amphi-Atlantic Distribution Research Articles

How complex is the Naineris setosa species complex? First integrative study of a presumed cosmopolitan and invasive annelid (Sedentaria: Orbiniidae).

We performed a comparative study of the specimens from the Naineris setosa complex from the Pacific and the Atlantic Oceans and re-described the syntype of N. setosa, including the selection of the lectotype. Molecular phylogenetic and species delimitation analyses based on two mitochondrial (COI and 16S) and one nuclear (28S) marker revealed the presence of three species. One clade with wide Amphi-Atlantic distribution was attributed as Naineris setosa s. str. The second Atlantic clade restricted to Southern and Southeastern Brazil was described as a new species, Naineris lanai sp. n. The third clade, reported from the Northwestern Pacific, was identified as a new species but was not formally described due to the presence of only juvenile-sized worms in the studied material. Detailed morphological descriptions of several diagnostic characters in the Naineris setosa complex are provided.

The Lower Pliocene marine gastropods of Santa Maria Island, Azores: Taxonomy and palaeobiogeographic implications.

In this work, all the Lower Pliocene gastropod assemblages of Santa Maria Island are revised. These all form part of the Touril Complex. Seventy-seven species are identified representing 61 genera. Two species are described as new: Bittium miradouroense nov. sp. and Erato mayeri nov. sp. The name Tritonium secans Bronn in Reiss 1862 is considered a junior subjective synonym of Monoplex comptus (A. Adams, 1855). Pleurotoma perturrita Bronn in Reiss 1862 is considered a junior subjective synonym of Crassopleura maravignae (Bivona, 1838). However, due to the difficulties in collecting from these deposits, this is likely to be a considerable underestimate of the original diversity of local Early Pliocene gastropod faunas. The assemblage reflects a fully tropical with mean annual sea surface temperatures (SSTs) estimated about 3.7°C to 6.3°C higher than the present-day 20.6°C, and with mean monthly SSTs ranging from 20°C to 28°C, with six months with mean SSTs over 24°C. The assemblages all represent relatively shallow water, fully saline marine environments. At genus level the assemblage is typical of that seen in the tropical Mediterranean-West African Palaeobiogeographical Province during the early Pliocene (MPPMU1; roughly equivalent to the Zanclean and earliest Piacenzian). At species level, 35% of the species taxa found in Santa Maria are also found in the Mediterranean during MPPMU1. There is a much weaker association with the northern warm temperate Pliocene Boreal-Celtic Province, with only 17% of species occurring in both. Moreover, most of those are ubiquitous European species with both wide geographic and stratigraphic distributions. The assemblage is relatively endemic (29%) suggesting that the Azorean subprovince/ecoregion, which is recognised today, was already in place in the Lower Pliocene. A small number of tonnoidean species found in Santa Maria are species known to have had an amphiatlantic distribution during the Pliocene, and for Distorsio mcgintyi Emerson & Puffer, 1953, a well-known and widely distributed tropical American Atlantic species from the Early Miocene to present-day, its presence in Santa Maria marks the most easterly range expansion for the species, as today is not found in the Azores.

Possible causes of amphi-Atlantic distribution of Orchestia gammarellus (Pallas, 1776) (Crustacea, Amphipoda, Talitridae) in the North Atlantic: a review

Hypotheses concerning the modern distribution of Orchestia gammarellus (Crustacea, Amphipoda, Talitridae) and its causes in the North Atlantic are discussed. The synanthropic dispersal hypothesis of Henzler and Ingólfsson (2008) considers O. gammarellus as originating on the eastern shore of the North Atlantic and being transported by humans to Iceland and the western Atlantic shore (Newfoundland and the Maritime Provinces of Canada). The Eocene and natural dispersal hypothesis of Myers and Lowry (2020) proposes a geologically earlier origin of O. gammarellus when the west and east shores of the North Atlantic were still connected. Present day amphi-Atlantic distribution was explained by vicariance, with the vicariant event causing separation of O. gammarellus being continental drift drawing apart the west and east shores of the North Atlantic. A post-glacial natural dispersal hypothesis proposed herein, involves transport on ice floes or in driftwood from European shores to Iceland and the Atlantic Provinces of Canada. The small genetic distances amongst populations found by Henzler and Ingólfsson (2008) at the COI gene are inconsistent with the Eocene vicariance hypothesis. On evolutionary grounds, we question Myers and Lowry’s (2020) designation of the Icelandic and Canadian populations as a new species of Orchestia. Existing molecular and morphological data are insufficient to distinguish between human-aided dispersal and natural rafting.

