Do Geoplaninae (Platyhelminthes: Tricladida), a neotropical subfamily of land planarians, regenerate well?

ABSTRACT Knowledge on the regeneration capacity of land planarians is very scarce and focused on a few species. Here we studied the regeneration capacity of 104 animals from 23 species (genera Cephaloflexa, Choeradoplana, Cratera, Geoplana, Imbira, Xerapoa, Luteostriata, Notogynaphallia, Obama, Pasipha, plus an unidentified species) of the neotropical Geoplaninae and also two species (genera Dolichoplana and Endeavouria) of Rhynchodeminae under laboratory conditions. When cut in two, 17 flatworm species regenerated head and/or tail within 5 to 27 days, apparently depending on how flattened their bodies were. Issoca rezendei (Schirch, 1929) was the geoplanin species that regenerated the fastest, while Obama species regenerated the slowest. Five species did not survive long enough to begin regeneration, while Imbira marcusi Carbayo et al., 2013, survived up to 15 days after sectioning but did not form the blastema, seemingly due to its sensitivity to laboratory conditions. The shape of the blastema varied according to the body shape of the species, as did the re-pigmentation of the newly formed tissue, which began in the early stages of regeneration in Obama species. Issoca rezendei showed some characteristics that make it a good candidate species as a model organism for further study of regeneration. In nature, geoplanins often show injuries, some of which may have been caused by predator-prey interactions. This variation in regeneration capacity raises questions such as if their regeneration capacity could also be maintained by direct selection.