First molecular evidence for the existence of a Tardigrada + Arthropoda clade

Evolution and homology of leg segments in Chelicerata: Evo-devo solutions to century-old challenges

A major theme in the evolution of Arthropoda is the origin and diversification of jointed appendages. One appealing framework for the evolution of arthropod appendage diversity has long been that a small network of homologous genes in the panarthropod ancestor established and subdivided the proximo-distal (PD) appendage axis, with lineage-specific modifications of these genes' expression domains resulting in novel types of appendages. A corollary of this idea is the inference that each segment in the arthropod leg can be directly homologized to other such segments, based on anatomical or developmental genetic landmarks. Here, we explore the evolution of leg segments in Chelicerata, a group which exhibits marked diversity in leg architecture and number of leg segments, and thereby poses a greater challenge to the exercise of assigning segmental homologies. Focusing on the controversial nomenclature of leg segments in Pycnogonida (sea spiders), we identify potential markers of positional homology in different parts of the sea spider and arachnid PD axis, using comparative gene expression data. Nevertheless, we identify caveats to the use of transcription factor expression domains as landmarks for inference of positional homology, highlighting cases where datasets conflict in homology assignment. We postulate that the utility of gene expression data for inferring homologies is a function of phylogenetic distance.

Perched on the Plateau: Speciation in a Cape Fold Mountain Velvet Worm Clade, With the Description of Seven New Species (Onychophora: Peripatopsidae: Peripatopsis) From South Africa

During the present study, we re-examined species boundaries in three mountain-dwelling velvet worm species complexes (Peripatopsis balfouri s.l., P. bolandi s.l. and P. purpureus s.l.) along the Cape Fold Mountains of South Africa. We obtained DNA sequence data for both the mitochondrial cytochrome c oxidase subunit one (COI) and the nuclear 18S rRNA loci. Phylogenetic inferences were derived with the use of maximum likelihood and Bayesian inference coupled with a divergence time estimation. Four species delimitation methods (ASAP, bPTP, bGYMC and STACEY) together with gross morphological analyses and scanning electron microscopy (SEM) were used to validate the diagnosis of novel species. Combined phylogenetic results demonstrated the presence of three geographically discrete clades (A-C). Corroborative evidence for the novel lineages could be derived from the dorsal integument colour of live specimens and fixed dorsal and ventral papilla scales rank counts. The four species delimitation methods produced variable results. Divergence time estimations indicated that the Miocene epochs was a major period of cladogenesis. The seven novel velvet worm species, P. barnardi sp. nov., P. fernkloofi sp. nov., P. jonkershoeki sp. nov., P. kogelbergi sp. nov., P. landroskoppie sp. nov., P. limietbergi sp. nov., and P. palmeri sp. nov., are herein described.

A new species of an unusual polychaete genus Ctenophoricola (Phyllodocida, Phyllodocidae, Alciopini) from the Indian Ocean

A new species belonging to an unusual polychaete genus Ctenophoricola is described as Ctenophoricola tzetlini sp. nov.. The new species differs from the two valid species of the genus in body proportions and in having: external eyes with well-developed cornea resembling those in free-living Alciopini, acicular chaetae in the anterior body region, a large pygidium with long anal cirri, and distinct bundles of cilia scattered over the posterior body region. The new species' similarity to an undescribed Ctenophoricola sp. from the Gulf of California is discussed. We hypothesize that the genus Ctenophoricola consists of two lineages, one strongly specialized as ectoparasites and the sister group closer to free-living Alciopini.

Mass Die-Off Events in Swarming Hyperiid Amphipods: Potential Drivers

Beach mass stranding events of marine organisms, widely documented worldwide, are triggered by a range of biotic and abiotic environmental factors, often unexplained. Such occurrences among pelagic crustaceans are less frequent, yet not uncommon. Here we studied mass mortality events of hyperiid amphipods-abundant members of pelagic zooplankton, commonly associated with gelatinous organisms. Our study examined consecutive mass die-off and stranding events of free-living hyperiids in the Red Sea during 2023 and 2024. We investigated three potential causes: semelparous reproduction, thermal stress, and physical oceanographic conditions. To place our findings in a broader context, we further performed a global review of hyperiid swarming and mass mortality events from scientific literature and a citizen science repository. Morphological and molecular analyses confirmed that the hyperiid species in the die-off events at the Red Sea was Anchylomera blossevillei (Phrosinidae). The balanced male: female sex ratio (0.99), combined with the absence of gravid or brooding females, led to the rejection of semelparity as a driving factor. The environmental data did not indicate thermally stressful conditions, and no evidence of parasitic infection was found. Nonetheless, previous studies have shown that under weak wind conditions, as measured during the stranding events, coherent cyclonic eddies with diameters of 5-6 km are developed in the northern Gulf of Aqaba, persisting for about a day. These eddies can exceed velocities of 100 cm s-1 and may have facilitated the hyperiid stranding events. Future research should unveil the impacts of such events on marine ecosystems.

New Asian pseudoscorpions improve the phylogenetic resolution of Garypinoidea (Pseudoscorpiones)

The recent subdivision of the pseudoscorpion family Garypinidae into three subfamilies, Garypininae, Amblyolpiinae and Protogarypininae, used a combination of molecular and morphological criteria. Newly obtained sequence data from several new garypinoid pseudoscorpions has helped clarify the relationships between various clades. Most importantly, we were able to include the type species of the family, Garypinus dimidiatus (L. Koch, 1873), and two additional species of Amblyolpium Simon, 1898, including A. shenzhou sp. nov. from southern China, which provided a better resolved phylogeny with Amblyolpium as sister to all other Garypinoidea. We raise the subfamily Amblyolpiinae to full family level, Amblyolpiidae stat. nov. In addition, we describe a new genus and species from the Himalayan Plateau, Absensus zhangi sp. nov., which has a morphological feature that allows placement in Amblyolpiidae. ZooBank: urn:lsid:zoobank.org:pub:4BDE596B-6EFE-4AB8-932E-1D4379849677.

First record of Morimotobathynella Serban, 2000 (Bathynellacea, Bathynellidae) from subterranean waters of South Korea, with the description of a new species

This study describes Morimotobathynellakoreana sp. nov., the first new species of Bathynellidae family reported in East Asia since 2000, and it presents the first molecular analysis using CO1 and 18S gene sequences. Morphological analysis reveals that the new species and previously known Morimotobathynella species uniquely share key characteristics in the male and female thoracopods VIII. However, the presence or absence of the median seta on the antenna exopod, along with the length differences between the four spines in the furca, distinguish the new species from M.miurai, 2000. A molecular phylogenetic analysis indicates that the new species has a relatively close relationship to species from the genus Altainella in Mongolia and Russia.

A faunal inventory of methane seeps on the Pacific margin of Costa Rica

The methane seeps on the Pacific margin of Costa Rica support extensive animal diversity and offer insights into deep-sea biogeography. During five expeditions between 2009 and 2019, we conducted intensive faunal sampling via 63 submersible dives to 11 localities at depths of 300-3600 m. Based on these expeditions and published literature, we compiled voucher specimens, images, and 274 newly published DNA sequences to present a taxonomic inventory of macrofaunal and megafaunal diversity with a focus on invertebrates. In total 488 morphospecies were identified, representing the highest number of distinct morphospecies published from a single seep or vent region to date. Of these, 131 are described species, at least 58 are undescribed species, and the remainder include some degree of taxonomic uncertainty, likely representing additional undescribed species. Of the described species, 38 are known only from the Costa Rica seeps and their vicinity. Fifteen range extensions are also reported for species known from Mexico, the Galápagos seamounts, Chile, and the western Pacific; as well as 16 new depth records and three new seep records for species known to occur at vents or organic falls. No single evolutionary narrative explains the patterns of biodiversity at these seeps, as even morphologically indistinguishable species can show different biogeographic affinities, biogeographic ranges, or depth ranges. The value of careful molecular taxonomy and comprehensive specimen-based regional inventories is emphasized for biodiversity research and monitoring.

