Nuclear 18S rRNA Gene Research Articles

Pseudosperma pamukkalense (Inocybaceae: Agaricomycetes), a new species from Turkey

A new species, Pseudosperma pamukkalense, discovered in Pinus nigra subsp. pallasiana forests is described from the Mediterranean climate zone of south-western Turkey. The novel species is recognized by the presence of pale straw to brownish yellowish pileus, mingled with reddish-brownish streaks with age, smooth to finely innately fibrillose pileus surface, whitish stipe with mainly cylindrical to clavate caulocystidia, large subphaseoliform basidiospores, and mostly narrowly to broadly clavate cheilocystidia. The description of the new species is based on morphological characters, and illustrations, line drawings and comparisons with allied species are provided. A molecular phylogenetic analysis of the internal transcribed spacer (ITS) and the nuclear 28S rRNA gene (nrLSU) regions supported the taxonomic recognition of the new species which was on a separate branch within the genus Pseudosperma.

Systematic position of the genus Metacanthocephalus Yamaguti, 1959 (Palaeacanthocephala: Echinorhynchida) inferred from molecular evidence, with a redescription of Metacanthocephalus ovicephalus (Zhukov, 1960).

The familial affiliation of the echinorhynchid palaeacanthocephalan genus Metacanthocephalus has been uncertain, with the three families Echinorhynchidae, Leptorhynchoididae, and Rhadinorhynchidae having been suggested as its parent taxon. In this study, adult individuals of Metacanthocephalus ovicephalus from the intestine of the cresthead flounder Pseudopleuronectes schrenki (new host) and the dark flounder Pseudopleuronectes obscurus in Hokkaido, Japan, were examined. Using three gene markers (mitochondrial cytochrome c oxidase subunit I; nuclear 18S and 28S rRNA genes) determined from two specimens of M. ovicephalus, a molecular phylogenetic analysis was performed along with relevant sequences available in public databases representing 26 species in eight families of the order Echinorhynchida, along with five species from Polymorphida and two from Eoacanthocephala. The resulting phylogram showed that M. ovicephalus was nested within a clade along with nine species in eight genera (Brentisentis yangtzensis, Dentitruncus truttae, Dollfusentis bravoae, Koronacantha mexicana, K. pectinaria, Leptorhynchoides thecatus, Neotegorhynchus cyprini, Pseudoleptorhynchoides lamothei, and Tegorhynchus [= Illiosentis] sp.). In this paper, we propose i) a set of morphological characters to circumscribe members represented by this clade as a Linnaean higher taxon, ii) to place this taxon at the rank of family, iii) to refer to it as Leptorhynchoididae, and iv) to regard Illiosentidae as a junior synonym of Leptorhynchoididae. Our morphological examination revealed a single vaginal sphincter in M. ovicephalus, a character that was not mentioned in any of the previous literature. By this character, along with geographical distribution and host fish, six congeners currently recognized in Metacanthocephalus can be divided into two groups.

Occurrence of an unidentified harrimaniid acorn worm in the genus Stereobalanus (Hemichordata: Enteropneusta) from the Japan Trench hadal zone

A number of soft fragments of uncertain identity, mostly taking a form of a disk or button, were found among trawled material from the hadal zone (7426–7654 m in depth) in the Japan Trench during the cruise KH-22-8 of the R/V Hakuho-maru in October 2022. These enigmatic ‘disks’ subsequently turned out to be the proboscides of enteropneusts severed from the collar. A molecular phylogenetic analysis based on the mitochondrial 16S rRNA and nuclear 18S rRNA gene sequences determined from one of the fragments along with others available in public databases indicated that the species in question was sister to the harrimaniid enteropneust Stereobalanus canadensis (Spengel, 1893). Some morphological features of the fragments—the proboscis longitudinal musculature arranged in radial plates, the four tubular ovaries, and the absence of synapticula on the gill bars—support that the Japan Trench species would belong to Stereobalanus Spengel, 1902. This study represents the deepest record of Stereobalanus and the first report of enteropneusts from the Japan Trench hadal zone, albeit identified to the genus level. While the species is putatively undescribed, a formal taxonomic description should await intact specimens in future studies.

First record of molecular and pathological investigations of physalopterid larvae infection in northern palm squirrel Funambulus pennantii.