Population structure of the fireworm Hermodice carunculata in the wider Caribbean, Atlantic and Mediterranean Sea

Abstract The bearded fireworm Hermodice carunculata is a conspicuous omnivorous benthic invertebrate distributed in the wider Atlantic Ocean, Mediterranean Sea and the Red Sea. Questions were raised in the past regarding the taxonomic status of amphiatlantic fireworm specimens but subsequent analysis of morphological data with new molecular data reconfirmed the presence of only one species, H. carunculata with amphiatlantic distribution. Hermodice carunculata has been the subject of several taxonomic and genetic studies but there are still questions regarding the genetic diversity and population structure of the species throughout its range. We contributed to the genetic studies of H. carunculata with ~200 new samples from over 20 locations in the Caribbean, Eastern Atlantic Ocean and the Mediterranean Sea. We sequenced the mitochondrial markers Cytochrome c oxidase Subunit I (COI) and Cytochrome b (Cytb) from each polychaete to examine the patterns of genetic diversity of H. carunculata. Our data revealed a significant population structure between the Caribbean H. carunculata including those from Brazil compared with those from the eastern Atlantic (Tenerife, Canary Islands) and eastern Mediterranean (Greece and Malta). We inferred rates of gene flow between eastern and western Atlantic populations by estimating the bidirectional effective migration rate (Nem). We corroborate previous studies indicating the existence of one species with genetically distinct populations. However, the biological significance of the observed population divergence should be evaluated with cross-breeding experiments.

Munidopsis geyeri and M. exuta (Crustacea: Munidopsidae): A study of two deep-sea, amphi-Atlantic species that co-occur in the southern Gulf of Mexico

The history of colonization and dispersal of fauna among deep-sea chemosynthetic ecosystems remains enigmatic and poorly understood. The distribution of squat lobsters of the genus Munidopsis Whiteaves, 1874 can be influenced by the rich organic matter and associated organism communities of chemosynthetic ecosystems. The present work analyzed the molecular relationships and morphology of individuals from different populations of Munidopsis exuta Macpherson & Segonzac, 2005 and M. geyeri Pequegnat & Pequegnat, 1970 in such ecosystems along the Atlantic Equatorial Belt, including the Chapopote Knoll, in the southern Gulf of Mexico. Munidopsis geyeri is re-described based on the present findings and reference to the literature. This analysis documented the genetic distances, as well as range of variation in the diagnostic characters that support the separation of M. exuta and M. geyeri. Our results confirm that the two species coexist in seep ecosystems and have an amphi-Atlantic distribution.

From synonym to valid species: Redescriptions of Ampharete acutifrons (Grube, 1860) and A. cirrata Webster amp; Benedict, 1887, and brief descriptions of A. baltica Eliason, 1955 and A. grubei Malmgren, 1865 (Annelida: Terebellida: Ampharetidae).

This paper aims mainly to provide clarity on the morphological characters of the type species of Ampharete, Ampharete acutifrons (Grube, 1860). Its common occurrence and wide distribution are most likely a result of misidentification of different species. Possible reasons for that are the brief original description of this species that is available solely in Latin and a series of questionable synonymizations, resulting in a confusing history of A. acutifrons. In addition to a detailed redescription of the holotype of A. acutifrons, we describe an Ampharete species from the Baltic Sea that has also been incorrectly identified as A. acutifrons for many decades. The individuals of this species agree in all diagnostic characters with those of the Northwest Atlantic species Ampharete cirrata Webster Benedict, 1887. Since no differences were found, but it is clearly distinct from A. acutifrons, A. cirrata is recognised as a valid species and consequently deleted from the synonym list of A. acutifrons. We additionally examined type material of A. grubei Malmgren, 1865 and those of A. grubei baltica Eliason, 1955, now accepted as A. baltica. According to this, both species are valid, and A. grubei must therefore also be deleted from the list of synonyms of A. acutifrons. Information on five molecular markers (Histone H3, COI, 16S, 18S, 28S) is provided for A. cirrata from the Baltic Sea. DNA sequences (H3, 16S, 28S) were identical to sequences of a specimen found in Iceland that was incorrectly determined as A. acutifrons, supporting the assumption of an amphiatlantic distribution of A. cirrata. By comparing obtained sequences to available sequences in GenBank and BOLD, we found evidence that at least four species were previously misidentified as A. acutifrons. The historical course of the taxonomy of A. acutifrons demonstrates the importance of carefully studying type material and type locality material, respectively. We believe that most previous records and synonyms of A. acutifrons have been identified incorrectly and should be re-evaluated. Additionally, an updated key to all species of Ampharete from the North Atlantic is provided.

