planocarina planocarina planocarina (from latin planus 'flat', and carina 'keel') is a genus of arcellinid testate amoebae belonging to the family hyalospheniidae. it was created in 2016 to agglutinate a clade of species that were previously assigned to the paraphyletic genus nebela. all species of planocarina have a compressed keel surrounding the posterior part of their shell. it is the sister group of alabasta. planocarina p. carinata scientific classification domain: eukaryota phylum: amoebozoa class: tubulinea order: arcellinida family: hyalospheniidae genus: planocarinakosakyan, lahr, mulot, meisterfeld, mitchell & lara 2016 type species planocarina carinata(archer 1867) kosakyan, lahr, mulot, meisterfeld, mitchell & lara 2016 species p. carinata p. marginata p. maxima p. spumosa morphology members of planocarina have an elongated, pyriform test with a distinct neck, and lateral margins tapering towards the test opening. the posterior part of the test is surrounded entirely by a flat keel. the test hyaline or slightly yellowish in color, composed of circular and elongated scales recycled from the organism's prey, such as euglyphid testate amoeba. classification planocarina contains all former species of nebela that have a flat keel, with the exception of those that have a lateral horn, which are assigned to cornutheca. there are 4 species in total: planocarina carinata (archer 1867) kosakyan, lahr, mulot, meisterfeld, mitchell & lara 2016 (=nebela carinata (archer 1867) leidy 1879) planocarina marginata (penard 1902) kosakyan, lahr, mulot, meisterfeld, mitchell & lara 2016 (=nebela marginata penard 1902) planocarina maxima (awerintzew 1907) kosakyan, lahr, mulot, meisterfeld, mitchell & lara 2016 (=nebela maxima awerintzew 1907) planocarina spumosa (awerintzew 1907) kosakyan, lahr, mulot, meisterfeld, mitchell & lara 2016 (=nebela spumosa awerintzew 1907)