Molecular phylogenetics facilitates the first historical biogeographic analysis of the hammerhead worms (Platyhelminthes: Tricladida: Bipaliinae), with the description of twelve new species and two new genera

The hammerhead worms constitute a land planarian subfamily (Platyhelminthes: Tricladida: Bipaliinae) that is popular among natural historians as well as citizen scientists due to their characteristic semi-lunar-shaped head, the striking colours of many species, and the worldwide presence of introduced species, which has raised much concern about their putative impact on the receiving ecosystems. Despite such current awareness, the majority of Bipaliinae species was described before the second half of the 20th century. Over the past few decades, description of new species has been rather scarce. In the present paper, we describe twelve new species and two new genera from Madagascar, Borneo, and Japan, mainly using specimens that form part of the collections of Naturalis Biodiversity Center, Leiden. Species identification has been based on morphology, inner anatomy, and, when available, molecular information. Our molecular phylogenetic tree suggests that either Malagasy or Bornean representatives form the sister-group to the rest of Bipaliinae. The phylogeny suggests also that the Bipaliinae comprises several new and, as yet, undescribed genera. Although the geographical origin of the subfamily is uncertain and may involve either Madagascar or the Bornean region, a molecular time-calibration of the phylogenetic tree indicated that the origin of the Bipaliinae may date back to about 253 Mya, placing its origin near the Permian-Triassic transition and, thus, on Pangea.

First molecular phylogeny of the freshwater planarian genus Girardia (Platyhelminthes: Tricladida) unveils hidden taxonomic diversity and initiates resolution of its historical biogeography

The genus Girardia (Platyhelminthes: Tricladida) comprises several species of which some have spread from their original areas of distribution in the Americas to other parts of the globe. Due to great anatomical similarity between species, morphology-based phylogenetic analyses have struggled to resolve the affinities between species and species-groups. This problem is exacerbated by the fact that populations of Girardia may show only asexual reproduction by fissiparity and, thus, do not exhibit a copulatory apparatus, which hampers taxonomic identification of phylogenetic characters. In the present work, this problem has been resolved by constructing a molecular phylogeny of the genus. Although our samples do not include representatives of all known species, they cover a large part of the original distributional range of the genus Girardia. Our phylogenetic results suggest the presence of two main clades, which are genetically and karyologically highly differentiated. North and South American populations of G. tigrina actually constitute two sibling species that are not even closely related. The South American form is here described as a new species. The phylogenetic tree brings to light that Girardia arose on the South American portion of Gondwanaland, from which it, subsequently, dispersed to the Nearctic Region, probably more than once.

Addition to the known diversity of Chinese freshwater planarians: integrative description of a new species of Dugesia Girard, 1850 (Platyhelminthes, Tricladida, Dugesiidae)

The present paper describes a new species of freshwater flatworm of the genus Dugesia from Guizhou province, China, based on an integrative approach, combining morphological, histological and molecular information. This new species, Dugesia gemmulata Sun & Wang, sp. nov., is characterized by the ventral part of the most posterior section of the bursal canal being provided with a voluminous, ellipsoidal muscular swelling; sac- or egg-shaped seminal vesicle situated near the ventral body surface in anterior portion of the penis bulb; postero-dorsal wall of seminal vesicle communicating with a narrow duct that first runs almost vertically but then shows a postero-dorsally directed loop before connecting with a small diaphragm; an ejaculatory duct opening terminally or subterminally; an asymmetrical penis papilla, with its dorsal lip being provided with a bump; oviducts opening asymmetrically into female copulatory apparatus, with the left oviduct opening into the common atrium and the right oviduct opening into the vaginal section of the bursal canal. Molecular phylogenetic analyses revealed that the new species belongs to a clade comprising species from the Australasian and Oriental regions, while it shares a sister-group relationship with D. umbonata Song & Wang, 2020, a species characterized by a muscular swelling on the dorsal side of its bursal canal.

Two new species of Dugesia (Platyhelminthes, Tricladida, Dugesiidae) from the subtropical monsoon region in Southern China, with a discussion on reproductive modalities

Background

Freshwater planarians of the genus Dugesia (Platyhelminthes, Tricladida, Dugesiidae) are distributed in a major part of the Old World and Australia, although until recently only very few species were known from China.

