Planarian Species Research Articles

Can morphometrics help us predict the diet of land planarians?

AbstractThe 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.

Hammerhead flatworms (Platyhelminthes, Geoplanidae, Bipaliinae): mitochondrial genomes and description of two new species from France, Italy, and Mayotte.

BackgroundNew records of alien land planarians are regularly reported worldwide, and some correspond to undescribed species of unknown geographic origin. The description of new species of land planarians (Geoplanidae) should classically be based on both external morphology and histology of anatomical structures, especially the copulatory organs, ideally with the addition of molecular data.MethodsHere, we describe the morphology and reproductive anatomy of a species previously reported as Diversibipalium “black”, and the morphology of a species previously reported as Diversibipalium “blue”. Based on next generation sequencing, we obtained the complete mitogenome of five species of Bipaliinae, including these two species.ResultsThe new species Humbertium covidum n. sp. (syn: Diversibipalium “black” of Justine et al., 2018) is formally described on the basis of morphology, histology and mitogenome, and is assigned to Humbertium on the basis of its reproductive anatomy. The type-locality is Casier, Italy, and other localities are in the Department of Pyrénées-Atlantiques, France; some published or unpublished records suggest that this species might also be present in Russia, China, and Japan. The mitogenomic polymorphism of two geographically distinct specimens (Italy vs France) is described; the cox1 gene displayed 2.25% difference. The new species Diversibipalium mayottensis n. sp. (syn: Diversibipalium “blue” of Justine et al., 2018) is formally described on the basis of external morphology and complete mitogenome and is assigned to Diversibipalium on the basis of an absence of information on its reproductive anatomy. The type- and only known locality is the island of Mayotte in the Mozambique Channel off Africa. Phylogenies of bipaliine geoplanids were constructed on the basis of SSU, LSU, mitochondrial proteins and concatenated sequences of cox1, SSU and LSU. In all four phylogenies, D. mayottensis was the sister-group to all the other bipaliines. With the exception of D. multilineatum which could not be circularised, the complete mitogenomes of B. kewense, B. vagum, B. adventitium, H. covidum and D. mayottensis were colinear. The 16S gene in all bipaliine species was problematic because usual tools were unable to locate its exact position.ConclusionNext generation sequencing, which can provide complete mitochondrial genomes as well as traditionally used genes such as SSU, LSU and cox1, is a powerful tool for delineating and describing species of Bipaliinae when the reproductive structure cannot be studied, which is sometimes the case of asexually reproducing invasive species. The unexpected position of the new species D. mayottensis as sister-group to all other Bipaliinae in all phylogenetic analyses suggests that the species could belong to a new genus, yet to be described.

Culturomics revealed the bacterial constituents of the microbiota of a 10-year-old laboratory culture of planarian species S. mediterranea

The planarian species Schmidtea mediterranea is a flatworm living in freshwater that is used in the research laboratory as a model to study developmental and regeneration mechanisms, as well as antibacterial mechanisms. However, the cultivable microbial repertoire of the microbes comprising its microbiota remains unknown. Here, we characterized the bacterial constituents of a 10-year-old laboratory culture of planarian species S. mediterranea via culturomics analysis. We isolated 40 cultivable bacterial species, including 1 unidentifiable species. The predominant phylum is Proteobacteria, and the most common genus is Pseudomonas. We discovered that parts of the bacterial flora of the planarian S. mediterranea can be classified as fish pathogens and opportunistic human pathogens.

Regeneration of Planarian Auricles and Reestablishment of Chemotactic Ability.