Around 100 reported species of Physaloptera commonly infect mammals, reptiles, birds, and amphibians. The identification of Physaloptera species solely on morphological characteristics is difficult, especially in the case of larval and congeneric infections. The present study is an attempt to identify molecularly and to perform phylogeny and pathology of natural Physaloptera larval infection in northern palm squirrels. The molecular confirmation of the recovered parasitic stages was performed by targeting the nuclear 18S rRNA gene sequence. Phylogenetic analysis and evolutionary divergence of the present study isolate with GenBank™ archived Physaloptera sequences were performed. The cysts (containing the larval stages) were subjected to histopathological examination. Morphological identification of the larval stages revealed the presence of pseudolabia, two spines, and a collar-like projection at the anterior end. Histopathology of the cysts revealed transverse sections of parasites in the lumen along with the thickened cystic wall, infiltration of mononuclear cells, fibrous tissue proliferation in the wall, and cellular debris in the cystic lumen. The molecularly confirmed and sequenced present study isolate was submitted to GenBank™ under the accession number LC706442. Blast analysis revealed 96.82-98.64% nucleotide homology of the present study isolate to the GenBank™ archived Physaloptera sequences. The isolate of the present study was monophyletic with Physaloptera sp. and P. praeputialis recovered from the cats of Haryana, India. Also, evolutionary divergence studies revealed no difference among these sequences. The present study evinced the most probable role of the northern palm squirrel Funambulus pennantii as an aberrant or second intermediate host for P. praeputialis.

Insights into the evolutionary history of Diestramimini cave crickets (Orthoptera, Rhaphidophoridae)

AbstractDiestramimini is one of the two tribes of Aemodogryllinae and is mainly distributed in southern China and Southeast Asia. The intergeneric phylogenetic relationship and historical biogeography of this tribe remain unclear. Here, we present the first phylogenetic and biogeographical analyses of Diestramimini based on three mitochondrial (COI, 12S rRNA and 16S rRNA) and two nuclear (18S rRNA and 28S rRNA) gene fragments. The molecular phylogenetic inference strongly supports the monophyly of Diestramimini and recovers the sister‐group relationship between Diestramima + Tamdaotettix and Arboramima + Gigantettix. A new genus, Bidiestramima Zhu & Shi gen. n., is established and recovered as sister to all the remaining genera of Diestramimini. Moreover, a new species Bidiestramima hekouensis Zhu & Shi gen. et sp. n. is described. Mimadiestra is recovered as paraphyletic, and thus, we propose two new combinations based on the combination of morphological and molecular evidence: Bidiestramima dicha comb. n. and Tamdaotettix (Laotettix) gracilus comb. n. Divergence time estimation and reconstruction of ancestral areas indicate that Diestramimini in China may have originated from Southern Yunnan and Guangxi during the mid‐Oligocene and had two separate evolutionary routes. The diversification of Diestramimini has been driven by several dispersal and vicariance events since the Miocene, linked to the uplift of the Himalaya–Tibetan Plateau, the formation of the monsoon and climate fluctuations.

Species boundaries among extremely diverse and sexually dimorphic Arrenurus water mites (Acariformes: Hydrachnidia: Arrenuridae)

Arrenurus (Arrenuridae) is the most species-rich genus of mites with about 1000 named species that inhabit standing, and to a lesser extent, running water habitats around the world. To date, distinguishing species of Arrenurus has been based on male reproductive morphology. Here, we use morphological and molecular approaches to examine species boundaries among 42 named species of Arrenurus, including four named species that have colour variants (red and green A. americanus, and red and blue A. intermedius, A. manubriator and A. apetiolatus), and two unnamed morphospecies. In this study, we examine male genital structures with the use of SEM techniques, and apply mitochondrial (COI barcode region) and nuclear (28S rRNA) gene fragments to test whether male morphology reflects species boundaries in Arrenurus assessed by molecular analyses. Our results reveal that male reproductive morphology parallels species boundaries as judged by molecular data. We discuss the cases of genetically poorly diversified, yet morphologically clearly defined named species. Moreover, we show that based on the species we examined, colour morphs within otherwise morphologically similar specimens represent within-species variation and, in the absence of other diagnostic traits, colour itself can be misleading in distinguishing species. Our outcomes on molecular taxonomy of Arrenurus provide a background for testing hypotheses about speciation rate in water mites.