Systematics ofVignasubgenusLasiospron(Leguminosae: Papilionoideae: Phaseolinae)

Abstract—A taxonomic treatment is herein provided for the six primarily Neotropical species ofVignasubg.Lasiospron. This subgenus is distinguished, in part, by its close relationship with Old WorldVignaspecies, but rather than having an Old WorldVignafloral asymmetry where distal floral parts can have a right-hand curvature (from a face-view perspective), distal parts ofVignasubg.Lasiospronflowers, like those of American Phaseolinae, curve to the left. Our proposed taxonomy reflects published phylogenetic analyses that resolve theVignasubg.Lasiospronspecies in a subclade of the primarily Old World clade of species ofVignasensu stricto.Vignasubg.Lasiospronis therefore distinctive in having a primarily neotropical distribution. Three of the sixVignasubg.Lasiospronspecies have an amphi-Atlantic distribution, which we suggest was achieved naturally by the ability of these species to disperse and colonize coastal habitats. Nomenclatural and taxonomic synonyms are reported, along with species descriptions and the biogeographical, genetic, and morphological evidence that argues for each of the sixVignasubg.Lasiospronspecies fitting a unified species concept.

Split distribution, biogeography and morphological and genetic diversity of the Iberobathynellini Tribe in the family Parabathynellidae (Crustacea, Malacostraca, Bathynellacea)

Abstract The “Iberobathynella group”, or Iberobathynellini tribe, is a complex of six genera consisting of 33 nominal species and several cryptic species with an amphiatlantic distribution (in Europe, North Africa and North America). A modern systematic revision of this group of subterranean crustaceans is presented here. A phylogenetic and biogeographic study using morphological and molecular data (mitocondrial coi and nuclear 18S) was carried out and allowed to a) re-evaluate the taxonomic status and validity of previously erected subtribes, genera and subgenera that show congruence in the data; b) assess whether the identified mitochondrial lineages represent cryptic species; c) provide a plausible phylogenetic hypothesis for the relationships within Iberobathynellini and with the other two genera of the family Parabathynellidae that inhabit North America and Europe (Montanabathynella and Parabathynella, respectively); d) propose a plausible temporal and historical framework (paleobiogeographic scenario) for the diversification and evolution of the Iberobathynellini tribe based on the current distribution of morphotypes and their estimated times of divergence. Our results show that in parabathynellids, molecular and morphological divergences are not always congruent. Subtribe and subgenus are invalid categories so they must be eliminated. Paraiberobathynella genus needs to be revisited. The molecular dating results support the early divergence of the Iberobathynellini Tribe (Upper Cretaceous, around 78 Mya) and the vicariance by plate tectonics as main factor to explain the amphi-Atlantic distribution shown by this ancient subterranean crustacean group. Since there are species morphologically very similar to I. magna and I. imuniensis, but genetically different, we can ensure the existence of at least three cryptic species. Texanobathynella is undoubtedly a valid genus distinct from Iberobathynella. Montanabathynella and Parabathynella are two well-differentiated genera closely related to the Iberobathynellini tribe.

