Scott Lyell Gardner

Are Ascaris lumbricoides and Ascaris suum a single species

Since the original description and naming of Ascaris lumbricoides from humans by Linnaeus in 1758 and later of Ascaris suum from pigs by Goeze 1782, these species have been considered to be valid. Four hypotheses relative to the conspecificity or lack thereof (and thus origin of these species) are possible: 1) Ascaris lumbricoides (usually infecting humans) and Ascaris suum (recorded mostly from pigs) are both valid species, with the two species originating via a speciation event from a common ancestor sometime before the domestication of pigs by humans, or 2) Ascaris lumbricoides in humans is derived directly from the species A. suum found in pigs with A. suum then existing as a persistent ancestor after formation of A. lumbricoides, or 3) Ascaris suum is derived directly from A. lumbricoides with the persistent ancestor being A. lumbricoides and A. suum being the newly derived species, and finally, 4) Ascaris lumbricoides and A. suum are the same species, this hypothesis being supported by studies showing both low morphological and low genetic divergence at several genes. We present and discuss paleoparasitological and genetic evidence that complement new data to evaluate the origin and evolution of Ascaris spp. in humans and pigs, and the uniqueness of the species in both hosts. Finally, we conclude that Ascaris lumbricoides and A. suum are a single species and that the name A. lumbricoides Linnaeus 1758 has taxonomic priority; therefore A. suum Goeze 1782 should be considered a synonym of A. lumbricoides.

A PHYLOGENETIC HYPOTHESIS FOR SPECIES OF THE GENUS TAENIA (EUCESTODA: TAENIIDAE)

Cladistic analysis of a numerical data matrix describing 27 characters for species of Taenia resulted in 4 most parsimonious phylogenetic trees (174 steps; consistency index = 0.28; homoplasy index = 0.72; retention index = 0.48). Monophyly for Taenia is diagnosed by the metacestode that is either a cysticercus or a form derived from a bladder-like larva; no other unequivocal synapomorphies are evident. Tree structure provides no support for recognition of a diversity of tribes or genera within the Taeniinae: Fimbriotaeniini and Taeniini have no phylogenetic basis. Hydatigera, Fimbriotaenia, Fossor, Monordotaenia, Multiceps, Taeniarhynchus, Tetratirotaenia must be subsumed within Taenia as synonyms. Taenia saginata and Taenia asiatica are sister species and distantly related to Taenia solium. Cospeciation with respect to carnivorous definitive hosts and Taenia appears to be limited. Although felids are putative ancestral hosts, contemporary associations appear to have resulted from extensive host-switching among felids, canids, hyaenids, and others. In contrast, relationships with herbivorous intermediate hosts are indicative of more pervasive coevolution; rodents as intermediate hosts are postulated as ancestral for the Taeniidae, Taenia + Echinococcus. Patterns appear consistent with rapid shifts between phylogenetically unrelated carnivores but among those that historically exploited a common prey resource within communities in specific biogeographic regions.

Parasites as Probes for Prehistoric Human Migrations

Host-specific parasites of humans are used to track ancient migrations. Based on archaeoparasitology, it is clear that humans entered the New World at least twice in ancient times. The archaeoparasitology of some intestinal parasites in the New World points to migration routes other than the Bering Land Bridge. Helminths have been found in mummies and coprolites in North and South America. Hookworms (Necator and Ancylostoma), whipworms (Trichuris trichiura) and other helminths require specific conditions for life-cycle completion. They could not survive in the cold climate of the northern region of the Americas. Therefore, humans would have lost some intestinal parasites while crossing Beringia. Evidence is provided here from published data of pre-Columbian sites for the peopling of the Americas through trans-oceanic or costal migrations.

Parasites As Probes for Biodiversity

Cestodes of the genus Linstowia, parasitic in marsupials, show patterns of coevolution and ancient historical-ecological connections. Correlated with the breakup of the austral landmasses (Gondwanaland) of the Neotropical and Australian regions from the Antarctic continent, the age of this host-parasite community is estimated to be between 60 and 70 million years old. Based on the data from the survey of parasites of mammals from throughout Bolivia and from the phylogenetic analysis of the cestodes, we urge the planners of biodiversity preserves in the neotropics to consider the Yungas of Bolivia as a region that supports an ancient ecological community worthy of consideration as a biopreserve.

