Description, life cycle, and phylogenetics of Proterometra wigglewomble n. sp. (Digenea: Azygiidae) from the Cahaba River, Alabama, U.S.A.

We herein describe Proterometra wigglewomble n. sp. (Digenea: Azygiidae: Azygiinae) from the Cahaba River, Alabama, USA, which asexually reproduces in the compact elimia, Elimia showalteri (Lea, 1860) (Cerithioidea: Pleuroceridae) and matures in the oesophagus of the blackbanded darter, Percina nigrofasciata (Agassiz, 1854) (Perciformes: Percidae). Adults of the new species differ from congeners by having a small body and eggs having a wholly fimbriated surface that appears as a cilia-like brush border. Live naturally-shed cercariae of the new species differ from those of its congeners by having a strongly claviform tail stem bearing aspinose mammillae, a single furca, excretory pores that open on the posterior margin of the single furca, and few eggs in the cercarial distome. The behaviour of the cercaria further differentiates the new species. Naturally-shed cercariae of P. wigglewomble secrete a jelly-like adhesive that coats the surface of the furca and evidently facilitates attachment to the surface of glass, plastic, and snail shell. Attached cercariae vigorously wiggle and thrash about once attached, as if mimicking the larva of a stream insect so as to lure the blackbanded darter to eat it. Phylogenetic analyses recovered monophyletic Azygiidae, comprising monophyletic Leuceruthrinae Goldberger, 1911 and polyphyletic Azygiinae Lühe, 1909. The present study is the largest taxon sampling for Azygiidae and the first to include 28S sequences of Leuceruthrus. Compact elimia and blackbanded darter are new host records for Proterometra. The new species is the 3rd congener reported from the Cahaba River, a region renowned for its fish and snail endemic biodiversity.

Using genomics, morphometrics, and environmental niche modeling to test the validity of a narrow-range endemic snail, Pateranantahala (Gastropoda, Polygyridae).

Terrestrial gastropods are among the most imperiled groups of organisms on Earth. Many species have a complex taxonomic history, often including poorly defined subspecies, most of which have not been the focus of modern systematics research. Genomic tools, geometric morphometrics, and environmental niche modeling were used to assess the taxonomic status of Pateraclarkiinantahala (Clench & Banks, 1932), a subspecies of high conservation concern with a restricted range of approximately 3.3 km2 in North Carolina, USA. A genome-scale dataset was generated that included individuals with morphologies matching P.c.nantahala, P.c.clarkii, and one individual with an intermediate form between P.c.nantahala and P.c.clarkii that was initially hypothesized as a potential hybrid. Mitochondrial phylogenetics, nuclear species tree inference, and phylogenetic networks were used to assess relationships and gene flow. Differences in shell shape via geometric morphometrics and whether the environmental niches of the two subspecies were significantly different were also examined. Molecular analyses indicated an absence of gene flow among lineages of P.clarkii sensu lato. Analyses rejected our hypothesis that the intermediate shelled form represented a hybrid, but instead indicated that it was a distinct lineage. Environmental niche models indicated significant differences in environmental niche between P.c.clarkii and P.c.nantahala, and geometric morphometrics indicated that P.c.nantahala had a significantly different shell shape. Given multiple lines of evidence, species-level recognition of P.nantahala is warranted.

A novel assembly pipeline and functional annotations for targeted sequencing: A case study on the globally threatened Margaritiferidae (Bivalvia: Unionida).

The proliferation of genomic sequencing approaches has significantly impacted the field of phylogenetics. Target capture approaches provide a cost-effective, fast and easily applied strategy for phylogenetic inference of non-model organisms. However, several existing target capture processing pipelines are incapable of incorporating whole genome sequencing (WGS). Here, we develop a new pipeline for capture and de novo assembly of the targeted regions using whole genome re-sequencing reads. This new pipeline captured targeted loci accurately, and given its unbiased nature, can be used with any target capture probe set. Moreover, due to its low computational demand, this new pipeline may be ideal for users with limited resources and when high-coverage sequencing outputs are required. We demonstrate the utility of our approach by incorporating WGS data into the first comprehensive phylogenomic reconstruction of the freshwater mussel family Margaritiferidae. We also provide a catalogue of well-curated functional annotations of these previously uncharacterized freshwater mussel-specific target regions, representing a complementary tool for scrutinizing phylogenetic inferences while expanding future applications of the probe set.

