When looks can be deceiving: a new cryptic land planarian species of Choeradoplana Graff, 1896 (Platyhelminthes: Geoplanidae) from Argentina

Abstract

A new species of the genus Choeradoplana found in the east-central region of Argentina is herein described, Choeradoplana malaria sp. nov. This new entity shows a striking similarity regarding the pigment pattern with other land planarian species of this genus, viz. Choeradoplana langi, Choeradoplana gladismariae, and Choeradoplana minima. Besides, the internal anatomy of Ch. malaria sp. nov. is remarkably similar to that of Ch. gladismariae, a species recorded in southeastern Brazil, some 2300 km distant from the new species. Although there are minimal differences in the colour pattern of the dorsum, both species can be differentiated by some anatomical and histological details, such as the thickness of the cutaneous musculature, the width of the creeping sole, and some features related to the reproductive system. This low morphological disparity between both species fits within the term ‘cryptic species’. These subtle differences were also corroborated in a phylogenetic analysis using Cox-1 gene sequences. Likewise, species delimiters reinforced the identity of the new taxon herein proposed and allowed us to differentiate Ch. malaria sp. nov. from Ch. gladismariae at the genetic level.