Results

Two new species of Dugesia from Southern China are described on the basis of an integrative taxonomic approach. BI and ML phylogenetic trees based on the independent genes and on the concatenated dataset had similar topologies, only differing in some nodes that were weakly supported. Phylogenetic trees based on the concatenated dataset revealed that D. adunca Chen & Sluys, sp. nov. and D. tumida Chen & Sluys, sp. nov. are not closely related and belong to different clades. The two new species occupy separate long branches with high support values and, thus, are well-differentiated from their congeners. Separate species status of D. adunca and D. tumida is supported also by the genetic distances between the species included in our analysis, albeit that COI distances varied greatly among species. Dugesia adunca from Guangxi Province is characterized by the following features: living mature animals rather small; asymmetrical openings of the oviducts into the bursal canal; penis papilla with shape of an aquiline bill, albeit with a blunt tip; asymmetrical penis papilla, with a large antero-dorsal lip and a much smaller ventro-posterior lip; very large seminal vesicle, provided with trabeculae; small diaphragm; mixoploid karyotype with diploid complements of 2n = 2x = 16 and triploid complements of 2n = 3x = 24, with all chromosomes being metacentric. Dugesia tumida from Guangdong Province is characterized by a penis papilla provided with a large, symmetrical penial valve from the middle of which arises the small, distal section of the papilla; a duct intercalated between the seminal vesicle and the small diaphragm; ventrally displaced ejaculatory duct curving upwards before opening to the exterior; penis papilla highly asymmetrical, having a slim and long ventral portion and a short and stubby dorsal part; vasa deferentia separately opening into antero-dorsal portion of seminal vesicle; oviducts openings symmetrically into ventral portion of the bursal canal, near its opening into the atrium; mixoploid karyotype, with diploid chromosome portraits of 2n = 2x = 16, and triploid complements of 2n = 3x = 24, with all chromosomes being metacentric. In the context of the various kinds of mixoploidy and the sexualization of specimens, reproductive modalities within the genus Dugesia are shortly discussed.

Conclusion

Molecular, morphological, and karyological markers show that the two populations examined represent members of the genus Dugesia and constitute two new, distinct species.

Amphibioplanidae: a new branch and family on the phylogenetic tree of the triclad flatworms (Platyhelminthes: Tricladida), represented by a species from Sardinian caves with a remarkable lifestyle

In this study we document the phylogenetic position and the anatomical and ecological characteristics of a new taxon of cave-dwelling triclad flatworms. This species from the Mediterranean island of Sardinia (Italy) forms a separate branch on the phylogenetic tree of the planarians for which we proposed a new genus and placed it in a new family. Molecular analysis reveals a sister-group relationship between this new family, Amphibioplanidae, and the family Dimarcusidae of the suborder Cavernicola, together constituting the sister-group of the suborder Maricola. The new species Amphibioplana onnisi Stocchino & Sluys, sp. nov. is slender and furnished with an epidermis that is abundantly and uniformly provided with cilia and rhabdites. The pharynx presents an oesophageal projection pointing into the pharynx lumen. Ovaries are located far behind the brain. A relatively long common oviduct opens into the diverticulum of the bursal canal. The probursal copulatory bursa is lined with a highly vacuolated, syncytial epithelium. The habitat of this species is formed by groundwater in microcrevices of the epikarst and temporary cave pools, but the animals can survive in a basically terrestrial environment, thus exhibiting an amphibious lifestyle. Some tentative scenarios are discussed for the evolution of the new taxon and for the presence of the new species in three separate caves in Sardinia.

Integrative taxonomy unveils a new species of Dugesia (Platyhelminthes, Tricladida, Dugesiidae) from the southern portion of the Taihang Mountains in northern China, with the description of its complete mitogenome and an exploratory analysis of mitochondrial gene order as a taxonomic character

A new species of Dugesia (Platyhelminthes, Tricladida, Dugesiidae) from northern China is described on the basis of an integrative approach, involving morphology, karyology, histology, molecular distance, molecular phylogeny, and mitochondrial gene order. Here, we present the complete mitogenome of the new species Dugesia constrictiva Chen & Dong, sp. nov. This new species is mainly characterized by the presence of the following features: asymmetrical openings of the oviducts; large, cuboidal copulatory bursa; vasa deferentia opening through the ventro-lateral wall of the seminal vesicle; laterally compressed seminal vesicle; ventrally displaced ejaculatory duct, opening at the blunt tip of the penis papilla; long duct intercalated between seminal vesicle and diaphragm; chromosome complement diploid, with 16 metacentric chromosomes; mitochondrial gene order as follows: cox1-E-nad6-nad5-S2-D-R-cox3-I-Q-K-atp6-V-nad1-W-cox2-P-nad3-A-nad2-M-H-F-rrnS-L1-Y-G-S1-rrnL-L2-T-atp8-C-N-cob-nad4l-nad4. In triclads, mitochondrial gene order is considerably conserved between freshwater planarians and land flatworms, whereas it is variable between marine planarians and both freshwater and land flatworms. The secondary structures of tRNAs are all equipped with 4 arms, excepting tRNA S1 and tRNA S2, which lack the D arm and have excessively enlarged loops. Numerous transpositions of tRNA are present between D. constrictiva and its congeners. Mitochondrial gene arrangements may form a new, additional tool for taxonomic studies. The phylogenetic tree based on analysis of the mitochondrial genome basically corroborates current classification of the higher taxa of planarian flatworms.

