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The dynamic climate history that drove sea level fluctuation during past glacial periods mediated the movement of organisms between Asia and North America via the Bering Land Bridge. Investigations of the biogeographic histories of small mammals and their parasites demonstrate facets of a complex history of episodic geographic colonization and refugial isolation that structured diversity across the Holarctic. We use a large multi-locus nuclear DNA sequence dataset to robustly resolve relationships within the cestode genus Arostrilepis (Cyclophyllidea: Hymenolepididae), a widespread parasite of predominantly arvicoline rodents (voles, lemmings). Using this phylogeny, we confirm that several Asian Arostrilepis lineages colonized North America during up to four distinct glacial periods in association with different rodent hosts, consistent with taxon-pulse dynamics. A previously inferred westward dispersal across the land bridge is rejected. We also refine interpretations of past host colonization, providing evidence for several distinct episodes of expanding host range, which probably contributed to diversification by Arostrilepis. Finally, Arostrilepis is shown to be paraphyletic with respect to Hymenandrya thomomyis, a parasite of pocket gophers, confirming that ancient Arostrilepis species colonized new host lineages upon arriving in North America., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Investigations of intercontinental dispersal between Asia and North America reveal complex patterns of geographic expansion, retraction and isolation, yet historical reconstructions are largely limited by the depth of the record that is retained in patterns of extant diversity. Parasites offer a tool for recovering deep historical insights about the biosphere, improving the resolution of past community-level interactions. We explored biogeographic hypotheses regarding the history of dispersal across Beringia, the region intermittently linking Asia and North America, through large-scale multi-locus phylogenetic analyses of the genus Schizorchis , an assemblage of host-specific cestodes in pikas (Lagomorpha: Ochotonidae). Our genetic data support palaeontological evidence for two separate geographic expansions into North America by Ochotona in the late Tertiary, a history that genomic evidence from extant pikas does not record. Pikas descending from the first colonization of Miocene age persisted into the Pliocene, subsequently coming into contact with a second wave of Nearctic colonists from Eurasia before going extinct. Spatial and temporal overlap of historically independent pika populations provided a window for host colonization, allowing persistence of an early parasite lineage in the contemporary fauna following the extinction of its ancestral hosts. Empirical evidence for ancient 'ghost assemblages' of hosts and parasites demonstrates how complex mosaic faunas are assembled in the biosphere through episodes of faunal mixing encompassing parasite lineages across deep and shallow time.

Species of the genus Arostrilepis were discovered and definitively identified for the first time in rodents from geographically disparate localities along the Appalachian Mountain range of eastern North America (West Virginia, Virginia, and Maine). These are the first confirmed records for species of Arostrilepis occurring east of the Rocky Mountains and the Mississippi River in North America. Arostrilepis gardneri n. sp. is described on the basis of specimens obtained from two phylogenetically divergent rodent hosts: Southern Red-Backed Vole Myodes gapperi (Cricetidae: Arvicolinae) (from West Virginia) and the Woodland Jumping Mouse Napaeozapus insignis (Dipodidae: Zapodinae) (West Virginia, Virginia, and Maine). Additionally, in a mixed infection, specimens of Arostrilepis insperata n. sp. were also found in a Southern Red-Backed Vole from West Virginia. These previously unknown species are primarily distinguished from congeners based on shape, dimensions, and spination (pattern, shape, and size of spines) of the cirrus. Specimens of A. gardneri n. sp. are further characterized by the relative position and length of the cirrus-sac, arrangement of the testes, and relative size of the external seminal vesicle and seminal receptacle. Specimens of A. insperata n. sp. are structurally most similar to A. macrocirrosa from the western Nearctic and Palearctic but with consistently greater dimensions for the cirrus-sac, testes, and seminal receptacle. Phylogenetic analysis of Arostrilepis spp. using partial sequences of the mitochondrial cytochrome b gene and the nuclear second ribosomal internal transcribed spacer strongly supported the status of A. gardneri n. sp. and A. insperata n. sp. within an unresolved clade of congeners in Red-Backed Voles (Myodini and species of Myodes). Our observations extend the known geographic distribution for species of Arostrilepis to the Appalachian Mountains in either a disjunct or possibly continuous but patchy range across North America. Prior observations, summarizing field and museum collections, had suggested that geographic ranges for a diverse assemblage of Arostrilepis in North America were largely restricted to the north-western region of the continent, with historical connections to Beringia and Eurasia. Recognition of a more extensive distribution is consistent with a history of episodic biotic expansion and isolation under a dynamic of taxon pulses for arvicoline rodents and an associated parasite fauna in the Nearctic during the Quaternary. Occurrence in a dipodid rodent represents an event of host colonization from an arvicoline source.