Detection of chemical stimuli is crucial for living systems and also contributes to quality of life in humans. Since loss of olfaction becomes more prevalent with aging, longer life expectancies have fueled interest in understanding the molecular mechanisms behind the development and maintenance of chemical sensing. Planarian flatworms possess an unsurpassed ability for stem cell-driven regeneration that allows them to restore any damaged or removed part of their bodies. This includes anteriorly-positioned lateral flaps known as auricles, which have long been thought to play a central role in chemotaxis. The contribution of auricles to the detection of positive chemical stimuli was tested in this study using Girardia dorotocephala, a North American planarian species known for its morphologically prominent auricles. Behavioral experiments staged under laboratory conditions revealed that removal of auricles by amputation leads to a significant decrease in the ability of planarians to find food. However, full chemotactic capacity is observed as early as 2 days post-amputation, which is days prior from restoration of auricle morphology, but correlative with accumulation of ciliated cells in the position of auricle regeneration. Planarians subjected to x-ray irradiation prior to auricle amputation were unable to restore auricle morphology, but were still able to restore chemotactic capacity. These results indicate that although regeneration of auricle morphology requires stem cells, some restoration of chemotactic ability can still be achieved in the absence of normal auricle morphology, corroborating with the initial observation that chemotactic success is reestablished 2-days post-amputation in our assays. Transcriptome profiles of excised auricles were obtained to facilitate molecular characterization of these structures, as well as the identification of genes that contribute to chemotaxis and auricle development. A significant overlap was found between genes with preferential expression in auricles of G. dorotocephala and genes with reduced expression upon SoxB1 knockdown in Schmidtea mediterranea, suggesting that SoxB1 has a conserved role in regulating auricle development and function. Models that distinguish between possible contributions to chemotactic behavior obtained from cellular composition, as compared to anatomical morphology of the auricles, are discussed.

Let it rip: the mechanics of self-bisection in asexual planarians determines their population reproductive strategies

Asexual freshwater planarians reproduce by transverse bisection (binary fission) into two pieces. This process produces a head and a tail, which fully regenerate within 1–2 weeks. How planarians split into two offspring—using only their musculature and substrate traction—is a challenging biomechanics problem. We found that three different species, Dugesia japonica, Girardia tigrina and Schmidtea mediterranea, have evolved three different mechanical solutions to self-bisect. Using time lapse imaging of the fission process, we quantitatively characterize the main steps of division in the three species and extract the distinct and shared key features. Across the three species, planarians actively alter their body shape, regulate substrate traction, and use their muscles to generate tensile stresses large enough to overcome the ultimate tensile strength of the tissue. Moreover, we show that how each planarian species divides dictates how resources are split among its offspring. This ultimately determines offspring survival and reproductive success. Thus, heterospecific differences in the mechanics of self-bisection of individual worms explain the observed differences in the population reproductive strategies of different planarian species.

The complete mitochondrial genome of a planarian flatworm Girardia tigrina (Tricladida: Dugesiidae)

Girardia tigrina, a freshwater planarian species native to America and introduced to other continents, has been usually used as model organism in many research fields of biology. In this study, we determined the complete mitochondrial genome of G. tigrina using next-generation sequencing (NGS). The complete mitogenome was 15,938 bp in length, with 36 genes, including 12 protein-coding genes, 2 ribosomal RNAs and 22 transfer RNAs, and ATP8 was absent in the mitogenome of G. tigrina as in the mitogenomes of some other flatworms. The maximum-likelihood phylogenetic tree suggested that G. tigrina was closely related to genus Dugesia in the clade of Tricladida.

A new species of terrestrial planarian of the genus Microplana (Platyhelminthes: Turbellaria; Tricladida: Continenticola) from Yorkshire, United Kingdom; with a discussion of Microplana humicola Vejdovsky 1890

Two mostly white terrestrial planarians, about 7 mm long, found in a garden in Yorkshire, UK, are described. They have a single pair of eyes and both specimens are fully mature, with a single pair of ovaries, several testes, a conical penis papilla and a genito-intestinal duct, characters of the genus Microplana, but differ in color and size from other species of the genus and are described as Microplana edwardsi sp. nov.

