Carlos Eduardo Falavigna da Rocha

Phylogenetic position of the acariform mites: sensitivity to homology assessment under total evidence.

BackgroundMites (Acari) have traditionally been treated as monophyletic, albeit composed of two major lineages: Acariformes and Parasitiformes. Yet recent studies based on morphology, molecular data, or combinations thereof, have increasingly drawn their monophyly into question. Furthermore, the usually basal (molecular) position of one or both mite lineages among the chelicerates is in conflict to their morphology, and to the widely accepted view that mites are close relatives of Ricinulei.ResultsThe phylogenetic position of the acariform mites is examined through employing SSU, partial LSU sequences, and morphology from 91 chelicerate extant terminals (forty Acariformes). In a static homology framework, molecular sequences were aligned using their secondary structure as guide, whereby regions of ambiguous alignment were discarded, and pre-aligned sequences analyzed under parsimony and different mixed models in a Bayesian inference. Parsimony and Bayesian analyses led to trees largely congruent concerning infra-ordinal, well-supported branches, but with low support for inter-ordinal relationships. An exception is Solifugae + Acariformes (P. P = 100%, J. = 0.91). In a dynamic homology framework, two analyses were run: a standard POY analysis and an analysis constrained by secondary structure. Both analyses led to largely congruent trees; supporting a (Palpigradi (Solifugae Acariformes)) clade and Ricinulei as sister group of Tetrapulmonata with the topology (Ricinulei (Amblypygi (Uropygi Araneae))). Combined analysis with two different morphological data matrices were run in order to evaluate the impact of constraining the analysis on the recovered topology when employing secondary structure as a guide for homology establishment. The constrained combined analysis yielded two topologies similar to the exclusively molecular analysis for both morphological matrices, except for the recovery of Pedipalpi instead of the (Uropygi Araneae) clade. The standard (direct optimization) POY analysis, however, led to the recovery of trees differing in the absence of the otherwise well-supported group Solifugae + Acariformes.ConclusionsPrevious studies combining ribosomal sequences and morphology often recovered topologies similar to purely morphological analyses of Chelicerata. The apparent stability of certain clades not recovered here, like Haplocnemata and Acari, is regarded as a byproduct of the way the molecular homology was previously established using the instrumentalist approach implemented in POY. Constraining the analysis by a priori homology assessment is defended here as a way of maintaining the severity of the test when adding new data to the analysis. Although the strength of the method advocated here is keeping phylogenetic information from regions usually discarded in an exclusively static homology framework; it still has the inconvenience of being uninformative on the effect of alignment ambiguity on resampling methods of clade support estimation. Finally, putative morphological apomorphies of Solifugae + Acariformes are the reduction of the proximal cheliceral podomere, medial abutting of the leg coxae, loss of sperm nuclear membrane, and presence of differentiated germinative and secretory regions in the testis delivering their products into a common lumen.

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.

On the genus Penthesilenula Rossetti and Martens, 1998 (Crustacea, Ostracoda, Darwinulidae) from (semi-) terrestrial habitats in São Paulo State (Brazil), with the description of a new species

Three species of darwinulid ostracods, belonging to the genus Penthesilenula, are reported from terrestrial and semi-terrestrial habitats in São Paulo State (Brazil). Penthesilenula reidae n. sp. is here described as new to science. It belongs to the africana-group in the genus and was found exclusively in bromeliad pouches. Penthesilenula aotearoa (in the incae-group) was previously known from New Zealand only and is here reported for the first time from South America. The third species, Penthesilenula brasiliensis, is here described from leaf litter in forests, constituting the first darwinulid taxon to be found in fully terrestrial habitats. The morphological diversity within P. brasiliensis s. l. is discussed and various lineages on different continents are retained within this species. The evolutionary significance of the high incidence of teratologies in the Darwinulidae is discussed. A tentative homology for the apical chaetotaxy of A2 between Darwinulidae and Cyprididae is offered.

Diversity and distribution of marine Gastrotricha along the northern beaches of the state of São Paulo (Brazil), with description of a new species of Macrodasys (Macrodasyida, Macrodasyidae)

