Cinthya Simone Gomes Santos

Morphological variations caused by fixation techniques may lead to taxonomic confusion in Laeonereis (Polychaeta: Nereididae)

The nereidid polychaete Laeonereis acuta (Treadwell, 1923) is either considered to be a valid species, or a synonym of Laeonereis culveri (Webster, 1879). The species epithet, acuta, refers to the acuminate anterior region of the body followed by a widening that is visible up to the 10th setiger. The relative width of the anterior region of the body, however, has been reported in the taxonomic literature as variable for Laeonereis Hartman, 1945, a genus known from the eastern coast of North America to Patagonia (southern South America). To test whether variations in this character are real, or whether they correspond to an artifact, we analyzed morphological changes associated with different anesthesia and fixation techniques regularly used to prepare specimens of Laeonereis from southern Brazil (formerly reported as L. acuta). Six treatments, including combinations of anesthetics and fixative agents, and a control, were evaluated in groups of 25 adult animals. A simple model II regression analysis on living specimens showed that the growth is approximately isometric. One-way ANOVA was used to compare the treatment effect on the ratio of peristome width: setiger 6 width. This ratio was smaller in non-anesthetized individuals, especially when prepared in formalin and freshwater. When anesthetized with menthol and fixed in formalin with sea water, individuals retained a shape that was closest to their in vivo shape. Consequently, our results suggest that fixation without prior anesthesia is not recommended for morphological and taxonomical studies. Since morphology and morphometrics of the anterior region are consistently influenced by preparation techniques, it is likely that inadequate fixation routines have introduced several errors in the taxonomic and ecological literature of Laeonereis.

Description of a new species of Namalycastis (Annelida: Nereididae: Namanereidinae) from the Brazilian coast with a phylogeny of the genus

The subfamily Namanereidinae represents one of the few groups of Polychaeta strongly adapted to low salinity and freshwater. Recently, some new species of the subfamily have been described, but no new phylogenetic analyses for the group have been undertaken since 1999. Here, we describe a new species of Namanereidinae, Namalycastis caetensis sp. nov., and provide a morphology-based phylogenetic analysis of the genus Namalycastis with the aim of assessing the evolutionary relationships for this new species. The designation of this new species is supported by the presence of elongated falcigers (also known as pseudospinigers, an unusual character in the genus), lack of an anterior cleft in the prostomium, slightly indistinct cirrophores, four pairs of tentacular cirri, and subconical acicular ligulae. Our results suggest that Namalycastis caetensis is closely related to N. geayi and N. fauveli. The existence of poorly-characterized species, from a morphological and molecular point of view, still limits our understanding of Namanereidinae relationships.

Morphometric analysis of two sympatric species of Perinereis (Annelida: Nereididae) from the Brazilian coast

Species definition is not an easy task, when considering the more than 27 known species concepts. Among them, the morphospecies concept has been one of the most applied since it is based on the use of observable morphological features. Morphometry has been used to delimitate morphospecies or similar taxa complementing the morphological observations and contributing to clarify taxonomic problems. Specimens from the sympatric species Perinereis anderssoni and Perinereis ponteni, collected from the north-eastern to southern coast of Brazil and considered synonymous by some authors, were compared through morphometric analyses for the evaluation of their taxonomic status. Morphometric analysis indicates that notopodial cirri lengths in the median and posterior regions on the body clearly allowed differentiation between the two species. Our results indicate that the number and arrangement of paragnaths demonstrate a pattern of variation that effectively differs and could be used to discriminate these two Perinereis species. This distinction was confirmed by the restricted among-population variability within each species, even when populations that are geographically very distant from each other were considered.

A Review of “Polychaeta” Chemicals and their Possible Ecological Role

Despite the many publications concerning the isolation of substances and the many reviews of marine natural products, some groups of organisms remain poorly studied, including “Polychaeta”. In response, this review covers articles published through December 2016 that address marine natural products produced from polychaetes, with a focus on antipredatory strategies, competitors, fouling, and pathogens. A total of 121 compounds were isolated from 1934 to 2016, which includes halogenated aromatics, proteins, amino acids and Lumazine derivatives most notably—with a defensive function were found in the literature, most frequently in the families Sabellidae, Terebellidae, Glyceridae, and Nereididae. The period of highest discovery of natural products in defensive actions for the group was the 2000s. Polychaetes were addressed in 26 revisions of the total 51 articles analyzed and are less reported than other marine invertebrates such as sponges, cnidarians, mollusks, and tunicates. In sum, the present review provides a basis for future research on the marine chemical ecology of polychaetes.