The Enterobiinae subfam. nov. (Nematoda, Oxyurida) pinworm parasites of primates and rodents

Recent redescriptions of most members of the Oxyuridae Cobbold, 1864 parasitic in primates revealed that they share following derived characters: sexual dimorphism of lateral alae (single-crested in the males, double-crested in the females); in males a second pair of genital papillae always surrounded by strongly cuticularized rings; in females, uterine tube divided into 2 parts by a cellular wall forming a diaphragm. These characters are interpreted as synapomorphies, providing evidence that these taxa represent a monophyletic group, and we propose to classify them in a new subfamily of the Oxyuridae: the Enterobiinae subfam.nov. The Enterobiinae as recognized herein occurs in both Old World and New World Primates and rodents of the family Sciuridae (tribe Sciurini in the Holarctic region and tribe Xerini in the Ethiopian region). The new subfamily includes the following genera: Enterobius Leach, 1853; Colobenterobius Quentin, Betterton & Krishnasamy, 1979; Rodentoxyuris Quentin & Tenora 1974; Xeroxyuris Hugot, 1995; Lemuricola Chabaud & Petter, 1959; Protenterobius Inglis, 1961; Madoxyuris Chabaud, Brygoo & Petter, 1965; Trypanoxyuris Vevers, 1923; Hapaloxyuris Inglis & Cosgrove, 1965 and Paraoxyuronema Artigas, 1936. The genus Paraoxyuronema is revalidated as a subgenus of Trypanoxyuris due to its specialized buccal structures. This genus groups all pinworm nematodes specific for primates of the family Atelidae, including: P. brachytelesi Artigas, 1937 occurring in Brachyteles arachnoides; P. atelis (Cameron, 1929) occurring in Ateles spp., and P. duplicidens (Buckley, 1931) and P. lagothricis (Buckley, 1931), which are parasites of Lagothrix spp. Inglisoxyuris inglisi Chabaud, Petter & Golvan, 1961, included in the monospecific genus Inglisoxyuris and previously classified as a subgenus of the Lemuricola, does not share the characters of the new subfamily and, until its precise classification can be considered with more information, it is proposed to refer to this species as an Oxyuridae sensu lato. A diagnosis and a key of the genera included in the new subfamily are given.

Body Size Evolution of Oxyurid (Nematoda) Parasites: The Role of Hosts

Studying the diversification of body size in a taxon of parasites allows comparison of patterns of variation observed in the parasites with patterns found in free-living organisms. The distributions of body size of oxyurid nematodes (obligate parasites of vertebrates and invertebrates) are lognormally right-skewed, except for male oxyurids in invertebrates which show left-skewed distributions. In these parasitic forms, speciose genera do not have the smallest body sizes. Parasite body size is positively correlated with host body size, the largest hosts possessing the largest parasites. This trend is shown to occur within one monophyletic group of oxyurids, those of Old World primates. Comparative methods are used to take account of the effects of phylogeny. The use of multiple linear regression on distance matrices allows measurements of the contribution of phylogeny to the evolution of body size of parasites. Evolution of body size in female pinworms of Old World primates appears to be dependent only on the body size of their hosts. The tendency of parasite body size to increase with host body size is discussed in the light of the evolution of life-history traits.

Finding Them Before They Find Us: Informatics, Parasites, and Environments in Accelerating Climate Change

ABSTRACT: Parasites are agents of disease in humans, livestock, crops, and wildlife and are powerful representations of the ecological and historical context of the diseases they cause. Recognizing a nexus of professional opportunities and global public need, we gathered at the Cedar Point Biological Station of the University of Nebraska in September 2012 to formulate a cooperative and broad platform for providing essential information about the evolution, ecology, and epidemiology of parasites across host groups, parasite groups, geographical regions, and ecosystem types. A general protocol, documentation–assessment–monitoring–action (DAMA), suggests an integrated proposal to build a proactive capacity to understand, anticipate, and respond to the outcomes of accelerating environmental change. We seek to catalyze discussion and mobilize action within the parasitological community and, more widely, among zoologists and disease ecologists at a time of expanding environmental perturbation.