Description of a new Osedax (Annelida, Polychaeta, Siboglinidae) species colonizing cow bones in the South Atlantic Ocean

A new species of Osedax is described here using molecular and morphological data. It was found at the depth of 550 m off the Brazilian coast through experimental deployment of cow bones. Osedaxnataliae sp. nov. is the second Osedax species from the Southwest Atlantic Ocean and had been previously reported as Osedax 'BioSuOr-4'. Phylogenetic analysis of five concatenated genetic makers (28S rDNA, Histone H3, 18S rDNA, 16S rDNA, and cytochrome c oxidase I) placed Osedaxnataliae sp. nov. within a well-supported Osedax Clade V, nested within a clade of Pacific Ocean Osedax though with poor support. The minimum interspecific COI distance between O.nataliae sp. nov. and another known Osedax was 13.92% (closest to O. 'sagami-3'). The maximum intraspecific COI diversity (uncorrected) within O.nataliae sp. nov. sampled here was 2.44% and population structure was visualized via haplotype network analysis. Morphologically, O.nataliae sp. nov. is characterized by its reddish orange crown of palps and a ventral yellowish collar on the anterior trunk where it meets the base of the crown. Osedaxnataliae sp. nov. shares features with other Clade V species, notably pinnules inserted on the outer margin of palps. Additionally, the presence of dwarf males within the tube lumen of females was documented. Further sampling and research in the Southern Hemisphere are needed to understand the diversity and biogeography of Osedax across the world's oceans.

Advances in bioinformatic approaches to tardigrade phylogeny

The quest to discover the evolutionary relationships of organisms is an evolving, long-time topic of research. Such research gave rise to many different taxonomic databases and various definitions of systematic groups. One such group is the phylum Tardigrada. Tardigrades are an important field of study because of their biotechnological potential as well as their complex biological processes, which have the potential to answer questions about animal evolution. The evolutionary relationships within the phyla are subject to rigorous research, and new data is added to the literature constantly. For these studies, a widespread technique is the use of bioinformatic approaches in order to put forward concrete phylogenetic evidence. Bioinformatics is a field of computational biology that interprets large amounts of data in order to compute and demonstrate results. It is widely used not only for phylogeny but also for various different types of analyses and has been growing as a field since its foundation. This review discusses the different aspects, advantages, and methods of the use of bioinformatics in tardigrade phylogeny. It aims to put forward a defining picture of how the bioinformatic methods prove useful for providing phylogenetic results and elaborate on future perspectives.

A targeted gene phylogenetic framework to investigate diversification in the highly diverse yet geographically restricted red devil spiders (Araneae, Dysderidae)

The family Dysderidae is a highly diverse group of nocturnal ground-dwelling and active-hunter spiders. Dysderids are mostly restricted to the Western Palearctic, and particularly rich and abundant around the Mediterranean region. Interestingly, the distribution of species richness among its 24 genera and three subfamilies is highly biased-80% of its 644 documented species belong to just two genera, Dysdera (326) and Harpactea (211). Dysderidae provides an excellent study case for evolutionary and ecological research. It includes cases of trophic specialization, which are uncommon among spiders, and exhibit other remarkable biological (e.g. holocentric chromosomes), behavioural (e.g. cryptic female choice), evolutionary (e.g. adaptive radiation) and ecological features (e.g. recurrent colonization of the subterranean environment). The lack of a quantitative hypothesis on its phylogenetic structure has hampered its potential as a testing ground for evolutionary, biogeographical and ecological hypotheses. Here, we present the results of a target, multi-locus phylogenetic analysis, using mitochondrial (cox1, 16s and 12s) and nuclear genes (h3, 28s and 18s), of the most exhaustive taxonomic sample within Dysderidae (104 spp.) to date and across related families (Synspermiata) (83 spp.). We estimate divergence times using a combination of fossil and biogeographic node calibrations and use this timeline to identify shifts in diversification rates. Our results support the monophyly of the Dysderidae subfamilies Rhodinae and Dysderinae but reject Harpacteinae as currently defined. Moreover, the clades recovered within Harpacteinae do not support its current taxonomy. The origin of the family most likely post-dated the break-up of Pangea, and cave colonization may be older than previously considered. After correcting for the taxonomic artefacts, we identified a significant shift in diversification rates at the base of the genus Dysdera. Although the unique coexistence of specialist and generalist diets within the lineage could be suggested as the potential driver for the rate acceleration, further quantitative analyses would be necessary to test this hypothesis.

Phylogenetics of Lepidonotopodini (Macellicephalinae, Polynoidae, Annelida) and Comparative Mitogenomics of Shallow-Water vs. Deep-Sea Scaleworms (Aphroditiformia)

Within Polynoidae, a diverse aphroditiform family, the subfamily Macellicephalinae comprises anchialine cave-dwelling and deep-sea scaleworms. In this study, Lepidonotopodinae is synonymized with Macellicephalinae, and the tribe Lepidonotopodini is applied to a well-supported clade inhabiting deep-sea chemosynthetic-based ecosystems. Newly sequenced "genome skimming" data for 30 deep-sea polynoids and the comparatively shallow living Eulagisca gigantea is used to bioinformatically assemble their mitogenomes. When analyzed with existing scaleworm mitogenomes, deep-sea scaleworms exhibit increased gene order rearrangement events compared to shallow-water relatives. Additionally, comparative analyses of shallow-water vs. deep-sea polynoid substitution rates in mitochondrial protein-coding genes show an overall relaxed purifying selection and a positive selection of several amino acid sites in deep-sea species, indicating that polynoid mitogenomes have undergone selective pressure to evolve metabolic adaptations suited to deep-sea environments. Furthermore, the inclusion of skimming data for already known Lepidonotopodini species allowed for an increased coverage of DNA data and a representation of the taxa necessary to create a more robust phylogeny using 18 genes, as opposed to the six genes previously used. The phylogenetic results support the erection of Cladopolynoe gen. nov., Mamiwata gen. nov., Photinopolynoe gen. nov., Stratigos gen. nov., and Themis gen. nov., and emended diagnoses for Branchinotogluma, Branchipolynoe, Lepidonotopodium, and Levensteiniella.

Convergent Evolution of Armor: Thermal Resistance in Deep-Sea Hydrothermal Vent Crustaceans

Organisms occupy diverse ecological niches worldwide, each with characteristics finely evolved for their environments. Crustaceans residing in deep-sea hydrothermal vents, recognized as one of Earth's extreme environments, may have adapted to withstand severe conditions, including elevated temperatures and pressure. This study compares the exoskeletons of two vent crustaceans (bythograeid crab Austinograea sp. and squat lobster Munidopsis lauensis) with four coastal species (Asian paddle crabs, blue crab, hermit crab, and mantis shrimp) to identify traits influenced by vent environments. The goal was to identify distinctive exoskeletal characteristics commonly observed in vent crustaceans, resulting from their exposure to severe abiotic factors, including elevated temperatures and pressures, found in vent environments. Results show that the exoskeletons of vent crustaceans demonstrated significantly enhanced thermal stability compared to coastal species. These vent crustaceans consistently featured exoskeletons characterized by a reduced proportion of volatile components, such as water, and an increased proportion of CaCO3, compared with coastal crustaceans. Furthermore, vent crustaceans lacked carotenoid pigments that had low heat resistance. However, no apparent differences were observed in the mechanical properties. Our findings suggest that the similar composition of exoskeletons in vent crustaceans evolved convergently to withstand high temperatures.