Subterranean freshwater gastropod biodiversity and conservation in the United States and Mexico.

Many taxonomic groups successfully exploit groundwater environments and have adapted to a subterranean (stygobiotic) existence. Among these groups are freshwater gastropods (stygosnails), which represent a widespread and taxonomically diverse component of groundwater ecosystems in North America. However, owing to sampling difficulty and lack of targeted study, stygosnails remain among the most understudied of all subterranean groups. We conducted a literature review to assess the biodiversity and geographic associations of stygosnails, along with the threats, management activities, and policy considerations related to the groundwater systems they inhabit. We identified 39 stygosnail species known to occur in a range of groundwater habitats from karst regions in the United States and Mexico. Most stygosnails exhibit extreme narrow-range endemism, resulting in a high risk of extinction from a single catastrophic event. We found that anthropogenically driven changes to surface environments have led to changes in local hydrology and degradation of groundwater systems inhabited by stygosnails such as increased sedimentation, introduction of invasive species, groundwater extraction, or physical collapse of water-bearing passages. Consequently, 32 of the 39 described stygosnail species in the United States and Mexico have been assessed as imperiled under NatureServe criteria, and 10 species have been assessed as threatened under International Union for Conservation of Nature criteria. Compared with surface species of freshwater snails, stygosnail conservation is uniquely hindered by difficulties associated with accessing subterranean habitats for monitoring and management. Furthermore, only three species were found to have federal protection in either the United States or Mexico, and current laws regulating wildlife and water pollution at the state and federal level may be inadequate for protecting stygosnail habitats. As groundwater systems continue to be manipulated and relied on by humans, groundwater-restricted fauna such as stygosnails should be studied so unique biodiversity can be protected.

Diversidad y Conservación de Gasterópodos Subterráneos de Agua Dulce en los Estados Unidos y en México Resumen Muchos grupos taxonómicos aprovechan exitosamente los ambientes de aguas subterráneas y se han adaptado eficazmente a una existencia subterránea (estigobiótica). Entre estos grupos están los gasterópodos (estigocaracoles), los cuales representan un componente taxonómicamente diverso y de amplia distribución en los ecosistemas de aguas subterráneas en América del Norte. Sin embargo, debido a la dificultad del muestreo y a la falta de estudios enfocados, los estigocaracoles todavía son de los grupos menos estudiados de los taxones subterráneos. Realizamos una revisión de la literatura para evaluar las asociaciones geográficas y la biodiversidad de los estigocaracoles, junto con las amenazas, actividades de manejo y consideraciones políticas relacionadas con los sistemas de aguas subterráneas que habitan. Identificamos a 39 especies de estigocaracoles que se sabe se encuentran en una gama de hábitats de aguas subterráneas de las regiones kársticas en los Estados Unidos y en México. La mayoría de los estigocaracoles exhiben un endemismo extremo de extensión limitada, lo que resulta en un riesgo elevado de extinción a partir de un evento catastrófico único. Descubrimos que los cambios causados por el hombre en los ambientes superficiales han resultado en cambios en la hidrología local y en la degradación de los sistemas de aguas subterráneas habitadas por los estigocaracoles. Dichos cambios incluyen incremento de la sedimentación, la introducción de especies invasoras, la extracción de aguas subterráneas y el colapso físico de los pasos de agua. Como consecuencia, 32 de las 39 especies descritas de estigocaracoles en los Estados Unidos y en México han sido valoradas como en peligro bajo los criterios de NatureServe, y diez especies han sido valoradas como amenazadas bajo los criterios de la Unión Internacional para la Conservación de la Naturaleza. Comparada con las especies superficiales de caracoles de agua dulce, la conservación de los estigocaracoles está singularmente obstaculizada por las dificultades asociadas con el acceso a los hábitats subterráneos para su monitoreo y manejo. Además, se encontró que sólo tres especies cuentan con protección federal ya sea en Estados Unidos o en México, y puede que las leyes actuales que regulan la vida silvestre y la contaminación del agua a nivel estatal y federal sean inadecuadas para la protección de los hábitats de los estigocaracoles. Mientras los sistemas de aguas subterráneas sigan siendo manipulados y los humanos sigan dependiendo de ellos, la fauna restringida a las aguas subterráneas, como los estigocaracoles, debería ser estudiada para proteger a la biodiversidad tan única.