Planarians, a Neglected Component of Biodiversity in Groundwaters

Underground waters are still one of the most important sources of drinking water for the planet. Moreover, the fauna that inhabits these waters is still little known, even if it could be used as an effective bioindicator. Among cave invertebrates, planarians are strongly suited to be used as a study model to understand adaptations and trophic web features. Here, we show a systematic literature review that aims to investigate the studies done so far on groundwater-dwelling planarians. The research was done using Google Scholar and Web of Science databases. Using the key words “Planarian cave” and “Flatworm Cave” we found 2273 papers that our selection reduced to only 48, providing 113 usable observations on 107 different species of planarians from both groundwaters and springs. Among the most interesting results, it emerged that planarians are at the top of the food chain in two thirds of the reported caves, and in both groundwaters and springs they show a high variability of morphological adaptations to subterranean environments. This is a first attempt to review the phylogeny of the groundwater-dwelling planarias, focusing on the online literature. The paucity of information underlines that scarce attention has been dedicated to these animals. Further revisions, including old papers and books, not available online will be necessary.

A new species of Pacifides from the Western Pacific Coast and the first fully freshwater species of the maricolan planarian genus Paucumara (Platyhelminthes, Tricladida, Maricola)

The present paper describes two new Chinese species of maricolan planarians through an integrated approach, including morphological, histological and molecular phylogenetic analyses. One new species forms the third species of the genus Pacifides and represents the first record of this genus from the Western Pacific. Further we document a third, new species of the genus Paucumara that is fully restricted to freshwater habitats, as it occurs on the shores of the Jialing River in Chongqing municipality far into the interior of China. Molecular phylogenetic analyses enabled us to determine, for the first time, the position of the genus Pacifides in the phylogenetic tree of the marine triclads. We also provide information on the feeding and reproduction of the new species of Pacifides. The paper concludes with two speculative scenarios on the evolutionary history that may have led to the present-day far inland occurrence and freshwater ecology of the new species of Paucumara; one scenario involves tectonic uplift-driven speciation and niche evolution, while the other invokes passive upstream dispersal via the Yangtze River. http://www.zoobank.org/urn:lsid:zoobank.org:act:43AE0799-EF9E-452F-99E5-AEE2271D3EA9 http://www.zoobank.org/urn:lsid:zoobank.org:act:79AD55BC-CAA1-4769-853E-7B11CC6ED1A7

Revision and description of six species of Choeradoplana (Platyhelminthes, Tricladida), with an emendation to the genus.

Living representatives of the Neotropical genus Choeradoplana Graff, 1896 (Geoplaninae, Tricladida, Platyhelminthes) are easily recognized by the typical shape of the head which is laterally expanded, rolled-up, and ventrally provided with two glandular cushions. In this study, the morphology and phylogeny (cytochrome C oxidase subunit I gene) of several species of land planarians are taxonomically investigated. Four of the six species studied are new to science, namely: Ch. eudoxiae Silva & Carbayo, sp. nov., Ch. claudioi Lago-Barcia & Carbayo, sp. nov., Ch. onae Lago-Barcia & Carbayo, sp. nov., and Ch. riutortae Lago-Barcia & Carbayo, sp. nov. The species Choeradoplana albonigra and Ch. eudoxiae deviate from the usual body shape pattern in that the head does not present lateral expansions nor glandular cushions, becoming indistinguishable from its sister genus Cephaloflexa. Pseudogeoplana tristriata (Schultze & Müller, 1857) is also redescribed from a newly collected specimen and was discovered to be a member of Choeradoplana. Graff (1899) also studied another specimen that was considered to be conspecific with P. tristriata; however, in this new it is concluded that it is not conspecific but rather a new species. The name Pseudogeoplana aevipandemiae Lago-Barcia & Carbayo, sp. nov. is suggested for Graff’s specimen.

Enhancing the still scattered knowledge on the taxonomic diversity of freshwater triclads (Platyhelminthes: Dugesiidae) in caves from two Brazilian Biomes

