L. Forró szerk.: Miscellanea Zoologica Hungarica 9. 1994 (Budapest, 1994)

Forró, L.: Distribution and occurrence of Daphnia atkinsoni Baird, 1859 and Daphnia similis Claus, 1876 (Crustacea, Anomopoda) in Hungary

MISCELLANEA ZOOLOGICA HUNGARICA Tomus 9. 1994 p. 83-88 Distribution and occurrence of Daphnia atkinsoni Baird, 1859 and Daphnia similis Claus, 1876 (Crustacea, Anomopoda) in Hungary by L. Forró (Received June 22, 1993) Abstract: Daphnia atkinsoni and D. similis occur in various kinds of small, temporary water bodies, rarely also in permanent ponds, in the Hungarian Plain. D. atkinsoni is a very variable species, it showed considerable morphological variation also in the present material. Body size was in the range of published data in the case of both species. It was found, that D. similis inhabits less saline waters, co-occurrence of these species was detected in some pools. Key words: Daphnia atkinsoni, D. similis, distribution, seasonality, temporary waters Introduction Three species of Daphnia (Ctenodaphnia) are known from Hungary (Gulyás 1974). Daphnia magna is widely distributed in the country. Daday (1900) listed this species as "sat frequens esse videtur". The other two species of the subgenus Ctenodaphnia (D. atkinsoni and D. similis) are less common, particularly the latter one was rarely found. During 1991 and 1992, within the frames of a project funded by the National Scientific Research Fund (OTKA), I have collected microcrusteaceans from several small, temporary water bodies in the Hungarian Plain. Many of the collected samples contained one, some even both of these species. The purpose of this paper is to summarize Hungarian literature data on D. atkinsoni and D. similis and to present the results of the more recent collectings. Materials methods Collectings were made between March and November in 1991 and 1992. It should be noted, however, that because these years were rather dry, most of the material was collected between March and June. Most water bodies dried out during summer and only a few of them had water again in autumn. Qualitative samples were taken, a plankton net of 100 U mesh size was used. In some cases, water temperature, pH and conductivity were measured in the field. Body size was also measured and number of eggs per female counted in samples where at least 5-10 specimens could be used for this purpose.