Coevolutionary Implications of Obligate Commensalism in Sea Turtles: the Case of the Genus Hyachelia Barnard, 1967 (Crustacea, Amphipoda).

Obligate commensalism in the marine environment and its evolutionary role are still poorly understood. Although sea turtles may serve as ideal substrates for epibionts, within amphipods, only the genus Hyachelia evolved in obligate commensalism with turtles. Here, we report a new host record for Hyachelia lowryi on the hawksbill turtle and describe a larger distribution of the genus in the Atlantic Ocean on green and loggerhead turtles. Hyachelia spp. were sampled from nesting sites of Caretta caretta and feeding grounds of Eretmochelys imbricata and Chelonia mydas along the Brazilian coast. Insights regarding the coevolution of this remarkable genus with its hosts based on molecular analyses are inferred based on mitochondrial (COI) and nuclear (18SrRNA) genes using new and previously available sequences from the infraorder Talitrida. Divergence times for Hyachelia are around the Cretaceous (~127.66 Mya), corresponding to an ancient origin and in agreement with modern green turtle (Chelonioidea) radiation. Later, diversification of Hyachelia species is dated at about 26 Mya, suggesting a coevolutionary association between amphipods and Carettini/Chelonini sea turtles.

Redescription of a rarely encountered species Travisachinensis Grube, 1869 (Annelida, Travisiidae), including a description of a new species of Travisa from Amoy, China.

The original description of Travisiachinensis Grube, 1869 was incomplete, leading to confusion with other species. To clarify the status of this species, we provide a redescription of, and remarks on, T.chinensis based on an examination of the type specimen. We also describe Travisiaamoyanus sp. nov., collected from Xiamen (Amoy), China, and originally identified as T.chinensis by Monro (1934). The new species can be distinguished from its congeners by a combination of the following characters: the total number of segments (34 or 35) and chaetigers (33 or 34), parapodial lappets first from chaetiger 15, and a pygidium with a large ventral triangular cirrus and about six encircling lateral cirri. Genetic distances and phylogenetic analyses based on the mitochondrial (16S rRNA) and nuclear (18S rRNA) genes support the identity of the new species.

Assigning Culicoides larvae to species using DNA barcoding of adult females and phylogenetic associations

BackgroundOrbivirus-induced hemorrhagic diseases cause high mortality in wild and captive white-tailed deer in North America. The role of different Culicoides species in Orbivirus transmission outside of areas of intensive animal production has not been established. At our study location, bluetongue virus (BTV) RNA-positive female Culicoides debilipalpis pools have been detected annually since 2012 when BTV transmission was noted in a captive deer herd. Identifying specific larval habitats of suspected vectors at active transmission sites is crucial both for identifying the source of the vectors and for subsequently planning intervention actions. Since C. debilipalpis larvae are known to develop in tree holes, this study was designed to use DNA barcoding to identify larvae collected from tree holes.MethodsAdult female Culicoides were collected using light or emergence traps and morphologically identified to 11 species. Culicoides sonorensis were also obtained from a laboratory colony. Substrate was collected from tree holes and flooded with water to harvest floating larvae. Total DNA from three to seven adult females per species and 19 larvae was extracted. Two loci of the nuclear 18S ribosomal RNA (rRNA) gene, one locus each of the mitochondrial cytochrome oxidase subunit I (COI) gene and the nuclear 28S rRNA gene were amplified using loci-specific primers.ResultsAll 61 adults were sequenced at each of the four loci under study. Since no single locus delineated all putative species and the COI locus yielded unreliable pseudogenes for two individuals of C. arboricola, sequences of all four loci were concatenated to maximize species separation and allow for larval association with identified adults. Sixteen larvae were clearly assigned to species based on DNA barcoding and phylogenetic results. Multiple larvae were assigned to each of the C. debilipalpis clade, the C. villosipennis clade, the C. arboricola clade and the C. nanus clade.ConclusionsOf the approximately 62 species described in the southeast USA, 21 have now been barcoded and sequences are publicly available. In this study, we constructed a database composed of species-specific sequences of adult Culicoides and then identified larvae to species by matching their corresponding sequences with adults. Since Culicoides larvae are difficult to identify, using DNA barcoding to facilitate larval habitat surveys can be a valuable tool.Graphical