Assessing Genomic Diversity, Connectivity, and Riverscape Genetics Hypotheses in the Endangered Rough Hornsnail, Pleurocera Foremani, Following Habitat Disruption.

The southeastern United States is home to some of the richest biodiversity in the world. Over the last 200 years, however, rapid industrialization and urbanization have threatened many natural areas, including freshwater habitats. River impoundments have also rapidly altered freshwater habitats, often resulting in species extirpation or extinction. The Coosa River in Alabama experienced one of the largest faunal declines in modern history after impoundment, making it an ideal system for studying how invertebrate species are affected by reservoir creation. One such species, the Rough Hornsnail, Pleurocera foremani, is an endangered freshwater snail in the family Pleuroceridae. We sampled all known localities of P. foremani and used 2bRAD-seq to measure genetic diversity. We assessed riverscape genomic patterns across the current range of P. foremani and measured gene flow within and between impoundments. We also investigated the degree to which P. foremani displays an isolation by distance pattern and conforms to broad hypotheses that have been put forth for population genetics of riverine species like the Mighty Headwater Hypothesis that predicts greater genetic diversity in headwater reaches compared with mainstem populations. Like most other freshwater species, a pattern of isolation by distance was observed in P. foremani. We also found that Coosa River dams are a barrier to gene flow, and genetic fragmentation of P. foremani is likely to increase. However, gene flow appeared common within reservoirs and tributaries. Additionally, we found that spatial genetic structure of P. foremani deviates from what is expected under the Mighty Headwaters Hypothesis, adding to a growing body of research suggesting that the majority of genetic diversity in low-dispersing gastropods is found in mainstem populations.

First Record of a Polystome from Alligator Snapping Turtle, Macrochelys temminckii (Cryptodira: Chelydridae) or Mississippi; with Comments on "Neopolystoma orbiculare (Stunkard, 1916)" and Its Junior Subjective Synonyms.

Herein, we describe several newly-collected specimens of Neopolystoma cf. orbiculare from the urinary bladder of 2 alligator snapping turtles, Macrochelys temminckii (Troost in Harland, 1835) (Cryptodira: Chelydridae Gray, 1831) from Comet Lake (30°35'46.94″N, 88°36'3.12″W), Pascagoula River, Mississippi. Our specimens differed from all previous descriptions of N. orbiculare and its junior subjective synonyms by the combination of having intestinal ceca adorned with triangular pockets and that terminate dorsal to the haptor, distinctive hooklets each having a handle and guard of approximately equal length and having a much longer and curved blade, 16 genital coronet spines that each possess 1-2 flanges per spine, pre-testicular vaginal pores, and vaginal ducts that are anterior to the junction of the oviduct and genito-intestinal canal. Some of our specimens were enantiomorphic (4 and 3 had a dextral and sinistral ovary, respectively). Nucleotide sequences (large subunit ribosomal DNA [28S], small subunit ribosomal DNA [18S], and cytochrome oxidase subunit 1 mitochondrial gene [COI]) for our specimens were most similar to GenBank sequences ascribed to N. orbiculare. Single-gene and concatenated phylogenetic analyses confirmed that NeopolystomaPrice, 1939 is polyphyletic and that our isolates share a recent common ancestor with those ascribed to N. orbiculare. This is the first record of a polystomatid from Mississippi, from the Pascagoula River, and from the alligator snapping turtle (and only the second species of Neopolystoma reported from any snapping turtle).

