The Filose Amoeba Vampyrellidium perforans nov. sp. (Vampyrellidae, Aconchulinida): Axenic Culture, Feeding Behaviour and Host Range Specifity

Summary The filose amoeba Vampyrellidium perforans is described as a new member of the vampyrellidae (Aconchulinida). The amoeba was brought into axenic culture using heat killed cells of Chlamydomonas cribrum as food. Growth of amoebae in axenic culture was comparable to that in dual culture with living Chlamydomonas cells. Vampyrellidium exists either in a “planktonic” or an “amoeboid” life form. In the planktonic life form the amoeba is spherical with long, filose pseudopodia, in the amoeboid life form it is ovoid to elongate exhibiting both filose and lobose pseudopodia. The amoeba feeds by either ingesting food organisms or by penetration of the algal cell wall followed by uptake of cell contents with a specialized pseudopodium. In either case the algal cell wall is not digested but expelled. Host range studies have indicated that members of the Chlamydomonadineae and Volvocineae sensu F OTT primarily serve as food organisms. In addition only members of the Tetrasporales, Chlorococcales (i.e. Chlorococcum species) and a few Xanthophyceae can be used as food. It is suggested that algal cell wall penetration is enzymatic and involves prior recognition of cell wall receptors of maybe glycoprotein nature. Taxonomic criteria in the Vampyrellidae are discussed.