The Cyclophyllidea is the most diverse order of tapeworms, encompassing species that infect all classes of terrestrial tetrapods including humans and domesticated animals. Available phylogenetic reconstructions based either on morphology or molecular data lack the resolution to allow scientists to either propose a solid taxonomy or infer evolutionary associations. Molecular markers available for the Cyclophyllidea mostly include ribosomal DNA and mitochondrial loci. In this study, we identified 3641 single-copy nuclear coding loci by comparing the genomes of Hymenolepis microstoma, Echinococcus granulosus and Taenia solium. We designed RNA baits based on the sequence of H. microstoma, and applied target enrichment and Illumina sequencing to test the utility of those baits to recover loci useful for phylogenetic analyses. We captured DNA from five species of tapeworms representing two families of cyclophyllideans. We obtained an average of 3284 (90%) of the targets from the test samples and then used captured sequences (2 181 361 bp in total; fragment size ranging from 301 to 6969 bp) to reconstruct a phylogeny for the five test species plus the three species for which genomic data are available. The results were consistent with the current consensus regarding cyclophyllidean relationships. To assess the potential for our method to yield informative genetic variation at intraspecific scales, we extracted 14 074 single nucleotide polymorphisms (SNPs) from alignments of four Arostrilepis macrocirrosa and two A. cooki and successfully inferred their relationships. The results showed that our target gene tools yield data sets that provide robust inferences at a range of taxonomic scales in the Cyclophyllidea., (© 2016 John Wiley & Sons Ltd.)

Specimens originally identified provisionally as Hymenolepis horrida (Linstow, 1901) [later Arostrilepis horrida (Linstow, 1901)] in Myodes californicus (Merriam) from near the Pacific coastal zone of southern Oregon are revised. Specimens in western red-backed voles represent an undescribed species of Arostrilepis Mas Coma & Tenora, 1997, contributing to recognition and resolution of a broadening complex encompassing cryptic diversity for these hymenolepidid tapeworms distributed across the Holarctic region. Consistent with recent studies defining diversity in the genus, the form, dimensions, and spination (pattern, shape and size) of the cirrus are diagnostic. Among 12 nominal congeners, specimens of A. kontrimavichusi n. sp. are further distinguished by the relative position and length of the cirrus-sac, arrangement of the testes and relative size of the external seminal vesicle and seminal receptacle. Specimens from Oregon voles represent the fifth endemic hymenolepidid in this genus from the Nearctic. Host range for the North American assemblage of species includes Cricetidae (Arvicolinae and Neotominae), Heteromyidae, Geomyidae, and rarely Sciuridae.

We previously reported fatal infection of a captive Bornean orangutan with metacestodes of a novel taeniid tapeworm, Versteria sp. New data implicate mustelids as definitive hosts of these tapeworms in North America. At least 2 parasite genetic lineages circulate in North America, representing separate introductions from Eurasia.