Two new species of Dugesia (Platyhelminthes, Tricladida, Dugesiidae) from the tropical monsoon forest in southern China

Two new species of the genus Dugesia (Platyhelminthes, Tricladida, Dugesiidae) from the tropical monsoon forest in southern China are described on the basis of an integrative taxonomic study involving morphology, karyology, histology, and molecular analyses. The new species Dugesiacircumcisa Chen & Dong, sp. nov. is characterised by asymmetrical openings of the oviducts; right vas deferens opening at anterior portion of the seminal vesicle and the left one opening at mid-lateral portion of the seminal vesicle; two diaphragms in ejaculatory duct, the latter being ventrally displaced and opening at the tip of the penis papilla, which is provided with a nozzle; wide duct connecting male atrium and common atrium; chromosome complement triploid with 24 metacentric chromosomes. The other new species, Dugesiaverrucula Chen & Dong, sp. nov., is characterised by the large size of the living worm, usually exceeding 3.5 cm in length; asymmetrical openings of the oviducts; subterminal opening of ventrally displaced ejaculatory duct; vasa deferentia symmetrically opening into the postero-lateral portion of the seminal vesicle; well-developed duct between the seminal vesicle and diaphragm; single dorsal bump near the root of the penis papilla; bursal canal with pleated wall and spacious posterior section; unstalked cocoons; chromosome complement diploid with 16 metacentric chromosomes. Inter-specific molecular distances and their positions in the phylogenetic tree reveal that D.circumcisa and D.verrucula are clearly separated from their congeners.

Integrative descriptions of two new species of Dugesia from Hainan Island, China (Platyhelminthes, Tricladida, Dugesiidae)

Two new species of the genus Dugesia (Platyhelminthes, Tricladida, Dugesiidae) from Hainan Island of China are described on the basis of morphological, karyological and molecular data. Dugesiasemiglobosa Chen & Dong, sp. nov. is mainly characterized by a hemispherical, asymmetrical penis papilla with ventrally displaced ejaculatory duct opening terminally at tip of penis papilla; vasa deferentia separately opening into mid-dorsal portion of intrabulbar seminal vesicle; two diaphragms in the ejaculatory duct; copulatory bursa formed by expansion of bursal canal, lined with complex stratified epithelium, which projects through opening in bursa towards intestine, without having open communication with the gut; mixoploid chromosome complement diploid (2n = 16) and triploid (3n = 24), with metacentric chromosomes. Dugesiamajuscula Chen & Dong, sp. nov. is mainly characterized by oviducts opening asymmetrically into female reproductive system; hyperplasic ovaries; expanded posterior section of bursal canal; vasa deferentia separately opening into mid-dorsal portion of seminal vesicle; asymmetrical penis papilla due to ventral course of ejaculatory duct, which has subterminal and dorsal opening at tip papilla; mixoploid chromosome complement diploid (2n = 16) and triploid (3n = 24); chromosomes metacentric. Apart from their anatomy, separate species status of the two new species is supported also by their genetic distances and by their positions in the phylogenetic tree. The sexualization process may have been induced by the lower temperatures, in comparison with their natural habitat, under which the worms were cultured in the laboratory.

A new species of Dugesia (Platyhelminthes, Tricladida, Dugesiidae) from China, with an account on the histochemical structure of its major nervous system

By means of an integrated approach, including molecular, morphological, anatomical and histological data, we describe a new species of freshwater flatworm of the genus Dugesia from southwest China, representing the third species recorded for the country. Morphologically, the new species, Dugesia umbonata Song & Wang, sp. nov., is particularly characterised by the presence of a muscularised hump immediately antero-dorsally to a knee-shaped bend in its bursal canal and by an ejaculatory duct that opens subterminally through the dorsal side of the penis papilla. Four molecular datasets (18S rDNA; ITS-1; 28S rDNA; COI) facilitated determination of the phylogenetic position of the new species, which belongs to a clade comprising other species from the Australasian and Oriental regions. We also analysed the structure of its major nervous system by means of the acetylcholinesterase (AChE) histochemical method and compared these results with data available for three other species of Dugesia.

