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
More recently Forró (1989) studied the microcrustacean faune of sodic waters near Fülöpháza and found D. atkinsoni in a small, astatic pond in March. Unfortunately, none of the authors mentioned above gave a morphological description of the specimens they had collected. The only exception is Daday (1888), however, he described the species very briefly and the illustrations also are of limited value. Thus it is a difficult task to figure out what taxon was indicated by the name Daphnia psittacea. For example, it is very likely that Woynárovich (1938) recorded D. atkinsoni as other authors found this species in sodic waters in spring. On the other hand, I think, when both species were reported in a paper, most probably D. psittacea should be considered as a synonym of D. similis. Although, because D. atkinsoni is a very variable species, as it was noted by many authors (e. g. Hrbácek 1987), it cannot be completely excluded that forms of this species were misidentified as D. psittacea. Results and discussion Material examined: Daphnia atkinsoni Baird, 1859: Angyalháza, reconstructed pool, 24. 03. 1992; Balmazújváros, Nagyszik, small pool, 05. 06. 1991(E) 1 ; Balmazújváros, Nagyszik, several pools, 24. 03. 1992, 08. 04. 1992 (E), 22. 04. 1992 (E), 29. 04. 1992 (E); Furta, small pool on pasture, 21. 03. 1991 (E); Furta, turbid pool on pasture, 07. 06. 1992; Fülöpszállás, Kelemenszék, 09. 03. 1992, 24. 03. 1992, 21. 11. 1992; Nagyiván, small pool, 23. 03. 1992 (E); Nagykunsági puszta, pools on pasture near 74th kilometre stone of mainroad 4; Poroszló, small pools in wheeltracks, 08. 06. 1991; Tiszacsege, small pool, 08. 06. 1991 (E); Tiszaug, small dug hole with brownish water, 23. 03. 1992. Daphnia similis Claus, 1876: Angyalháza, reconstructed pool, 24. 03. 1992; Balmazújváros, Nagyszik, small pool. 05. 06. 1991; Balmazújváros, Nagyszik, small pools 08. 04. 1992, 24. 04. 1992, 29. 04. 1992; Berettyóújfalu, roadside pool, 07. 06. 1991 (E); Furta, small pool on pasture, 21. 03. 1992 (E); Tiszafüred, pool on arable land, 08. 06. 1991 (E); Tiszavasvári, small pool in wheel-track, 24. 06. 1992. Notes on the morphological variation of Daphnia atkinsoni Daphnia atkinsoni is a very variable species and there is no clear definition of it. The authors are of different opinion, e.g. Hudec (1981), in addition to the earlier synonyms, included D. ulomskyi Behning also into the synonymy of D. atkinsoni, while Alonso (1991) considered D. holivari as distinct species, not a form of D. atkinsoni. The material investigated was also quite variable. A detailed morphological analysis will be published elsewhere, here I just want to note, that size and shape of rostrum, height and width of the head, size of the anterior extension of the carapace and the spinulation of its suture, size of the shell spine varied to a great extent. The presence of well visible spines on the suture of the anterior extension of the carapace was more characteristic in specimens collected in June, similar varieties were observed by Kubicek (1959) in Moravia. Frequent sampling and detailed investigation were needed in order to be able to decide if different forms of the same species or different species occur after each other in these cases. „E" indicates gamogenetic populations.