Systematics of cybaeid spiders endemic to the Japanese Archipelago, and their historical biogeographic implications (Araneae: Cybaeidae)

The epigean and subterranean spiders of the genus Cybaeus L. Koch, 1868 are distributed in the Holarctic, and are highly diversified in western North America and Japan. More than 100 species have been described from the Japanese Archipelago and several species assemblages have also been recognised among the Japanese Cybaeus based on their morphological similarities. However, their phylogenetic backbone remains unclear. Moreover, genus-level classification of several of the Japanese species appear to be questionable. In this study we performed extensive molecular analyses of the family Cybaeidae in East Asia, mainly the Japanese Archipelago, to clarify their fundamental phylogenetic relationships. We also conducted a divergence time estimation to provide insights into their historical biogeography and evolutionary history. Our divergence dating results indicate that the diversification of the major lineages of the East Asian cybaeid spiders might be related to the opening of the Sea of Japan c .20million years ago. On the basis of the morphological evaluation and obtained phylogenies, some East Asian species formerly placed in Cybaeus are transferred to the cybaeid genera Allocybaeina Bennett, 2020, Sincybaeus Wang & Zhang, 2022 and Cybaeina Chamberlin & Ivie, 1932, i.e. Allocybaeina petegarina (Yaginuma, 1972), comb. nov., Sincybaeus monticola (Kobayashi, 2006), comb. nov., Sincybaeus rarispinosus (Yaginuma, 1970), comb. nov., Sincybaeus yoshiakii (Yaginuma, 1968), comb. nov., and Cybaeina whanseunensis (Paik & Namkung, 1967), comb. nov. Our results clarify the genus-level richness of cybaeids in the Japanese Archipelago for the first time, and reveal the fine-scale phylogenetic relationships of Cybaeus species endemic to the Japanese Archipelago and adjacent regions. ZooBank: urn:lsid:zoobank.org:pub:AF2A3C0E-7F0F-4253-85BA-D995A075F00D.

A new species of Thoracophelia (Annelida, Opheliidae) from the Yellow Sea of South Korea

Background

Thoracophelia Ehlers, 1897 is a genus of Opheliidae characterised by the body divided into three distinct regions, modified parapodia in chaetiger 10 and a ventral groove restricted to the posterior half of the body. To date, 18 species have been described in the genus. Amongst them, six species have been recorded in northeast Asia.

New information

A new species, Thoracopheliafoliformis sp. nov., was discovered in the intertidal zone of the Yellow Sea, South Korea. This is the first Thoracophelia species report from the Yellow Sea. This new species is closely related to T.dillonensis (Hartman, 1938) from California and T.ezoensis Okuda, 1936 from Japan in having pectinate branchiae. However, the new species can be distinguished from the two species by the unique combination of the following characteristics: 15 pairs of wrinkled pectinate branchiae with 12-15 filaments at best development and a foliaceous mid-ventral plate in the pygidium instead of one or two thick ventral cirri. Detailed descriptions and illustrations of T.foliformis sp. nov. are provided. Sequences of the mitochondrial cytochrome c oxidase subunit I (COI), nuclear 18S ribosomal DNA (rDNA) and 28S rDNA of the new species were determined and analysed.

First record of Phoronopsis (Phoronida) from Japan, with a description of Phoronopsiscalifornica Hilton, 1930 from Okinawa

Background

Phylum Phoronida currently contains two genera, Phoronis Wright, 1856 and Phoronopsis Gilchrist, 1907, with approximately thirteen speices. Phoronida is distributed worldwide, ranging from northern Europe to southern New Zealand and also from intertidal to 400 m depths. From Japanese waters, four species of Phoronis have been reported, viz. Phoronisijimai Oka, 1897, Phoronisaustralis Haswell, 1883, Phoronispsammophila Cori, 1889 and Phoronisemigi Hirose et al., 2014.

New information

We describe the morphology of Phoronopsiscalifornica Hilton, 1930, based on five specimens collected at a sandy-mud habitat in Nago Bay and Oura Bay, Okinawa, Japan. We examined the internal anatomy by serial paraffin sections. We also examined the genetic distance of Japanese specimens from the other phoronid sequences in GenBank. This is the first record of Phoronopsis from Japanese waters and the fifth species record of phoronids in addition to the previously recorded four species of Phoronis.

A new species of stauromedusa, Calvadosia festivala (Cnidaria: Staurozoa: Kishinouyeidae) from India

Staurozoa is a cnidarian class represented by marine benthic animals, mainly observed in intertidal and subtidal cold waters. As one of the few exceptions, in this study we described a tropical species, Calvadosia festivala n. sp., from Dwarka, Gujarat, India. We combined the morphological description with molecular data, placing the new species into a phylogenetic context with other species of Calvadosia. Calvadosia festivala n. sp. is unique in the arrangement of white nematocyst spots and in the dark (purplish brown) lines in the nodular gonads and in manubrium. The new species is closely related to Calvadosia lewisi, Calvadosia corbini, and Calvadosia tasmaniensis, sharing the pad-like adhesive structures on the exumbrellar tips of arms, externally separated from the secondary tentacles. This is the first formal description of a staurozoan species from India, the fourth species of Staurozoa described for the Indian Ocean, and the fourth recorded in tropical waters, providing relevant data to biogeographic and diversity discussions on the group.

From ctenophores to scyphozoans: parasitic spillover of a burrowing sea anemone

Most host-parasite associations are explained by phylogenetically conservative capabilities for host utilization, and therefore parasite switches between distantly related hosts are rare. Here we report the first evidence of a parasitic spillover of the burrowing sea anemone Edwardsiella carnea from the invasive ctenophore Mnemiopsis leidyi to two scyphozoan hosts: the native Mediterranean barrel jellyfish Rhizostoma pulmo and the invasive Indo-Pacific nomad jellyfish Rhopilema nomadica, collected from the Eastern Mediterranean Sea. Edwardsiella carnea planulae found in these jellyfish were identified using molecular analyses of the mitochondrial 16S and nuclear 18S rRNA genes. Overall, 93 planulae were found on tentacles, oral arms, and inside of the gastrovascular canals of the scyphomedusae, whereas no infection was observed in co-occurring ctenophores. DNA metabarcoding approach indicated seasonal presence of Edwardsiella sp. in the Eastern Mediterranean mesozooplankton, coinciding with jellyfish blooms in the region. Our findings suggest a non-specific parasitic relationship between Edwardsiella carnea and various gelatinous hosts based on shared functionality rather than evolutionary history, potentially driven by shifts in host availability due to jellyfish blooms. This spillover raises questions about the ecological impacts of parasitism on native and invasive scyphozoan hosts and the potential role of Edwardsiella in controlling their populations.

The first report of Bathynellacea in the subterranean water of Mongolia: A new species of Altainella Camacho, 2020 (Crustacea, Bathynellidae)

Background

We report the first finding of Bathynellacea, discovered in Mongolia. We also report a new species of the genus Altainella Camacho, 2020, which was previously recorded only in the western edge of Russia.

New information

Altainellamongoliensis sp. nov. was found in the interstitial hyporheic region of the Onon River Basin, Mongolia, by inserting a core approximately 1.2 m deep and extracting the underground interstitial water. The new species exhibited sexual dimorphism in thoracopod VII, uniquely observed within the genus Altainella. We provide a morphological description and remarks on the new species with molecular information based on the 18S rDNA and partial CO1 gene sequences. We emphasise the need for continued research on the subterranean biodiversity in previously neglected regions by reporting the first discovery of macro-stygobionts in Mongolia.

