Carolina Noreña

A transcriptomic-phylogenomic analysis of the evolutionary relationships of flatworms

Summary The interrelationships of the flatworms (phylum Platyhelminthes) are poorly resolved despite decades of morphological and molecular phylogenetic studies [1, 2]. The earliest-branching clades (Catenulida, Macrostomorpha, and Polycladida) share spiral cleavage and entolecithal eggs with other lophotrochozoans. Lecithoepitheliata have primitive spiral cleavage but derived ectolecithal eggs. Other orders (Rhabdocoela, Proseriata, Tricladida and relatives, and Bothrioplanida) all have derived ectolecithal eggs but have uncertain affinities to one another. The orders of parasitic Neodermata emerge from an uncertain position from within these ectolecithal classes. To tackle these problems, we have sequenced transcriptomes from 18 flatworms and 5 other metazoan groups. The addition of published data produces an alignment of >107,000 amino acids with less than 28% missing data from 27 flatworm taxa in 11 orders covering all major clades. Our phylogenetic analyses show that Platyhelminthes consist of the two clades Catenulida and Rhabditophora. Within Rhabditophora, we show the earliest-emerging branch is Macrostomorpha, not Polycladida. We show Lecithoepitheliata are not members of Neoophora but are sister group of Polycladida, implying independent origins of the ectolecithal eggs found in Lecithoepitheliata and Neoophora. We resolve Rhabdocoela as the most basally branching euneoophoran taxon. Tricladida, Bothrioplanida, and Neodermata constitute a group that appears to have lost both spiral cleavage and centrosomes. We identify Bothrioplanida as the long-sought closest free-living sister group of the parasitic Neodermata. Among parasitic orders, we show that Cestoda are closer to Trematoda than to Monogenea, rejecting the concept of the Cercomeromorpha. Our results have important implications for understanding the evolution of this major phylum.

New Species of Gieysztoria (Platyhelminthes, Rhabdocoela) from Peruvian Amazon Floodplain with Description of their Stylet Ultrastructure

Abstract The free-living Platyhelminthes of the Amazon basin are poorly known. Presently only four turbellarian species have been mentioned from the Amazon river, a fact that confirms the lack of information on this kind of faunas in this huge basin. Three new species of Gieysztoria from Amazonian floodplain in Peru are described herein: G. chiqchi n. sp., G. kasasapa n. sp. and G. sasa n. sp. The samples were taken in the Pacaya-Samiria National Reserve (Peru) during September 2002. Besides the usual description of the stylet based on whole mounted specimens, we provide a complementary description using SEM, which allowed differentiation of the new species within the currently yet imperfect picture of the Amazonian turbellarian fauna. Although further research is desired, current findings are suggestive of high diversity of free-living Turbellaria in the surveyed region.

Microturbellarian species richness and community similarity among temporary pools:relationships with habitat properties

Temporary water bodies exhibit a high level of biodiversity,much of which is unique tothese habitats.Studies of microturbellarian community ecology in temporary pools are scarce,eventhough turbellarians are potentially important in organizing community structure.Moreover,therehas been virtually no documentation of microturbellarians from Israel.We examined the re-lationships between several pool properties (surface area,water depth,permanence and sedimentdepth)and microturbellarian species richness among 52 temporary pools at a single site.A total of17 taxa of microturbellarians were identi ed,of which 14 were determined to genus or species level.Richness was positively related with surface area and with maximal sediment depth,togetherexplaining 54%of the variance.In more intensive sampling of a subset of 18 pools,surface areawas the only signi cant predictor,explaining 76%of the variance.Community dissimilarity waspositively related with di erences in both surface area and permanence.We identi ed three cate-gories of pool size,each characterized by di erent turbellarian species:large pools were dominatedbyCastrada viridis andGieysztoria cuspidata ,intermediate pools byDochmiotrema limicola ,and many of the small pools byGieysztoria ornata andOlisthanella obtusa .Large pools contributed themost to regional diversity,with 11 of the 17 observed taxa.However,some species were unique tosmall pools.Thus,in order to maintain maximal regional diversity of temporary water turbellar-ians,it is important to conserve habitats containing pools of various sizes.

New freshwater interstitial Otoplanidae (Platyhelminthes: Proseriata) from the Paraná and Uruguay rivers, South America

This study describes two new freshwater otoplanid species (Platyhelminthes, Proseriata), Itaspiella parana n. sp. and Philosyrtis rauli n. sp., from interstitial habitats of the middle Paraná river (Argentina) and lower Uruguay river (Uruguay), respectively. Kata sp. from the Uruguay river is briefly characterized. This is the first report of otoplanids from freshwater environments of South America. The studied areas are particular biotopes. At present, only a few studies on the turbellarian fauna and its ecology have been carried out in the Paraná river and the records presented here are the first for the Uruguay river. The main difference between other known otoplanid species and Itaspiella parana, Philosyrtis rauli and Kata sp. is their ecological characterization. Until now the family Otoplanidae was known only from marine environments, with a few exceptions.