Forty-three putative species were found in this first-ever survey of the marine gastrotrich fauna of Brazil. Samples from 23 locations and 37 sites along the northern coasts of the state of São Paulo yielded 21 species of Macrodasyida (12 genera and five families) and 22 species of Chaetonotida (seven genera and two families). Based on morphology, 26 species appear to be taxa not previously described and thus far endemic to Brazil, 13 are known species, while one in each of the genera Diplodasys, Paradasys and Tetranchyroderma remains undetermined. The overall high diversity contrasts with the generally low number of species from single locations, averaging 4.3 (SD 3.5) spp. per location; very few species were found in sites characterized by very fine sand sediment loaded with detritus and by high water turbidity (e.g. 1 sp. in praia da Fazenda), whereas a well-diversified gastrotrich community was found in localities characterized by medium or fine sand with little detritus and clear water (e.g. 14 spp. in praia de Castelhanos). The macrodasyidans, Paraturbanella sp. 1, Pseudostomella sp. 1 and Tetranchyroderma sp. 1, and the chaetonotidan Heteroxenotrichula sp. 1 were the most common species, often sympatric and particularly frequent and abundant along the continental shoreline (recorded in 50–65% of these localities); on the other hand, Macrodasys fornerise n. sp., Ptychostomella sp. 1, Tetranchyroderma sp. 3 and Thaumastoderma sp. 2, while occurring sometimes in very high numbers, exhibited a much narrower range, being encountered only once or twice during the survey. The main morphometric traits are described of the 13 species considered to be cosmopolitan or with at least an amphi-Atlantic distribution, including Chaetonotus apechochaetus and Halichaetonotus marivagus, reported here for the first time from the Americas; of the 26 species thus far endemic to Brazil, Macrodasys fornerise n. sp., which is characterized by a noticeable 145 µm-long frontal organ, is also described and figured.

New morphological characters useful for the taxonomy of the genus Microcyclops (Copepoda, Cyclopoida)

Traditionally, Microcyclops species have been defined according to differences in a few morphological characters of antennule segmentation, swimming legs 1 and 4, caudal rami, and mainly leg 5. Moreover, these characters have been very often referred to as variable. In five species of Microcyclops from Brazil, namely M. alius, M. anceps anceps, M. ceibaensis, M. finitimus, and M. mediasetosus, new or rarely mentioned structures were found to be useful in separating the species, such as the border ornamentation of the prosomal somites, the shape and ornamentation of the terminal spine on the endopod of leg 1, the presence and number of integumental pores on the terminal endopodal segment of leg 1, and details in the ornamentation of the middle caudal setae. Since no intraspecific variation has been observed in these features, it is proposed to consider them in future descriptions of Microcyclops species in order to have better characterized taxa.

Speleoithonidae, a new family of Copepoda (Cyclopoida) from anchialine caves on the Bahama Islands

Abstract Two new species of minute troglobitic cyclopoid copepods belonging to Speleoithona gen. nov. and Speleoithonidae fam. nov. are described based on adult females and males caught from the plankton in anchialine caves on Eleuthera and San Salvador Islands, Bahamas. Speleoithona is distinguished from other cyclopoids by the structure of the P5, rostrum and mandibular palp, number of segments and armature of the A1, presence of a row of pinnules on the caudal face of the Exp3 P2-P4, and absence of the inner apical seta on the caudal rami. Interspecific variation has been observed on the Enp P4, apical setae of the caudal rami, P5 of both sexes, and P6 of males.

Therodamas tamarae, a new species of copepod (Poecilostomatoida: Ergasilidae) parasitic on Plagioscion squamosissimus (Heckel) from the Araguaia River, Brazil; with a key to the species of the genus

Therodamas tamarae n.sp. is described based on females removed from branchial filaments of Plagioscion squamosissimus (Teleostei, Sciaenidae) caught in a lake near the Araguaia River, State of Goiás, Brazil. The new species shares with Therodamas elongatus (Thatcher, 1986) the same host, a similar reaction from the host to the presence of the parasites, and the same general shape of body; in addition, the two species are from the Amazon basin. On the other hand, it resembles T. fluviatilis Paggi, 1976 in the structure of legs 1 to 4. An identification key for Therodamas species, as well as comments on the distribution of the species, are included.

Conservation of Continental Copepod Crustaceans

A discussion on the conservation problems of continental copepods from several parts of the world is presented, based on the experience of local experts. The status of some copepod species of concern for the IUCN Red List is evaluated.

New cyclopoids (Copepoda) from Anchialine caves in Bermuda

Abstract A new species of Speleoithona and two new species of Halicyclops are described from plankton samples taken in anchialine caves in Bermuda. Halicyclops ytororoma, previously known from interstitial intertidal waters along the coast of the State of Sao Paulo, Brazil, is also found in these troglobiont samples. Speleoithona is redefined to contain the new species from Bermuda.

A new species of Halicyclops (Copepoda, Cyclopoida,Cyclopidae) from cenotes of the Yucatan Peninsula, Mexico, with an identification key for the species of the genus from the Caribbean region and adjacent areas

Abstract Halicyclops cenoticola sp. nov. is described from cenotes of the Yucatan Peninsula, Mexico. The new species shares exclusively with H. caridophilus and H. tetracanthus the presence of 2 inner setae on the leg 5 exopod in the males. As far as is known, the new species is distinguished trom all its congeners in having the dorsal caudal seta as long as the outer middle caudal seta; legs 2 and 3 are dimorphic concerning the structure of the 3 inner setae on the terminal endopodal segment; and leg 6 of both the male and female consists of only 2 elements. An identification key for the Halicyclops species known trom the Caribbean Region, the Gulf of Mexico, Bermuda, and the coast of French Guiana is included.