Phylogeny and biogeography of the Cavernicola (Platyhelminthes: Tricladida): Relicts of an epigean group sheltering in caves?

The planarian suborder Cavernicola Sluys, 1990 was originally created to house five species of triclad flatworms with special morphological features and a surprisingly discontinuous and broad geographic distribution. These five species could not be accommodated with any degree of certainty in any of the three taxonomic groups existing at that moment, viz., Paludicola Hallez, 1892, Terricola Hallez, 1892, and Maricola Hallez, 1892. The scarce representation of the group and the peculiarities of the morphological features of the species, including several described more recently, have complicated new tests of the monophyly of the Cavernicola, the assessment of its taxonomic status, as well as the resolution of its internal relationships. Here we present the first molecular study including all genera currently known for the group, excepting one. We analysed newly generated 18S and 28S rDNA data for these species, together with a broad representation of other triclad flatworms. The resulting phylogenetic trees supported the monophyly of the Cavernicola, as well as its sister-group relationship to the Maricola. The sister-group relationship to the Maricola and affinities within the Cavernicola falsify the morphology-based phylogeny of the latter that was proposed previously. The relatively high diversity of some cavernicolan genera suggests that the presumed rarity of the group actually may in part be due to a collecting artefact. Ancestral state reconstruction analyses suggest that the ancestral habitat of the group concerned epigean freshwater conditions. Our results point to an evolutionary scenario in which the Cavernicola (a) originated in a freshwater habitat, (b) as the sister clade of the marine triclads, and (c) subsequently radiated and colonized both epigean and hypogean environments. Competition with other planarians, notably members of the Continenticola, or changes in epigean habitat conditions are two possible explanations -still to be tested- for the loss of most epigean diversity of the Cavernicola, which is currently reflected in their highly disjunct distributions.

The evolutionary terrestrialization of planarian flatworms (Platyhelminthes, Tricladida, Geoplanidae): a review and research programme

The terrestrialization of animal life from aquatic ancestors is a key transition during the history of life. Planarian flatworms form an ideal group of model organisms to study this colonization of the land because they have freshwater, marine, and terrestrial representatives. The widespread occurrence of terrestrial flatworms is a testament to their remarkable success occupying a new niche on land. This lineage of terrestrial worms provides a unique glimpse of an evolutionary pathway by which a group of early divergent aquatic, invertebrate metazoans has moved onto land. Land flatworms are among the first groups of animals to have evolved terrestrial adaptations and to have extensively radiated. Study of this terrestrialization process and the anatomical key innovations facilitating their colonization of the land will contribute greatly to our understanding of this important step in Metazoan history. The context and scientific background are reviewed regarding the evolutionary terrestrialization of land flatworms. Furthermore, a framework of a research programme is sketched, which has as its main objective to test hypotheses on the evolution of land planarians, specifically whether particular anatomical and physiological key innovations have contributed to their evolutionary successful terrestrial colonization and radiation. In this context special attention is paid to the respiration in aquatic and terrestrial planarians. The research programme depends on a comprehensive phylogenetic analysis of all major taxa of the land flatworms on the basis of both molecular and anatomical data. The data sets should be analyzed phylogenetically with a suite of phylogenetic inference methods. Building on such robust reconstructions, it will be possible to study associations between key innovations and the evolutionary terrestrialization process.

A new continent in the geographic distribution of the genus Oregoniplana (Platyhelminthes: Tricladida: Maricola), its rediscovery in South Africa and its molecular phylogenetic position

Here we describe a new species for the genus Oregoniplana from the coast of China, representing the third species for the genus and the first record of this genus for Asia. The other species are known from Oregon, USA, and from South Africa. Specimens of the South African species, Oregoniplana pantherina, were recently rediscovered, forming the second record for the species, which provided the basis for a necessary re-description. Molecular data (18S rDNA and 28S rDNA) obtained for the new Chinese species facilitated determination of the position of the genus Oregoniplana in the phylogenetic tree of the marine triclads. We report molecular data also for species previously discovered in China, viz. Miroplana shenzhensis and Pentacoelum sinensis, thus enabling us to determine for the first time the phylogenetic position of the genus Miroplana. These new molecular data revealed that Pentacoleum sinensis occupies an unexpected position in the phylogenetic tree. Laboratory cultures of the new Chinese species provided information on food preferences and reproduction. Oregoniplana pantherina exhibits a peculiar kind of locomotion and an unusual resting position in which the animal has three points of contact on either side.