Morphology and larval development of Polydora cf. websteri (Polychaeta: Spionidae) in a tropical region of north-eastern Brazil

ABSTRACT Polydora websteri belongs to a group of the Spionidae known as the Polydora complex, members of which are known for building tubes within the shells of mussels and for their ability to infest commercially valuable bivalves, which causes serious losses for malacoculture. P. websteri is a species subjected to increasing research due to the global scale at which these infestations occur. In this paper, we describe the larval development of P.cf. websteri associated with the oyster Crassostrea cf. brasiliana in a tropical region of north-east Brazil. The main structures of all stages of development were analysed and compared to other populations of P. websteri. Ovigerous capsules of P.cf. websteri were cultured in the laboratory and the larval stages were analysed until metamorphosis. Ovigerous capsules were present in all sampling intervals, indicating that this population exhibits continuous reproduction. Up to 21 capsules per tube were found, and the number of eggs per capsule varied from 20 to 40. All observed eggs developed into larvae. Larval development from egg to recruitment stage did not exceed 13 days. Metamorphosis occurred when larvae attained 17 chaetigers, at which stage important diagnostic characteristics were revealed, such as the spines on chaetiger 5. The developmental stages of P.cf. websteri larvae, and the morphological features found at each stage, are in accordance with what has been recorded for temperate populations. In our study, the planktonic stage was found to be of shorter duration than elsewhere, which might be associated with the higher temperatures at which larvae were cultured compared to previous studies.

Orbinia (Polychaeta: Orbiniidae) from the Brazilian coast: two new species and two new records

Representatives of the Family Orbiniidae are very common in marine sediments and are found in both shallow and deep waters. Currently, 26 species and 10 genera have been recorded along the Brazilian coast. The specimens examined in this study were collected at depths ranging from 25 to 400 m in the Campos Basin (20-24ºS; 39-42ºW), Rio de Janeiro, in the summer and winter of 2008 and 2009. We describe two new species, Orbinia sagitta n. sp. and Orbinia camposiensis n. sp., and record the occurrences of Orbinia johnsoni (Moore, 1909), which was originally described in California, and Orbinia oligopapillata (López, Cladera & San Martin, 2006), which was previously described from the Pacific coasts of Panama. We provide a key for all the species of Orbinia recorded in the Campos Basin.

A new species of Pisionidens (Aiyar & Alikunhi, 1943) (Annelida: Sigalionidae) from Southeastern Brazil

Herein we describe specimens found along the southeastern coast of Brazil which belong to a new species, P. caissara sp. nov. This species differs from the other species of the genus by the glabrous antennae and palps, proboscis extending up to the sixth segment, jaws with smooth cutting edge and a pair of lateral wing-like sheaths, two pairs of seriate male copulatory organs, first pair of testes on segment 19 and ovaries from segment 26 onward. Reproductive characters commonly used for characterizing species are also discussed.

Three new species of Diplocirrus Haase, 1915 (Polychaeta: Flabelligeridae) from Campos Basin in SE Brazil.

Currently, 16 species of Flabelligeridae have been recorded in Brazil, four in the genus Diplocirrus: D. glaucus Malmgren, 1867 from Ubatuba, D. capensis Day, 1961 from Santos (São Paulo State) and Diplocirrus sp. from off north of Rio de Janeiro. Diplocirrus glaucus australis Nonato, 1981 is considered a nomen nudum. In the present study, three new species are described: Diplocirrus rugosus sp. nov., Diplocirrus salazarvallejoi sp. nov. and Diplocirrus acafi sp. nov., all collected from soft bottoms off southeast Brazil. A key to all Diplocirrus species is provided.

First record of Linopherus cf. canariensis (Polychaeta: Amphinomidae) from Rio de Janeiro, Brazil

The amphinomid polychaete Linopherus cf. canariensis was recorded for the first time in the coast of Rio de Janeiro (South-east Brazil). In 2011, a total of 15 specimens were collected in the intertidal zone of Itaipu Beach (Niteroi) in dead Encope emarginata test fragments. In this study, the specimens are described, and a brief discussion about their morphological variation and invading potential is provided.

A new species and two new records of Poecilochaetus (Polychaeta: Poecilochaetidae) from Hawaii

A new species, Poecilochaetus anterospinus sp. nov., is described from the east and south shores of Oahu, Hawaii. Poecilochaetus anterospinus sp. nov. is unique in the genus by the presence of noto- and neuropodial spines from chaetiger 11 to posterior segments. Neuropodial spines on anterior chaetigers are absent in all other Poecilochaetus species while notopodial spines are limited to segments preceding the pygidium. Poecilochaetus cf. koshikiensis, originally described from Japan, is newly recorded from Hawaii and apparently widely distributed in the western Pacific and South-east Asian Seas. Poecilochaetus sp. is distinguished from the other two species by the distribution of the ampullaceous cirri (7–12) and its chaetal characters.