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

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

MISCELLANEA ZOOLOGICA HUNGARICA Tomus 10. 1995 p. 117-126 Biometrical investigation of water frogs in the Szigetköz Landscape Protection Area by A. Gubányi (Received May 16, 1995) Abstract: An identification function key is given for the discrimination of two water frog forms (Rana lessonae - Rana kl. esculenta population) in the Szigetköz Landscape Protection Area. Distribution pattern of morphometric characters of the two water frog forms represented normal distribution, except inner metatarsal tubercle for both forms and first toe length for female Rana kl. esculenta specimens. Considerable correlations were found both between body length and tibia length and between tibia length and first toe length for the two water frog forms. Key words: water frogs, Rana lessonae - esculenta systems, biochemical analysis, LDH-B isozymes, multivariate analysis, discriminant analysis, morphological analysis Introduction Central Europe is inhabited by three distinct forms of water frogs. Rana ridibunda Pallas, 1771 and Rana lessonae Camerano, 1882 are biologically good species, however, Rana kl. esculenta Linnaeus, 1758 is a hybridogenetic hybrid between the above two (see Graf & Pelaz 1989 for review). Owing to the hybridization morphological measurements of Rana kl. esculenta individuals usually show intermediate characteristics between the parent species. Water frogs were already investigated by Boulenger (1885, 1891) from morphological point of view in the last century (Table 1). Morphological measurements and indices, applied by him constituted the basis of further biometrical studies (Terentjev 1923, 1927). Terentjev (1931) pointed out that strong correlation (0.5-0.9) was found among the morphometric characters and suggested the direct use of the equations of regressions in the systematics of frogs (Terentjev 1936). In most cases, indices computed from measurements have hardly been correlated with each other and/or body length for Rana ridibunda (Terentjev 1943). March (1937) reported a remarkable observation, that the growth rate of extremities, compared to body length has been modified by the maturation, and thereafter a decrease has been found in it. This Table 1. Range of indexes for three forms of water frogs (Boulenger 1891) FTL/IMTL TL/IMTL ridibunda 2.5-4.0 9.5-14.0 typica (esculenta) 2.0-3.0 7.0-10.0 lessonae 1.5-2.0 5.0 -8.0 FTL/IMTL = first toe length / inner metatarsal tubercle length; TL/IMTL = tibia length / inner metatarsal tubercle length.