Description of Vahlkampfia signyensis n. sp. (Heterolobosea), based on morphological, ultrastructural and molecular characteristics

Vahlkampfia signyensis n. sp. was isolated from two soil sites at Signy Island, South Orkney Islands, maritime Antarctic. Trophozoites of the species had a typical vahlkampfiid morphology, showed eruptive movement and did not form flagellates. However, Vahlkampfia signyensis differs from other described species of the genus in a range of morphological and ultrastructural characters, as well as in its 5.8S rDNA sequence. According to its 5.8S rDNA sequence, the new species is most closely related to Vahlkampfia avara. An isolate of the new species had a temperature growth optimum of only 10 °C, and did not grow at either 30 °C or 37 °C. The low optimal growth temperature is adaptively significant for life in the maritime Antarctic.