Genus level molecular phylogeny of Aegisthidae Gisbrecht, 1893 (Copepoda: Harpacticoida) reveals morphological adaptations to deep-sea and plagic habitats.

BACKGROUND: The family Aegisthidae is known as typical component of deep-sea hyperbenthic waters that gradually colonized other marine environments. The phylogenetic relationships within this family have been examined here including hyperbenthic, planktonic, benthic forms and two associated Aegisthidae species. RESULTS: Ninety four specimens belong to 14 genera were studied using 18S and 28S rRNA and COI mtDNA. Bayesian analysis supports the monophyly of 10 genera whereas Andromastax, Jamstecia, Nudivorax and Aegisthus revealed to be paraphyletic. The first offshoot of the phylogenetic tree is a clade consists of the undescribed genus Aegisthidae gen.1 sister to the two monophyletic genera Cerviniella and Hase, whereas the other Cerviniinae members (represented by Cervinia and Expansicervinia) assemble a monophylum, sister to the hyperbenthic and planktonic aegisthid genera, resulting in the paraphyly of the subfamily Cerviniinae. Hence, we defined the new subfamily Cerviniellinae subfam. nov. encompassing the three benthic genera Cerviniella, Hase and Eucanuella. The subfamily Cerviniinae has been re-defined to include Cervinia, Expansicervinia and Paracerviniella. Members of the subfamily Pontostratiotinae were clustered into two clades, one consists of the genus Stratiopontotes sister to an undescribed genus + Cerviniopsis and Siphonis. The second contains Pontostratiotes sister to the members of the planktonic subfamily Aegisthinae, resulting in the paraphyly of the Pontostratiotinae. Therefore, the Pontostratiotinae has been re-defined to include only members of the genus Pontostratiotes; whereas the subfamily Cerviniopseinae has been re-erected and re-defined containing Stratiopontotes, Cerviniopsis, Siphonis, Aegisthidae gen. 2, Herdmaniopsis, Hemicervinia and Tonpostratiotes. Within this subfamily, the associated Siphonis clusters as sister to the Cerviniopsis represents an example of convergent evolution in which the possession of a stylet-like mandible and an oral cone reminiscent of the Siphonostomatoida. The planktonic Aegisthus, Andromastax, Jamstecia, Nudivorax and Scabrantenna confirm the monophylom Aegisthinae, sister to the Pontostratiotinae. CONCLUSIONS: Our DNA based phylogeny reveals the deep-sea origin of Aegisthidae by placing benthic Aegisthidae gen.1 and Cerviniellinae subfam. nov. as the most basal lineages. Secondary adaptations to hyperbenthic and planktonic realms, as well as associated lifestyle were discovered here by the derived positions of Pontostratiotinae, Aegisthinae and Siphonis respectively.

Molecular evidence for the retention of the Thaumatopsyllidae in the order Cyclopoida (Copepoda) and establishment of four suborders and two families within the Cyclopoida.

The classification of the Thaumatopsyllidae within the Copepoda has been an issue of ongoing discussion since the discovery of Thaumatopsyllus paradoxus G.O. Sars, 1913 from the Norwegian coast. The family has been formally placed in the Monstrilloida, the Cyclopoida and even in its own order, the Thaumatopsylloida, based on different morphological criteria. We examined for the first time, the phylogenetic position of the Thaumatopsyllidae using gene sequences of 28S and 18S rRNA, as well as COI mtDNA, obtained from two thaumatopsyllid species occurring off the coast of southern California. We also fortuitously explored the phylogenetic relationships of the Cyclopoida in more detail than Khodami et al. (2017) by including a wider sample of key families such as the Erebonasteridae and Gisellinidae. Both Maximum Likelihood and Bayesian analyses revealed the Thaumatopsyllidae is nested in the Cyclopoida and is related to the marine Speleoithonidae. In addition, 16 families of the Cyclopoida are supported to be monophyletic, but surprisingly, the Cyclopidae is paraphyletic. The Cyclopicinidae is the first monophyletic offshoot of the cyclopoid tree, followed by two derived clades. The first clade contains a monophylum consisting of the Schminkepinellidae + Giselinidae which is sister to a clade including the monophyletic Erebonasteridae and all other poecilostome families. The second clade is divided into two main, well-supported family clusters. One includes the Cyclopidae encompassing two subfamilies (Eucylopinae and Cyclopinae), but unexpectedly the parasitic Lernaeidae cluster as a sister-group to the brackish water Halicyclops (subfamily Halicyclopinae) and the Euryteinae is the sister to all the rest of Cyclopidae s. l., making the Cyclopidae paraphyletic. To resolve this conundrum, we erected two families, Euryteidae and Halicyclopidae. The Cyclopidae s. str. retains the subfamilies Eucyclopinae and Cyclopinae, although our phylogeny does not support the reciprocal monophyly of these subfamilies. Our results support the gradual invasion of fresh water by the four families in this cluster. The highly supported monophyletic marine Euryteidae is the first offshoot followed by the brackish-water, free-living Halicyclopidae and the freshwater, parasitic Lernaeidae. The Cyclopidae fulfilled the colonization of freshwater bodies. The other clade of families comprises 12 monophyletic families recovered by our analysis, including the Pterinopsyllidae (at first offshoot), the Smirnovipinidae sister to the Hemicyclopinidae + Psammocyclopinidae, the Thaumatopsyllidae + Speleoithonidae, an undescribed family sister to the Archinotodelphyidae + Notodelphyidae and the Cyclopinidae sister to the Oithonidae + Cyclopettidae. We propose suborder ranks for each of the four main phylogenetic subdivisions of the Cyclopoida. These are named Cyclopicinida, Ergasilida, Cyclopida and Oithonida after the type genus of the oldest described family in the respective group.