Taxonomy, genetic diversity, and phylogeny of the Antarctic mud dragon, Polacanthoderes (Kinorhyncha: Echinorhagata: Echinoderidae)

A new species Polacanthoderes shiraseae sp. nov. from three Antarctic regions (off Cape Darnley, off Totten Glacier, and in Lützow-Holm Bay) is described. In addition, type species of Polacanthoderes, Polacanthoderes martinezi, is redescribed. The new species is distinguished from P. martinezi by the presence of conspicuously thick lateroventral acicular spines on segments 8 and 9 and the presence of sublateral small acicular spines on segment 7. Both P. martinezi and P. shiraseae sp. nov. occasionally show intraspecific morphological variations in the position of some small acicular spines. The K2P genetic distances based on the mitochondrial cytochrome c oxidase subunit 1 gene sequences in P. shiraseae sp. nov. are 0–1.5%, equivalent to those in other echinoderid species. Phylogenetic analyses of Polacanthoderes based on the nuclear 18S rRNA and 28S rRNA gene sequences support the inclusion of the genus in Echinorhagata/Echinoderidae and suggest that the genus represents the most basal group of this order/family.

First Record of Spirometra erinaceieuropaei spargana Infection in Amphibians of South Asia: A Causative Agent of Surficial Abnormalities.

Sparganosis is a zoonotic disease caused by Plerocercoid larvae (spargana) of the genus Spirometra. We aimed to provide molecular evidence for the infection of amphibians with Spirometra sp. in the inside and outside of Horton Plains National Park (HPNP), Sri Lanka. The prevalence of sparganum infection in wild frogs (Truga eques and Minverya agricola) was investigated in the inside and outside of HPNP from June 2019 to April 2021.A total of 1,434 Amphibians samples were surveyed to examine the spargana infection from the study site. To identify the species identity of the collected spargana, a portion of the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene and nuclear 18S rRNA gene were amplified, sequenced, and analyzed. A total of 539 infected amphibians (T. eques and M. agricola) samples were examined to survey from the study area. Spargana were detected in all dissected specimens belonging to the species Spirometra erinaceieuropaei that were genetically confirmed using the evolutionary conserved nuclear 18S rRNA gene and then compared to the GenBank deposit, indicating that S. erinaceieuropaei is the primary causal agent of sparganosis both inside and outside the HPNP. Our finding is the first genetically confirmed record of S. erinaceieuropaei in amphibians in South Asia. However, further studies are needed to investigate the prevalence of sparagna infection in amphibians all over the island.

Phylogenetic position of the enigmatic genus Atherospio and description of Atherospio aestuarii sp. nov. (Annelida: Spionidae) from Japan.

BackgroundThere are currently two species within the small enigmatic genus Atherospio Mackie & Duff, 1986, which belongs to the Pygospiopsis-Atherospio group in the family Spionidae Grube, 1850. The taxonomic relationship of the genus Atherospio with other spionid or spioniform genera is currently not well understood due to its unusual morphological characteristics.MethodsHere, we describe a new Atherospio species, Atherospio aestuarii sp. nov., based on materials collected from three localities in Japan: Hirota Bay (Iwate Prefecture), Ago Bay (Mie Prefecture), and Yakushima Island (Kagoshima Prefecture). We have also evaluated the possible systematic position of this new species by conducting molecular phylogenetic analyses using the nuclear 18S, 28S, and mitochondrial 16S rRNA gene sequences.ResultsThe morphology of A. aestuarii sp. nov. resembles that of A. disticha Mackie & Duff, 1986 and A. guillei (Laubier & Ramos, 1974) in having branchiae fused to the notopodial lamellae on a restricted number of segments from chaetiger 7, modified neurochaetae on chaetiger 5, and at least some bidentate neuropodial hooks with the secondary tooth below the main fang. The form and arrangement of the modified aristate neurochaetae in double vertical rows closely resemble those found on chaetigers 4 and 5 of A. disticha. The new species lacks the occipital antenna present in A. disticha. In this respect it resembles A. guillei, however, that species differs in having robust neuropodial spines on chaetiger 5 and peristomial papillae, and a preponderance of unidentate neurochaetae. Both A. guillei and the new species have slender needle-like notochaetae in their posteriormost chaetigers. Atherospio aestuarii sp. nov. is distinguished from both congeneric species by its branchial and neuropodial hook distributions. The new species is also unique in that it was recorded at relatively shallow depths, which included intertidal zones. The results of our molecular phylogenetic analysis indicate that the new species was included in a clade that included the genera of the Polydora complex, Pygospio Claparède, 1863, Glandulospio Meißner, Bick, Guggolz, Götting, 2014, Spio Fabricius, 1785, Microspio Mesnil, 1896, Marenzelleria Mesnil, 1896, Rhynchospio Hartman, 1936, Scolelepis Blainville, 1828, Dispio Hartman, 1951, and Malacoceros Quatrefages, 1843 with robust statistical support. The new species formed a clade with Dispio and Scolelepis, however, statistical support for the node was not significant.