An extensive phylogenetic analysis and genus-level taxonomic revision of Paranoplocephala Lühe, 1910-like cestodes (Cyclophyllidea, Anoplocephalidae) are presented. The phylogenetic analysis is based on DNA sequences of two partial mitochondrial genes, i.e. cytochrome c oxidase subunit 1 (cox1) and NADH dehydrogenase subunit 1 (nad1), and includes 51 cestode isolates. The revision concerns all 34 Paranoplocephala-like species considered valid, of which 21 species could be included in the molecular phylogenetic analysis. Based on the phylogenetic relationships and main morphological features, with emphasis on the structure of the scolex, suckers and neck, length of the vagina (relative to the cirrus sac) and distribution of testes, 12 new genera are proposed for cestodes traditionally assigned to Paranoplocephala s. l. This results in 23 new combinations. The new genera are: Gulyaevia n. g., Chionocestus n. g., Microticola n. g., Beringitaenia n. g., Arctocestus n. g., Rauschoides n. g., Eurotaenia n. g., Douthittia n. g., Lemminia n. g., Tenoraia n. g., Rodentocestus n. g. and Cookiella n. g. In addition, Paranoplocephala (s. s.) and Parandrya Gulyaev & Chechulin, 1996 are redescribed; the latter genus is considered valid, although it has been earlier synonymized with Paranoplocephala. A new species (Beringitaenia nanushukensis n. sp.) from Microtus miurus is described. Based on the DNA sequence data, several additional lineages probably representing independent species are identified, but not described as new taxa because of lack of good-quality specimens or absence of reliable morphological differences. The study also presents the first evidence for the phylogenetic position of the monotypic genus Gallegoides Tenora & Mas-Coma, 1978 based on DNA sequence data. A key for the Paranoplocephala-like genera is presented. The patterns of diversity and zoogeography of cestodes representing the "arvicoline clade" (72 species) are complex, involving mechanisms of dispersal, geographic colonization and host switching linking faunas across Eurasia and North America.

Hymenolepidid cestodes in Myodes glareolus from Lithuania and additional specimens originally attributed to Arostrilepis horrida from the Republic of Belarus are now referred to A. tenuicirrosa. Our study includes the first records of A. tenuicirrosa from the European (western) region of the Palearctic, and contributes to the recognition of A. horrida (sensu lato) as a complex of cryptic species distributed broadly across the Holarctic. Specimens of A. tenuicirrosa from Lithuania were compared to cestodes representing apparently disjunct populations in the eastern Palearctic based on structural characters of adult parasites and molecular sequence data from nuclear (ITS2) and mitochondrial (cytochrome b) genes. Morphological and molecular data revealed low levels of divergence between eastern and western populations. Phylogeographic relationships among populations and host biogeographic history suggests that limited intraspecific diversity within A. tenuicirrosa may reflect a Late Pleistocene transcontinental range expansion from an East Asian point of origin.

Previously unrecognized species of hymenolepidid cestodes attributable to Arostrilepis Mas-Coma & Tenora, 1997 in arvicoline rodents from the greater Beringian region and western North America are described. Discovery and characterization of these tapeworms contributes to the recognition of a complex of cryptic species distributed across the Holarctic region. Three species are proposed: Arostrilepis gulyaevi sp. n. is named for cestodes in Myodes rufocanus from the Republic of Buryatia, southeastern Siberia and from the Khabarovskiy Kray, Chukotka Autonomous Okrug, and Magadanskaya Oblast', Russian Far East (western Beringia); A. cooki sp. n. is named for cestodes in Myodes gapperi from British Columbia, Canada and Montana, USA; and A. rauschorum sp. n. is named for cestodes in Microtus oeconomus, M. longicaudus, M. pennsylvanicus and M. xanthognathus from the Brooks Range, Seward Peninsula, north-central interior, and Arctic coastal plains of Alaska (eastern Beringia) and Montana, USA. Consistent with recent studies defining diversity in the genus, the form, size, and spination (pattern, shape and size) of the cirrus are diagnostic; species are further distinguished by the relative position and length of the cirrus sac, and arrangement of the testes. Assessment of genetic data from the cytochrome b gene of mitochondrial DNA complements differentiation of this complex based on morphological attributes and confirms known species diversity within the genus. New data for geographical distribution and host specificity of known Arostrilepis spp. indicate that 3 of 12 recognized species have Holarctic distributions extending across Beringia. These include Arostrilepis beringiensis (Kontrimavichus & Smirnova, 1991) in lemmings (species of Lemmus and Synaptomys), A. cf. janickii Makarikov & Kontrimavichus, 2011 in root voles (M. oeconomus) MAKARIKOV ET AL. 402 · Zootaxa 3608 (6) © 2013 Magnolia Press and A. macrocirrosa Makarikov, Gulyaev & Kontrimavichus, 2011 in red backed voles (species of Myodes) and less often other rodent host species.

