New findings of the family Pardaliscidae from the deep-sea southwestern Atlantic: the genus Caleidoscopsis Karaman, 1974.

Caleidoscopsis is a deep-sea pardaliscid genus known previously only from the SE Atlantic Ocean (Angola Basin), NE Pacific Ocean (Mexico, Cedros Trench) and Indian Ocean (Madagascar). This is the first record of Caleidoscopsis from off the Brazilian coast, SW Atlantic Ocean. Samples were collected with box core and/or van veen grabs between Espírito Santo, Campos and Santos Basin (19o-27o S), and around 417-1974 m depths. Two new species is herein described, Caleidoscopsis carlosi sp. nov., which differs from all Caleidoscopsis species by antenna 1 geniculate; maxilliped palp, article 4 shorter than 3; pereopods 5-7, propodus shorter than dactylus; and pereopod 7 with propodus 7x longer than wide; and Caleidoscopsis karamani sp. nov., which can be distinguished by rostrum more developed, reaching half-length of article 1 of peduncle of antenna 1; antenna 2, peduncle, article 5 longer than 3 and 4; pereopod 7, propodus 13x longer than wide, subequal to dactylus; urosomite 1 covering part of urosomite 2, with 1 long dorsal tooth; urosomite 2 with 1 very long and thin dorsal tooth almost reaching the end of urosomite 3. Further on, Caleidoscopsis carlosi sp. nov. turn out to be a very common and abundant species along the study area, being found in 126 samples with a total of 146 specimens examined, when comparing with C. karamani sp. nov. that was found in only 5 samples with one individual each. A table of comparison and an identification key of the currently six known species of the genus are provided. The present study is an effort in understanding and unrevealing the deep-sea macrofauna from the Brazilian margin bringing new data on the family Pardaliscidae found in the slope of the Campos, Santos and Espírito Santo Basins.

Two new sponge inhabiting leucothoid amphipod species from the Western Atlantic.

Two new leucothoid amphipod species are described from the Western Atlantic Ocean. Leucothoe mucifibrosa sp. nov., collected from Belize, may represent a member of the Paraleucothoe group with a specific sponge host preference. Leucothoe darthvaderi sp. nov., collected from South Florida, is part of the Leucothoe spinicarpa species complex and has demonstrated a shift in host preference over time, possibly associated with environmental perturbances.

Description of a novel genus with three new species of Phoxocephalidae G. O. Sars, 1891 (Crustacea: Amphipoda) from off northeastern Brazil.

Magnaphoxus ajaja gen. et sp. nov., Ma. simplex gen. et sp. nov. and Ma. longicarpus gen. et sp. nov. are described. The material examined was collected off the states of Cear, Rio Grande do Norte and Bahia during the projects Avaliao da Biota Bentnica e Planctnica na poro offshore das Bacias Potiguar e Cear (BPOT) and Programa de Avaliao do Potencial Sustentvel de Recursos Vivos na Zona Econmica Exclusiva (REVIZEE). Additionally, material from other surveys off Brazilian northeastern coast is included. The samples were collected by rectangular dredges, box corer and Van Veen grabs, ranging from shallow waters to 168 meters in depth. The new genus is morphologically similar to the genera Grandifoxus Barnard, 1979, Metharpinia Schellenberg, 1931, Microphoxus Barnard, 1960 and Rhepoxynius Barnard, 1979. However, it can be recognized by the exclusive constricted and very broad rostrum and bilobated coxa 6, plus the combination of characters such as: lower lip outer plate with apical cusps; right mandible without lacinia mobilis; pereopods 34 carpus posterior margin with one distal robust long seta; propodus strongly armed with robust setae; uropods 12 peduncle dorsolateral margin combed distally; telson with two apical robust setae on each side. All three new species, are fully described, illustrated, and discussed.

Floresorchestia xueli, a new terrestrial crustacean (Amphipoda, Talitridae) from Yunnan, China.

A new species, Floresorchestia xueli Tong Hou, sp. nov. is described from high altitude habitats of Yunnan, China. The species differs morphologically from its congeners by left mandible lacinia mobilis having four teeth; coxal gills complexly lobed and convoluted; epimeral plates IIIII without slits; telson with one slender facial spine and two terminal spines on each lobe. Analysis of DNA barcode sequences and niche distinctiveness support recognition of the new species.