Panmixia and local endemism: a revision of the Eubranchus rupium species complex with a description of new species

Species of the genus Eubranchus Forbes, 1838 (Mollusca: Gastropoda: Nudibranchia) are common faunistic elements of boreal benthic ecosystems, associated with hydroid communities. Recent studies have suggested that the widely distributed trans-Arctic E. rupium (Møller, 1842) constitutes a complex of at least three candidate species, but the detailed taxonomy of the complex remains unresolved. The purpose of the present paper is to conduct an integrative taxonomic study including molecular genetic methods (a phylogenetic analysis using COI , 16S rRNA and histone H3 with application of species delimitation methods) and morphological study (light and scanning electron microscopy) of E. rupium and closely related species. The specific aims of this study were to establish the species boundaries, morphological variability, and the phylogeographic structure within this group. The phylogeographic analysis included a TCS -based network analysis, an analysis of molecular variance (AMOVA), divergence time estimations, and ancestral area reconstructions. We demonstrate that specimens initially identified as E. rupium included three distinctive species: the nominal E. rupium with an amphiboreal range, the new species Eubranchus novik sp. nov. from the Sea of Japan, for which a taxonomic description is provided in this paper, and Eubranchus sp. from the northern Kuril Islands, which requires the collection and study of additional material for formal description. Our results confirm the amphiboreal distribution of E. rupium , as no geographic structure was found across Pacific, Arctic and Atlantic populations, and the results of the AMOVA analysis showed no differences between groups of samples from different geographic regions. The divergence of the 'Eubrancus rupium species complex' is estimated from the late Miocene or the Miocene-Pliocene boundary to the late Pliocene. It is hypothesised that the most probable ancestral region for the Eubranchus rupium species complex is the north-western Pacific, and the subsequent speciation likely occurred due to dispersal followed by allopatric speciation. ZooBank: urn:lsid:zoobank.org:pub:228E0C46-0BF7-4DDD-9C00-67B50E298D65.

Exoskeletal Trade-off between Claws and Carapace in Deep-sea Hydrothermal Vent Decapod Crustaceans

Limitations on energetic resources create evolutionary trade-offs, prompting us to investigate if investment in claw strength remains consistent across crustaceans living in diverse habitats. Decapod crustaceans living in deep-sea hydrothermal vents are ideal for this study due to their extreme environment. In this study, we investigated whether decapods (blind crab Austinograea sp. and the squat lobster Munidopsis lauensis) living in deep-sea hydrothermal vents prioritize investing in strong claws compared to the carapace, like coastal decapods. We analyzed exoskeleton morphology, mechanical properties, structures, and elemental composition in both the carapace and claws of four Decapoda species (two each from Brachyura and Anomura infraorders) in vent and coastal habitats. Coastal decapods had ∼4-9 times more teeth on their claw cutting edge than the vent species. Further, only the coastal species exhibited higher firmness in their claws than in their carapaces. Each infraorder controlled exoskeletal hardness differently: Brachyura changed the stacking height of the Bouligand structure, while Anomura regulated magnesium content in the exoskeleton. The vent decapods may prioritize strengthening their carapace over developing robust claws, allocating resources to adapt to the harsh conditions of deep-sea hydrothermal vents. This choice might enhance their survival in the extreme environment, where carapace strength is crucial for protecting internal organs from environmental factors, rather than relying on the powerful claws seen in coastal decapods for a competitive advantage.

Systematic revision of the South American "Nuncia" (Opiliones, Laniatores, Triaenonychidae)

The genus Nuncia has long been the most speciose within the Opiliones family Triaenonychidae, comprising 63 species and subspecies distributed across New Zealand and South America. Recent molecular studies utilizing Sanger sequencing and ultraconserved elements (UCEs) have indicated that this genus is not monophyletic, and true Nuncia are actually confined to New Zealand. Here, the morphology of all South American triaenonychids is re-examined and DNA sequence data compiled from three markers (18S rRNA, 28S rRNA and cytochrome c oxidase subunit I) for a large number of triaenonychid species, including specimens from all areas with species currently and formerly classified in Nuncia to reassess their phylogenetic position. Based on our findings we 1) revalidate the genus Chilenuncia (Muñoz-Cuevas, 1971) nom. rest.; 2) describe five new genera: Fresiax gen. nov., Mistralia gen. nov., Laftrachia gen. nov., Lautaria gen. nov., Nerudiella gen. nov.; 3) redescribe five species: Fresiaxspinulosa comb. nov., Mistraliaverrucosa comb. nov., Chilenunciachilensis comb. nov., Chilenunciarostrata comb. nov., Nerudiellaamericana comb. nov.; and 4) describe 22 new species of South American triaenonychids: Fresiaxconica sp. nov., Fresiaxfray sp. nov., Fresiaxmauryi sp. nov., Fresiaxpichicuy sp. nov., Mistraliaramirezi sp. nov., Laftrachiarobin sp. nov., Lautariaceachei sp. nov., Nerudiellacachai sp. nov., Nerudiellacaramavida sp. nov., Nerudiellacautin sp. nov., Nerudiellachoapa sp. nov., Nerudiellacuri sp. nov., Nerudiellagoroi sp. nov., Nerudiellajaimei sp. nov., Nerudiellamalleco sp. nov., Nerudiellapenco sp. nov., Nerudiellapichi sp. nov., Nerudiellaportai sp. nov., Nerudiellaquenes sp. nov., Nerudiellavilches sp. nov., Nerudiellawekufe sp. nov., and Nerudiellazapallar sp. nov. Furthermore, we provide detailed illustrations of all the South American species belonging to these lineages formerly classified in Nuncia.

Revisiting Stygocapitella (Annelida, Parergodrilidae) in Japan, with insights into their amphi-Pacific diversification

Polychaetes are typically found in marine environments with limited species adapting to semi-terrestrial habitats. The genus Stygocapitella comprises interstitial polychaetes dwelling in sandy beach areas around or above the high-water line. Based on molecular data, previous studies suggested the presence of multiple cryptic species in some different localities in the world lumped together as Stygocapitella subterranea. In Japan, reports on Stygocapitella were scarce, with only one species having been documented 40 years ago at Ishikari Beach in Hokkaido by the name of S. subterranea. We revisited these earlier findings and uncovered the presence of two distinct species in Stygocapitella. One of these species is herein named Stygocapitella itoi sp. nov., while the other corresponds to S. budaevae, originally described from the Russian Far East. Stygocapitella itoi sp. nov. possesses a chaetal pattern similar to that of S. australis, S. furcata and S. pacifica but can be distinguished from the congeners by two characters: a slightly forked pygidium and forked chaetae consisting of two teeth and two outer prongs. Our multi-locus phylogenetic analysis showed close relationships across the Pacific Ocean in two separated lineages in the genus, suggesting ancient dispersal or allopatric speciation after vicariance events.

New Species of Osedax (Siboglinidae: Annelida) from New Zealand and the Gulf of Mexico

Osedax is now known to be distributed around the world with more than 30 named and undescribed species. Here we report the discovery of four new species from two localities: Osedax bozoi n. sp. and Osedax craigmcclaini n. sp. from the Gulf of Mexico and Osedax estcourti n. sp. and Osedax traceyae n. sp. from off New Zealand. Osedax bozoi n. sp., Osedax estcourti n. sp., and Osedax traceyae n. sp. belong to Clade II within Osedax, one of the nude palp or apinnulate clades. Osedax craigmcclaini n. sp. belongs to the pinnulate palp Clade V. This study relies primarily on phylogenetic analysis, with some morphological analysis. Genetic data clearly show that the four new species are distinctive from their closest Osedax relatives. Two of the new species were found from less than 400 m depth, and incidences of shallower water Osedax in Clade II are shown here for the first time.

Environmental Transmission of Symbionts in the Mangrove Crabs Aratus pisonii and Minuca rapax: Acquisition of the Bacterial Community through Larval Development to Juvenile Stage

Aratus pisonii and Minuca rapax are two brachyuran crabs living with bacterial ectosymbionts located on gill lamellae. One previous study has shown that several rod-shaped bacterial morphotypes are present and the community is dominated by Alphaproteobacteria and Bacteroidota. This study aims to identify the mode of transmission of the symbionts to the new host generations and to identify the bacterial community colonizing the gills of juveniles. We tested for the presence of bacteria using PCR with universal primers targeting the 16S rRNA encoding gene from gonads, eggs, and different larval stages either obtained in laboratory conditions or from the field. The presence of bacteria on juvenile gills was also characterized by scanning electron microscopy, and subsequently identified by metabarcoding analysis. Gonads, eggs, and larvae were negative to PCR tests, suggesting that bacteria are not present at these stages in significant densities. On the other hand, juveniles of both species display three rod-shaped bacterial morphotypes on gill lamellae, and sequencing revealed that the community is dominated by Bacteroidota and Alphaproteobacteria on A. pisonii juveniles, and by Alphaprotobacteria, Bacteroidota, and Acidimicrobia on M. rapax juveniles. Despite the fact that juveniles of both species co-occur in the same biotope, no shared bacterial phylotype was identified. However, some of the most abundant bacteria present in adults are also present in juveniles of the same species, suggesting that juvenile-associated communities resemble those of adults. Because some of these bacteria were also found in crab burrow water, we hypothesize that the bacterial community is established gradually during the life of the crab starting from the megalopa stage and involves epibiosis-competent bacteria that occur in the environment.