The invasive alien freshwater flatworm Girardia tigrina (Girard, 1850) (Platyhelminthes, Tricladida) in Western Europe: new insights into its morphology, karyology and reproductive biology

Invasions of alien species form one of the major threats to global biodiversity. Among planarian flatworms many species are known to be invasive, in several cases strongly affecting local ecosystems. Therefore, a detailed knowledge on the biology of an invasive species is of utmost importance for understanding the process of invasion, the cause of its success, and the subsequent ecological impact on native species. This paper provides new information on the biology of introduced populations of the freshwater flatworm Girardia tigrina (Girard, 1850) from Europe. This species is a native of the Nearctic Region that was accidentally introduced into Europe in the 1920s. Since then, numerous records across the European continent bear witness of the invasiveness of this species, although only a few studies focused on the biology of the introduced populations. We report on the morphology of sexualized individuals from a fissiparous Italian population, representing the second record of spontaneous sexualization of fissiparous individuals in this species. A detailed morphological account of the reproductive apparatus of these ex-fissiparous animals is presented. Our results increased the number of morphological groups previously recognized for European populations of G. tigrina, thus corroborating the hypothesis on multiple independent introductions to this continent. Karyological results obtained from our fissiparous Italian individuals revealed a constant diploid chromosome complement of sixteen chromosomes. Further, we document the marked intraspecific variation in several morphological features of this species.

Two new species of marine flatworm from southern China facilitate determination of the phylogenetic position of the genus Nerpa Marcus, 1948 and the histochemical structure of the nervous system in the genus Paucumara Sluys, 1989 (Platyhelminthes, Tricladida, Maricola)

Two new species of flatworm, collected from a beach at eastern Shenzhen, China, were studied through an integrative approach by combining morphological, histological, histochemical (acetylcholinesterase, AChE), and molecular (18S r- DNA) data. These species belong to two genera of marine triclads, previously unrecorded from China, viz. Nerpa Marcus, 1948 and Paucumara Sluys, 1989.        Nerpa fistulata Wang Chen, sp. nov. is characterized by: transparent body; principally pentamerous intestine with three distinct commissures; two very large, prepharyngeal testis follicles; a semi-circular lens in each eye cup; a penis papilla provided with a chitinized, pointed stylet; lateral bursae communicating with the oviduct and opening ventrally to the exterior via a duct. Phylogenetically N. fistulata groups with one member of the family Bdellouridae. This new, Chinese species of Nerpa introduces a major geographic disjunction, as the type species N. evelinae was described from the bay of Santos, Brazil, so that the genus is now known from both Atlantic as well as Pacific coasts.        The species Paucumara falcata Wang Li, sp. nov. is characterized by: three distinct pale yellow transverse pigmentation bands on its dorsal side, between which some snowflake-like specks are randomly distributed, and a brown transverse band anteriorly to the eyes; 8-11 testicular follicles on either side of the body, the follicles extending from immediately behind the ovaries to half-way along the pharyngeal pocket; a musculo-parenchymatic organ with a sclerotic, curved tip projecting from the anterior wall of the male atrium, ventrally to the root of the penis papilla. Phylogenetically P. falcata groups with its congener P. trigonocephala, with the genus Paucumara forming the sister taxon of the genus Ectoplana. Comparison of the nerve structure of P. falcata, as revealed by AChE histochemistry, with that of eight other species of triclad suggested that the nervous system of marine planarians is simpler than that of species of freshwater planarians, but revealed also that the nerve structure is rather variable among species.        The copulatory position exhibited by two partners in Paucumara falcata is remarkable in that they intertwine, with their heads pointing downwards and the tails pointing upwards, the entire process lasting about 10 min. Such a copulatory position has never before been reported for triclad flatworms.