Two new species add to the diversity of Eoniphargus in subterranean waters of Japan, with molecular phylogeny of the family Mesogammaridae (Crustacea, Amphipoda)

Amphipod crustaceans are a major group of invertebrates that predominantly occur in groundwater ecosystems. Eoniphargus is a mesogammarid genus with only two known species from the groundwater systems of the Japanese archipelago and Korean Peninsula. However, there is a dearth of taxonomic studies on this genus, and the species diversity within Eoniphargus is unclear. Here, we describe two new species, E. iwataorumsp. nov. and E. toriiisp. nov., collected from the interstitial waters in Tochigi and Shizuoka Prefectures in the Japanese archipelago. These two new species are distinguished from their congeners by the following features: head, urosomite 3, first and second antennae, mandibles, and maxilla 1. Eoniphargus kojimai is redescribed here based on material collected near the type locality. Molecular phylogenetic analyses based on the nuclear 28S rRNA and mitochondrial COI genes revealed that E. kojimai is sister to E. iwataorumsp. nov. In this study, we also briefly discuss the phylogenetic relationships of Mesogammaridae based on the molecular phylogenetic analyses.

Molecular Diversity of Far-Eastern Trematodes of the Genus Crepidsotomum (Allocreadiidae) by Means of Nuclear 28S rRNA and Mitochondrial COI Gene Sequences

The ribosomal 28S rRNA and mitochondrial cytochrome oxidase subunit I (COI) gene fragments variation of several Crepidostomum species, collected from different fish species in Japan and south of Russian Far East, was estimated. On the basis of these data, taxonomical and population genetic structure conclusions for these trematodes were studied. Results of the analysis of the COI gene-based median-joining network indicate the presence of at least five groups of haplotypes that can be distinguished on the basis of definitive host-specificity. Genetic differentiation between these groups has been estimated. Occurrence of C. metoecus and C. farionis and the presence of at least one new Crepidostomum species in Japanese parasite fauna have been confirmed. Ribosomal 28S rDNA-based median-joining analysis indicates low diversity of several Crepidostomum species, reported in latest studies. Critical comments about the evidence of validity of the genus Stephanophiala and species Crepidostomum nemachilus were provided.

Combining multi-marker metabarcoding and digital holography to describe eukaryotic plankton across the Newfoundland Shelf

The planktonic diversity throughout the oceans is vital to ecosystem functioning and linked to environmental change. Plankton monitoring tools have advanced considerably with high-throughput in-situ digital cameras and genomic sequencing, opening new challenges for high-frequency observations of community composition, structure, and species discovery. Here, we combine multi-marker metabarcoding based on nuclear 18S (V4) and plastidial 16S (V4–V5) rRNA gene amplicons with a digital in-line holographic microscope to provide a synoptic diversity survey of eukaryotic plankton along the Newfoundland Shelf (Canada) during the winter transition phase of the North Atlantic bloom phenomenon. Metabarcoding revealed a rich eukaryotic diversity unidentifiable in the imaging samples, confirming the presence of ecologically important saprophytic protists which were unclassifiable in matching images, and detecting important groups unobserved or taxonomically unresolved during similar sequencing campaigns in the Northwest Atlantic Ocean. In turn, imaging analysis provided quantitative observations of widely prevalent plankton from every trophic level. Despite contrasting plankton compositions portrayed by each sampling method, both capture broad spatial differences between the northern and southern sectors of the Newfoundland Shelf and suggest complementary estimations of important features in eukaryotic assemblages. Future tasks will involve standardizing digital imaging and metabarcoding for wider use and consistent, comparable ocean observations.