Review of amphipods of the family Pleustidae Buchholz, 1874 (Crustacea: Amphipoda) from the coastal waters of Sakhalin Island (Far East of Russia). I. Subfamily Neopleustinae Bousfield amp; Hendrycks, 1994.

Taxonomic analysis of the subfamily Neopleustinae Bousfield Hendrycks, 1994, is performed. Cladistic analysis of morphological relationships within the genera Hendrycksopleustes gen. nov., Neopleustes Stebbing, 1906, and Shoemakeroides Hendrycks Bousfield, 2004, is performed. A new genus Hendrycksopleustes gen. nov. is described. A review of the subfamily Neopleustinae from the shelf of Sakhalin Island and adjacent water area, based on all literature and own data, is provided. Based on new material, a new species Hendrycksopleustes neimanii sp. nov. is described from the shelf of Sakhalin Island. Status of the species Neopleustes euacanthus (G. Sars, 1877) is restored. New subspecies Neopleustes boecki pacifica ssp. nov. and Neopleustes pulchellus asiaticus ssp. nov. are described from the shelf of Sakhalin Island. Keys to the amphipod genera of the subfamily Neopleustinae and to the world species of the genera Neopleustes and Shoemakeroides are provided.

Pelagic amphipods (Crustacea: Amphipoda: Hyperiidea) in western Mexico. 3. Family Lestrigonidae.

Thirteen species belonging to five genera of pelagic amphipods of the family Lestrigonidae were collected during a deep-water survey off western Mexico: four species of Hyperietta, two species of Hyperioides, five species of Lestrigonus, and one species each of Phronimopsis and Themistella. This represents 93% of all known species of Lestrigonidae world-wide. A total of 1092 specimens were obtained in 40 sampling localities in the Gulf of California (35) and off southwestern Mexico (5). Although sampling methodology was rather heterogeneous, two species, Hyperioides sibaginis and Lestrigonus bengalensis, were particularly abundant (336 and 562 specimens) and frequent (present in 24 and 31 localities) in the samples, representing 82% of the total catch. The southernmost distribution limit of Hyperietta stebbingi is extended to off SW Mexico. Of the 13 species that were collected during this survey, 10 and 8 species co-occurred at two sampling localities in the SE Gulf of California.

Three new species of Hyalella (Crustacea: Amphipoda: Hyalellidae) from the Southern Brazilian Coastal Plain.

In this study, three new species of Hyalella (Crustacea: Amphipoda: Hyalellidae) are described based on specimens collected in wetlands located in three freshwater ecoregions (Southeastern Mata Atlântica, Tramandaí-Mampituba and Laguna dos Patos) of the southern Brazilian Coastal Plain (states of Rio Grande do Sul and Santa Catarina). Hyalella minuana n. sp. was recorded in the southernmost region of the state of Rio Grande do Sul. This species is characterized by presenting smooth body surface, epimeral plates not acuminated, nine serrate setae on the inner face of gnathopod 1, and peduncle of uropod 3 with four cuspidate setae with accessory seta and without plumose seta on the margin of the telson. Hyalella lagoana n. sp. was recorded in the northern region of Rio Grande do Sul and southern region of Santa Catarina. This species shows body surface smooth, epimeral plates not acuminated, nine serrate setae on the inner face of gnathopod 1, peduncle of uropod 3 with five cuspidate setae with accessory seta, and telson with six cuspidate setae with accessory seta without plumose seta on the margins. Hyalella sambaqui n. sp. was recorded in the state of Santa Catarina. This species is characterized by presenting smooth body surface, epimeral plates not acuminated, six serrate setae on the inner face of gnathopod 1, peduncle of uropod 3 with three cuspidate setae with accessory seta, and telson with three cuspidate setae with accessory seta and four plumose setae on the margin of the telson. The new records elevates the known diversity of species of Hyalella in the Brazilian territory to 33 species (19 in the southern Brazilian region) and to 83 species in the Americas.

