Insights about Diversity of Tetrabothriidae (Eucestoda) among Holarctic Alcidae (Charadriiformes): What Is \u3ci\u3eTetrabothrius jagerskioeldi\u3c/i\u3e?

Tetrabothriid cestodes are characteristic helminths that infect species of seabirds globally. We begin with the exploration of the diversity of tapeworms of the genus Tetrabothrius Rudolphi, 1819 (Eucestoda: Tetrabothriidae), some of which are distributed among seabirds of the family Alcidae (Charadriiformes) at boreal to higher latitudes of Holarctic seas. During the course of 2 decades of field inventory from 1975 through the early 1990s (in addition to earlier collections assembled by Robert L. Rausch and colleagues in Alaska initiated in the late 1940s), an extensive series of tapeworm specimens attributable to species of Tetrabothrius was recovered from seabirds across the North Pacific Basin. It was assumed based on published records of species richness in this fauna that a single species, Tetrabothrius jagerskioeldi Nybelin, 1916, would predominate among alcid hosts. In contrast, detailed study revealed considerable morphological complexity that could not be accommodated within a single species. Further, it was apparent that the limits for the primary morphological attributes of T. jagerskioeldi were not clearly defined. We redescribe T. jagerskioeldi based on direct examination of the type series of specimens from Sweden and an assemblage of specimens largely from alcid hosts from the North Pacific basin. Specimens of T. jagerskioeldi are diagnosed by a characteristic configuration of the genital atrium, position of the male and female genital canals, structure of the male and female organ systems, and numbers of testes. Based on the spectrum of characters we explored, it was apparent that numerous specimens of Tetrabothrius among genera and species of Alcidae from the North Pacific inventory could not be accommodated in T. jagerskioeldi and provisionally are referred to Tetrabothrius undescribed n. sp. pending ongoing evaluations. Superficially, these are all large and robust tapeworms referable to Tetrabothrius, potentially contributing to misidentifications and misattribution that have occurred both in the literature and in the few archived specimens in museums. We summarize the results of extensive inventory collections since 1950, establishing a distributional baseline for species of Tetrabothrius from a wide range of geographic localities and an assemblage of host species among the Alcidae and some species of Laridae, Stercorariidae, and Phalacrocoracidae. We further evaluate the validity of historical published records for T. jagerskioeldi and other congeners among alcids and other seabirds. A conclusion that emerges is that T. jagerskioeldi is a rare tapeworm with a patchy distribution in pelagic to nearshore marine environments, showing considerable heterogeneity in space and time, among alcid seabirds across high-latitude seas of the Holarctic. Prior concepts for host range require reevaluation. We demonstrate that the associations for T. jagerskioeldi are relatively narrow and appear to involve a more limited spectrum of alcid hosts, and less often other species of marine birds, than currently assumed. A robust understanding of parasite species diversity and distribution is critical in establishing baselines across marine ecosystems. Our current study among species of Tetrabothrius, especially in the North Pacific basin and Bering Sea ecosystem contributes to development of a series of specimen-centered baselines derived primarily from the late 1970s to the early 1980s against which accelerating perturbations linked to climate warming and ocean-atmosphere interactions may be explored. Detailed knowledge of specimen-based faunal diversity for parasites provides a cumulative, temporal, and spatial snapshot and proxy for conditions in marine foodwebs and the continuity of trophic linkages

Parasite Biodiversity and Emerging Pathogens: A Role for Systematics in Limiting Impacts on Genetic Resources

Emergence of pathogenic organisms continues as a threat to overall biodiversity and genetic resources. Macroparasites including helminths constitute a potential threat to economically important resources in agriculture and conservation biology. Limitation of this threat can be achieved through survey and inventory for biodiversity and the application of systematics to understand the host range , biogeography and history of faunas. Systematics constitutes the foundation for recognition of endemic and introduced elements of faunas and the basis for predicting the behavior of pathogens introduced to new ecological settings or host groups. The basis for emergence of pathogens has both a deep historical and a contemporary component. These concepts are addressed through an examination of the history of emergence of nematode parasites of ruminants, including Nematodirus battus in sheep and Umingmakstrongylus pallikuukensis in muskoxen. Anthropogenic factors, particularly translocation of hosts and parasites leading to introduction and establishment of exotic species. continue as determinants of emergence. Ownership of biodiversity and genetic resources also constitutes responsibility to control the introduction and dissemination of pathogenic organisms

\u3ci\u3ePseudostertagia bullosa\u3c/i\u3e (Nematoda: Trichostrongyloidea) in Artiodactyl Hosts from North America: Redescription and Comments on Systematics