New molecular sequences for two genera of marine planarians facilitate determination of their position in the phylogenetic tree, with new records for two species (Platyhelminthes, Tricladida, Maricola)

For the first time, molecular sequences of the 18S ribosomal DNA were generated for representatives of the genera Obrimoposthia Sluys & Ball, 1989 and Paucumara Sluys, 1989 of the suborder of the marine triclads, or Maricola, by analyzing the species Obrimoposthiawandeli (Hallez, 1906) and Paucumaratrigonocephala (Ijima & Kaburaki, 1916). On the basis of this molecular data the phylogenetic position of these two genera in the phylogenetic tree of the Maricola was determined and compared with their position in the phylogeny based on the analysis of anatomical features. New records for these two species are documented and their taxonomic status is determined on the basis of histological studies.

New molecular sequences for two genera of marine planarians facilitate determination of their position in the phylogenetic tree, with new records for two species (Platyhelminthes, Tricladida, Maricola)

For the first time, molecular sequences of the 18S ribosomal DNA were generated for representatives of the genera Obrimoposthia Sluys & Ball, 1989 and Paucumara Sluys, 1989 of the suborder of the marine triclads, or Maricola, by analyzing the species Obrimoposthiawandeli (Hallez, 1906) and Paucumaratrigonocephala (Ijima & Kaburaki, 1916). On the basis of this molecular data the phylogenetic position of these two genera in the phylogenetic tree of the Maricola was determined and compared with their position in the phylogeny based on the analysis of anatomical features. New records for these two species are documented and their taxonomic status is determined on the basis of histological studies.

Basic Histological Techniques for Planarians

The chapter provides a concise account of collecting techniques, and basic histological techniques for investigating planarians, intended for use by practicing scientists and postgraduate students new to the field. Selected hands-on methods are described that will lead to well-stained preparations suitable for light microscopic examination for subsequent taxonomic identification or general investigations into planarian functional cytology and histology. Major equipment items that are minimal essential requirements of a functional histological laboratory are indicated. The chapter includes sectioning and staining troubleshooting guides that will be very helpful for those who must work in the laboratory without the opportunity to consult qualified and experienced technicians or microscopists.

Bipolarity in planarians is not induced by space travel

Available evidence strongly suggests that alternative, Earth-bound explanations should be sought first for the occurrence of a single bipolar planarian flatworm returning from space travel. Double-headed worms have been amply documented as arising under experimental conditions as well as spontaneously in stock cultures of planarians.

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.

First report of the land planarian Diversibipalium multilineatum (Makino & Shirasawa, 1983) (Platyhelminthes, Tricladida, Continenticola) in Europe