ABSTRACT Recent studies have recorded new species of freshwater planarians in caves of the biomes Amazonia, Atlantic Forest, Cerrado, and Caatinga. Herein we contribute to enhancing this knowledge by describing three new cave-dwelling species of Girardia from three different cave systems situated in two biomes (Atlantic Forest and Cerrado) in eastern Brazil. Girardia spelaea sp. n., from a limestone cave, is eyeless and shows a whitish body. The other two species, G. asymmetrica sp. n. and G. ibitipoca sp. n., from limestone and quartzite caves, show pigmented bodies and eyes. The three species are characterized by dorsal and/or dorsoventral testes and a bulbar cavity with forked ental portions, varying from round or ovoid to elongate. Each new species is easily recognized by a unique combination of characters of their external morphology and reproductive system. Girardia spelaea is probably a troglobitic species and the two other species may be trogrophiles, all of them with a restricted known distribution. urn:lsid:zoobank.org:act:AC4F9F3C-EF6D-4BB8-ACBA-EB5812036314 urn:lsid:zoobank.org:act:6BD22CDA-99E7-46DC-98D6-8FD1ECB46320 urn:lsid:zoobank.org:act:C5D97034-9F1A-4020-9635-DE76202A85C1

A Novel Taxon of Monosegmented Double-Stranded RNA Viruses Endemic to Triclad Flatworms.

Freshwater planarians, flatworms from order Tricladida, are experimental models of stem cell biology and tissue regeneration. An aspect of their biology that remains less well studied is their relationship with viruses that may infect them. In this study, we identified a taxon of monosegmented double-stranded RNA (dsRNA) viruses in five planarian species, including the well-characterized model Schmidtea mediterranea Sequences for the S. mediterranea virus (abbreviated SmedTV for S. mediterranea tricladivirus) were found in public transcriptome data from multiple institutions, indicating that SmedTV is prevalent in S. mediterranea lab colonies, though without causing evident disease. The presence of SmedTV in discrete cells was shown through in situ hybridization methods for detecting the viral RNA. SmedTV-staining cells were found to be concentrated in neural structures (eyes and brain) but were also scattered in other worm tissues as well. In contrast, few SmedTV-staining cells were seen in stem cell compartments (also consistent with RNA sequencing data) or early blastema tissue. RNA interference (RNAi) targeted to the SmedTV sequence led to apparent cure of infection, though effects on worm health or behavior were not observed. Efforts to transmit SmedTV horizontally through microinjection were unsuccessful. Based on these findings, we conclude that SmedTV infects S. mediterranea in a persistent manner and undergoes vertical transmission to progeny worms during serial passage in lab colonies. The utility of S. mediterranea as a regeneration model, coupled with the apparent capacity of SmedTV to evade normal host immune/RNAi defenses under standard conditions, argues that further studies are warranted to explore this newly recognized virus-host system.IMPORTANCE Planarians are freshwater flatworms, related more distantly to tapeworms and flukes, and have been developed as models to study the molecular mechanisms of stem cell biology and tissue regeneration. These worms live in aquatic environments, where they are likely to encounter a variety of viruses, bacteria, and eukaryotic organisms with pathogenic potential. How the planarian immune system has evolved to cope with these potential pathogens is not well understood, and only two types of planarian viruses have been described to date. Here, we report discovery and inaugural studies of a novel taxon of dsRNA viruses in five different planarian species. The virus in the best-characterized model species, Schmidtea mediterranea, appears to persist long term in that host while avoiding endogenous antiviral or RNAi mechanisms. The S. mediterranea virus-host system thus seems to offer opportunity for gaining new insights into host defenses and their evolution in an important lab model.

A new species of alien terrestrial planarian in Spain: Caenoplana decolorata.

Terrestrial planarians found in a plant nursery in Spain in 2012 are described as a new species, Caenoplana decolorata. Dorsally they are mahogany brown with a cream median line. Ventrally they are pastel turquoise fading to brown laterally. Molecular data indicate that they are a member of the genus Caenoplana, but that they differ from other Caenoplana species found in Europe. One mature specimen has been partially sectioned, and the musculature and copulatory apparatus is described, confirming the generic placement but distinguishing the species from other members of the genus. It is probable that the species originates from Australia.

New records of the giant planarian Polycladus gayi Blanchard, 1845 (Platyhelminthes: Geoplanidae) with notes on its conservation biology.

