Gastrotricha: A Marine Sister for a Freshwater Puzzle

Background: Within an evolutionary framework of Gastrotricha Marinellina flagellata and Redudasys fornerise bear special interest, as they are the only Macrodasyida that inhabit freshwater ecosystems. Notwithstanding, these rare animals are poorly known; found only once (Austria and Brazil), they are currently systematised as incertae sedis. Here we report on the rediscovery of Redudasys fornerise, provide an account on morphological novelties and present a hypothesis on its phylogenetic relationship based on molecular data. Methodology/Principal Findings: Specimens were surveyed using DIC microscopy and SEM, and used to obtain the 18 S rRNA gene sequence; molecular data was analyzed cladistically in conjunction with data from 42 additional species belonging to the near complete Macrodasyida taxonomic spectrum. Morphological analysis, while providing new information on taxonomically relevant traits (adhesive tubes, protonephridia and sensorial bristles), failed to detect elements of the male system, thus stressing the parthenogenetic nature of the Brazilian species. Phylogenetic analysis, carried out with ML, MP and Bayesian approaches, yielded topologies with strong nodal support and highly congruent with each other. Among the supported groups is the previously undocumented clade showing the alliance between Redudasys fornerise and Dactylopodola agadasys; other strongly sustained clades include the densely sampled families Thaumastodermatidae and Turbanellidae and most genera. Conclusions/Significance: A reconsideration of the morphological traits of Dactylopodola agadasys in light of the new information on Redudasys fornerise makes the alliance between these two taxa very likely. As a result, we create Anandrodasys gen. nov. to contain members of the previously described D. agadasys and erect Redudasyidae fam. nov. to reflect this novel relationship between Anandrodasys and Redudasys. From an ecological perspective, the derived position of Redudasys, which is deeply nested within the Macrodasyida clade, unequivocally demonstrates that invasion of freshwater by gastrotrichs has taken place at least twice, in contrast with the single event hypothesis recently put forward

Towards a phylogeny of Euthelepus (Polychaeta : Terebellidae): the absence of synapomorphies in the subfamily Thelepodinae and genera

The phylogenetic relationships of Euthelepus (Polychacta: Terebellidae: Thelepodinae) were studied by means of a parsimony analysis of 40 external characters. The ingroup terminals included four species of Euthelepus, and the outgroup included 14 species of eight Thelepodinae genera, three belonging to the subfamily Terebellinae, one species of Trichobranchinae, and one species of Polycirrinae. Only two most parsimonious cladogranis were found. However, the analysis revealed a large number of homoplastic characters supporting the thelepodin branches. The monophyly of the genus Euthelepus was not supported, and the monophyly of the other thelepodin genera, as well as the entire subfamily, is questioned. The large number of homoplasies indicated by the analysis emphasizes the need to further evaluate these hypotheses by using additional characters. A re- classification based on phylogenetic results must be considered.o TEXTO COMPLETO DESTE ARTIGO, ESTARÁ DISPONÍVEL À PARTIR DE AGOSTO DE 2015.87369570

A new application of morphometrics in a study of the variation in uncinal shape present within the Terebellidae (Polychaeta): a reevaluation from digital images

In this study, the morphometric approach was used to establish distinct morphological groups in regard to uncini shape within the four subfamilies of Terebellidae (Polychaeta). To achieve this objective, 24 distances were measured, based on photographs of the three uncini dissected from segment 7 and another three on segment 16, from 31 species, 2 belonging to Trichobranchinae, 2 to Polycirrinae, 6 to Thelepodinae and 21 to Terebellinae. Those distances were based on 7 real landmarks and 6 'extrapolated' landmarks, and measurements of the area, perimeter, greatest length, shortest length, diagonal perimeter, horizontal perimeter and vertical perimeter. The multidimensional approach to assess the similarity and dissimilarity of the distinct uncini patterns was done using n-MDS, ANOSIM and PCA. A prediction model was developed to identify the Terebellidae subfamily based on neural network. The n-MDS performed on the 31 Terebellidae species recognized three distinct groups: one group composed of species belonging to the subfamilies Thelepodinae-Terebellinae and two other distinct groups formed by the species of Trichobranchinae and Polycirrinae. The permutation tested by ANOSIM confirmed the trends observed in the n-MDS. The ordination of the two PCA axes explained 64.20% of the variance on the PCA realized on uncini of segment 7 and 65.05% of the variance on the PCA realized on uncini of segment 16. The PCA showed that most of the measurements made on the uncini were important to obtain a better classification of the data. Thus, these three different patterns can be assumed to be three different character states that define the overall uncini shape and can be used in future cladistics analyses. Finally, the model developed based on the neural network showed good success in classifying the four subfamilies.48322924