Introduction of alien species may significantly affect soil ecosystems, through predation or disruption of components of native ecosystems (Winsor et al. 2004; Álvarez-Presas et al. 2014; Justine et al. 2014). Land planarians have been reported as alien species in soils throughout the world and, among those, some species are considered to be successful invaders, e.g. Platydemus manokwari de Beauchamp, 1963, Arthurdendyus triangulatus (Dendy, 1894), Bipalium adventitium Hyman, 1943, Bipalium kewense Moseley, 1878 and Dolichoplana striata Moseley, 1877 (Winsor et al. 2004; Álvarez-Presas et al. 2014; Justine et al. 2014, 2015). Soil moisture status seems to be an important element for their successful invasion (Fraser & Boag 1998). In Europe at least 18 species of alien land planarians have been recorded since now and some of them are considered as invasive ones, e.g. P. manokwari (cf. Justine et al. 2014). Although the alien land planarian B. kewense has been reported to occur in many greenhouses in Italy (Bello et al. 1995), no data are available on its establishment and/or impact on natural environments. On 28^th September 2014, 20 specimens (~1 individual/m²) of the land planarian Diversibipalium multilineatum (Makino & Shirasawa, 1983) (Fig. 1), native to Japan, were collected under pots, branches and plastic materials in a private garden located in the center of Bologna (Emilia Romagna, Central Italy), near the urban park Giardini Margherita (44°29' N, 11°21' E; WGS84). Thirty plant species (both indigenous and alien), mainly cultivated as bonsai (e.g. Lagerstroemia indica L., Juniperus procumbens (Siebold ex Endl.) Miquel), were present in this shady, wet garden (25 m²). Between March 2014 and June 2015, 70 more specimens of D. multilineatum were collected at the same site, mainly at dusk and dawn after rain. Reproduction by fission and regeneration processes were observed in several of those specimens, which were kept for some time in captivity. A specimen of D. multilineatum was also collected in a garden in Léguevin (Haute-Garonne, France), which will be described in a forthcoming paper by Justine et al. (in prep.) (see also Kawakatsu et al. 2014). Specimens without a genital pore were initially ascribed to D. multilineatum on the basis of their external appearance: the dorsal surface was brownish yellow and presented five longitudinal stripes at the head plate and the neck, showing the typical appearance of the species. The middorsal stripe was widened at its anterior end, on the head plate, and at the pharynx level. The ventral pattern of the animals at the pharyngeal region was also characteristic, with the middorsal stripe widened at this level. The Italian Diversibipalium specimens used for the molecular analysis were fixed and preserved in absolute ethanol. Fragments of the mitochondrial gene COI and 28S ribosomal RNA nuclear gene (GenBank Acc. Numbers KU245358 and KU245357, respectively) were obtained using the procedure and COI primers described in Álvarez-Presas et al. (2008) and Solà et al. (2013). The French specimen's COI (Specimen MNHN JL177, GenBank Acc. Number KT922162) was obtained as described in Justine et al. (2015). 28S sequences of 14 Bipaliinae specimens and four Microplana species (outgroup) retrieved from GenBank were included in the phylogenetic analyses (Fig. 2). Sequence alignment was obtained by using the online software MAFFT version 7 (Katoh & Standley 2013), while ambiguously aligned positions were removed using the program Gblocks (Talavera & Castresana 2007) with default settings, excepting the minimum number of sequences for a flank position at the minimum value (set at 10) and with half of the allowed gap positions. The final alignment had a length of 1589 bp. We used two phylogenetic inference approaches: maximum likelihood (ML), using the RaxML 8.2.3 software (Stamatakis 2014), and Bayesian inferences (BI), using MrBayes 3.2.4 (Ronquist et al. 2012). The evolutionary model used, GTR+I+G, was estimated to be the best with the software jModeltest 2.1.7 (Darriba et al. 2012; Guindon & Gascuel 2003), using the Akaike Information Criterion (AIC). MrBayes analyses were performed for 10-milion generation with sampling parameters every 10³ and a 25% default burn-in value for the final trees. Convergence of the two runs (average standard deviation of split frequencies &lt;&lt; 0.01) and likelihood stationarity were checked. The maximum likelihood analyses were performed under 1000 bootstrap pseudoreplicates. The phylogenetic results show a close and highly supported relationship of the Italian Diversibipalium specimens with those from Japan and South Korea that have been identified as D. multilineatum (Fig. 2). Diversibipalium multilineatum is the sister-group of B. nobile Kawakatsu & Makino, 1982, but with low support. The COI sequences of the French (MNHN JL177) and the Italian Diversibipalium specimens were compared in Geneious v. 8.0.5 (<a href="http://www.geneious.com/">http://</a>www.geneious.com, Kearse et al. 2012) and were found to be identical. These results indicate that the species introduced in both countries is the same, and most probably concerns the species D. multilineatum. The pathways of introduction of D. multilineatum are currently unknown, although a relationship between the horticultural trade and the introduction of alien land planarians is well known (Álvarez-Presas et al. 2014 and references therein). Here we report the first occurrence of individuals of D. multilineatum outside Asia. The GenBank sequence of D. multilineatum from South Korea is not yet supported by a published description of the specimen, while it is debatable whether South Korea should be considered part of the natural range of D. multilineatum, which only seems to include Japan. In the present paper, we consider the South Korean animal to be an introduced specimen. Soil moisture status, temperature, and food availability are considered to be the main factors determining the presence of terrestrial planarians (Boag et al. 1998); the microclimatic conditions of the Italian garden were similar to plant nurseries and greenhouses, while an abundance of food was available, such as isopods [Porcellionides pruinosus (Brandt, 1833)], oligochaetes [Dendrobaena attemsi (Michaelsen, 1902) and several juveniles of Lumbricus spp.] and gastropods [Cernuella cisalpina (Rossmassler, 1837), Cornu aspersum (O.F. Müller 1774), Deroceras reticulatum (O.F. Müller, 1774), Discus rotundatus (O.F. Müller, 1774), Limacus flavus (Linnaeus, 1758), Milax nigricans (Philippi, 1836), Papillifera papillaris (Linnaeus, 1758), Pomatias elegans (O.F. Müller, 1774)]. Moreover, winter 2014 reached the highest temperatures and rainfall of the last two decades (source: CNR-ISAC, Bologna), thus favouring establishment and spread of D. multilineatum. The potential environmental impacts of some invasive flatworms are well documented (Álvarez-Presas et al. 2014; Justine et al. 2014) and, even if these effects have not yet been assessed for D. multilineatum, the adoption of precautionary measures and of early intervention is here strongly recommended (Genovesi & Shine 2004). Finally, knowledge of the introduction pathway(s), together with the analysis of prey preference and possible impact on the invertebrate fauna, will be essential to halt or at least to limit the spread of this introduced land flatworm.

