New species of Lepidocyrtus (Collembola, Entomobryidae) from Italy with a discussion of characters defining European Lepidocyrtus lignorum-group

Springtails are a group of hexapods whose true diversity is currently underestimated. This is because the morphological characters normally used in species diagnosis do not have the necessary resolution. This situation is especially evident in Entomobryidae, which is currently the most diverse family of springtails. The combination of morphological and molecular data has allowed us to describe a new species of the genus Lepidocyrtus, based on specimens from Northern Italy, as well as to redefine the diagnosis of the European Lepidocyrtus lignorum-group.

The discovery of new Chilean taxa revolutionizes the systematics of Geoplaninae Neotropical land planarians (Platyhelminthes: Tricladida)

Two subfamilies of land planarians (Geoplanidae) are endemic to the Neotropical region, namely Geoplaninae (with 29 genera and 346 nominal species, most of which are from Brazil) and its sister-group Timyminae, with only two Chilean species. The systematics of these groups through morphology and molecular data (COI and 28S rDNA genes), including nine new Chilean species, is re-assessed in this study. The great morphological diversity of the Chilean species is congruent with the molecular trees and, accordingly, five new genera (Adinoplana, Harana, Myoplana, Sarcoplana and Transandiplana) are proposed, each characterized by putative synapomorphies. Seven new tribes are also erected (Adinoplanini, Gusanini, Haranini, Inakayaliini, Myoplanini, Polycladini and Sarcoplanini), each one monogeneric, except Geoplanini (which includes all genera under the current concept of Geoplaninae plus the Chilean Transandiplana) and Sarcoplanini (with Sarcoplana and the already known Mapuplana, Pichidamas and Wallamapuplana). Re-diagnoses of Geoplaninae, Timymini, Gusana, Inakayalia, Polycladus and Pichidamas are proposed and biogeographic remarks on Transandiplana are provided

<i>Corrigendum to</i>: Integrative taxonomy increases biodiversity knowledge of <i>Gusana</i> (Platyhelminthes, Tricladida, Geoplanidae) with the description of four new Chilean species

The Chilean land planarian genus <i>Gusana</i> (Platyhelminthes, Tricladida, Geoplaninae) currently comprises three species that were described in the 19th century. Four new species of the genus are described herein, namely <i>G. hualpensis</i> Carbayo, sp. nov., <i>G. lujanae</i> Almeida & Carbayo, sp. nov., <i>G. melipeucensis</i> Almeida & Carbayo, sp. nov. and <i>G. purensis</i> Bolonhezi, Almeida & Carbayo, sp. nov. An integrative taxonomy approach was adopted by combining morphological (anatomy, histology) and molecular (<i>COI</i> and <i>28S</i> genes) information. Additionally, the monophyletic status of <i>Gusana</i> is investigated and the species are delimited by a recently introduced molecular delimitation method based on pairwise genetic distances. All <i>Gusana</i> species are very similar in attributes such as body shape, dorsal colour pattern and internal organs, namely the pharynx and copulatory apparatus and only differ in the details. <i>Gusana</i> is retrieved as monophyletic and the molecular delimitation method recovered the same species recognised morphologically. A re-diagnosis of the genus and replacement of <i>G. lata</i> into <i>Pseudogeoplana</i> are also proposed. A new role of the penis papilla is also suggested based on the spermatophore found in <i>Gusana lujanae</i>.

New morphological and molecular data reveal an important underestimation of species diversity and indicate evolutionary patterns in European Lepidocyrtus (Collembola : Entomobryidae)

The correct identification of morphological species is a key task for species richness estimation of any ecosystem. Although body colour is a widely used character identifying European Lepidocyrtus species, recent investigations using molecular data have revealed that species delineation using body colour can result in an underestimation of real species diversity because of the presence of cryptic species. Lepidocyrtus violaceus is a European species characterised by its dark violet body colour. Its wide distribution leads us to suspect that several cryptic species can be present within this morphospecies. Since traditional morphological characters have appeared insufficient for real diversity identification in Lepidocyrtus, new morphological characters were needed in order to describe the cryptic diversity detected by molecular data in this genus. Pseudopores are integumentary structures present in all Lepidocyrtus species, but the distribution of these structures has not been properly described in the genus, as well as in Entomobryioidea overall. In the present work we aimed to analyse whether L. violaceus is a monophyletic entity in Europe. Moreover, we aimed to determine if the position and number of pseudopores on the different parts of the body and appendages is a phylogenetically useful character in the identification of the species or superspecific entities. Fourteen populations of L. violaceus from five European countries, and another 25 Lepidocyrtus species from nine European countries have been studied. In total, 208 specimens have been analysed morphologically and half of them were studied molecularly using sequences of the genes COXII and EF-1α. Molecular data revealed that the widely distributed Lepidocyrtus violaceus morphospecies is a polyphyletic entity in Europe. Between 6 and 12 diferent cryptic species have been detected within this European morphospecies, and only the presence of pseudopores on the basal plate of the fourth abdominal segment has been found to be a promising diagnostic character between them. A common basal pattern of pseudopore distribution has been recognised in the European members of the genus, and also a diferential pattern within each European species group. As a general trend, an increase in the number of pseudopores has been detected from the most basal to the most derived species groups in the phylogeny of the genus in Europe.