Предварительный хорологический анализ флоры сосудистых растений горно-тундрового пояса и пояса гольцовых пустынь Хибинских гор (Мурманская область)

Percentage of bio-geographic elements of vascular plants was analysed in Mountain Tundra (MT) and the cold Arctic Mountain (goltzovy) desert (AMD) belts in Khibiny Mountains. Flora of MT (191 species) is richer than flora of AMD (62 species) more than three times. Arctic group of species in MT comprises 42 %, hypoarctic (26 %) and boreal together with polyzonal (32 %). In flora of AMD prevails arctic group of species (63 %), hypoarctic group is on the second place (23 %) and boreal (14 %). The ratio of latitudinal bio-geographical groups in MT corresponds to the hypoarctic type of flora, and in AMD — to the arctic type, that confirms the differentiation of treeless belts in Khibiny Mountains. Groups of species with circumpolar distribution prevail in the species lists of both treeless belts (45 % in MT and 55 % in AMD). Other longitudinal groups in MT include species with east-American-European (10 %), east-American-European-Asiatic (10 %), Euro-Siberian (Euro-Asiatic) (15 %), and European (10 %) distribution. In AMD species with amphi-Atlantic distribution comprise 25 %, species with Euro-Siberian (Euro-Asiatic) and European distribution have less share (8 and 3 %)

Malpighiaceae de Colombia: Patrones de distribución, riqueza, endemismo y diversidad filogenética

Malpighiaceae constitutes a family of 77 genera and ca. 1300 species, distributed in tropical and subtropical regions of both hemispheres. They are mainly diversified in the American continent and distributed in a wide range of habitats and altitudinal gradients. For this reason, this family can be a model plant group to ecological and biogeographical analyses, as well as evolutive studies. In this context, an analysis of distribution, richness, endemism and phylogenetic diversity of Malpighiaceae in natural regions and their altitudinal gradients was undertaken. Malpighiaceae are represented in Colombia by 34 genera and 246 species (19.1% of endemism). Thus, Colombia and Brazil (44 genera, 584 species, 61% of endemism) are the two richest countries on species of this family. The highest species richness and endemism in Colombia is found in the lowlands (0-500 m a.s.l.: 212 species, 28 endemics); only ten species are distributed on highlands (2500-3200 m a.s.l.). Of the Malpighiaceae species in Colombia, Heteropterys leona and Stigmaphyllon bannisterioides have a disjunct amphi-Atlantic distribution, and six other species show intra-American disjunctions. Both richness and endemism decrease with altitude (y = -0.061x + 173.57; R2 = 0.82; y = -0.009x + 27.76; R2 = 0.95, respectively). Amazonia (116 species, 4 endemics) and the Andes (89 species, 23 endemics) exhibit the highest richness among the family. In Colombia, 15 of the 19 clades among the family are represented, where the most diversified are the Stigmaphyllon clade (5 genera, 48 species, 10 endemics), the Byrsonima clade (3/39/5) and the Hiraea clade (3/31/9). The relationship of phylogenetic diversity with altitude is similar to the pattern of specific richness by altitudinal interval. Amazonia, Orinoquia, and Magdalena Valley show highest phylogenetic diversity. These results, combined with those of other highly diversified biological groups in the country, could be important to define and delimitate new priority areas for conservation in Colombia.

Naming and describing the diversity in the Usnea cornuta aggregate (lichenized Ascomycota, Parmeliaceae) focusing on Brazilian specimens

This study is a reassessment of the Usnea cornuta aggregate diversity mainly in Brazil. Based on previous multi-locus species delimitation analyses using the multispecies coalescent model (MSC), we carried out a posteriori morphological and anatomical studies. The following corticolous new species are described: Usnea arianae with norstictic or fatty or lobaric acids, convex and efflorescent soralia and a lax medulla; U. flabelliformis with protocetraric acid, fan-shaped main branches and a high medulla/cortex ratio; U. rubropallens with protocetraric acid and a faint orange cortical/subcortical pigment; U. stipitata with constictic acid, stipitate soralia and a high medulla/cortex ratio; and U. tenuicorticata with protocetraric acid, a thin cortex and a high medulla/cortex ratio. The newly described species were found to occur so far only in the Americas, except U. arianae which shows an amphi-atlantic distribution in Europe and on the American continent. Seven species already described belonging to the U. cornuta aggr. in Brazil are further treated here: Usnea boomiana with caperatic acid and large, concave soralia, new to South America; U. brasiliensis with protocetraric acid, minute and irregular soralia; U. cornuta with mainly salazinic acid and minute soralia fusing into consoralia; U. macaronesica (syn. nov.: U. subglabrata) with barbatic acid, large excavate soralia and a lax medulla; Usnea subpectinata, a so far european species resurrected from the U. cornuta synonymy, with stictic acid and numerous isidiofibrils, new to South America; and U. trachyclada with thamnolic acid and K+ bright yellow stipitate soralia. Full descriptions with morphological, anatomical and chemical features, geographical distributions, and illustrations are provided for each species along with an identification key.