Low annual temperature likely prevents the Holarctic amphipod Gammarus lacustris from invading Lake Baikal.

Species with effective thermal adaptation mechanisms allowing them to thrive within a wide temperature range can benefit from climatic changes as they can displace highly specialized species. Here, we studied the adaptive capabilities of the Baikal endemic amphipods Eulimnogammarus verrucosus (Gerstfeld, 1858) and Eulimnogammarus cyaneus (Dybowsky, 1874) compared to the potential Holarctic Baikal invader Gammarus lacustris Sars, 1863 at the cellular level including the energy metabolism and the antioxidant system. All species were long-term exposed to a range of temperatures (1.5 °C to mimic winter conditions and the three species-specific preferred temperatures (i.e., 6 °C for E. verrucosus, 12 °C for E. cyaneus and 15 °C for G. lacustris). At 1.5 °C, we found species-specific metabolic alterations (i.e., significantly reduced ATP content and lactate dehydrogenase activity) indicating limitations on the activity level in the Holarctic G. lacustris. Although the two Baikal endemic amphipod species largely differ in thermal tolerance, no such limitations were found at 1.5 °C. However, the cold-stenothermal Baikal endemic E. verrucosus showed changes indicating a higher involvement of anaerobic metabolism at 12 °C and 15 °C, while the metabolic responses of the more eurythermal Baikal endemic E. cyaneus may support aerobic metabolism and an active lifestyle at all exposure temperatures. Rising temperatures in summer may provide a competitive advantage for G. lacustris compared to the Baikal species but the inactive lifestyle in the cold is likely preventing G. lacustris from establishing a stable population in Lake Baikal.

The Caucasian relicts: a new species of the genus Niphargus /(Crustacea: Amphipoda: Niphargidae) from the Gelendzhik-Tuapse area of the Russian southwestern Caucasus.

A new species of the genus Niphargus is described from the Gelendzhik-Tuapse area of the Russian southwestern Caucasus. It belongs to the "puteanus" species group and phylogenetically related to Caucasian N. ciscaucasicus and N. talikadzei, separating from other Caucasian species of the genus by the presence of 2 hooks in retinacules on pleopods, different rami of uropod I both in males and females, and relatively large inner ramus of uropod III. Molecular study has revealed that Niphargus bzhidik sp. nov. and related N. ciscaucasicus are relicts of the Late Miocene speciation, associated with the Messinian crisis (5.96-5.33Mya) separated widespread Paratethys species, which survived in long-term genetic isolation for a long time. The new species is blind and epigean, and probably unable to spread over long distances, but this way of life probably allowed surviving in refugee during the Quaternary period with a colder climate. Analysis of stable isotopes (δ13C/δ15N) revealed that the new species is carnivorous, in contrast to another studied stygobiotic herbivorous Niphargus species (e.g., Niphargus cf. tauricus). The key to the Caucasian and Eastern Asian species of the genus Niphargus, known from the territory of the former USSR, is presented in the article. [http://zoobank.org/urn:lsid:zoobank.org:act:E0019189-2432-4B64-B153-94C43FDD93E3].

Testing the impact of non-destructive DNA extraction on setae structure of Amphipoda (Crustacea).

Intact voucher specimens are essential to allow detailed morphological observations on specimens that are used in molecular genetic studies. This can be achieved either by dissection of small, taxonomically uninformative parts of the body for DNA extraction or by employing non-destructive DNA extraction methods. The latter is particularly important for small-bodied animals. Here we test the effects of Chelex-based DNA extraction on the integrity of setae and setules in Amphipoda, fragile structures of great taxonomic importance. Our results show that DNA extraction using Chelex had no influence on the setae and setule structure and is well suited for reverse taxonomic approaches and the long-term storage of morphological vouchers. A detailed protocol for non-destructive DNA extraction is provided.

Comparative Mitogenomics in Hyalella (Amphipoda: Crustacea).

