Search

Three new eyeless species of Nereis from organic falls (whale bones and wood parcels) in the Southwestern Atlantic from depths between 550 and 3285 m are described, and the eyeless species Neanthes shinkai is transferred to Nereis. All new species and Nereis shinkai comb. nov. can be distinguished from the majority of Nereis species by the absence of eyes and by the presence of small and delicate paragnaths. Interestingly, the species Nereis anoculepitoka sp. nov. presents epitoky, with sexual dimorphism and the morphological variations described herein. This is the first description of an eyeless epitoke form from organic falls in the deep ocean. We conducted molecular phylogenetic analyses using COI and 16S mitochondrial genes, confirmed the morphological identification and established an eyeless clade within Nereis including the three new species and Nereis shinkai comb. nov. The presence of different species in a relatively small geographical area can be explained, in part, by the action of different water masses in each sampling site and suggests that organic islands are potential hotspots for specialization of Nereis in the deep sea. [ABSTRACT FROM AUTHOR]

Aim: Seascape genomic studies aim to understand how environmental variables shape species diversity through genotype–environment associations. Identifying these effects on lecithotrophic larval species that live in intertidal zones is particularly challenging because they are subject to environmental heterogeneity and anthropogenic events. Here, we evaluate how biotic and abiotic features in the Southwest Atlantic littoral zone can affect a high dispersal species' present and historical demography. Location: Brazilian coast, covering more than 3000 km. Taxon: Perinereis ponteni. Methods: We investigated population genetic diversity, connectivity and past dynamics using 23,300 single‐nucleotide polymorphisms (SNPs) generated using genotyping by sequencing. We tested whether environmental abiotic variables could explain the variance found in genotype frequencies using isolation‐by‐environment (IBE) and landscape association approaches. These data, combined with palaeodistribution simulations and oceanic circulation modelling, were used to infer species demographic history and connectivity patterns. Results: Along with high levels of connectivity detected, we found a genetic boundary in the southeastern region of Brazil around Cabo Frio (Rio de Janeiro), and a cline trend for some loci. The palaeodistribution simulations reveal a spatial refuge in the southeast during the Last Glacial Maximum (21 kya), with the expansion of the northern region. We identified 1421 SNPs with frequencies associated with eight environmental variables, most of which were related to temperature—the main environmental factor determining IBE. Main Conclusions: Perinereis ponteni, a polychaete with high gene flow capability responds to biogeographic barriers, highlighting the importance of biotic and abiotic factors in shaping population connectivity. Furthermore, the effect of temperature indicates that future climate change and ocean warming can hugely impact this species. [ABSTRACT FROM AUTHOR]

The perceived cosmopolitanism of polychaete worms could be an artefact of historical factors such as poor original species descriptions, lack of type material and the European taxonomic bias, to name a few. Thus, it is possible that several cosmopolitan species hide complexes of cryptic and pseudocryptic species. Two putative cosmopolitan species, Platynereis dumerilii and Platynereis australis , collected in South Africa were investigated here (1) to determine whether the South African taxa are conspecific with the morphologically identical taxa from France and New Zealand (the respective type localities of P. dumerilii and P. australis), (2) to compare the South African species morphometrically to determine whether their morphological characters are reliable enough to separate them, and (3) to investigate whether these species have geographically structured populations along the coast of South Africa. Molecular data (COI and ITS1) confirm that P. dumerilii and P. australis do not occur in South Africa. Instead, the South African taxon formerly thought to be Platynereis dumerilii is new and is described here as Platynereis entshonae , sp. nov.; the identity of the other South African species is currently unresolved and is treated here as Platynereis sp. Surprisingly, Platynereis massiliensis (type locality: Marseilles) nested within the South African Platynereis sp. clade but, since it is part of a cryptic species complex in the Mediterranean, the name is considered doubtful. Morphological characters traditionally used to define these South African Platynereis species are not reliable as predefined morphological groupings do not match phylogenetic clades and principal component scores revealed no separation in morphological characters that could distinguish between them. Haplotype networks and phylogenetic trees revealed that P. entshonae , sp. nov. and Platynereis sp. have geographically structured populations along the South African coast. http://zoobank.org/urn:lsid:zoobank.org:pub:6E36A210-9E48-430F-8A93-EDC27F0C5631 Polychaetes were historically considered to have cosmopolitan distributions, but are now found to comprise local cryptic species. Two supposedly cosmopolitan species, Platynereis dumerilii and Platynereis australis , from South Africa were investigated to confirm their identities, and to investigate genetic structure. Neither species occur in South Africa. Instead, the South African taxon formerly thought to be Platynereis dumerilii is new and is described here as Platynereis entshonae , sp. nov.; the identity of the other South African species is currently unresolved and is treated here as Platynereis sp. The two South African species are indistinguishable but differ in temperature preferences. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM PUBLISHER]

Polychaetes play a key role in benthic functioning and organic matter recirculation. We performed a meta-analysis to investigate the effects of organic matter on polychaetes, considering its origin, type and measurement along the east coast of South America. We summarize 276 effect sizes, mostly representing the Tropical Southwestern Atlantic and Warm Temperate Southwestern Atlantic provinces. We observed that the effect of organic matter depends on its origin and type. We also reveal that the predominance of tolerant species of Capitellidae, Nereididae and Spionidae explains the great variability in effect sizes and non-significant effects. Organic matter negatively affected assessment of polychaete assemblages, such as aspects of diversity and trophic groups. This result suggests that the impact of organic matter can be more intense for communities than for individual species. We suggest that researchers should investigate more complex ecological scales to understand the overall effect of organic matter on polychaetes., (Copyright © 2019 Elsevier Ltd. All rights reserved.)