Description of Alvaniawangi Xu, Qi & Kong, sp. nov. (Mollusca, Gastropoda, Littorinimorpha, Rissoidae) from the East China Sea.

Alvaniawangi Xu, Qi & Kong, sp. nov. (Mollusca, Gastropoda, Littorinimorpha, Rissoidae) was discovered within the intertidal zone in the Nanji Islands and Zhoushan Islands, Zhejiang Province, China. It has a radula characteristic of Alvania Risso, 1826, a protoconch sculptured with micro pits and lamellae between spiral lirae, and a teleoconch with growth lines and subobsolete cords. Specimens were examined using an integrative taxonomic approach incorporating morphological observations and phylogenetic analyses of concatenated mitochondrial 16S rRNA and nuclear 28S rRNA gene sequences. The findings suggest that the new species is sister to Alvaniacircinata A. Adams, 1861 and is probably endemic to the shallow waters of the East China Sea.

Linguatula serrata in an imported dog in Germany: Single-case or emerging disease?

Linguatula serrata is a worm-like parasite with zoonotic potential that inhabits the nasal cavities of canids. Although most cases of linguatulosis are associated with unspecific and rather mild respiratory symptoms, cases of unusual infestations and severe courses in both animals and humans have been reported. In central and northern Europe, the pathogen used to appear only sporadically, however, within the last few years the number of detections has increased noticeably. In July 2020 an approximately nine-month-old dog, imported from Romania, was presented in a veterinary practice in Gotha, central Germany, due to persistent worsening cough. Despite antibiotic treatment the tussis became more severe until the dog expectorated multiple worm-like structures. Three of these specimens were sent to the Institute of Parasitology (Faculty of Veterinary Medicine, University of Leipzig, Leipzig) for morphological and genetic species identification. The latter was based on a 1000-bp fragment of the mitochondrial cytochrome c oxidase subunit I gene (cox1) and the complete nuclear 18S rRNA gene. The dog presented in this study suffered from a severe respiratory impairment caused by worm-like parasites inhabiting its upper respiratory tract. The detected parasites were morphologically identified as female specimens of the so-called tongue-worm L. serrata, which was confirmed by pairwise alignment and phylogenetic analysis of the produced sequences. We report an unusually severe case of L. serrata infection in an imported dog and discuss the spread of this potentially dangerous parasite in central and northern Europe.

Molecular insights into the population structure and haplotype network of Theileria annulata based on the small-subunit ribosomal RNA (18S rRNA) gene.

The present study was conducted to elucidate the population genetic diversity and haplotype network of Theileria annulata based on all available nearly complete 18S rRNA gene sequences in the GenBank™. In total, 52 sequences of the nuclear 18S rRNA gene used to assess the relationship of T. annulata with their country of origin identified 34 haplotypes. Haplotype 4 was widespread, occurring in India, China, Turkey and Iran, while the remaining haplotypes were singleton and unique to one country. Haplotype 4 displayed numerous single haplotypes around it and the stellate shape of the network suggested a rapid population expansion. India exhibited the largest number of haplotypes (h=25) followed by Turkey (h=6), China (h=4), and Iran and Italy (h=1). No geographical clustering of haplotypes was recorded. Nucleotide diversity was the highest in the Turkish followed by the Indian and Chinese populations. Similarly, haplotype diversity was the highest in China followed by Turkey, and the lowest in India. The overall dataset exhibited a low nucleotide diversity (0.00253±0.00035), but high haplotype diversity (0.917±0.034). It suggested the presence of only minor differences (01-11 nucleotide) between haplotypes which was also evident from the haplotype network. A high level of genetic diversity was documented within the Indian, Chinese and Turkish populations of T. annulata, whereas little genetic differentiation was noticed among these populations with a very high level of gene flow. Analysis of molecular variance (AMOVA) of T. annulata sequences revealed higher genetic variation within countries (83.58%) as compared to the variation among countries (16.42%). Neutrality indices, viz., Tajima's D, Fu and Li's F, Fu's Fs, and R2, along with the unimodal mismatch distributions demonstrated a recent population expansion of T. annulata in India and the overall dataset. However, the non-significant values of Tajima's D, Fu and Li's F, and Fu's Fs for the Chinese population along with a bimodal mismatch distribution signified a constant population size. For the Turkish population, the neutrality and mismatch distribution tests either indicated a constant or a slight increase in population size. The present study provides novel insights into the population genetics and haplotype network of T. annulata based on the 18S rRNA gene for the first time.