Genetic diversity and historical demography in Bellamya gastropods from the Lake Victoria ecoregion reveal early and severe population collapse.

Understanding the interplay between ecological and population genetic processes through space and time is a central goal of landscape genetics. However, most studies that place diversification dynamics in an ecological context have focused on vertebrates, leaving a significant gap in our understanding of the effects of ecosystem change on community composition and demography of invertebrates. In the East African Rift System, cichlid fishes have emerged as a powerful model system for understanding adaptive radiation (Kornfield & Smith, 2000), but few studies have examined diversification of other taxa. In this issue of Molecular Ecology, Van Bocxlaer et al. (2020) use landscape genetic approaches to model historical demography and diversification of viviparid gastropods in the Lake Victoria ecoregion. They show that while phylogeographic patterns are similar between the two, viviparids and cichlids have responded in very different ways to the climatic upheavals of the Pleistocene and that their responses have been at least partially asynchronous. Viviparids have experienced population collapse 30- to 50-fold more severe than that seen in haplochromine cichlids from the region, and population declines began 100K years earlier, prior to the last glacial maximum (~15,000-18,000 years ago). Their results reveal a new facet to the profound and lasting impacts of Pleistocene climate change on the modern fauna of the Lake Victoria ecoregion and its ability to respond to current human-mediated stressors.

A new species of Myxobolus Bütschli, 1882 (Bivalvulida: Myxobolidae) infecting stratum spongiosum of the imperiled sicklefin redhorse, Moxostoma sp. (Cypriniformes: Catostomidae) from the Little Tennessee River, North Carolina, USA.

The sicklefin redhorse, Moxostoma sp. (Cypriniformes: Catostomidae), is an innominate imperiled catostomid endemic to the Hiwassee and Little Tennessee river basins, which has been restricted to a few tributaries of these systems by impoundments. During collections to propagate sicklefin redhorse for reintroduction, a myxozoan, described herein, was observed infecting sicklefin redhorse in the Little Tennessee River Basin, North Carolina. Myxobolus naylori Ksepka et Bullard sp. n. infects the stratum spongiosum covering the scales of sicklefin redhorse. Myxospores of the new species differ from all congeners by the combination of having a mucous envelope, intercapsular process, and sutural markings as well as lacking an iodinophilic vacuole in the sporoplasm. A phylogenetic analysis of the 18S rDNA gene recovered the new species in a polytomy with Myxobolus marumotoi Li et Sato, 2014 and a clade comprised of species of Myxobolus Bütschli, 1882; Thelohanellus Kudo, 1933, and Dicauda Hoffman et Walker, 1973. Histological sections of infected sicklefin redhorse skin revealed myxospores within a plasmodium in the stratum spongiosum dorsal to scales, encapsulated in collagen fibres, and associated with focal erosion of scales directly beneath the plasmodium; in some instances, the scale was perforated by the plasmodium. The specificity of the new species to sicklefin redhorse may make it a useful biological tag to differentiate sicklefin redhorse from morphologically similar species. The new species is the first parasite reported from sicklefin redhorse, a species of concern to the United States Fish and Wildlife Service. No species of Myxobolus has been reported from species of Moxostoma in the Southeast United States. As it was observed that Myxobolus minutus Rosser, Griffin, Quiniou, Alberson, Woodyard, Mischker, Greenway, Wise et Pote, 2016 is a primary junior homonym of Myxobolus minutus Nemeczek, 1911, we propose the replacement name Myxobolus diminutus (Rosser, Griffin, Quiniou, Alberson, Woodyard, Mischker, Greenway, Wise et Pote, 2016).

Range reduction of Oblong Rocksnail, Leptoxis compacta, shapes riverscape genetic patterns.