Sample design in biodiversity studies matters: a fine-scale study of Lawrence's velvet worm, Peripatopsis lawrencei (Onychophora: Peripatopsidae), reveals hidden diversity

A fine-scale phylogenetic and phylogeographic analysis of Peripatopsis lawrencei s.l. was conducted with both mitochondrial and nuclear DNA sequence data, using both external morphology and scanning electron microscopy of taxonomically important characters. A total of 119 sequences were used for the mitochondrial cytochrome c oxidase subunit I (COI ) whereas a single representative specimen from each locality was sequenced for the nuclear 18S rRNA locus. Phylogenetic analyses were conducted on the total COI data set and the combined COI + 18S rRNA data set using a Bayesian analysis and maximum likelihood analyses. For the combined DNA sequence data set, a divergence time estimation was further undertaken in BEAST and specimens placed in a phylogenetic framework including all the described Peripatopsis species from South Africa. In addition, a phylogeographic study was conducted exclusively on P. lawrencei s.s. (clade A) using an analysis of molecular variance and haplotype network. Phylogenetic results indicated that, at the Oubos sample locality, two highly distinct genetic lineages were present (clades A and B), whereas a divergence time estimation suggests a Miocene cladogenesis of the novel Oubos lineage. Marked phylogeographic structure was observed for P. lawrencei s.s. (restricted to clade A) across the distribution range with limited maternal dispersal. Morphologically, the two sympatric lineages at Oubos A and B differed in leg pair number, ventral colour and dorsal scale rank counts, as evident from scanning electron microscopy. Our results support the recognition of a distinct species that occurs in sympatry with P. lawrencei s.s. The new species, P. aereus sp. nov. (clade B) is described and the implication for fine-scale taxonomic studies on saproxylic taxa is discussed. ZooBank: urn:lsid:zoobank.org:pub:AB6E0BDA-7B5F-4FD3-A863-BA7C814E278C.

Inconsistencies in the Classification of the Family Cydnidae (Hemiptera: Heteroptera: Pentatomoidea) Revealed by Molecular Apomorphies in the Secondary and Tertiary Structures of 18S rRNA Length-Variable Region L (LVR L)

The SSU nuclear rDNA (encoding 18S ribosomal RNA) is one of the most frequently sequenced genes in the molecular analysis of insects. Molecular apomorphies in the secondary and tertiary structures of several 18S rRNA length-variable regions (LVRs) located within the V2, V4, and V7 hypervariable regions can be good indicators for recovering monophyletic groups within some heteropteran families. Among the LVRs that have been analysed, the LVR L in the V4 hypervariable region is the longest and most crucial for such assessments. We analysed the 18S rRNA V4 hypervariable region sequences of 45 species from the family Cydnidae, including all 6 subfamilies (Amaurocorinae, Amnestinae, Cephalocteinae, Cydninae, Garsauriinae, and Sehirinae) and three pentatomoid families (Parastrachiidae, Thaumastellidae, and Thyreocoridae), which have often been included in the broadly defined Cydnidae family. This is the first time that representatives of all Cydnidae subfamilies have been included in a molecular analysis. Only taxa from two subfamilies, Sehirinae and Cydninae, have been used in previous molecular studies. The secondary and tertiary structures of the LVR L were predicted for each species using the two-step procedure already accepted for such analyses to recover any molecular apomorphy essential for determining monophyly. The results of our comparative studies contradict the current understanding of the relationships among burrowing bugs and the current family classification.

Ciliates from the faeces of the free-ranging dromedary from Oman: Morphology and molecular phylogeny

Ciliates Infundibulorium cameli from the faeces of the free-ranging dromedary from Oman were studied using a set of methods of the light and immunofluorescence microscopy and molecular phylogeny. With the use of molecular genetic methods, it was confirmed that the cysts found in the samples simultaneously with trophozoites actually belong to the species I. cameli. Tubulin cytoskeleton organization of trophozoites and cysts of this species were described for the first time. A striking morphological similarity between species I. cameli and Buxtonella sulcata was demonstrated, including the organization of ciliature. Different isolates of I. cameli and B. sulcata formed a common clade on the phylogenetic tree. The level of evolutionary divergence between the 18 S rRNA sequences of I. cameli, B. sulcata and species closest to them according to the results of molecular phylogenetic analysis was estimated. It was demonstrated that the divergence between I. cameli and B. sulcata is extremely low compared to members of other genera included in the analysis. Taxonomic position of I. cameli and B. sulcata was discussed in according to the data of comparative morphology and molecular phylogeny.

The Abyssal Parasitic Flatworm Fecampia cf. abyssicola: New Records, Anatomy, and Molecular Phylogeny, with a Discussion on Its Systematic Position

AbstractThe order Fecampiida, a group of parasitic turbellarians, has been poorly studied in terms of its species diversity, morphology, and ecology. Fecampiida is positioned within the monophyletic clade Adiaphanida, along with Tricladida and Prolecithophora, but their phylogenetic relationships are not well understood. Although the nervous and muscular systems of only two species in Fecampiida have been studied, recent research inferred morphological similarities between Fecampiida and Prolecithophora. In this study, we collected fecampiid cocoons and juveniles at depths of 1861-4438 m in Japanese waters. We identified the species on the basis of swimming juvenile specimens and by using histological and molecular methods, while we also examined its musculature and nervous system. Our study revealed a more complex nervous system than previously reported, with dorsal, lateral, and ventral pairs of longitudinal nerve cords connected through an anterior neuropile and posterior transverse commissures. While the nervous and muscular morphology suggested similarities with Prolecithophora, our phylogenetic analysis did not support a close relationship between Fecampiida and Prolecithophora.

Radula and Shell Microstructure Variations are Congruent with a Molecular Estimate of Shallow-Water Japanese Chitons

Variations of the radula and shell microstructures in 33 species of Japanese chiton were investigated along with molecular phylogenetic trees. The molecular phylogenetic trees indicated that Chitonida was composed of four clades, of which two clades formed Acanthochitonina and corresponded to Mopalioidea and Cryptoplacoidea, respectively, and the other clades formed Chitonina. In the radula, the shapes of the central and centro-lateral teeth and the petaloid process varied greatly among species or genera and were useful for the identification of particular species or genera. The presence of accessory and petaloid processes and the cusp shape were relatively conserved and useful for recognizing particular genera or even suborders. In the valves, four to six shell layers were found at the section, but the ventral mesostracum was not observed in Acanthochitonina. The shell microstructures in the ventral sublayer of the tegmentum varied at suborder, but those in the other layers were almost constant. The megalaesthete chamber type varied at superfamily and was helpful to identify particular families or superfamilies. The characteristics of the shell layers and shell microstructures appear to be a synapomorphy shared by the members of Acanthochitonina. The classification within Chitonina needs to be reexamined because the variations of the cusp shape and megalaesthete chamber type were relatively large and did not correspond to the current classification. Callochiton formed a sister group with Chitonida and would be equally closely related to Chitonina and Acanthochitonina because of possessing a mosaic of characteristics from both.