The Morphology, Mitogenome, Phylogenetic Position, and Symbiotic Bacteria of a New Species of Sclerolinum (Annelida: Siboglinidae) in the South China Sea

Sclerolinum annulatus n. sp. (Annelida: Siboglinidae) is described based on specimens collected from soft sediment of the Haima cold seep in the South China Sea. Morphologically, S. annulatus n. sp. is distinct in having a tube with transverse rings and a forepart (i.e., anterior region) containing one arched row of elongated plaques on both sides of the dorsal furrow. Genome skimming, assembly, and annotation produced a nearly complete mitogenome of S. annulatus n. sp. with 15,553 bp nucleotides that encodes 13 protein-coding genes, two rRNA, and 22 tRNA. Phylogenetic analyses based on the mitochondrial cytochrome c oxidase I (cox1) gene and a concatenated dataset comprising the mitochondrial cox1 and 16S rRNA genes along with the nuclear 18S rRNA gene both strongly support the placement of S. annulatus n. sp. in the genus SclerolinumSouthward, 1961. Based on cox1, S. annulatus n. sp. is most closely related to an undescribed siboglinid from off Kushiro in Japan (“Pogonophora” sp. Kushiro-SK-2003). Transmission electron microscopy, microbial 16S rRNA amplicon sequencing, phylogenetic reconstruction, and stable isotope analyses together indicate that S. annulatus n. sp. hosts a single phylotype of sulfur-oxidizing endosymbionts.

DNA Barcoding of Scavenging Amphipod Communities at Active and Inactive Hydrothermal Vents in the Indian Ocean

Hydrothermal vent areas have drawn increasing interest since they were discovered in 1977. Because of chemoautotrophic bacteria, they possess high abundances of vent endemic species as well as many non-vent species around the fields. During the survey conducted by the Bundesanstalt für Geowissenschaften und Rohstoffe (Federal Institute for Geosciences and Natural Resources, BGR) to identify inactive polymetallic sulfide deposits along Central and Southeast Indian Ridges, the INDEX project studied the scavenging amphipod community at three newly discovered hydrothermal fields. A sample consisting of 463 representatives of Amphipoda (Malacostraca: Crustacea) was collected by means of baited traps in active and inactive vents of three different sites and subsequently studied by both morphological and genetic methods. Molecular methods included the analysis of two mitochondrial (cytochrome c oxidase subunit I [COI] and 16S rRNA) and one nuclear (18S rRNA) genes. By six delimitation methods, 22 molecular operational taxonomic units (MOTUs) belonging to 12 genera and 10 families were defined. The existence of potential species complexes was noted for the representatives of the genus Paralicella. The inactive site, where 19 species were found, showed higher species richness than did the active one, where only 10 taxa were recorded. Seven genera, Ambasiopsis, Cleonardo, Eurythenes, Parandania, Pseudonesimus, Tectovalopsis, and Valettiopsis, were observed only at inactive sites, whereas Haptocallisoma, was collected exclusively at active ones. The species Abyssorchomene distinctus (Birstein and Vinogradov, 1960), Hirondellea brevicaudata Chevreux, 1910, and Hirondellea guyoti Barnard and Ingram, 1990, have been previously reported from vent sites in the Atlantic or Pacific oceans. The present study provides the first report of Eurythenes magellanicus (H. Milne Edwards, 1848) and five other already described species in the Indian Ocean. The addition of 356 sequences strongly increases the number of amphipod barcodes in reference databases and provides for the first time COI barcodes for Cleonardo neuvillei Chevreux, 1908, Haptocallisoma abyssi (Oldevig, 1959), Hirondellea guyoti, Tectovalopsis fusilus Barnard and Ingram, 1990, and the genera Haptocallisoma, Pseudonesimus, and Valettiopsis.