Abstract : Specimens originally identified as Arostrilepis horrida from the Nearctic are revised, contributing to the recognition of a complex of cryptic species distributed across the Holarctic region. Previously unrecognized species are described based on specimens in cricetid (Neotominae) and geomyid rodents. Arostrilepis mariettavogeae n. sp. in Peromyscus californicus from Monterey County, California and Arostrilepis schilleri n. sp. in Thomomys bulbivorus from Corvallis, Oregon are characterized. Consistent with recent studies defining diversity in the genus, form, size, and spination (pattern, shape, and size) of the cirrus are diagnostic; species are further distinguished by the relative position and length of the cirrus sac and arrangement of the testes. Species of Arostrilepis have not previously been described in rodents outside of the Arvicolinae or from localities in the Nearctic. These studies emphasize the need for routine deposition of archival specimens and information, from survey, ecological, and biogeographic studies, in museum collections to serve as self-correcting records for biodiversity at local, regional, and continental scales.

Phylogenetic analysis of the families of the Cyclophyllidea based on comparative morphology revealed support for monophyly of the order. Four equal length trees (CI = 0.71) resulted from analysis of 42 binary and multistate characters. Major conclusions are the following: (1) a basal position for the arostellate groups, with Mesocestoididae + Nematotaeniidae representing the basal subclade; (2) polyphyly for the Anoplocephalidae with sister-group associations postulated respectively for Anoplocephalinae + Thysanosomatinae and Linstowiinae + Inermicapsiferinae; (3) recognition within the rostellate cyclophyllideans of taeniid, dilepidid and davaineid subclades and the Dipylidiidae: (4) designation of Metadilepididae + Paruterinidae as sister taxa; (5) monophyly for the Davaineidae with all inclusive subfamilies; and (6) a close relationship for the Hymenolepididae and acoleate cyclophyllideans. Monophyly for such classically defined groups as the Mesocestoididae, Taeniidae and Davaineidae is corroborated. Polyphyly of the Dilepididae sensu lato, with independence of the Dipylidiidae, Dilepididae sensu Bona (1994), the Metadilepididae + Paruterinidae, and the Gryporhynchidae is confirmed. As presented these constitute testable hypotheses for monophyly and relationships among the families of the Cyclophyllidea. Initial diversification of the cyclophyllideans occurred in mammalian hosts and three independent events of colonisation of avian taxa are postulated. Origins of the cyclophyllideans extend into the Mesozoic or earlier, with extant taxa representing lineages that were persistent across the extinction event that defines the Cretaceous-Tertiary boundary.

A preliminary phylogenetic analysis of the Pseudophyllidea, based on the 16 type-genera of putative families, indicates that a division into two suborders is reasonable. The subordinal grouping are, on the whole, congruent with those suggested by earlier workers, but the positions of three genera, Hexagonoporus, Cephalochlamys and Parabothriocephalus, are somewhat anomalous with respect to earlier work.