Many freshwater gastropod species face extinction, including 79% of species in the family Pleuroceridae. The Oblong Rocksnail, Leptoxis compacta, is a narrow range endemic pleurocerid from the Cahaba River basin in central Alabama that has seen rapid range contraction in the last 100 years. Such a decline is expected to negatively affect genetic diversity in the species. However, precise patterns of genetic variation and gene flow across the restricted range of L. compacta are unknown. This lack of information limits our understanding of human impacts on the Cahaba River system and Pleuroceridae. Here, we show that L. compacta has likely seen a species-wide decline in genetic diversity, but remaining populations have relatively high genetic diversity. We also report a contemporary range extension compared to the last published survey. Our findings indicate that historical range contraction has resulted in the absence of common genetic patterns seen in many riverine taxa like isolation by distance as the small distribution of L. compacta allows for relatively unrestricted gene flow across its remaining range despite limited dispersal abilities. Two collection sites had higher genetic diversity than others, and broodstock sites for future captive propagation and reintroduction efforts should utilize sites identified here as having the highest genetic diversity. Broadly, our results support the hypothesis that range contraction will result in the reduction of species-wide genetic diversity, and common riverscape genetic patterns cannot be assumed to be present in species facing extinction risk.

Neotropical Turtle Blood Flukes: Two New Genera and Species from the Amazon River Basin with a Key to Genera and Comments on a Marine-Derived Parasite Lineage in South America.

Two new genera and species of freshwater turtle blood flukes (TBFs) are described herein based on specimens infecting the nephritic and mesenteric blood vessels of "matamatas" (a side-necked turtle, Chelus fimbriata [Schneider, 1783] [Pleurodira: Chelidae]) from the Amazon River Basin, Peru. These taxa comprise the first-named species and the first-proposed genera of freshwater TBFs from the continent of South America. A new comparison of all TBF genera produced 6 morphologically diagnosed groups that are discussed in light of previous TBF classification schemes and a novel phylogenetic hypothesis based on the nuclear large subunit ribosomal DNA (28S). Considering external and internal anatomical features, species of the new genera (Atamatam Bullard and Roberts n. gen., Paratamatam Bullard and Roberts n. gen.) are most similar to each other and are together most similar to those of several marine TBF genera. The 28S phylogenetic analysis supported the monophyly of all 6 morphologically diagnosed groups of genera. Most notably, the freshwater TBFs of South America comprise a derived group nested within the clade that includes the paraphyletic marine TBFs. Not surprisingly in light of morphology, another marine TBF lineage (Neospirorchis Price, 1934) clustered with the freshwater TBFs of Baracktrema Roberts, Platt, and Bullard, 2016 and Unicaecum Stunkard, 1925. Our results, including an ancestral state reconstruction, indicated that (1) freshwater TBFs have colonized marine turtles twice independently and that (2) the South American freshwater TBFs comprise a marine-derived lineage. This is the first evidence that TBFs have twice independently transitioned from a marine to freshwater definitive host. Marine incursion is considered as a possible mechanism affecting the natural history of marine-derived freshwater TBFs in South America. A dichotomous key to accepted TBF genera is provided.

Assessing the diversity of Western North American Juga (Semisulcospiridae, Gastropoda).

Juga is a genus of freshwater gastropods distributed in Pacific and Interior drainages of the Pacific Northwest from central California to northern Washington. The current classification has relied heavily on features of the shell, which vary within and across drainages, and often intergrade without sharp distinctions between species. The only previous molecular analysis included limited population sampling, which did not allow robust assessment of intra- versus interspecific levels of genetic diversity, and concluded almost every sampled population to be a distinct OTU. We assembled a multilocus mitochondrial (COI, 16S) and nuclear gene (ITS1) dataset for ∼100 populations collected across the range of the genus. We generated primary species hypotheses using ABGD with best-fit model-corrected distances and further explored our data, both individual gene partitions and concatenated datasets, using a diversity of phylogenetic and species delimitation methods (Bayesian inference, maximum likelihood estimation, StarBEAST2, bGMYC, bPTP, BP&P). Our secondary species delimitation hypotheses, based primarily on the criterion of reciprocal monophyly, and informed by a combination of geography and morphology, support the interpretation that Juga comprises a mixture of geographically widespread species and narrow range endemics. As might be expected in taxa with low vagility and poor dispersal capacities, analysis of molecular variance (AMOVA) revealed highly structured populations with up to 80% of the observed genetic variance explained by variation between populations. Analyses with bGMYC, bPTP, and BP&P appeared sensitive to this genetic structure and returned highly dissected species hypotheses that are likely oversplit. The species diversity of Juga is concluded to be lower than presently recognized, and the systematics to require extensive revision. Features of the teleoconch considered significant in species-level and subgeneric classification were found to be variable within some species, sometimes at a single site. Of a number of potentially new species identified in non-peer reviewed reports and field guides, only one was supported as a distinct OTU.