A relationship for Pseudostertagia bullosa within the trichostrongyloids has been enigmatic or unresolved. Studies of the synlophe in males and females of P. bullosa revealed a tapering system anterior to the deirids and a pattern of parallel ridges extending to near the caudal extremity in both lateral and median fields. Structurally, the synlophe differs considerably from that seen among the Cooperiinae and exhibits homoplasy with respect to ridge systems among some Ostertagiinae. Other structural characters due to symplesiomorphy, homoplasy or because they represent autapomorphies do not serve to reveal the putative relationships for P. bullosa with other trichostrongyloids. Although somewhat equivocal, the 2-2-1 pattern of the bursa and position of rays 2 and 3 suggest an association with the Cooperinae, as postulated by Durette-Desset and others. Pseudostertagia bullosa appears to be a species that has survived in the pronghorn, Antilocapra americana, a relictual pecoran artiodactyl that occurs in xeric regions of western North America; pronghorn are the sole remnant of the late Tertiary radiation for Antilocapridae across North America. Pseudostertagia bullosa may occur in mixed infections with a number or ostertagiines in the abomasa of mule deer (Odocoileus hemionus) and domestic sheep (Ovis aries) in regions of sympatry for pronghorn and these artiodactyl hosts

Evolution and Biogeography of Haemonchus contortus: Linking Faunal Dynamics in Space and Time

History is the foundation that informs about the nuances of faunal assembly that are essential in understanding the dynamic nature of the host-parasite interface. All of our knowledge begins and ends with evolution, ecology and biogeography, as these interacting facets determine the history of biodiverse systems. These components, relating to Haemonchus, can inform about the complex history of geographical distribution, host association and the intricacies of host-parasite associations that are played out in physiological and behavioural processes that influence the potential for disease and our capacity for effective control in a rapidly changing world. Origins and evolutionary diversification among species of the genus Haemonchus and Hae- monchus contortus occurred in a complex crucible defined by shifts in environmental structure emerging from cycles of climate change and ecological perturbation during the late Tertiary and through the Quaternary. A history of sequential host colonization associated with waves of dispersal bringing assemblages of ungulates from Eurasia into Africa and processes emerging from ecosystems in collision and faunal turnover defined the arena for radiation among 12 recognized species of Haemonchus. Among congeners, the host range for H. contortus is exceptionally broad, including species among artiodactyls of 40 genera representing 5 families (and within 12 tribes of Bovi- dae). Broad host range is dramatically reflected in the degree to which translocation, introduction and invasion with host switching, has characterized an expanding distribution over time in North America, South America, southern Eurasia, Australia and New Zealand, coincidental with agriculture, husbandry and global colonization by human populations driven particularly by European exploration after the 1500s. African origins in xeric to mesic habitats of the African savannah suggest that historical constraints linked to ecological adaptations (tolerances and developmental thresholds defined by temperature and humidity for larval stages) will be substantial determinants in the potential outcomes for widespread geographical and host colonization which are predicted to unfold over the coming century. Insights about deeper evolutionary events, ecology and biogeography are critical as understanding history informs us about the possible range of responses in complex systems under new regimes of environmental forcing, especially, in this case, ecological perturbation linked to climate change. A deeper history of perturbation is relevant in understanding contemporary systems that are now strongly structured by events of invasion and colonization. The relaxation of abiotic and biotic controls on the occurrence of H. contortus, coincidental with inception and dissemination of anthelmintic resistance may be synergistic, serving to exacerbate challenges to control parasites or to limit the socioeconomic impacts of infection that can influence food security and availability. Studies of haemonchine nematodes contribute directly to an expanding model about the nature of diversity and the evolutionary trajectories for faunal assembly among complex hosteparasite systems across considerable spatial and temporal scales

\u3ci\u3ePseudostertagia bullosa\u3c/i\u3e (Nematoda: Trichostrongyloidea) in Artiodactyl Hosts from North America: Redescription and Comments on Systematics