Phylogenetic analysis based on 18S ribosomal RNA gene sequences supports the existence of class polyacanthocephala (acanthocephala)

Members of phylum Acanthocephala are parasites of vertebrates and arthropods and are distributed worldwide. The phylum has traditionally been divided into three classes, Archiacanthocephala, Palaeacanthocephala, and Eoacanthocephala; a fourth class, Polyacanthocephala, has been recently proposed. However, erection of this new class, based on morphological characters, has been controversial. We sequenced the near complete 18S rRNA gene of Polyacanthorhynchus caballeroi (Polyacanthocephala) and Rhadinorhynchus sp. (Palaeacanthocephala); these sequences were aligned with another 21 sequences of acanthocephalans representing the three widely recognized classes of the phylum and with 16 sequences from outgroup taxa. Phylogenetic relationships inferred by maximum-likelihood and maximum-parsimony analyses showed Archiacanthocephala as the most basal group within the phylum, whereas classes Polyacanthocephala + Eoacanthocephala formed a monophyletic clade, with Palaeacanthocephala as its sister group. These results are consistent with the view of Polyacanthocephala representing an independent class within Acanthocephala.

New and Known Species of Litomosoides (Nematoda: Filarioidea): Important Adult and Larval Characters and Taxonomic Changes

Abstract During field surveys in Venezuela, Peru, and French Guiana, species of Litomosoides were recovered from bats and from a didelphid marsupial. Their morphology was studied, giving particular attention to the head and caudal papillae, the spicules (used to distinguish the carinii and sigmodontis groups of Litomosoides), and the microfilariae. Litomosoides wilsoni sp. n. from the short-tailed opossum Monodelphis emiliae is described from Peru; Litomosoides brasiliensis, Litomosoides chandleri, and Litomosoides guiterasi from bats are redescribed, and new hosts are recorded. For the first time, larval stages were recovered from bats (1 male and 1 female fourth-stage larvae of Litomos. brasiliensis). Litomosoides solarii sp. n. from the fringe-lipped bat Trachops cirrhosus (Phyllostomidae) in Peru is distinguished from the other species by its peculiar microfilaria (the male is unknown). Filaria serpicula from Phyllostomus sp. in Brazil is renamed Litomosoides serpicula (Molin, 1858) comb. n. This study confirms the close morphological resemblance between the species of Litomosoides from flying and terrestrial mammals and reinforces the hypothesis of host-switching in the evolution of this genus. The 2 North American species of Litomosoides from the Geomyidae were reexamined and are peculiar in several adult and microfilarial characters that resemble those of Litomosa, parasitic in Old World bats. The following new combinations are proposed: Litomosa westi (Gardner and Schmidt, 1986) comb. n. and Litomosa thomomydis (Gardner and Schmidt, 1986) comb. n. However, Litomosa and Litomosoides have in common a thick buccal capsule embedded posteriorly in the esophagus, which suggests that they are closely related. Litomosoides andersoni, a parasite of a caviomorph rodent, likely results from conflation of a species of Litomosoides and one of Ackertia.

POLYMORPHISM OF EIMERIAN OOCYSTS CAN BE A PROBLEM IN NATURALLY INFECTED HOSTS: AN EXAMPLE FROM SUBTERRANEAN RODENTS IN BOLIVIA

Since 1986, 364 tuco-tucos (Ctenomys spp.) representing 7 species were collected from 16 major collecting areas representing at least 4 distinct ecological habitats in Bolivia, South America. All were examined for coccidia, and 125 (34%) had oocysts in their feces including 84 of 236 (36%) Ctenomys boliviensis from tropical palm/savanna habitats; 1 of 3 (33%) Ctenomys conoveri from a chaco thorn forest; 3 of 7 (33%) Ctenomys frater from medium altitude grass habitats; and 6 of 8 (75%) Ctenomys lewisi and 31 of 35 (88%) Ctenomys opimus from high altitude/puna habitats. None of 3 Ctenomys leucodon (high altitude/puna) or 72 Ctenomys steinbachi (tropical palm/savanna) were passing oocysts when examined. The 5 infected host species all had oocysts of Eimeria opimi Lambert, Gardner, and Duszynski, 1988, in their feces. These oocysts and their sporocysts varied greatly in size, both within and between host species, but qualitative characters (e.g., residua and wall texture) remained constant. Our conclusion, that all oocysts seen were E. opimi, was supported by multigroup discriminant analysis of 256 individual oocysts, 30-67 selected randomly from each Ctenomys sp. Minimum polygons enclosing the centroid (= multivariate mean) and the spread of individuals for each species group (OTU) showed significant overlap in discriminant space, and Geisser classification showed a 55% miss rate of individuals being classified into the wrong OTUs. Thus, oocyst and sporocyst lengths and widths cannot be used to separate morphotypes of E. opimi from different Ctenomys spp. from different geographic regions of Bolivia.