The basis for a preliminary analysis of the relationships within the monophyletic Diphyllidea is outlined. Information on morphological characters and their interpretation within a phylogenetic context are presented. A cladistic analysis at the species level was conducted based on a matrix of 21 morphological characters. Character polarity was determined by taxonomic outgroup analysis relative to the basal orders, Pseudophyllidea and Haplobothriidea. The phylogeny for the diphyllideans was found to be poorly resolved based on characters currently available for evaluation. Computer assisted cladistic analysis found three equally parsimonious trees with a consistency index of 0.54. The topology of these trees shows that Ditrachybothridium macrocephalum is the basal taxon and the putative sister group for species of Echinobothrium; Macrobothridium rhynchobati is grouped among species of Echinobothrium. If the classification is to be consistent with this tree, M. rhynchobati should be included in the genus Echinobothrium. This observation should be carefully examined, considering the relative paucity of useful morphological characters currently available for this group.

The phylogeny of the Eucestoda was evaluated based on a suite of 49 binary and multistate characters derived from comparative morphological and ontogenetic studies; attributes of adult and larval tapeworms were considered. A single most parsimonious tree (MPT) (consistency index = 0.872; retention index = 0.838; and homoplasy index = 0.527) was fully resolved and is specified by the following: (Gyrocotylidea, (Amphilinidea, ((Spathebothriidea, (Pseudophyllidea, ((Diphyllidea, (Trypanorhyncha, (Tetraphyllidea, (Lecanicephalidea, ((Nippotaeniidea, (Tetrabothriidea, Cyclophyllidea)), Proteocephalidea))))), Haplobothriidea))), Caryophyllidea))). Monophyly for the Eucestoda was firmly corroborated. Trees derived from the primary and bootstrap analyses were congruent, but low values, particularly for relationships among the tetrafossate tapeworms, indicated additional examination is warranted. The MPT was found to be the most efficient hypothesis for describing character evolution and in specifying relationships among the orders when compared to those concepts that had been developed for the tapeworms over the past century. Areas of congruence were shared among the current hypothesis and one or more of the prior hypotheses. Major conclusions include: (1) Caryophyllidea are basal and monozooy is ancestral; (2) difossate forms are primitive, and the Pseudophyllidea are the sister group of the strongly polyzoic tapeworms; (3) Nippotaeniidea are highly derived; (4) the higher tapeworms (Tetraphyllidea, Lecanicephalidea, Proteocephalidea, Nippotaeniidea, Tetrabothriidea, and Cyclophyllidea) are closely related or potentially coordinate groups: (5) Tetrabothriidea and the Cyclophyllidea are sister groups; and (6) Tetraphyllidea is paraphyletic, with the Onchobothriidae basal to the Phyllobothriidae. Character support for placement of the Tetrabothriidea continues to be contradictory, and this order may represent a key to understanding the phylogeny of the higher cestodes. The current study constitutes a complete historical review and poses a new and robust hypothesis for the phylogeny of the Eucestoda.

The structure of the scolex, neck, and adjacent strobila of 5 species of Tetrabothrius was evaluated using low to high magnification scanning electron microscopy. Species-specific patterns and morphotypes (spiniform, papilliform, and filiform) of microtriches were found on the scolices and strobilar tegument of Tetrabothrius (Oriana) affinis, Tetrabothrius (Oriana) filiformis, and Tetrabothrius (Culmenamniculus) laccocephalus; microtriches were absent in Tetrabothrius (Culmenamniculus) cylindraceus and Tetrabothrius (Tetrabothrius) sp. The presence, distribution, and form of microtriches may not be correlated with the subgeneric divisions of Tetrabothrius or the host taxon. Unique patterns do not appear to be shared with other groups of cestodes, particularly other tetraphyllideans. We suggest that the spiniform, filiform, and papilliform types of microtriches may be symplesiomorphic for the Eucestoda.