First Record of A Species of Mermithidae Braun, 1883 Infecting a Decapod, Palaemon paludosus (Palaemonidae).

The hemocoel of 26 of 30 (86%) eastern grass shrimps, Palaemon paludosus (Gibbes, 1850) (Decapoda: Palaemonidae), captured during June 2017 from several freshwater lakes near Leesburg and Lake Kissimmee, Florida, was infected by juveniles of a nematode species (Mermithidae sp.). Some infected eastern grass shrimps were preserved whole for histopathology, whereas others were dissected to excise parasitic juvenile nematodes, and still others were kept alive in glass aquaria such that post-parasitic (emerged) juvenile nematodes could be opportunistically observed alive and ultimately preserved. Parasitic and post-parasitic juvenile nematodes had cuticle cross-fibers, cephalic papillae, cup-shaped amphids, a horn-shaped vagina, a trophosome, and a caudal appendage, which collectively diagnosed them as Mermithidae sp. They differed from those of nematomorphs (Nematomorpha) by lacking 4 giant cells anteriorly, tegumental bristles, scale or plate-like areoles, a bifurcate or trifurcate posterior end, and an anus. A phylogenetic analysis of the small subunit rDNA (18S) that included all of the available mermithid sequences corresponding to morphologically diagnosed specimens recovered Mermithidae sp. within the clade of mermithids and sister to Ovomermis sinensis Chen, Jian, and Ren, 1991 . This is the first record of a mermithid infection in a decapod and first report of a mermithid infection in an aquatic crustacean from North America (another mermithid infects a terrestrial isopod there). The high prevalence of infection and the multiple geographic localities harboring infected eastern grass shrimps indicated that these infections were not spurious. Because no other decapod is confirmed as a mermithid host, we suspect that these specimens likely represent a new species with a life cycle worth studying, since none for a mermithid involving a decapod nor a crustacean has been elucidated to date. We also provide a table of all mermithid and nematomorph infections in crustaceans.

Riverscape genetic variation, migration patterns, and morphological variation of the threatened Round Rocksnail, Leptoxis ampla.

Within riverine systems, headwater populations are hypothesized to harbour higher amounts of genetic distinctiveness than populations in the main stem of a river and display increased genetic diversity in large, downstream habitats. However, these hypotheses were mostly developed with insects and fish, and they have not been tested on many invertebrate lineages. Pleuroceridae gastropods are of particular ecological importance to rivers of eastern North America, sometimes comprising over 90% of macroinvertebrate biomass. Yet, virtually nothing is known of pleurocerid landscape genetics, including whether genetic diversity follows predictions made by hypotheses developed on more mobile species. Moreover, the commonly repeated hypothesis that intraspecific morphological variation in gastropods results from ecophenotypic plasticity has not been well tested on pleurocerids. Using 2bRAD-seq to discover single nucleotide polymorphisms, we show that the threatened, Cahaba River endemic pleurocerid, Leptoxis ampla, has limited gene flow among populations and that migration is downstream-biased, conflicting with previous hypotheses. Both tributary and main stem populations harbour unique genomic profiles, and genetic diversity was highest in downstream populations. Furthermore, L. ampla shell morphology was more correlated with genetic differences among individuals and populations than habitat characteristics. We anticipate similar genetic and demographic patterns to be seen in other pleurocerids, and hypotheses about gene flow and population demographics that were based on more mobile taxa often, but not always, apply to freshwater gastropods. From a conservation standpoint, genetic structure of L. ampla populations suggests distinctive genetic diversity is lost with localized extirpation, a phenomenon common across the range of Pleuroceridae.