An Opiliones-specific ultraconserved element probe set with a near-complete family-level phylogeny

Sequence capture of ultraconserved elements (UCEs) has transformed molecular systematics across many taxa, with arachnids being no exception. The probe set available for Arachnida has been repeatedly used across multiple arachnid lineages and taxonomic levels, however more specific probe sets for spiders have demonstrated that more UCEs can be recovered with higher probe specificity. In this study, we develop an Opiliones-specific UCE probe set targeting 1915 UCEs using a combination of probes designed from genomes and transcriptomes, as well as the most useful probes from the Arachnida probe set. We demonstrate the effectiveness of this probe set across Opiliones with the most complete family-level phylogeny made to date, including representatives from 61 of 63 currently described families. We also test UCE recovery from historical specimens with degraded DNA, examine population-level data sets, and assess "backwards compatibility" with samples hybridized with the Arachnida probe set. The resulting phylogenies - which include specimens hybridized using both the Opiliones and Arachnida probe sets, historical specimens, and transcriptomes - are largely congruent with previous multi-locus and phylogenomic analyses. The probe set is also "backwards compatible", increasing the number of loci obtained in samples previously hybridized with the Arachnida probe set, and shows high utility down to shallow population-level divergences. This probe set has the potential to further transform Opiliones molecular systematics, resolving many long-standing taxonomic issues plaguing this lineage.

Updated phylogeny of Vestimentifera (Siboglinidae, Polychaeta, Annelida) based on mitochondrial genomes, with a new species

Siboglinid tubeworms are found at chemosynthetic environments worldwide and the Vestimentifera clade is particularly well known for their reliance on chemoautotrophic bacterial symbionts for nutrition. The mitochondrial genomes have been published for nine vestimentiferan species to date. This study provides new complete mitochondrial genomes for ten further Vestimentifera, including the first mitochondrial genomes sequenced for Alaysia spiralis, Arcovestia ivanovi, Lamellibrachia barhami, Lamellibrachia columna, Lamellibrachia donwalshi, and unnamed species of Alaysia and Oasisia. Phylogenetic analyses combining fifteen mitochondrial genes and the nuclear 18S rRNA gene recovered Lamellibrachia as sister to the remaining Vestimentifera and Riftia pachyptila as separate from the other vent-endemic taxa. Implications and auxiliary analyses regarding differing phylogenetic tree topologies, substitution saturation, ancestral state reconstruction, and divergence estimates are also discussed. Additionally, a new species of Alaysia is described from the Manus Basin.

Phylogenetic placement of eight poorly known spiders of Microdipoena (Araneae, Mysmenidae), with descriptions of five new species

Ten species of the spider genus Microdipoena Banks, 1895 are reported from China, Laos, Indonesia, Georgia, and Seychelles. DNA sequences of the eight species are obtained to confirm their correct identification. The molecular phylogenetic analysis based on five gene fragments (16S, 18S, 28S, COI, and H3) were used to test the relationships and taxonomic placements of eight Microdipoena species, of which five species are documented as new to science: i.e., M.huisunsp. nov. (♀, China), M.lisusp. nov. (♀, China), M.shenyangsp. nov. (♂♀, China), M.thatitousp. nov. (♀, Laos), and M.zhulinsp. nov. (♂♀, China). Five known species are redescribed: M.elsae Saaristo, 1978 (♂♀, Seychelles), M.gongi (Yin, Peng & Bao, 2004) (♂♀, China), M.menglunensis (Lin & Li, 2008) (♂♀, China), M.jobi (Kraus, 1967) (♂♀, Georgia), and M.yinae (Lin & Li, 2013) (♂♀, China). All but M.menglunensis are diagnosed and illustrated. The family Mysmenidae is also the first recorded from Laos and Georgia.

Morphological and molecular study of Syllinae (Annelida, Syllidae) from Bermuda, with the description of five new species

Although polychaetes from the Bermuda Archipelago have been studied since the beginning of the twentieth century, syllids have been particularly neglected in this area, which is surprising considering this family is usually a dominant group in marine benthic ecosystems. To fill this knowledge gap, we have carried out an extensive analysis of Bermudan Syllidae, combining morphological and molecular data including four nuclear and mitochondrial markers (cytochrome c oxidase subunit I, 18S rRNA, 16S rRNA and 28S rRNA). We have identified and established the phylogenetic position of five new species, Haplosyllis anitae n. sp., Haplosyllis guillei n. sp., Haplosyllis larsi n. sp., Haplosyllis vassiae n. sp. and Syllis laiae n. sp., together with Haplosyllis cf. cephalata. Overall, our results extend the knowledge on the diversity of Syllidae in Bermuda, increasing the number of species present in the area to 25. Our results also recover Opisthosyllis and Syllis as non-monophyletic genera, for which traditional diagnostic morphological features do not accurately reflect their evolutionary histories, and thus we propose that these groups should be reorganized based on molecular characters.

Tribe Acalyptaini (Hemiptera: Tingidae: Tinginae) Revisited: Can Apomorphies in Secondary and Tertiary Structures of 18S rRNA Length-Variable Regions (LVRs) Support Tribe Validity?

The lace bug tribe Acalyptaini (Tingidae: Tinginae) includes five genera, Acalypta, Derephysia, Dictyonota, Kalama, and Recaredus, and it was recently resurrected based on morphological and karyological characters. We aimed to validate the distinctiveness of this tribe using 18S rDNA sequences, which have not been used in previous Tingidae phylogenomic studies. Our results confirmed the monophyly of the tribe. Moreover, the monophyly of the subfamily Cantacaderinae and its basal position within the family Tingidae were indicated, as well as the position of the tribe Litadeini as sister to all other Tinginae. In addition, we attempted to determine the apomorphic morpho-molecular characters in the secondary and tertiary structures of length-variable regions of the 18S rRNA sequences of the analysed species. The results showed that two LVRs (LVR X and LVR L) of the hypervariable region V4 exhibited significant variability in the number of nucleotides and could be considered for apomorphic recognition.

Molecular and morphometric analyses reveal host-specific cryptic speciation in a mite species, Tetranychus neocaledonicus (Andre, 1933) (Acari: Tetranychidae)

Host- and habitat-induced morphological shape and size variations are common in phytophagous and parasitic taxa. Several integrated morphological and molecular techniques have been commonly used to understand host-induced morpho-cryptic species forms. Compared to other arthropods, cryptic speciation was more common in Acari. This study focused on the host-specific morphological cryptic shape and size variations of Tetranychus neocaledonicus, collected from moringa and cassava hosts. We used geometric morphometric analysis to uncover the shape and size of inter-and intra-spider mite populations, and discovered that host-specific shape and size variations existed in spider mites regardless of sex. Interestingly, there was no phylogenetic signal in spider mites, implying that the morpho-cryptic speciation of T. neocaledonicus is solely based on the host-induced selection. The molecular clock hypothesis was accepted in our CO1 and 18s rRNA phylogeny analyses, and spider mites collected from both hosts were genetically less diverse. We conclude that T. neocaledonicus exhibited morphologically detectable cryptic population diversity in each host but that these populations are evolutionarily young form. Apart from these host-induced variations, we also monitored the impact of the clearing agent (lactic acid) on the shape and size of T. neocaledonicus; from this study, we proved that the clearing agent significantly alters the taxonomically important morphological traits of spider mites irrespective of the mites' sex, as confirmed by multivariate statistical analysis. This is the first study report to investigated the host-induced morphological variations of spider mites and the impact of a clearing agent.