Twenty-two of 26 white-throated sparrows, Zonotrichia albicollis, from Algonquin Park, Ontario, Canada, hosted 1 or 2 species of platyhelminths. One species of cestode and 3 of digeneans were collected. Anonchotaenia quiscali inhabited 50% of the sparrows. This is the third report of A. quiscali; Z. albicollis is a new host. Brachylecithum nanum inhabited 43%, Zonorchis alveyi 15%, and Prosthogonimus macrorchis 8% of the sparrows examined. Ontario is a new geographic distribution record from all 4 parasite species. The proportion of hosts infected with 2 species was not significantly different from expected based on single species prevalences, indicating that there is no competitive interaction among these species of parasites for access to the avian hosts.

Congruence in biogeographic patterns among diverse assemblages of taxa indicates uniformity in the historical determinants of biotic distributions. Comparisons of host and parasite phylogenies and the elucidation of distributional area relationships are requisite components of analyses in historical biogeography. Host-parasite associations with broad geographic ranges are often archaic and have been structured largely by coevolutionary processes. In contrast, the origins and radiation of the primary cestode faunas of some seabirds (Alcataenia spp./Alcidae) and pinnipeds (Anophryocephalus spp./Phocidae and Otariidae) are associated with colonization. These young colonizing faunas, in the Holarctic Region, were influenced by a common history during the late Pliocene and Pleistocene epochs. Periodic range contraction, with isolation in refugial centers, and subsequent expansion into postglacial habitats for hosts and parasites coincided with the cyclic pattern of stadials and interstadials. During the past 2-3 million years following colonization, these dramatic climatic fluctuations strongly influenced the continuity of ecological associations in marine habitats and appear to have been the determinants of congruent and synchronic patterns of speciation among these disparate taxa of marine homeotherms and eucestodes.

Cladistic analysis of the generic-level relationships within the family Tetrabothriidae was conducted. A single cladogram resulted from evaluation of 28 homologous transformation series representing 41 character states. The genus Tetrabothrius was recognized as plesiomorphic followed by Chaetophallus and Trigonocotyle. The latter was considered as the sister group for the remaining tetrabothriid genera of marine mammals. Anophryocephalus, Strobilocephalus, and Priapocephalus are among the most highly derived genera and are postulated as having close evolutionary affinities. Comparisons to previous explicit hypotheses for relationships among the genera indicated the present analysis was the most efficient phylogenetic statement (consistency index = 85.4%) for the 28 attributes evaluated. The recognition of Tetrabothrius as primitive and a natural grouping of Anophryocephalus, Strobilocephalus, and Priapocephalus in part confirmed results of previous studies of the Tetrabothriidae.

Three Cestodes representing two species of the genus Alcataenia Spasskaia, 1971 and a subspecies of Alcataenia larina (Krabbe, 1869) are described. Alcataenia fraterculae sp. n. (Cestoda: Dilepididae) was found in horned puffins, Fratercula corniculata (Naumann), and other species of seabirds from localities in the western Aleutian Islands, Gulf of Alaska, Bering Sea, and Chukchi Sea. Alcataenia cerorhincae sp. n. is described from the rhinoceros auklet, Cerorhinca monocerata (Pallas) in the eastern North Pacific Ocean and western Aleutian Islands. Alcataenia larina pacifica ssp. n. is recognized from species of Laridae and other seabirds in the North Pacific Ocean, Sea of Okhotsk, Bering Sea and the region of the Arctic Ocean near Bering Strait. It is distinguished from A. larina larina (Krabbe, 1869) by a greater number of testes, a longer cirrus sac, and variation in the position of the genital ducts which may be either dorsal to or between the osmoregulatory canals. A fraterculae and A. cerorhincae are most similar to A. larina and particularly to the North Pacific form A. l. pacifica. Generally specimens of A. fraterculae can be distinguished from the other taxa by larger rostellar hooks, a longer cirrus sac, and a combination of other characters. A. fraterculae, A. cerorhincae, and A. l. pacifica however represent a complex of cryptic species in which there is extensive overlap in some morphological characters. Results of a discriminant analysis among these nominal taxa were significant and, in combination with data about other morphological characters and host and geographic distribution, clearly indicated that these represent three species in the North Pacific basin.