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.

Five new pseudocryptic land planarian species of Cratera (Platyhelminthes: Tricladida) unveiled through integrative taxonomy

Background

Cratera is a genus of land planarians endemic to the Brazilian Atlantic forest. The species of this genus are distinguished from each other by a series of external and internal characters, nonetheless they represent a challenging taxonomic issue due to the extreme alikeness of the species analysed in the present work. To resolve these difficulties, we have performed morphological analyses and used three nuclear markers (ribosomal 18S and 28S, Elongation Factor, a new anonymous marker named Tnuc813) and two mitochondrial fragments (Cytochrome c oxidase subunit I gene, and a fragment encompasing NADH deshydrogenase subunit 4 gene, trnF and the beginning of the Cytochrome c oxidase I gene) in an integrative taxonomic study.

Methods

To unveil cryptic species, we applied a molecular species delimitation approach based on molecular discovery methods, followed by a validation method. The putative species so delimited were then validated on the basis of diagnostic morphological features.

Results

We discovered and described four new species, namely Cratera assu, C. tui, C. boja, and C. imbiri. A fifth new species, C. paraitinga was not highly supported by molecular evidence, but was described because its morphological attributes are unique. Our study documents for the genus Cratera the presence of a number of highly similar species, a situation that is present also in other genera of land planarians. The high number of poorly differentiated and presumably recent speciation events might be explained by the recent geological history of the area.

The identity of the invasive yellow-striped terrestrial planarian found recently in Europe: Caenoplana variegata (Fletcher amp; Hamilton, 1888) or Caenoplana bicolor (Graff, 1899)?

Terrestrial planarians with a dorsal yellow stripe and dark lateral surfaces and up to 15-20 cm long have been found in several countries in Europe, the earliest in 2008. They are similar to two species originally from Australia, Caenoplana variegata (Fletcher Hamilton, 1888) and C. bicolor (Graff, 1899), both described on external characters only, with no anatomical information. Careful reading suggests that there is no significant difference between the original descriptions. Further: observations on live specimens show considerable variation between individuals and in individuals over time and before and after feeding, negating any distinction between descriptions. Examination of three sectioned specimens shows considerable difference in sexual maturity, though one seems almost fully mature and the reproductive system is described. Molecular results show that specimens from the United Kingdom and Spain are of the same species. It is concluded that the planarians should be referred to as C. variegata, C. bicolor being a junior synonym.

Diet assessment of two land planarian species using high-throughput sequencing data

Geoplanidae (Platyhelminthes: Tricladida) feed on soil invertebrates. Observations of their predatory behavior in nature are scarce, and most of the information has been obtained from food preference experiments. Although these experiments are based on a wide variety of prey, this catalog is often far from being representative of the fauna present in the natural habitat of planarians. As some geoplanid species have recently become invasive, obtaining accurate knowledge about their feeding habits is crucial for the development of plans to control and prevent their expansion. Using high throughput sequencing data, we perform a metagenomic analysis to identify the in situ diet of two endemic and codistributed species of geoplanids from the Brazilian Atlantic Forest: Imbira marcusi and Cephaloflexa bergi. We have tested four different methods of taxonomic assignment and find that phylogenetic-based assignment methods outperform those based on similarity. The results show that the diet of I. marcusi is restricted to earthworms, whereas C. bergi preys on spiders, harvestmen, woodlice, grasshoppers, Hymenoptera, Lepidoptera and possibly other geoplanids. Furthermore, both species change their feeding habits among the different sample locations. In conclusion, the integration of metagenomics with phylogenetics should be considered when establishing studies on the feeding habits of invertebrates.