Land planarians (Tricladida:Geoplanidae) comprise about 910 species distributed in four subfamilies and can be found on all continents except Antarctica (Sluys Riutort 2018; Sluys 2019). The Neotropical region possesses nearly 31% of all the described terrestrial planarian species, most of them belonging to the subfamily Geoplaninae (Sluys 1999; Grau Carbayo 2010). Land planarians are mostly habitat-specialists, living in the humid soils of native forest, and predating on invertebrates like earthworms, isopods, mollusks and harvestmen, among others (Ogren 1995; Carbayo Leal-Zanchet 2003; Boll Leal-Zanchet 2016). Although most planarian species seem to be physiologically sensitive, for example to environmental moisture, a few land planarian genera like Bipalium Stimpson and Obama Carbayo et al., have successfully invaded many habitats, even in highly perturbed areas (Kawaguti 1932; Sluys 2019). Therefore, some of these invertebrate species appear to be good candidates as habitat quality bioindicators according to some authors (Sluys 1998; Gerlach et al., 2013; Negrete et al., 2014).

Planarian Scrunching as a Quantitative Behavioral Readout for Noxious Stimuli Sensing

Freshwater planarians normally glide smoothly through ciliary propulsion on their ventral side. Certain environmental conditions, however, can induce musculature-driven forms of locomotion: peristalsis or scrunching. While peristalsis results from a ciliary defect, scrunching is independent of cilia function and is a specific response to certain stimuli, including amputation, noxious temperature, extreme pH, and ethanol. Thus, these two musculature-driven gaits are mechanistically distinct. However, they can be difficult to distinguish qualitatively. Here, we provide a protocol for inducing scrunching using various physical and chemical stimuli. We detail the quantitative characterization of scrunching, which can be used to distinguish it from peristalsis and gliding, using freely available software. Since scrunching is a universal planarian gait, albeit with characteristic species-specific differences, this protocol can be broadly applied to all species of planarians, when using appropriate considerations. To demonstrate this, we compare the response of the two most popular planarian species used in behavioral research, Dugesia japonica and Schmidtea mediterranea, to the same set of physical and chemical stimuli. Furthermore, the specificity of scrunching allows this protocol to be used in conjunction with RNA interference and/or pharmacological exposure to dissect the molecular targets and neuronal circuits involved, potentially providing mechanistic insight into important aspects of nociception and neuromuscular communication.

Anticancer effects of an extract from a local planarian species on human acute myeloid leukemia HL-60 cells in vitro

Current anti-cancer drugs can cause many undesirable side effects to patients. Thus, there is a constant need to develop alternative therapeutic drugs. Bioactive compounds derived from natural products including animals, plants and microorganisms are being actively studied as sources for anticancer treatments. Freshwater planarians are important models for stem cell research and regeneration. However, to date, no studies on the biological activities of planaria extracts on cancer have been published. The aim of this study was to examine the potential antitumoral activity of the extract from planaria species-Malta (PSM) on human acute myeloid leukemia (AML) HL-60 cells. Antiproliferative activity was studied in terms of proliferation, apoptosis and differentiation. The expression of genes involved in the regulation of these important cellular processes was also analyzed using real-time PCR. PSM extract exhibited a selective cytotoxic effect on HL-60 cells when compared to normal lymphocytes. Furthermore, cell cycle analysis and Annexin V/PI assay showed that the extract induced apoptosis in HL-60 cells. The PSM extract induced myeloid differentiation with HL-60 cells showing a decreased nucleo/cytoplasmic ratio, an increase in nitroblue tetrazolium-positive cells, and CD11b- and CD14-positive cells. Finally, we also found that the PSM extract increased the expression of CEBPA, CEBPB, CEBPE, SPI1, BAX, CDKN1A and CDKN2C; whereas it reduced the expression of c-MYC and BCL2.This is the first study to reveal the antiproliferative, cytotoxic, and differentiation potential of PSM on HL-60 cells and suggests that it may have considerable potential for development as a novel natural product-based anticancer agent against AML.

Dugesia hepta and Dugesia benazzii (Platyhelminthes: Tricladida): two sympatric species with occasional sex?