Gymnurahemecus bulbosus gen. et sp. nov. (Digenea: Aporocotylidae) infecting smooth butterfly rays, Gymnura micrura (Myliobatiformes: Gymnuridae) in the northern Gulf of Mexico, with a taxonomic key and further evidence for monophyly of chondrichthyan blood flukes.

Gymnurahemecus bulbosus gen. et sp. nov. infects the heart of smooth butterfly rays, Gymnura micrura in the Gulf of Mexico. Gymnurahemecus differs from all other accepted aporocotylid genera by having one column of C-shaped lateral tegumental spines, a medial oesophageal bulb anterior to a diverticulate region of the oesophagus, inverse U-shaped intestinal caeca, a non-looped testis, an oviducal ampulla, a Laurer's canal, and a post-caecal common genital pore. The new species, the shark blood flukes (Selachohemecus spp. and Hyperandrotrema spp.), and the chimaera blood fluke Chimaerohemecus trondheimensis are unique by having C-shaped lateral tegumental spines. Selachohemecus spp. and the new species have a single column of lateral tegumental spines, whereas Hyperandrotrema spp. and C. trondheimensis have 2-7 columns of lateral tegumental spines. The new species differs from Selachohemecus spp. most notably by having an inverse U-shaped intestine. The other ray blood flukes (Orchispirium heterovitellatum, Myliobaticola richardheardi, and Ogawaia glaucostegi) differ from the new species by lacking lateral tegumental spines, a medial oesophageal bulb, and a Laurer's canal and by having a looped testis. Phylogenetic analysis using large subunit ribosomal DNA (28S) indicated that the new species is sister to the clade that includes the other sequenced adult blood fluke (O. glaucostegi), which infects a ray in Australia. These results agree with and extend previous morphology- and nucleotide-based phylogenetic assertions that the blood flukes of early-branching jawed craniates (Chondrichthyes) are monophyletic and phylogenetically separated from the blood flukes of later-branching ray-finned fishes (Actinopterygii: Euteleostei).

On the identity of Leptoxis taeniata - a misapplied name for the threatened Painted Rocksnail (Cerithioidea, Pleuroceridae).

The Painted Rocksnail, currently known as Leptoxis taeniata, is a federally threatened species native to the Mobile River basin in Alabama, USA. Presently restricted to four disjunct populations, the species is at considerable risk of extinction after a range decline of over 95% in the 20th century because of habitat alteration following impoundment of the Coosa River. Here, we reassess the identity and historical range of the Painted Rocksnail to improve communication and conservation efforts for the species. We determined that L. taeniata is a synonym of L. picta and that the name L. taeniata has been misapplied to the current concept of the Painted Rocksnail for which L. coosaensis is the oldest available name. Leptoxis coosaensis and L. picta are herein redescribed. After examination of historical material, we determined that records of the Painted Rocksnail outside the Coosa River drainage were misidentifications. Thus, we redefine the historical range of the Painted Rocksnail as restricted to the Coosa River and select tributaries above the Fall Line at Wetumpka, Alabama, rather than extending into the Alabama River as previously thought. Leptoxis coosaensis is in dire need of conservation, and management plans should take into consideration the revised historical range of the species.

Author Correction: Ctenophore relationships and their placement as the sister group to all other animals.

In the version of this Article originally published the location of Punta Arenas was incorrect and should have read 'Chile' in Figures 3-5 and in the Supplementary Information. This has been corrected in all versions of the Article.

Ctenophore relationships and their placement as the sister group to all other animals.