Untangling Lepidocyrtus (Collembola, Entomobryidae): new molecular data shed light on the relationships of the European groups

European Lepidocyrtus species are usually grouped into five species-groups within two subgenera, Lepidocyrtus s.s. and Lanocyrtus, defined by the distribution of scale covering and dorsal head and body macrochaetotaxy. The discovery of several Lepidocyrtus populations with morphological characters intermediate between two species-groups suggested the need for the present study to test whether molecular data provide support to these groups. The morphology and gene sequences of 110 specimens belonging to 19 species of European Lepidocyrtus have been studied. Our molecular results are congruent with the distribution of the European species into the five groups established in the literature on the basis of morphological characters, but also indicated that subgenus Lanocyrtus is paraphyletic while subgenus Lepidocyrtus s.s. is monophyletic. A new species, Lepidocyrtus intermedius, is described, and a redefinition of European species-groups is proposed based on chaetotaxy.

Species richness in the genus Microplana (Platyhelminthes, Tricladida, Microplaninae) in Europe: as yet no asymptote in sight

This study forms a major step towards a comprehensive morphological and molecular analysis of the species diversity of European microplanid land planarians. It presents a molecular phylogenetic tree on the basis of information from the genes Cox1, 18S, 28S and elongation factor 1-α, and applies molecular and morphological species delimitation methodologies for Microplana specimens sampled over a wide geographic range within Europe. The study suggests that as yet there is no plateau or asymptote in the accumulation curve for European Microplana species, as our results facilitated an integrative delimitation of seven new species as well as the diagnosis of new populations of three already known species and one doubtful or problematic species. In some cases, the new records considerably enlarged the known range of a species. An integrative account is provided of each of these species. Molecular sequence information on newly collected land flatworms may quickly point the planarian systematist to taxa that need to be examined morphologically and thus may considerably reduce laborious and time-consuming histological analyses.

Evolutionary analysis of mitogenomes from parasitic and free-living flatworms

Mitochondrial genomes (mitogenomes) are useful and relatively accessible sources of molecular data to explore and understand the evolutionary history and relationships of eukaryotic organisms across diverse taxonomic levels. The availability of complete mitogenomes from Platyhelminthes is limited; of the 40 or so published most are from parasitic flatworms (Neodermata). Here, we present the mitogenomes of two free-living flatworms (Tricladida): the complete genome of the freshwater species Crenobia alpina (Planariidae) and a nearly complete genome of the land planarian Obama sp. (Geoplanidae). Moreover, we have reanotated the published mitogenome of the species Dugesia japonica (Dugesiidae). This contribution almost doubles the total number of mtDNAs published for Tricladida, a species-rich group including model organisms and economically important invasive species. We took the opportunity to conduct comparative mitogenomic analyses between available free-living and selected parasitic flatworms in order to gain insights into the putative effect of life cycle on nucleotide composition through mutation and natural selection. Unexpectedly, we did not find any molecular hallmark of a selective relaxation in mitogenomes of parasitic flatworms; on the contrary, three out of the four studied free-living triclad mitogenomes exhibit higher A+T content and selective relaxation levels. Additionally, we provide new and valuable molecular data to develop markers for future phylogenetic studies on planariids and geoplanids.

Insights into the origin and distribution of biodiversity in the Brazilian Atlantic forest hot spot: a statistical phylogeographic study using a low-dispersal organism

The relative importance of the processes that generate and maintain biodiversity is a major and controversial topic in evolutionary biology with large implications for conservation management. The Atlantic Forest of Brazil, one of the world's richest biodiversity hot spots, is severely damaged by human activities. To formulate an efficient conservation policy, a good understanding of spatial and temporal biodiversity patterns and their underlying evolutionary mechanisms is required. With this aim, we performed a comprehensive phylogeographic study using a low-dispersal organism, the land planarian species Cephaloflexa bergi (Platyhelminthes, Tricladida). Analysing multi-locus DNA sequence variation under the Approximate Bayesian Computation framework, we evaluated two scenarios proposed to explain the diversity of Southern Atlantic Forest (SAF) region. We found that most sampled localities harbour high levels of genetic diversity, with lineages sharing common ancestors that predate the Pleistocene. Remarkably, we detected the molecular hallmark of the isolation-by-distance effect and little evidence of a recent colonization of SAF localities; nevertheless, some populations might result from very recent secondary contacts. We conclude that extant SAF biodiversity originated and has been shaped by complex interactions between ancient geological events and more recent evolutionary processes, whereas Pleistocene climate changes had a minor influence in generating present-day diversity. We also demonstrate that land planarians are an advantageous biological model for making phylogeographic and, particularly, fine-scale evolutionary inferences, and propose appropriate conservation policies.