Benthic microbial biogeographic trends in the North Sea are shaped by an interplay of environmental drivers and bottom trawling effort.

Microbial composition and diversity in marine sediments are shaped by environmental, biological, and anthropogenic processes operating at different scales. However, our understanding of benthic microbial biogeography remains limited. Here, we used 16S rDNA amplicon sequencing to characterize benthic microbiota in the North Sea from the top centimeter of 339 sediment samples. We utilized spatially explicit statistical models, to disentangle the effects of the different predictors, including bottom trawling intensity, a prevalent industrial fishing practice which heavily impacts benthic ecosystems. Fitted models demonstrate how the geographic interplay of different environmental and anthropogenic drivers shapes the diversity, structure and potential metabolism of benthic microbial communities. Sediment properties were the primary determinants, with diversity increasing with sediment permeability but also with mud content, highlighting different underlying processes. Additionally, diversity and structure varied with total organic matter content, temperature, bottom shear stress and bottom trawling. Changes in diversity associated with bottom trawling intensity were accompanied by shifts in predicted energy metabolism. Specifically, with increasing trawling intensity, we observed a transition toward more aerobic heterotrophic and less denitrifying predicted metabolism. Our findings provide first insights into benthic microbial biogeographic patterns on a large spatial scale and illustrate how anthropogenic activity such as bottom trawling may influence the distribution and abundances of microbes and potential metabolism at macroecological scales.

Copepods and ostracods associated with bromeliads in the Yucatán Peninsula, Mexico.

A substantial fraction of the freshwater available in the Neotropical forests is enclosed within the rosettes of bromeliads that form small aquatic islands within a terrestrial landscape. These aquatic oases provide shelter, water, nutrients and resting of aggregation sites for several aquatic organisms, among them crustaceans. However, in comparison with the multitude of studies on open aquatic systems, our knowledge on crustaceans inhabiting semi-terrestrial habitats and phytotelmata is limited and their presence in such environments is poorly understood. The present study was carried out in two natural protected areas of the Yucatán Peninsula aiming to understand the diversity and dispersal strategies of crustaceans living in bromeliads. Sediment and water contained in four species of bromeliads have been collected in order to understand the diversity and dispersal strategies of crustaceans living in such habitats. From a total of 238 bromeliads surveyed, 55% were colonized by crustaceans. Sixteen copepod, three ostracod and one branchiopod species were recorded during this study, however only seven species are considered as true bromeliad inhabitants. Different degrees of association between crustaceans and bromeliad species were assessed with an indicator species analysis, where significant associations were found for all crustaceans. We found significant differences between bromeliad species and reserves and their associated fauna. In order to analyze the genetic diversity of this fauna, we sequenced several individuals of each species with two genetic markers (18S rRNA and COI mtDNA). Bayesian analyses and the Generalized Mixed Yule Coalescent method (GMYC), delimited 7 well supported species. A comparison of the dispersal strategies used by different species, including passive dispersal, phoretic behavior and active dispersal, is included. This study stresses the need of studying meiofauna of phytotelms, which could be used as an indicator of local diversity in Neotropical forests.

Retraction Note: Molecular Phylogeny and Revision of Copepod Orders (Crustacea: Copepoda).

Editor's Note: this Article has been retracted; the Retraction Note is available at https://www.nature.com/articles/s41598-020-72330-x.

Molecular Phylogeny and Revision of Copepod Orders (Crustacea: Copepoda).

For the first time, the phylogenetic relationships between representatives of all 10 copepod orders have been investigated using 28S and 18S rRNA, Histone H3 protein and COI mtDNA. The monophyly of Copepoda (including Platycopioida Fosshagen, 1985) is demonstrated for the first time using molecular data. Maxillopoda is rejected, as it is a polyphyletic group. The monophyly of the major subgroups of Copepoda, including Progymnoplea Lang, 1948 (=Platycopioida); Neocopepoda Huys and Boxshall, 1991; Gymnoplea Giesbrecht, 1892 (=Calanoida Sars, 1903); and Podoplea Giesbrecht, 1892, are supported in this study. Seven copepod orders are monophyletic, including Platycopioida, Calanoida, Misophrioida Gurney, 1933; Monstrilloida Sars, 1901; Siphonostomatoida Burmeister, 1834; Gelyelloida Huys, 1988; and Mormonilloida Boxshall, 1979. Misophrioida (=Propodoplea Lang, 1948) is the most basal Podoplean order. The order Cyclopoida Burmeister, 1835, is paraphyletic and now encompasses Poecilostomatoida Thorell, 1859, as a sister to the family Schminkepinellidae Martinez Arbizu, 2006. Within Harpacticoida Sars, 1903, both sections, Polyarthra Lang, 1948, and Oligoarthra Lang, 1948, are monophyletic, but not sister groups. The order Canuelloida is proposed while maintaining the order Harpacticoida s. str. (Oligoarthra). Cyclopoida, Harpacticoida and Cyclopinidae are redefined, while Canuelloida ordo. nov., Smirnovipinidae fam. nov. and Cyclopicinidae fam. nov are proposed as new taxa.