Insemination and embryonic development of some Mediterranean polyclad flatworms

We document the specific patterns of egg plates, the numbers and size of embryos per cocoon and the major stages of the spiralian embryonic development in four Mediterranean polyclads. These include the two cotylean species Prosthiostomum siphunculus (Delle Chiaje, 1828) Lang, 1884 and Thysanozoon brocchii (Risso, 1818) Grube, 1840, both with Müllers larvae, the directly developing acotylean Echinoplana celerrima Haswell, 1907 as well as the acotylean Imogine mediterranea (Galleni, 1976) JenningsandNewman, 1996 with Göttes larva. The duration of embryonic development in three polyclads was tested at different temperatures, suggesting a strong decrease in developmental time with higher temperature (17°C instead of 15°C). In P. siphunculus, we also controlled salinity and light conditions, observing slightly faster development at salinity of 3.5%, and no major effect of light on development. In polyclads, insemination can occur by true copulation, dermal impregnation or hypodermic insemination. We used live observations and sagittal serial sections to detect sperm in tissues of the recipient animal. We found that there is no clear relationship between the presence or absence of a penis or Langs vesicle and the mode of insemination, which can vary considerably even between species of the same genus.

A new species of Gieysztoria (Platyhelminthes, Rhabdocoela) from Argentina and a kinship analysis of South American species of the genus

This study describes a new species of Gieysztoria found in lentic environments in Argentina. Gieysztoria falx sp. n. appears to be closely related to G. therapaina and G. intricata, and is differentiated principally by the presence of two strongly developed pincer‐shaped spines of the cuticular stylet. A preliminary analysis of the phylogeny among the South American species of this genus is undertaken, and the monophyly verified. This study constitutes the first approach to interpreting these relationships.

Characterization of the complete mitochondrial genomes from Polycladida (Platyhelminthes) using next-generation sequencing.

The complete mitochondrial genomes of three polycladids, the acotylean Hoploplana elisabelloi and the cotyleans Enchiridium sp. and Prosthiostomum siphunculus have been assembled with high coverage from Illumina sequencing data. The mt genomes contain 36 genes including 12 of the 13 protein-coding genes characteristic for metazoan mitochondrial genomes, two ribosomal RNA genes, and 22 transfer RNA genes. Gene annotation, gene order, genetic code, start and stop codons and codon bias have been identified. In comparison with the well investigated parasitic Neodermata, our analysis reveals a great diversity of gene orders within Polycladida and Platyhelminthes in general. By analyzing representative genomes of the main groups of Platyhelminthes we explored the phylogenetic relationships of this group. The phylogenetic analyses strongly supported the monophyly of Polycladida, and based on a small taxon sampling suggest the monophyly of Acotylea and Cotylea.

First records of Cotylea (Polycladida, Platyhelminthes) for the Atlantic coast of the Iberian Peninsula

Abstract A study of polyclad fauna of the Atlantic coast of the Iberian Peninsula was carried out from 2010 to 2013. The paper reports nine new records belonging to three Cotylean families: the family Euryleptidae Lang, 1884, Pseudocerotidae Lang, 1884 and the family Prosthiostomidae Lang, 1884, and describes one new species, Euryleptodes galikias sp. n.

Composition of meiobenthonic Platyhelminthes from brackish environments of the Galician and Cantabrian coasts of Spain with the description of a new species of Djeziraia (Polycystididae, Kalyptorhynchia)

From 1997 to 1999, the fauna of free‐living Platyhelminthes of the rias ecosystem was studied along the Galician and Cantabrian coast in northern Spain. In total, 72 platyhelminth species are listed in this study. Forty‐two species represent new records for the Iberian Peninsula, three of which represent new genera records. A new species belonging to the genus Djeziraia (Polycystididae, Kalyptorhynchia), Djeziraia longistyla sp. nov., is described in this paper. In this broad‐scale study, a large data set (27 localities) of the estuaries of northern Spain allowed an analysis of the turbellarian species assemblages and the relation of species distributions to salinity, conductivity, oxygen, temperature, and sediment characteristics. Species assemblages (species diversity) of each habitat of the brackish water ecotone are shown. The present study contributes to knowledge on the ability of adaptation of free‐living Platyhelminthes to regimes of brackish water ecotones.

Morphology and DNA barcodes reveal the presence of the non-native land planarian Obama marmorata (Platyhelminthes : Geoplanidae) in Europe

Abstract. We report for the first time the occurrence of Obama marmorata in the Iberian Peninsula as an introduced species from the Neotropical Region. The species is also reported for the first time in Argentina. The identification was made on the basis of morphological evidence. The divergence levels of a fragment of the mitochondrial cytochrome c oxidase I gene from Argentinean and Iberian samples were studied. The morphology of samples from the two regions was the same and matched the original description of the species. A DNA barcoding matrix was constructed using new sequences from O. marmorata and sequences of related species taken from GenBank. Among the Geoplanidae, interspecific divergence ranged between 3.3 and 14.4%, while intraspecific divergence percentages were 0–1.2%, signalling the presence of a DNA barcoding gap. All O. marmorata sequences, irrespective of their geographic origin, form a well supported clade with an intraspecific divergence of 0–0.9 (average = 0.4%). These results indicate the utility of DNA barcoding to discover allochthonous species in this group of organisms.