The taxonomic status of Dugesiabiblica from Israel and Turkey (Platyhelminthes, Tricladida, Dugesiidae)

The taxonomic status of Dugesiabiblica (Platyhelminthes, Tricladida, Dugesiidae) from Israel and Turkey is problematic due to its morphological similarity with Dugesiasicula since these nominal species present overlapping characters. In this study we analyzed histological preparations of specimens of these two nominal species and also compared mitochondrial COI gene sequences from Israeli populations to the already known haplotype composition of Dugesiasicula. We concluded that these animals belong to the same species and therefore we consider Dugesiabiblica to be a junior synonym of Dugesiasicula. This implies that the distribution range of Dugesiasicula is even wider than previously thought, and that the species is present all around the Mediterranean Basin and on many of its islands.

A new and aberrant species of Dugesia (Platyhelminthes, Tricladida, Dugesiidae) from Madagascar

In this paper we report a new species of Dugesia of the family Dugesiidae from Madagascar, representing the fourth species of freshwater planarian known from this global biodiversity hotspot. In some respects the new species is aberrant, when compared with its congeners, being characterized by a head with smoothly rounded auricles, a peculiar course of the oviducts, including the presence of a common posterior extension, and by the asymmetrical openings of the vasa deferentia at about halfway along the seminal vesicle. Further, it is characterized by a ventral course of the ejaculatory duct with a terminal opening, very long spermiducal vesicles and unstalked cocoons. Its diploid chromosome complement with 18 chromosomes represents an uncommon feature among fissiparous species of Dugesia.

Integrative taxonomy of a new species of planarian from the Lake Ohrid basin, including an analysis of biogeographical patterns in freshwater triclads from the Ohrid region (Platyhelminthes, Tricladida, Dugesiidae)

A new species of the genus Dugesia is described from the Lake Ohrid region in the western part of the Balkan Peninsula, forming the first fully documented species description for this genus in the Ohrid area. The morphological species delimitation is supported by complementary molecular, karyological, and cytogenetic data available from the literature. Therefore, species delineation is based on a truly integrative approach. Further, a short account on the degree of freshwater planarian endemicity in the Ohrid region is provided.

Fluvial basin history in the northeastern Mediterranean region underlies dispersal and speciation patterns in the genus Dugesia (Platyhelminthes, Tricladida, Dugesiidae)

In this study we analyzed the phylogenetic relationships of eastern Mediterranean freshwater planarians of the genus Dugesia, estimated divergence times for the various clades, and correlated their phylogeographic patterns with geological and paleoclimatic events, in order to discover which evolutionary processes have shaped the present-day distribution of these animals. Specimens were collected from freshwater courses and lakes in continental and insular Greece. Genetic divergences and phylogenetic relationships were inferred by using the mitochondrial gene subunit I of cytochrome oxidase (COI) and the nuclear ribosomal internal transcribed spacer-1 (ITS-1) from 74 newly collected individuals from Greece. Divergence time estimates were obtained under a Bayesian framework, using the COI sequences. Two alternative geological dates for the isolation of Crete from the mainland were tested as calibration points. A clear phylogeographic pattern was present for Dugesia lineages in the Eastern Mediterranean. Morphological data, combined with information on genetic divergences, revealed that eight out of the nine known species were represented in the samples, while additional new, and still undescribed species were detected. Divergence time analyses suggested that Dugesia species became isolated in Crete after the first geological isolation of the island, and that their present distribution in the Eastern Mediterranean has been shaped mainly by vicariant events but also by dispersal. During the Messinian salinity crisis these freshwater planarians apparently were not able to cross the sea barrier between Crete and the mainland, while they probably did disperse between islands in the Aegean Sea. Their dependence on freshwater to survive suggests the presence of contiguous freshwater bodies in those regions. Our results also suggest a major extinction of freshwater planarians on the Peloponnese at the end of the Pliocene, while about 2Mya ago, when the current Mediterranean climate was established, these Peloponnese populations probably began to disperse again. At the end of the Pliocene or during the Pleistocene, mainland populations of Dugesia colonized the western coast, including the Ionian Islands, which were then part of the continent.