Postlarval development of Nicolea uspiana (Polychaeta: Terebellidae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)The postlarval development of Nicolea aspiono (Nogueira, 2003), a small intertidal terebellid polychaete from rocky habitats on the southeastern and southern Brazilian coast, was studied based on postlarval, juvenile and adult specimens. The specimens, ranging from 8 to 43 segments, were collected between May 2006 and May 2007. The youngest postlarval specimen was found crawling outside of the tube. In specimens at different stages of growth, the number of ocelli and tentacles increased; the first pair of nephridial papillae appeared early (before 8-segmented specimen), and the second and third pairs appeared later (31-segmented specimen); the circulatory system only developed when the first pair of branchial bulbs arose (32-segmented specimen), and the second branchial pair appeared later (40-segmented specimen); and the inversion of the uncini positions in some rows occurred in the transition from larva to juvenile (17-segmented specimen). In the course of development, segments 2-3 lost the notochaetae, and segments 3-4 lost the neurochaetae. The changes involved in the development from postlarval to adult animals are illustrated by SEM micrographs and photographs.2616166Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAEPEX/UNICAMPConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FAPESP [05/59809-7]CNPq [308072/2006-5

Are freshwater Macrodasyida as rare as previously thought? Integrative taxonomy identies a new taxon of Gastrotricha Macrodasyida

Macrodasyida are worm-like, hermaphroditic and marine gastrotrichs with about 350 species. Among all known Macrodasyida only Marinellina agellata, Redudasys fornerise and Redudasys sp. (Kanneby & Wicksten, 2014), were found in fresh waters respectively from an Austrian stream, a Brazilian articial reservoir and a USA aquifer. Herein we describe a new freshwater taxon of Macrodasyida from dierent streams in Minas Gerais State, Southeastern Brazil. The external morphology and internal anatomy were investigated using Dierential Interference Contrast (DIC), Confocal Laser Scanning Microscopy (CLSM) Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM). The systematization of the new taxon within Macrodasyida was inferred by 18S rRNA gene, and the relationships with the other freshwater Macrodasyida species were investigated by COI mtDNA. The adult has a body length from 193 to 376 m and 1+1 anterior adhesive tubes, 2 pairs of posterior adhesive tubes of unequal length, numerous cephalic cilia arranged into irregular bands, short around the mouth and longer on the anterolateral head margins, 6 pairs of lateral tactile bristles. Pharynx surrounded dorsally, laterally and ventrally by 1012 longitudinal muscles which are inserted on the mouth rim and lie externally to circular muscles; the pair of main ventrolateral longitudinal muscles is inserted at the level of the anterior adhesive tubes. Intestine circular musculature external to the splanchnic longitudinal one and not surrounding dorsal and ventrolateral somatic longitudinal muscles. Maximum Likelihood and Bayesian Inference analyses yielded topologies congruent with each other and the new taxon nested within the family Redudasyidae, but COI mtDNA analyses showed clear distances between Redudasys fornerise, Redudasys sp. and the new taxon. Results suggest that Macrodasyida invaded freshwater environment only once and the Neotropical region seems to be a peculiar place for the evolution of the freshwater macrodasyidan clade

A new genus and new species of freshwater Chaetonotidae (Gastrotricha: Chaetonotida) from Brazil with phylogenetic position inferred from nuclear and mitochondrial DNA sequences

Most studies of South American freshwater Gastrotricha have focused on the inland waters of Brazil including S~ao Paulo State, Mato Grosso do Sul State, and Para State. In this paper, we describe a new genus and species, Cephalionotus kisielewskii gen. et. sp. nov. (Chaetonotida, Chaetonotidae), from Minas Gerais State using morphological data and DNA sequence data (18S rDNA and COI genes). The new genus contains a single psammic species collected from high altitude streams. Cephalionotus gen. nov. exhibits a set of autapomorphic characters that easily distinguish it from all other genera of Chaetonotida: extremely large cephalion and hypostomium that completely cover the dorsal and ventral sides of the head, respectively; a single pair of pleurae; peculiar shape and arrangement of dorsal and ventral scales in the posterior trunk region; one paired, very large, keeled scale at the ventral posterior end; and very long adhesive tubes divided into three parts. Affinity of Cephalionotus kisielewskii gen. et sp. nov. with other Chaetonotida (Paucitubulatina) is discussed from morphological and molecular perspectives