A relationship for Pseudostertagia bullosa within the trichostrongyloids has been enigmatic or unresolved. Studies of the synlophe in males and females of P. bullosa revealed a tapering system anterior to the deirids and a pattern of parallel ridges extending to near the caudal extremity in both lateral and median fields. Structurally, the synlophe differs considerably from that seen among the Cooperiinae and exhibits homoplasy with respect to ridge systems among some Ostertagiinae. Other structural characters due to symplesiomorphy, homoplasy or because they represent autapomorphies do not serve to reveal the putative relationships for P. bullosa with other trichostrongyloids. Although somewhat equivocal, the 2-2-1 pattern of the bursa and position of rays 2 and 3 suggest an association with the Cooperinae, as postulated by Durette-Desset and others. Pseudostertagia bullosa appears to be a species that has survived in the pronghorn, Antilocapra americana, a relictual pecoran artiodactyl that occurs in xeric regions of western North America; pronghorn are the sole remnant of the late Tertiary radiation for Antilocapridae across North America. Pseudostertagia bullosa may occur in mixed infections with a number or ostertagiines in the abomasa of mule deer (Odocoileus hemionus) and domestic sheep (Ovis aries) in regions of sympatry for pronghorn and these artiodactyl hosts

Return to Beringia: Parasites Reveal Cryptic Biogeographic History of North American Pikas

Traditional concepts of the Bering Land Bridge as a zone of predominantly eastward expansion from Eurasia and a staging area for subsequent colonization of lower latitudes in North America led to early inferences regarding biogeographic histories of North American faunas, many of which remain untested. Here we apply a host–parasite comparative phylogeographical (HPCP) approach to evaluate one such history, by testing competing biogeographic hypotheses for five lineages of host-specific parasites shared by the collared pika (Ochotona collaris) and American pika (Ochotona princeps) of North America. We determine whether the southern host species (O. princeps) was descended from a northern ancestor or vice versa. Three parasite phylogenies revealed patterns consistent with the hypothesis of a southern origin, which is corroborated by four additional parasite lineages restricted to O. princeps. This finding reverses the traditional narrative for the origins of North American pikas and highlights the role of dispersal from temperate North America into Beringia in structuring northern diversity considerably prior to the Holocene. By evaluating multiple parasite lineages simultaneously, the study demonstrates the power of HPCP for resolving complex biogeographic histories that are not revealed by characteristics of the host alone

Silver Staining for Elucidation of the Synlophe in Trichostrongyle Nematodes

Staining techniques are relatively rare in the study of parasitic nematodes. A novel silver-staining method is described for elucidation of the synlophe (a system of longitudinal cuticular ridges), a character of great systematic importance among the trichostrongyloid nematodes. Ridges are stained optically black and appear in great contrast to the body of the nematode. This method augments current use of interference contrast for examination of the synlophe. Detailed studies of the configuration of the synlophe in entire specimens are possible with standard light microscopy for the first time

Insights about Diversity of Tetrabothriidae (Eucestoda) among Holarctic Alcidae (Charadriiformes): What Is \u3ci\u3eTetrabothrius jagerskioeldi\u3c/i\u3e?

Tetrabothriid cestodes are characteristic helminths that infect species of seabirds globally. We begin with the exploration of the diversity of tapeworms of the genus Tetrabothrius Rudolphi, 1819 (Eucestoda: Tetrabothriidae), some of which are distributed among seabirds of the family Alcidae (Charadriiformes) at boreal to higher latitudes of Holarctic seas. During the course of 2 decades of field inventory from 1975 through the early 1990s (in addition to earlier collections assembled by Robert L. Rausch and colleagues in Alaska initiated in the late 1940s), an extensive series of tapeworm specimens attributable to species of Tetrabothrius was recovered from seabirds across the North Pacific Basin. It was assumed based on published records of species richness in this fauna that a single species, Tetrabothrius jagerskioeldi Nybelin, 1916, would predominate among alcid hosts. In contrast, detailed study revealed considerable morphological complexity that could not be accommodated within a single species. Further, it was apparent that the limits for the primary morphological attributes of T. jagerskioeldi were not clearly defined. We redescribe T. jagerskioeldi based on direct examination of the type series of specimens from Sweden and an assemblage of specimens largely from alcid hosts from the North Pacific basin. Specimens of T. jagerskioeldi are diagnosed by a characteristic configuration of the genital atrium, position of the male and female genital canals, structure of the male and female organ systems, and numbers of testes. Based on the spectrum of characters we explored, it was apparent that numerous specimens of Tetrabothrius among genera and species of Alcidae from the North Pacific inventory could not be accommodated in T. jagerskioeldi and provisionally are referred to Tetrabothrius undescribed n. sp. pending ongoing evaluations. Superficially, these are all large and robust tapeworms referable to Tetrabothrius, potentially contributing to misidentifications and misattribution that have occurred both in the literature and in the few archived specimens in museums. We summarize the results of extensive inventory collections since 1950, establishing a distributional baseline for species of Tetrabothrius from a wide range of geographic localities and an assemblage of host species among the Alcidae and some species of Laridae, Stercorariidae, and Phalacrocoracidae. We further evaluate the validity of historical published records for T. jagerskioeldi and other congeners among alcids and other seabirds. A conclusion that emerges is that T. jagerskioeldi is a rare tapeworm with a patchy distribution in pelagic to nearshore marine environments, showing considerable heterogeneity in space and time, among alcid seabirds across high-latitude seas of the Holarctic. Prior concepts for host range require reevaluation. We demonstrate that the associations for T. jagerskioeldi are relatively narrow and appear to involve a more limited spectrum of alcid hosts, and less often other species of marine birds, than currently assumed. A robust understanding of parasite species diversity and distribution is critical in establishing baselines across marine ecosystems. Our current study among species of Tetrabothrius, especially in the North Pacific basin and Bering Sea ecosystem contributes to development of a series of specimen-centered baselines derived primarily from the late 1970s to the early 1980s against which accelerating perturbations linked to climate warming and ocean-atmosphere interactions may be explored. Detailed knowledge of specimen-based faunal diversity for parasites provides a cumulative, temporal, and spatial snapshot and proxy for conditions in marine foodwebs and the continuity of trophic linkages