Dugesia hepta Pala, Casu & Vacca, 1981 and Dugesia benazzii Lepori, 1951 are two freshwater planarian species from the islands of Corsica and Sardinia. Dugesia hepta is endemic of Sardinia and distributed in four northern hydrographic basins where it co-occurs with D. benazzii, which has a wider Tyrrhenian distribution. Although these species have been broadly studied—especially D. benazzii—as regards to their variety of reproductive patterns as well as for their karyological diversity, little is known about them from a molecular phylogenetic perspective. For the first time, we present a molecular phylogenetic tree of the two species and their populations based on two molecular markers—one mitochondrial, Cox1, and one nuclear, Dunuc12. Our results not only confirm that both species are molecularly distinct but also show that D. benazzii’s Corsican and Sardinian populations could belong to separate species. Furthermore, we present the first demonstration of a natural hybridization between different species in the genus Dugesia on the basis of molecular data.

Dugesia japonica is the best suited of three planarian species for high-throughput toxicology screening

High-throughput screening (HTS) using new approach methods is revolutionizing toxicology. Asexual freshwater planarians are a promising invertebrate model for neurotoxicity HTS because their diverse behaviors can be used as quantitative readouts of neuronal function. Currently, three planarian species are commonly used in toxicology research: Dugesia japonica, Schmidtea mediterranea, and Girardia tigrina. However, only D. japonica has been demonstrated to be suitable for HTS. Here, we assess the two other species for HTS suitability by direct comparison with D. japonica. Through quantitative assessments of morphology and multiple behaviors, we assayed the effects of 4 common solvents (DMSO, ethanol, methanol, ethyl acetate) and a negative control (sorbitol) on neurodevelopment. Each chemical was screened blind at 5 concentrations at two time points over a twelve-day period. We obtained two main results: First, G. tigrina and S. mediterranea planarians showed significantly reduced movement compared to D. japonica under HTS conditions, due to decreased health over time and lack of movement under red lighting, respectively. This made it difficult to obtain meaningful readouts from these species. Second, we observed species differences in sensitivity to the solvents, suggesting that care must be taken when extrapolating chemical effects across planarian species. Overall, our data show that D. japonica is best suited for behavioral HTS given the limitations of the other species. Standardizing which planarian species is used in neurotoxicity screening will facilitate data comparisons across research groups and accelerate the application of this promising invertebrate system for first-tier chemical HTS, helping streamline toxicology testing.

Multi-gene phylogeny of Tetrahymena refreshed with three new histophagous species invading freshwater planarians

Planarians represent an insufficiently explored group of aquatic invertebrates that might serve as hosts of histophagous ciliates belonging to the hymenostome genus Tetrahymena. During our extensive research on freshwater planarians, parasitic tetrahymenas were detected in two of the eight planarian species investigated, namely, in Dugesia gonocephala and Girardia tigrina. Using the 16S and 18S rRNA genes as well as the barcoding cytochrome oxidase subunit I, one ciliate species was identified as T. scolopax and three species were recognized as new forms: T. acanthophora, T. dugesiae, and T. nigricans. Thus, 25% of the examined planarian taxa are positive for Tetrahymena species and three of them represent new taxa, indicating a large undescribed ciliate diversity in freshwater planarians. According to phylogenetic analyses, histophagous tetrahymenas show a low phylogenetic host specificity. Although T. acanthophora, T. dugesiae, and T. scolopax clustered together within the "borealis" clade, the former species has been detected exclusively in G. tigrina, while the two latter species only in D. gonocephala. Tetrahymena nigricans, which has been isolated only from G. tigrina, was classified within the "paravorax" clade along with T. glochidiophila which feeds on glochidia. The present phylogenetic reconstruction of ancestral life strategies suggested that the last common ancestor of the family Tetrahymenidae was free-living, unlike the progenitor of the subclass Hymenostomatia which was very likely parasitic. Consequently, there were at least seven independent shifts back to parasitism/histophagy within Tetrahymena: one each in the "paravorax" and "australis" clades and at least five transfers back to parasitism in the "borealis" clade.

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.