Ephemerum homomallum (Pottiaceae) and Torrentaria aquatica (Brachytheciaceae), Two Additional American Moss Species New to Africa

Two American species of moss, <em>Ephemerum homomallum </em>Müll. Hal. (Pottiaceae) and <em>Torrentaria</em><em> </em><em>aquatica </em>(A. Jaeger) Ochyra (Brachytheciaceae), are reported as new to Africa, based on collections from the Limpopo and Eastern Cape provinces of South Africa, respectively. These discoveries changed the phytogeographical status of both species, which now belong to the Afro-American distribution element. Global geographical ranges of these two species are reviewed and mapped, and the amphiatlantic distribution pattern of mosses is briefly summarized. A history of the muscological exploration of southern Africa is briefly considered and recent additions to the moss flora of this area are reviewed.

First record of the rare deep-sea polychaete Rhamphobrachium (Rhamphobrachium) agassizii (Annelida: Onuphidae) in European waters

AbstractRhamphobrachium (Rhamphobrachium) agassizii is reported from the Cantabrian Sea, Spain, from depths of 925–1207 m. This is its first record off the Iberian Peninsula and in European waters, representing its northernmost distribution in the North Atlantic Ocean to date. Previous reports of R. (R.) agassizii from the eastern and western North Atlantic demonstrate its apparent amphi-Atlantic distribution, which appears consistent with the distribution of the main Atlantic currents. It is a typical deep-water species with its deepest record at 2165 m from the Azores archipelago. The specimens were collected singly at two stations, attesting to the rarity of the species in contrast to its congener R. (Spinigerium) brevibrachiatum which was the most dominant polychaete species in a previous study.

Lobophora (Dictyotales) Species Richness, Ecology and Biogeography Across the North-Eastern Atlantic Archipelagos and Description of Two New Species1.

The brown alga Lobophora (Dictyotales, Phaeophyceae) is an important macroalga in the North-eastern Atlantic archipelagos (i.e., Macaronesia). Notably in the Canaries it can dominate benthic assemblages. While the genus has been the subject of several ecological studies in the Canaries, no study has yet been conducted to assess species-level diversity of Lobophora in Macaronesia. We reassessed the diversity of Lobophora in Macaronesia, reporting the presence of seven species (L. caboverdeana sp. nov., L. canariensis, L. dagamae sp. nov., L. delicata, L. dispersa, L. littlerorum, and L. schneideri). Lobophora spp. from Macaronesia are morphologically and ecologically distinguishable. In the Canaries, L. schneideri dominates the photophilic assemblages from the intertidal to 20-30m depth. Lobophora dagamae sp. nov. grows in less illuminated shallow habitats, and replaces L. schneideri from 30 to ~80m. Lobophora canariensis also has a wide vertical distribution, from the intertidal to deep waters, while L. delicata, L. dispersa and L. littlerorum grow in shallow waters. The dominance of species with an upright habit versus prostrate or crustose species may be mediated by the pressure of herbivores. Four species have an amphi-Atlantic distribution: L. littlerorum, L. canariensis, L. delicata, and L. schneideri. Lobophora schneideri and L. delicata are furthermore distributed in the Mediterranean Sea. By sampling a pivotal region in the Atlantic, this study significantly improves our knowledge of Lobophora biogeography in the Atlantic Ocean. Macaronesia constitutes a species-poor region for Lobophora where no diversification events occurred, and a region of overlap between the Greater Caribbean and the Indo-Pacific.