Diversity of Tetrabothriidae (Eucestoda) among Holarctic Alcidae (Charadriiformes): Resolution of the \u3ci\u3eTetrabothrius jagerskioeldi\u3c/i\u3e Cryptic Species Complex— Cestodes of Alcinae—Provides Insights on the Dynamic Nature of Tapeworm and Marine Bird Faunas under the Stockholm Paradigm

We begin resolution of the Tetrabothrius jagerskioeldi–species complex with descriptions of Tetrabothrius alcae n. sp. based on numerous specimens, primarily in murres (species of Uria), from the greater North Pacific basin and Tetrabothrius sinistralis n. sp. based on cestodes in guillemots (species of Cepphus) from the central Bering Sea and West Greenland. These tetrabothriids are characterized, among 44 species of Tetrabothrius in avian hosts, by attributes of the scolex, male and female organ systems, structure and dimensions of the vitelline gland, numbers of testes, configuration of the genital atrium, genital papillae and the male and female atrial canals, position of the genital ducts relative to the poral osmoregulatory canals, structure, dimensions and position of the vaginal seminal receptacle, and dimensions of the embryophore and oncosphere, in addition to a broader array of characters. Remarkably, T. alcae, T. sinistralis, and a cryptic complex had remained unrecognized for the past century, given that these species are unequivocally differentiated by multiple suites of unique structural attributes relative to T. jagerskioeldi. Alcids and cestodes of the T. jagerskioeldi–complex are restricted to cold marine systems of advection and upwelling along coastal margins adjacent to the continental shelf or are associated with archipelagos (especially the Aleutian Arc), isolated islands and rocky headlands of the Bering Sea, Chukchi Sea, Gulf of Alaska, Sea of Okhotsk, and Sea of Japan. Tetrabothrius alcae, T. jagerskioeldi, and T. sinistralis may occur in sympatry but with minimal overlap in the faunas associated with murres (Alcini) and guillemots (Cepphini). Transmission for cestodes and persistence of this fauna is expected to be associated with pelagic and neritic systems adjacent to colony sites in zones where critical prey species are concentrated or secondarily dispersed downstream by predictable advective and upwelling processes and become available to foraging birds. Faunal assembly represents the outcomes of oscillating climate, shifting ranges (breakdown in isolation, ecological fitting, and exploration modes for cestodes) and the changing interfaces for resource availability maintained by trophic and habitat overlaps. Dynamics at these ecotones constitute the nexus of opportunity and capacity for infection by species of Tetrabothrius among avian hosts where capacity appears broad and opportunity is ecologically restricted in space and prevatime. Life history pathways for cestodes are tied to trophic associations and dynamics at mesoscales across marine domains and provinces. Resilience and connectivity through ecological fitting strongly suggest the influence of multiple trophic pathways for transmission and persistence of this complex fauna through differing assemblages of zooplankters, fishes, and cephalopods depending on locality, oceanographic conditions, and temporal variability. Changing conditions, especially ecological perturbations driven by climate oscillations, directly determine production cycles and distributions of micro- and macro-zooplankton, forage fishes, cephalopods, and trophic structure in high-latitude marine ecosystems. Expanding regimes of accelerating change emphasize the critical importance of field collections, archives, and baselines to assess biological outcomes across temporal and spatial scales. Parasite assemblages reveal macro- to meso-scale connectivity serving as adjuncts and proxies in recognizing and understanding outcomes for episodes of environmental oscillation and directional atmospheric and oceanic warming in marine ecosystems