Ctenophora, comprising approximately 200 described species, is an important lineage for understanding metazoan evolution and is of great ecological and economic importance. Ctenophore diversity includes species with unique colloblasts used for prey capture, smooth and striated muscles, benthic and pelagic lifestyles, and locomotion with ciliated paddles or muscular propulsion. However, the ancestral states of traits are debated and relationships among many lineages are unresolved. Here, using 27 newly sequenced ctenophore transcriptomes, publicly available data and methods to control systematic error, we establish the placement of Ctenophora as the sister group to all other animals and refine the phylogenetic relationships within ctenophores. Molecular clock analyses suggest modern ctenophore diversity originated approximately 350 million years ago ± 88 million years, conflicting with previous hypotheses, which suggest it originated approximately 65 million years ago. We recover Euplokamis dunlapae-a species with striated muscles-as the sister lineage to other sampled ctenophores. Ancestral state reconstruction shows that the most recent common ancestor of extant ctenophores was pelagic, possessed tentacles, was bioluminescent and did not have separate sexes. Our results imply at least two transitions from a pelagic to benthic lifestyle within Ctenophora, suggesting that such transitions were more common in animal diversification than previously thought.

Toll-like receptor pathway evolution in deuterostomes.

Animals have evolved an array of pattern-recognition receptor families essential for recognizing conserved molecular motifs characteristic of pathogenic microbes. One such family is the Toll-like receptors (TLRs). On pathogen binding, TLRs initiate specialized cytokine signaling catered to the class of invading pathogen. This signaling is pivotal for activating adaptive immunity in vertebrates, suggesting a close evolutionary relationship between innate and adaptive immune systems. Despite significant advances toward understanding TLR-facilitated immunity in vertebrates, knowledge of TLR pathway evolution in other deuterostomes is limited. By analyzing genomes and transcriptomes across 37 deuterostome taxa, we shed light on the evolution and diversity of TLR pathway signaling elements. Here, we show that the deuterostome ancestor possessed a molecular toolkit homologous to that which drives canonical MYD88-dependent TLR signaling in contemporary mammalian lineages. We also provide evidence that TLR3-facilitated antiviral signaling predates the origin of its TCAM1 dependence recognized in the vertebrates. SARM1, a negative regulator of TCAM1-dependent pathways in vertebrates, was also found to be present across all major deuterostome lineages despite the apparent absence of TCAM1 in invertebrate deuterostomes. Whether the presence of SARM1 is the result of its role in immunity regulation, neuron physiology, or a function of both is unclear. Additionally, Bayesian phylogenetic analyses corroborate several lineage-specific TLR gene expansions in urchins and cephalochordates. Importantly, our results underscore the need to sample across taxonomic groups to understand evolutionary patterns of the innate immunity foundation on which complex immunological novelties arose.

Discovery and evolution of novel hemerythrin genes in annelid worms.

BACKGROUND: Despite extensive study on hemoglobins and hemocyanins, little is known about hemerythrin (Hr) evolutionary history. Four subgroups of Hrs have been documented, including: circulating Hr (cHr), myohemerythrin (myoHr), ovohemerythrin (ovoHr), and neurohemerythrin (nHr). Annelids have the greatest diversity of oxygen carrying proteins among animals and are the only phylum in which all Hr subgroups have been documented. To examine Hr diversity in annelids and to further understand evolution of Hrs, we employed approaches to survey annelid transcriptomes in silico. RESULTS: Sequences of 214 putative Hr genes were identified from 44 annelid species in 40 different families and Bayesian inference revealed two major clades with strong statistical support. Notably, the topology of the Hr gene tree did not mirror the phylogeny of Annelida as presently understood, and we found evidence of extensive Hr gene duplication and loss in annelids. Gene tree topology supported monophyly of cHrs and a myoHr clade that included nHrs sequences, indicating these designations are functional rather than evolutionary. CONCLUSIONS: The presence of several cHrs in early branching taxa suggests that a variety of Hrs were present in the common ancestor of extant annelids. Although our analysis was limited to expressed-coding regions, our findings demonstrate a greater diversity of Hrs among annelids than previously reported.