Micromenia amphiatlantica sp. nov.: First solenogaster (Mollusca, Aplacophora) with an amphi-Atlantic distribution and insight into abyssal solenogaster diversity

Although many of the most recently described Solenogastres (Mollusca, Aplacophora) come from abyssal locations (3500–6000 m depth), most members of the group have been described from the continental shelf and slope with just 23 of the 290 formally described species known from depths below 3500 m. In addition, most solenogasters are described from one or very few sampling localities, so practically nothing is known about their actual distribution. This lack of information may be attributed to the somewhat labor-intensive nature of the traditional taxonomy of this group, which often results in the exclusion of solenogasters from biodiversity or biogeographic studies. Further, the abyssal basins are one of the most unknown habitats of the planet. Projects such as DIVA (Latitudinal Gradients of Deep-Sea BioDIVersity in the Atlantic Ocean) aim to eliminate such a lack of knowledge about abyssal biodiversity by shedding light on the abundance and distribution of species in this habitat. During the DIVA expeditions (DIVA1: Angola Basin, DIVA 2: Angola, Guinea, and Cape Basin and DIVA·3: Argentina and Brazil Basin), a large number of solenogasters was collected. Here we describe a new species, Micromenia amphiatlantica sp. nov., which occurs in three of the explored basins (Angola, Guinea, and Brazil). This species is characterized by a distinct scleritome, a monoserial radula with paired denticles, and a unique combination of internal anatomical characters. To our knowledge, this is the first described abyssal member of the solenogaster clade Pholidoskepia and the first solenogaster with an amphi-Atlantic distribution.

The age and diversification of metacrangonyctid subterranean amphipod crustaceans revisited

The Metacrangonyctidae are a small family of amphipod crustaceans of marine origin found only in subterranean continental waters. They display a broad but punctuated distribution between the Caribbean and the Arabian Peninsula, with major disjunctions either due to vicariance by plate tectonics or to occurrence of recent episodes of long-distance transoceanic dispersal. We re-examine the phylogeny of the family and the time frame for its diversification using mitochondrial genomes in the light of two key taxa recently discovered, from Oman (Arabian Peninsula) and the Rif area of Morocco, respectively. We also use a novel fossil calibration scheme of the mitogenome phylogeny. Results of previous analyses based on palaeogeographic calibrations are not contradicted by the new approach, with vicariance by plate tectonics remaining as the main explanatory factor for the amphi-Atlantic distribution displayed by this ancient group of subterranean amphipods.

Karyological traits related to phylogenetic signal and environmental conditions within the Hymenaea clade (Leguminosae, Detarioideae)

The Hymenaea clade is a lineage of the subfamily Detarioideae of Leguminosae. The clade is currently composed of three genera: Guibourtia, Hymenaea, and Peltogyne. The genera Guibourtia and Hymenaea present an Amphi-Atlantic distribution, whereas Peltogyne is exclusively found in the Neotropics. Previous studies have focused on the phylogeny of the group but there are no studies that demonstrate mechanisms that could be involved in the evolution of this Amphi-Atlantic clade. The present work is the largest cytogenetic analysis for the group published so far. We aimed to provide a study of karyotypic characteristics of the Hymenaea clade, interpreted using the plastidial trnK phylogenetic reconstruction as background. We analyzed karyological characteristics such as chromosome number, chromosome size, centromeric position, CMA/DAPI patterns, and banding for 5S and 45S rDNA. With the present data available, multivariate analyses (PCA) and Phylogenetic Eigenvector Regression (PVR) demonstrated that centromeric asymmetry and number of 5S rDNA sites may present a strong phylogenetic signal, whereas number of CMA+ sites is associated with geography/climate characteristics. The association of CMA bands and geography has been reported for other legumes of the Caesalpinia group. This study demonstrates that the use of statistical tools for analyzing karyotypic characteristics can result in more precise interpretation of evolutionary processes related to structural changes in chromosomes and how these changes can also be related to environmental conditions.

Taxonomic status of the amphi-Atlantic species Plesionika acanthonotus (Caridea: Pandalidae): a multi-locus and morphological approach.

