X-ray microcomputed tomography applied to the taxonomic study of rare material: redescriptions of seven of Schirch's Brazilian species of land planarians (Geoplanidae, Platyhelminthes)

In 2016, the type-material of ten of the 15 Brazilian land planarians (Platyhelminthes, Tricladida, Geoplanidae) described by Schirch (1929) was discovered deposited in the Museu Nacional do Rio de Janeiro (MNRJ). Schirch only described the external morphology of these species, all originally placed in the genus Geoplana. By the 1930s and 1950s Geoplana itatiayana, G. plana, and G. rezendei underwent taxonomic revision based on the study of non-type specimens. The remaining 12 species also underwent a taxonomic revision but only based on the literature. Current names of these species are Geoplana goettei, Pseudogeoplana arpi, Ps. blaseri, Ps. bonita, Ps. bresslaui, Ps. cardosi, Ps. doederleini, Ps. lumbricoides, Ps. obscura, Ps. riedeli, Ps. theresopolitana, and Ps. wetzeli. The species Geoplana maximiliani sensu Schirch (1929) was renamed as Ps. schirchi Ogren & Kawakatsu, 1990.

The present study reports a taxonomic revision of seven of Schirch's species using type material, namely Obama itatiayana, Pasipha plana, Pseudogeoplana arpi, Ps. bresslaui, Ps. doederleini, Ps. schirchi and Ps. wetzeli. Additional specimens of some of these species were also examined. Morphological data from histological preparations and from virtual sections were obtained through a non-destructive technique of X-ray computed microtomography (µCT). This approach resulted in the preservation of the entire body of at least one type-specimen of each species, and the holotype of Ps. bresslaui. Conspecificity of O. itatiayana and P. plana was confirmed, as previously reported in the literature. It is also proposed that Ps. bresslaui belongs to the genus Paraba, while the other species should remain in Pseudogeoplana, since type-specimens are either immature, poorly preserved or simply lost.