Actinarctus doryphorus (Tanarctidae) DNA barcodes and phylogenetic reinvestigation of Arthrotardigrada with new A. doryphorus and Echiniscoididae sequences

Little is still known about the diversity and evolution of marine arthrotardigrades, as they are generally difficult to sample, resulting in a limited amount of molecular data for barcoding and phylogenetic studies. With the current study, we provide the first investigation into COI haplotype diversity in a marine tanarctid and at the same time readdress arthrotardigrade phylogeny. Specifically, we provide COI mtDNA, 18S and 28S rDNA sequences from a population of Actinarctus doryphorus (Tanarctidae) sampled off the coast of Roscoff, France and further provide new 18S sequences from two marine echiniscoidids. A. doryphorus COI sequences confirmed the presence of a single species and further revealed five haplotypes shared among nine sequenced individuals. Our 18S and 28S rDNA datasets were individually and combined analysed with Bayesian inference and Maximum Likelihood. Actinarctus doryphorus was placed together with Tanarctus sequences within a maximally supported Tanarctidae, confirming previous interpretations that the clade is distinct from Halechiniscidae. Although several studies in recent decades have concluded that the marine arthrotardigrades are paraphyletic, recent studies have argued that the clade may not be paraphyletic. Our phylogenetic analyses consistently inferred Arthrotardigrada as paraphyletic, as the clade includes the monophyletic Echiniscoidea. Accordingly, we propose that it is time to suppress the order Arthrotardigrada as it clearly does not reflect tardigrade phylogeny.

Ecology determines appearance: a new taxonomic solution for the soft bottom dwelling spider crab Pisoides bidentatus (A. Milne-Edwards, 1873) from the Sea of Japan, with remarks on Pisoides ortmanni (Balss, 1924) and the northwestern Pacific Pugettia Dana, 1851 (Majoidea: Epialtidae)

The northwestern Pacific soft bottom dwelling spider crab, Pisoides bidentatus (A. Milne-Edwards, 1873) (Brachyura: Majoidea: Epialtidae), is re-described using an integrative approach. As a result, it is transferred to the genus Scyra Dana, 1851 (Epialtidae) based on morphological and molecular data, as well as already described larval morphology, which certainly better reflects the phylogenetic relationships of the species. Japanese Pisoides ortmanni (Balss, 1924), for which morphology and ecology are very similar to P. bidentatus as well as Pugettia quadridens (De Haan, 1839) and the closely related Pugettia ferox Ohtsuchi & Kawamura, 2019, are also transferred to Scyra. The "reduced" morphology of both species is very different from the related northwestern Pacific Scyra spp. and Pugettia spp., which are mostly decorating algae-dwellers. We associate the relatively long ambulatory legs, a smooth tear-drop shaped carapace with a reduced dorsal armature and slightly pronounced pseudorostral spines, characteristic of P. bidentatus and P. ortmanni with their open soft (mainly sand) bottom habitats, where it is difficult to find a foothold or shelter, but it is necessary to resist constant currents. Such morphology is also characteristic of spider crabs of the genera Libinia Leach, 1815 and Doclea Leach, 1815 (Epialtidae: Pisinae), which are also living in similar habitats/conditions and represent a convergent morphological appearance.

Recovery of the family status of Pericambalidae Silvestri, 1909, stat. nov. (Diplopoda: Spirostreptida: Cambalidea), with a revision of the genera and species from China

The millipede subfamily Pericambalinae Silvestri, 1909 is poorly understood and the taxonomic status remains controversial. Pericambalinae was regarded as either a subfamily of Cambalopsidae or an independent family. To address this issue, we conducted a molecular phylogenetic analysis and a morphological revision, and the genera and species from China are also revised. The results support the recovery of the family status, Pericambalidae, stat. nov. The morphological differences between Bilingulus Zhang & Li, 1981 and Parabilingulus Zhang & Li, 1981 are shown to be caused by post-embryonic development (anamorphosis and non-systemic metamorphosis) and both of these should be junior synonyms of Pericambala Silvestri, 1909 (Pericambala = Bilingulus, syn. nov. = Parabilingulus, syn. nov.). Three new combinations are proposed: Pericambala simplicia (Mauriès & Nguyen Duy-Jacquemin, 1997), comb. nov., Pericambala aramula (Zhang & Li, 1981), comb. nov. and Pericambala sinica (Zhang & Li, 1981), comb. nov. The mature specimens of Pericambala simplicia, comb. nov. and Pericambala aramula, comb. nov. were collected from the type localities and are described for the first time. A new species, Pericambala cordata, sp. nov. is described. After revision, Pericambalidae contains two genera and six species with one genus and four species recorded from China. Due to a deficiency in outgroup sampling, the phylogenetic status of Pericambalidae in the suborder Cambalidea remains uncertain. Variation of the gnathochilarium in Cambalidea is discussed and a key to the species of Pericambala in China is also provided. This research lays a foundation for further revision of Cambalidea in the future. ZooBank: urn:lsid:zoobank.org:pub:BDA46BCE-102B-45FE-A963-47F029A09E76.

Transcriptome analysis of the spider Phonotimpus pennimani reveals novel toxin transcripts

Background

Phonotimpus pennimani (Araneae, Phrurolithidae) is a small-sized (3-5 mm) spider endemic to the Tacaná volcano in Chiapas, Mexico, where it is found in soil litter of cloud forests and coffee plantations. Its venom composition has so far not been investigated, partly because it is not a species of medical significance. However, it does have an important impact on the arthropod populations of its natural habitat.

Methods

Specimens were collected in Southeastern Mexico (Chiapas) and identified taxonomically by morphological characteristics. A partial sequence from the mitochondrial gene coxI was amplified. Sequencing on the Illumina platform of a transcriptome library constructed from 12 adult specimens revealed 25 toxin or toxin-like genes. Transcripts were validated (RT-qPCR) by assessing the differential expression of the toxin-like PpenTox1 transcript and normalising with housekeeping genes.

Results

Analysis of the coxI-gene revealed a similarity to other species of the family Phrurolithidae. Transcriptome analysis also revealed similarity with venom components of species from the families Ctenidae, Lycosidae, and Sicariidae. Expression of the toxin-like PpenTox1 gene was different for each developmental stage (juvenile or adult) and also for both sexes (female or male). Additionally, a partial sequence was obtained for the toxin-like PpenTox1 from DNA.

Conclusion

Data from the amplification of the mitochondrial coxI gene confirmed that P. pennimani belongs to the family Phrurolithidae. New genes and transcripts coding for venom components were identified.

Additional data on Spinitectus petterae (Nematoda: Rhabditida) from Clarias gariepinus (Siluriformes: Clariidae) in the Vaal River system: conserved morphology or high intraspecific genetic variability?

Two species of Spinitectus Fourment, 1884 have been recorded from southern Africa, namely Spinitectus polli Campana-Rouget, 1961 and Spinitectus petterae Boomker, 1993, both from the Limpopo River system. Spinitectus petterae was described from North African catfish, Clarias gariepinus (Burchell), whereas S. polli infects squeakers, Synodontis spp. During parasitological surveys in the Vaal River system (Orange River catchment), Spinitectus specimens were collected from C. gariepinus. These systems are adjacent but not connected. Therefore, this study aimed to identify the specimens collected using morphological and molecular techniques. The morphological study included light and scanning electron microscopy of whole specimens and excised spicules. Specimens were genetically characterised using 18S rDNA, 28S rDNA and cox1 mtDNA. Additionally, immature specimens of S. petterae were collected near the type locality. Morphological characteristics were most similar to S. petterae from C. gariepinus, whereas genetic data were dissimilar to all available data for the genus. Additional morphological characteristics noted for S. petterae in the present study were the details of the left and right spicule structure and the porous structures on the pseudolabia. Specimens from the Vaal River system differed from those originally described as S. petterae by additional spines posterior to the third ring, lacking caudal alae and variable total body and male oesophagus length. Based on 18S rDNA, haplotypes from the type locality varied only slightly from the study material, supporting the morphological identification. However, 28S rDNA and, more conspicuously, cox1 mtDNA displayed substantial variation between specimens from these localities, which needs further investigation. Haplotypes generated in the present study were highly dissimilar to those characterised for S. petterae from Tanzania and Egypt. Nevertheless, the nematodes collected from C. gariepinus in the Vaal River system are considered S. petterae. This study expands the geographical distribution and adds additional morphological and genetic information for S. petterae, contributing to the limited knowledge of African species of Spinitectus.

