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X-ray computed tomography applied to the taxonomic study of rare material: redescription of six Brazilian terrestrial flatworm species

Grant number: 17/05760-4
Support Opportunities:Scholarships in Brazil - Master
Effective date (Start): June 01, 2017
Effective date (End): March 31, 2019
Field of knowledge:Biological Sciences - Zoology - Taxonomy of Recent Groups
Acordo de Cooperação: Coordination of Improvement of Higher Education Personnel (CAPES)
Principal Investigator:Fernando Jesús Carbayo Baz
Grantee:Marcos Santos Silva
Host Institution: Escola de Artes, Ciências e Humanidades (EACH). Universidade de São Paulo (USP). São Paulo , SP, Brazil


Terrestrial flatworms (Geoplanidae, Tricladida, Platyhelminthes) are free living animals. They have a dorso-ventrally flattened body and measure a few centimetres in length. They live in humid environments on the soil, sheltered under fallen logs, rocks and litter.Approximately 170 Brazilian species are known. Most of them were described throughout the 20th century. Several species described up until now are in a dubious taxonomic position and require revision. These species are gathered in the collective genus Pseudogeoplana Ogren & Kawakatsu, 1990 (Geoplaninae). Most of the taxonomically important traits of the species of Pseudogeoplana remain unknown due to lack of study or because the type-specimens are immature. Recently, a set of type-specimens of Brazilian land planarians described by Schirch in 1929 was rediscovered in the Museu Nacional do Rio de Janeiro. They represent species that have never been restudied: Pseudogeoplana arpi, P. bonita, P. blaseri. P. bresslaui. P. doederleine and P. wetzeli. The specimens are unsectioned and preserved in ethanol, that is, their internal morphology is still unknown. In this project, a taxonomic revision of these species will be addressed. Initial observations revealed that the specimens are mature, so, they possess most important taxonomic traits. To ensure integrity of such rare material, non-destructive microcomputed tomography (mCT) will preferentially be applied. mCT is a 3D image reconstruction technique based on the combination of multiple x-ray images of the object in study, taken from various angles. The obtained images generate virtual reconstructions with a resolution of up to 60 nm. If mCT turned out to be unadequate for any specimen, traditional histological technique will be adopted. The species will be redescribed from the morphological data obtained from both techniques, and subsequently their taxonomic position will be reevaluated. (AU)

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