Deep-sea shrimps of the species Plesionika acanthonotus (Smith, 1882) and P. holthuisi Crosnier Forest, 1968 are morphologically similar and exhibit overlapping amphi-Atlantic distributions. In the literature, through morphological studies, there are reports of doubts about the validity of P. holthuisi and some authors believe that the eastern and western Atlantic populations of P. acanthonothus could represent two distinct species. The objective of the present study was to use molecular data to elucidate the taxonomic status of the two populations of P. acanthonothus. DNA sequences of two mitochondrial genes (16S rDNA and Cytochrome Oxidase subunit I) and a nuclear gene (Histone 3) were obtained for both species and for both populations of P. acanthonotus. The sequences were also obtained from Genbank for comparison. The trees (separate and multi-locus/partitioned genes) were generated by Bayesian Inference analyzes, and genetic divergence (Kimura-2-parameters) was also calculated. All specimens that had their DNA sequenced were examined morphologically to confirm their identification; morphological variations were noted. The genetic data showed that Plesionika holthuisi is closely related to P. acanthonotus, but clearly separated, indicating that P. holthuisi is a valid species. In the multi-locus analysis, the P. acanthonothus specimens were divided into two clades, one with the eastern Atlantic specimens and another with the western Atlantic specimens. However, this genetic separation was considered to be a population structuring for three reasons: (1) the genetic divergences of the two mitochondrial genes between these two groups (eastern Atlantic X western Atlantic) were smaller than the interspecific divergence for Plesionika; (2) the P. acanthonothus sequences of the Histone 3 gene showed no genetic variation; (3) in the analyzed individuals, no valid morphological character was found to support this separation. Thus, the conclusion of this study is that P. holthuisi probably is a valid species and P. acanthonothus presents two populations with mitochondrial divergences that could be in the process of speciation, but which currently represent only one species.

Species delimitation and mitogenome phylogenetics in the subterranean genus Pseudoniphargus (Crustacea: Amphipoda)

The amphi-Atlantic distributions exhibited by many thalassoid stygobiont (obligate subterranean) crustaceans have been explained by fragmentation by plate tectonics of ancestral shallow water marine populations. The amphipod stygobiont genus Pseudoniphargus is distributed across the Mediterranean region but also in the North Atlantic archipelagos of Bermuda, Azores, Madeira and the Canaries. We used species delimitation methods and mitogenome phylogenetic analyses to clarify the species diversity and evolutionary relationships within the genus and timing their diversification. Analyses included samples from the Iberian Peninsula, northern Morocco, the Balearic, Canarian, Azores and Madeira archipelagoes plus Bermuda. In most instances, morphological and molecular-based species delimitation analyses yielded consistent results. Notwithstanding, in a few cases either incipient speciation with no involvement of detectable morphological divergence or species crypticism were the most plausible explanations for the disagreement found between morphological and molecular species delimitations. Phylogenetic analyses based on a robust calibrated mitochondrial tree suggested that Pseudoniphargus lineages have a younger age than for other thalassoid amphipods displaying a disjunct distribution embracing both sides of the Atlantic Ocean. A major split within the family was estimated to occur at the Paleocene, when a lineage from Northern Iberian Peninsula diverged from the rest of pseudoniphargids. Species diversification in the peri-Mediterranean area was deduced to occur in early Miocene to Tortonian times, while in the Atlantic islands it started in the Pliocene. Our results show that the current distribution pattern of Pseudoniphargus resulted from a complex admix of relatively ancient vicariance events and several episodes of long- distance dispersal.

Sphagnum divinum (sp. nov.) and S. medium Limpr. and their relationship to S. magellanicum Brid.

Sphagnum magellanicum has been viewed as being a predominantly circumpolar species in the northern hemisphere, but it occurs in the southern hemisphere and was originally described from the southern parts of Chile. It is an ecologically important species in mire ecosystems and has been extensively used as a model to study processes of growth, carbon sequestration and peat decomposition. Molecular and experimental studies have, however, revealed genetic structure within S. magellanicum, and morphological differences associated with these genetic groups. Here we describe Sphagnum divinum in Sphagnum subgenus Sphagnum (Sphagnaceae, Bryophyta) as a new species, based on molecular and morphological evidence. Sphagnum medium is reinstated as a distinct species and is epitypified. Consequently, a new species concept of S. magellanicum is presented including an epitypification. Important morphological characters to separate these three species in the field and under the microscope are presented. Ecology and distribution differ among the species; S. divinium has a wide habitat range including mire margin, forested peatlands and moist heaths, and a circumpolar distribution around the northern hemisphere. Sphagnum medium seems to be more restricted to ombrotrophic mire expanse habitats and shows an amphi-Atlantic distribution in the northern hemisphere. Sphagnum magellanicum has a very broad ecological niche in peatlands and is found in most mire habitats in Tierra del Fuego on the southern tip of South America.