Systematic notes on three troglobitic Anapistula (Araneae, Symphytognathidae) spiders from China, with the descriptions of two new species

Three cave-dwelling spider species belonging to the family Symphytognathidae Hickman, 1931, i.e., Anapistulasanjiao sp. nov. (♂♀), A.walayaku sp. nov. (♂♀), and A.panensis Lin, Tao & Li, 2013 (♂♀), are reported from southwest China. DNA sequences and detailed illustrations of the habitus, male palps and epigynes are provided, and their distributions are mapped. Their phylogenetic position within symphytognathids and relationships were tested and assessed using previously published phylogenetic analyses on symphytognathoids. The results showed that they form a clade with A.choojaiae Rivera-Quiroz, Petcharad & Miller, 2021 from Thailand.

Revealing the millipede and other soil-macrofaunal biodiversity in Hong Kong using a citizen science approach

Background

Soil biodiversity plays important roles in nutrient recycling in both the environment and agriculture. However, they are generally understudied worldwide. To reveal the diversity of soil macrofauna in Hong Kong, here we initiated a citizen science project involving university, non-governmental organisations and secondary school students and teachers. It is envisioned that the citizen science approach used in this study could be used as a demonstration to future biodiversity sampling and monitoring studies.

New information

Throughout a year of monitoring and species sampling across different localities in Hong Kong, 150 soil macrofaunal morphospecies were collected. Eighty five of them were further identified by morphology and DNA barcoding was assigned to each identified morphospecies, yielding a total of 646 DNA barcodes, with new millipede sequences deposited to the GenBank. The soil macrofauna morphospecies in Hong Kong found in this study are mainly dominated by millipedes (23 out of 150) and oligochaetes (15 out of 150). Amongst the twenty three identified millipedes, two polyxenid millipedes, Monographisqueenslandica Huynh & Veenstra, 2013 and Alloproctoidesremyi Marquet and Condé, 1950 are first recorded in Hong Kong. Information has been curated on an online platform and database (http://biodiversity.sls.cuhk.edu.hk/millipedes). A postcard summarising the findings of millipedes in Hong Kong has also been made as a souvenir and distributed to citizen participants. The identified macrofauna morphospecies and their 646 DNA barcodes in this study established a solid foundation for further research in soil biodiversity.

A new species of Allobathynella (Crustacea, Bathynellacea, Parabathynellidae) from the hyporheic zone of the Hangang River, South Korea

Bathynellacea including the parabathynellid genus Allobathynella Morimoto & Miura, 1957 is commonly found across the subterranean environment. The genus Allobathynella is the most species-rich genus known in Korea, and it now contains 23 species and one subspecies from South Korea and Japan. In this paper, we described a new species of Allobathynella from Danyang, South Korea. Allobathynella danyangensissp. nov. can be distinguished from its congeners by the presence of five simple setae on the antennule, seven spines on the maxillule and 3-5-10-6 setal formula of the maxilla. We describe the new species with molecular diagnosis based on the mitochondrial c oxidase subunit 1, the mitochondrial 16S rDNA, and the nuclear 18S rDNA gene sequences and morphological study.

PERUANOCOTYLE PELAGICA N. SP. (MONOGENEA: MONOCOTYLIDAE), PARASITE OF THE PACIFIC COWNOSE RAY RHINOPTERA STEINDACHNERI EVERMANN AND JENKINS, 1891 (BATOIDEA: RHINOPTERIDAE) FROM THE SOUTHERN MEXICAN PACIFIC OCEAN

Peruanocotyle pelagica n. sp. is described based on specimens collected from the wall of the pharyngeal cavity of the Pacific cownose ray Rhinoptera steindachneri offshore Oaxaca and Guerrero, Mexico. The new species is distinguished from Peruanocotyle chisholmae by its anchors, which include a slender guard that curves towards the tip of the blade and which lack an accessory piece, morphological differences of the seminal vesicle, the lack of a male copulatory organ accessory piece and a greater number of spines, and an unsclerotized vagina. Molecular data of Peruanocotyle pelagica were generated to place the phylogenetic position of the genus within Monocotylidae.

Morphological analysis of Rhynchospio aff. asiatica (Annelida: Spionidae) and comments on the phylogeny and reproduction of the family Spionidae

The genus Rhynchospio has fronto-lateral horns on prostomium, paired branchiae from chaetiger 2 to near the posterior end, capillary notochaetae only, and more than two pairs of pygidial cirri. Rhynchospio species are common in coastal soft bottom communities; nevertheless, many recorded Rhynchospio specimens around the world are currently undescribed. Here we described a Rhynchospio species based on specimens collected from Qingdao, China. Comparison with the reported DNA sequences of four gene markers (16S rRNA, 18S rRNA, 28S rRNA, and Histone H3) and brief morphological description of specimens collected from Jinhae Bay, South Korea, previously reported as Rhynchospio aff asiatica, indicated that they are conspecific. Morphologically, specimens of R. aff. asiatica from Qingdao are characterized by having neuropodial hooded hooks from chaetigers 14-17 (vs. 10-23 in R. asiatica) to near pygidial chaetigers, sperm from chaetiger 11 to 14 (vs. from chaetiger 11 to 21-22 in R. asiatica), oocytes from chaetigers 16-17 to 26-39 (vs. from 22-24 in R. asiatica), and 4-6 (vs. up to 6 in R. asiatica) pygidial cirri. Genetically, Rhynchospio aff. asiatica is most closely related to R. arenincola Hartman, 1936 from California, USA with the interspecific distances of 20.02% (16S rRNA), 4.50% (18S rRNA), 8.44% (28S rRNA), 2.74% (Histone H3), and 6.10% (concatenated sequences). Water flow across the dorsum created by ciliary beating of the branchiae and nototrochs, observed on live specimens, may help transport gametes from reproductive segments in anterior and middle parts to the posterior brooding segments. Phylogenetic trees based on concatenated sequences of four gene markers of 54 spioniform species in 25 genera revealed two clades, covering the two subfamilies Spioninae and Nerininae respectively. Two families (i.e., Poecilochaetidae and Trochochaetidae) in the order Spionida were clustered within Spionidae, supporting a morphology-based proposal that these families bearing a pair of prehensile, grooved palps should be grouped within a more broadly defined family Spionidae. Mapping morphological and reproductive characteristics to the phylogenetic trees indicated that the ancestor of spionids might lack branchiae, broadcast spawn thick-envelop oocytes and ect-aquasperm, and produce planktotrophic larvae.

Molecular Phylogenetics, Speciation, and Long Distance Dispersal in Tardigrade Evolution: A case study of the genusMilnesium

Microorganisms (sensu lato, i.e., including micrometazoans) are thought to have cosmopolitan geographic distributions due to their theoretically unlimited dispersal capabilities, a consequence of their tiny size, population dynamics, and resistant forms. However, several molecular studies of microorganisms have identified biogeographic patterns indicating cryptic speciation and/or weak species definitions. Using a multi-locus approach with the genus Milnesium (Tardigrada), we aimed to determine the genetic structure of populations worldwide and the effects of long distance dispersal (LDD) on genetic connectivity and relationships across the six continents. Our results on this micrometazoan's genetic structure and LDD at global and micro-local scales indicate contrasting patterns not easily explained by a unique or simple phenomenon. Overall, we report three key findings: (i) confirmation of long distance dispersal for tardigrades, (ii) populations with globally-shared or endemic micro-local haplotypes, and (iii) a supported genetic structure instead of the homogeneous genetic distribution hypothesized for microorganisms with LDD capabilities. Moreover, incongruences between our morphological and molecular results suggest that species delimitation within the genus Milnesium could be problematic due to homoplasy. Duality found for Milnesium populations at the global scale, namely, a molecular phylogenetic structure mixed with widely distributed haplotypes (but without any apparent biogeographic structure), is similar to patterns observed for some unicellular, prokaryotic and eukaryotic, microorganisms. Factors influencing these patterns are discussed within an evolutionary framework.