Can morphometrics help us predict the diet of land planarians?

Abstract

Abstract The use of morphometrics for taxonomy and to predict the diet of organisms based on related species has been applied to several groups. In this study, for the first time, we used morphometric data of land planarians to find patterns that could differentiate genera and feeding habits. We examined body shape, pharynx shape, mouth position and the thickness of the cutaneous musculature in 135 species of land planarians. Mouth position was explained, in part, by the position of the dorsal insertion of the pharynx, and transverse circularity by the relative thickness of the cutaneous musculature. The character that best separated genera and diet was the thickness of the cutaneous musculature. A principal components analysis recovered some patterns previously revealed by molecular phylogenetics, with some closely related genera appearing close to each other in the biplot. The same analysis also showed two clearly distinct groups, one of species that feed on woodlice and the other of species that feed on soft-bodied prey. We conclude that morphometrics can help to narrow down the potential prey of geoplaninid land planarians and aid taxonomic studies.