We present the sequencing and comparative analysis of 17 mitochondrial genomes of Nearctic and Neotropical amphipods of the genus Hyalella, most from the Andean Altiplano. The mitogenomes obtained comprised the usual 37 gene-set of the metazoan mitochondrial genome showing a gene rearrangement (a reverse transposition and a reversal) between the North and South American Hyalella mitogenomes. Hyalella mitochondrial genomes show the typical AT-richness and strong nucleotide bias among codon sites and strands of pancrustaceans. Protein-coding sequences are biased towards AT-rich codons, with a preference for leucine and serine amino acids. Numerous base changes (539) were found in tRNA stems, with 103 classified as fully compensatory, 253 hemi-compensatory and the remaining base mismatches and indels. Most compensatory Watson-Crick switches were AU -> GC linked in the same haplotype, whereas most hemi-compensatory changes resulted in wobble GU and a few AC pairs. These results suggest a pairing fitness increase in tRNAs after crossing low fitness valleys. Branch-site level models detected positive selection for several amino acid positions in up to eight mitochondrial genes, with atp6 and nad5 as the genes displaying more sites under selection.

Phylogenomics of the Hyalella amphipod species-flock of the Andean Altiplano.

Species diversification in ancient lakes has enabled essential insights into evolutionary theory as they embody an evolutionary microcosm compared to continental terrestrial habitats. We have studied the high-altitude amphipods of the Andes Altiplano using mitogenomic, nuclear ribosomal and single-copy nuclear gene sequences obtained from 36 Hyalella genomic libraries, focusing on species of the Lake Titicaca and other water bodies of the Altiplano northern plateau. Results show that early Miocene South American lineages have recently (late Pliocene or early Pleistocene) diversified in the Andes with a striking morphological convergence among lineages. This pattern is consistent with the ecological opportunities (access to unoccupied resources, initial relaxed selection on ecologically-significant traits and low competition) offered by the lacustrine habitats established after the Andean uplift.

Molecular phylogenetic position of Minamitalitrus zoltani elucidates a further troglobisation pattern in cave-dwelling terrestrial amphipods (Crustacea: Talitridae).

Talitrids are a highly diverse group of amphipod crustaceans that have colonized various terrestrial habitats. Three genera have successfully adapted to cave habitats on islands in the Pacific and Atlantic Oceans. However, the evolutionary origin of the Pacific troglobitic talitrids has remained unknown. We estimate the phylogenetic position of the troglobitic Minamitalitrus zoltani, which inhabits limestone caves on Minamidaito Island in the Northwestern Pacific, on the basis of the traditional multi-locus dataset. For the analyzed talitrids, we also reconstruct ancestral states of the maxilliped palp and male gnathopod 2. Our results indicate that Minamitalitrus zoltani is sister to the epigean Nipponorchestia curvatus with a deep divergence. Nipponorchestia curvatus inhabits coastal habitats in Japan, but is not indigenous to Minamidaito Island. A previous study estimated that the Atlantic troglobitic species had invaded subterranean habitats multiple times, but we provide new insight into the troglobisation history in talitrids. We also recover secondary shifts of character states of the maxilliped palp and male gnathopod 2 within the lineage composed of Minamitalitrus and its phylogenetically close genera. Our findings highlight the need for the genus-level reclassification of these genera; we split Nipponorchestia into two genera, establishing a new genus for Nipponorchestia nudiramus.

Molecular data suggest multiple origins and diversification times of freshwater gammarids on the Aegean archipelago.

Our main aim was to investigate the diversity, origin and biogeographical affiliations of freshwater gammarids inhabiting the Aegean Islands by analysing their mtDNA and nDNA polymorphism, thereby providing the first insight into the phylogeography of the Aegean freshwater gammarid fauna. The study material was collected from Samothraki, Lesbos, Skyros, Evia, Andros, Tinos and Serifos islands as well as from mainland Greece. The DNA extracted was used for amplification of two mitochondrial (COI and 16S) and two nuclear markers (28S and EF1-alpha). The multimarker time-calibrated phylogeny supports multiple origins and different diversification times for the studied taxa. Three of the sampled insular populations most probably represent new, distinct species as supported by all the delimitation methods used in our study. Our results show that the evolution of freshwater taxa is associated with the geological history of the Aegean Basin. The biogeographic affiliations of the studied insular taxa indicate its continental origin, as well as the importance of the land fragmentation and the historical land connections of the islands. Based on the findings, we highlight the importance of studying insular freshwater biota to better understand diversification mechanisms in fresh waters as well as the origin of studied Aegean freshwater taxa.

