMTW = inner metatarsal tubercle width