Thecamoebians are one of 30-45 lineages of amoebae known to science. During their evolution, they have developed the ability to produce an outer carapace or shell for their own protection.
Most amoebae in the genus Arcella vary considerably in morphology, typically being hemispherical or disk-shaped. Some resemble an Asian rice hat, while others are crown-like with denticulations, small ridges resembling bristles or spines around the edges. The genus comprises some 200 species and is one of the most diverse genera among thecamoebians.
The new species was named after a famous wizard as its carapace resembles the hat worn by Gandalf (Lord of the Rings).
For the experts: Arcellinida are free-living lobose amoebae that produce an outer shell (test). Here, we describe a conspicuous new species, Arcella gandalfi sp. nov, from Brazilian continental waters, along with a morphological and biometrical characterization. Test diameter and test height are on average 81 and 71 respectively. This new species has an apical conical extension, which differentiates it from other Arcella species. A. gandalfi seems to be closely-related to A. brasiliensis, due to the distinct marginal ring (test brim) present only in these two species. Since A. gandalfi is easily identified by morphological features and due to its apparent geographic restriction to South America, we discuss its possible use as a new flagship species