Continental-scale patterns of hyper-cryptic diversity within the freshwater model taxon Gammarus fossarum (Crustacea, Amphipoda).

Traditional morphological diagnoses of taxonomic status remain widely used while an increasing number of studies show that one morphospecies might hide cryptic diversity, i.e. lineages with unexpectedly high molecular divergence. This hidden diversity can reach even tens of lineages, i.e. hyper cryptic diversity. Even well-studied model-organisms may exhibit overlooked cryptic diversity. Such is the case of the freshwater crustacean amphipod model taxon Gammarus fossarum. It is extensively used in both applied and basic types of research, including biodiversity assessments, ecotoxicology and evolutionary ecology. Based on COI barcodes of 4926 individuals from 498 sampling sites in 19 European countries, the present paper shows (1) hyper cryptic diversity, ranging from 84 to 152 Molecular Operational Taxonomic Units, (2) ancient diversification starting already 26 Mya in the Oligocene, and (3) high level of lineage syntopy. Even if hyper cryptic diversity was already documented in G. fossarum, the present study increases its extent fourfold, providing a first continental-scale insight into its geographical distribution and establishes several diversification hotspots, notably south-eastern and central Europe. The challenges of recording hyper cryptic diversity in the future are also discussed.

Successful post-glacial colonization of Europe by single lineage of freshwater amphipod from its Pannonian Plio-Pleistocene diversification hotspot.

Gammarus roeselii Gervais, 1835 is a morphospecies with a wide distribution range in Europe. The Balkan Peninsula is known as an area of pre-Pleistocene cryptic diversification within this taxon, resulting in at least 13 Molecular Operational Taxonomic Units (MOTUs). The morphospecies diversified there during Neogene and has probably invaded other parts of the continent very recently, in postglacial or even historical times. Thus, the detailed goals of our study were to (1) identify which lineage(s) colonized Central-Western Europe (CWE), (2) determine their possible geographical origin, (3) verify, whether the colonisation was associated with demographic changes. In total, 663 individuals were sequenced for the cytochrome oxidase I (COI) barcoding fragment and 137 individuals for the internal transcribed spacer II (ITS2). We identified two MOTUs in the study area with contrasting Barcode Index Number and haplotype diversities. The Pannonian Basin (PB) appeared to be a potential ice age refugium for the species, while CWE was colonised by a single lineage (also present in PB), displaying low genetic diversity. Our results suggest that G. roeselii is a relatively recent coloniser in CWE, starting demographic expansion around 10 kya.

Deep-sea amphipods around cobalt-rich ferromanganese crusts: Taxonomic diversity and selection of candidate species for connectivity analysis.

The aim of this study was to select a candidate deep-sea amphipod species suitable for connectivity analyses in areas around cobalt-rich ferromanganese crusts (CRCs). We applied DNA barcoding based on the mitochondrial protein-coding gene, cytochrome c oxidase subunit I (COI), to specimens collected from the Xufu Guyot (the JA06 Seamount) off southeastern Minami-Torishima Island in the North Pacific, where CRCs are distributed. We used baited traps to collect 37 specimens. Comparison of COI sequences with public reference databases (GenBank, BOLD) showed that almost all of the specimens belonged to the superfamily Lysianassoidea, which is known to be ubiquitous in deep-sea areas. In a molecular taxonomic analysis of these sequences, we detected 11 clades. One of these clades (group 9) composed of 18 sequences and was identified by DNA barcoding as a putative species belonging to Abyssorchomene, which has been reported from the New Hebrides Trench in the South Pacific. We considered this species to be a candidate for connectivity analysis and analyzed its genome by restriction site-associated DNA sequencing. The results showed that the genetic variation in this species is adequate for analyzing connectivity patterns in CRC areas in the future.

The late blooming amphipods: Global change promoted post-Jurassic ecological radiation despite Palaeozoic origin.

The ecological radiation of amphipods is striking among crustaceans. Despite high diversity, global distribution and key roles in all aquatic environments, little is known about their ecological transitions, evolutionary timescale and phylogenetic relationships. It has previously been proposed that the amphipod ecological diversification began in the Late Palaeozoic. By contrast, due to their affinity for cold/oxygenated water and absence of pre-Cenozoic fossils, we hypothesized that the ecological divergence of amphipods arose throughout the cool Late Mesozoic/Cenozoic. We tested our hypothesis by inferring a large-scale, time-calibrated, multilocus phylogeny, and reconstructed evolutionary patterns for major ecological traits. Although our results reveal a Late Palaeozoic amphipod origin, diversification and ecological divergence ensued only in the Late Mesozoic, overcoming a protracted stasis in marine littoral habitats. Multiple independent post-Jurassic radiations took place in deep-sea, freshwater, terrestrial, pelagic and symbiotic environments, usually postdating deep-sea faunal extinctions, and corresponding with significant climatic cooling, tectonic reconfiguration, continental flooding, and increased oceanic oxygenation. We conclude that the profound Late Mesozoic global changes triggered a tipping point in amphipod evolution by unlocking ecological opportunities that promoted radiation into many new niches. Our study also provides a solid, time-calibrated, evolutionary framework to accelerate research on this overlooked, yet globally important taxon.

Genetic Diversity and Population Structure Analysis of Three Deep-Sea Amphipod Species from Geographically Isolated Hadal Trenches in the Pacific Ocean.

Amphipods of the superfamily Lysianassoidea that inhabit the hadal zone ( > 6000 m) have large bathymetric ranges and play a key role in deep ocean ecosystems. The endemism of these amphipod species makes them a good model for investigating potent natural selection and restricted dispersal in deep ocean trenches. Here, we describe genetic diversity and intraspecific population differentiation among three amphipod species from four Pacific trenches based on a mtDNA concatenated dataset (CO Ι and 16S rRNA genes) from 150 amphipod individuals. All amphipod populations had low genetic diversity, as indicated by haplotype and nucleotide diversity values. Population geographic relationship analysis of two Alicella gigantea populations revealed no genetic differentiation between these two localities (pairwise genetic differentiation coefficient = 0.00032, gene flow = 784.58), and the major variation (99.97%) was derived from variation within the populations. Historical demographic events were investigated using Tajima's D and Fu's F neutrality tests and analysis of mismatch distribution. Consistent results provided strong evidence to support the premise that demographic expansion occurred only for the Mariana population of Hirondellea gigas, possibly within the last 2.1-3.4 million years. These findings suggest that the formation of amphipod population structure might be the result of multiple factors including high hydrostatic pressure, food distribution, trench topographic forcing and potential ecological interactions.

Hidden cases of tRNA gene duplication and remolding in mitochondrial genomes of amphipods.

The evolution of tRNA genes in mitochondrial (mt) genomes is a complex process that includes duplications, degenerations, and transpositions, as well as a specific process of identity change through mutations in the anticodon (tRNA gene remolding or tRNA gene recruitment). Using amphipod-specific tRNA models for annotation, we show that tRNA duplications are more common in the mt genomes of amphipods than what was revealed by previous annotations. Seventeen cases of tRNA gene duplications were detected in the mt genomes of amphipods, and ten of them were tRNA genes that underwent remolding. The additional tRNA gene findings were verified using phylogenetic analysis and genetic distance analysis. The majority of remolded tRNA genes (seven out of ten cases) were found in the mt genomes of endemic amphipod species from Lake Baikal. All additional mt tRNA genes arose independently in the Baikalian amphipods, indicating the unusual plasticity of tRNA gene evolution in these species assemblages. The possible reasons for the unusual abundance of additional tRNA genes in the mt genomes of Baikalian amphipods are discussed. The amphipod-specific tRNA models developed for MiTFi refine existing predictions of tRNA genes in amphipods and reveal additional cases of duplicated tRNA genes overlooked by using less specific Metazoa-wide models. The application of these models for mt tRNA gene prediction will be useful for the correct annotation of mt genomes of amphipods and probably other crustaceans.