Reassignment of Lamanema from Nematodirinae to Molineinae (Nematoda: Trichostronglyloidea)

The monospecific Lamanema historically has been assigned to the Nematodirinae within the Molineidae. Inconsistencies in morphological characters, within a phylogenetic context for Nematodirinae, led to a re-evaluation of the putative relationships and taxonomic placement of Lamanema. Among 7 putative synapomorphies for Nematodirinae, Lamanema possesses only 1, large eggs. Large eggs, sporadically present in phylogenetically disparate taxa of trichostrongyles, are equivocal with respect to placement of Lamanema; it is considered that possession of this single homoplasious character alone is insufficient justification to retain the genus in Nematodirinae. Affinities with the Trichostrongylidae (Cooperiinae or Haemonchinae) have also been proposed; however, Lamanema possess neither of 2 synapomorphies that diagnose monophyly of the family. Lamanema is retained in the Molineidae and transferred to the Molineinae as it possesses all characters of the family as currently defined. The origin of Lamanema represents a secondary colonization of ruminants by molineids and provides no context for elucidating the history of the Nematodirinae and Nematodirus.     

Pseudostertagia bullosa (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 of ostertagiines in the abomasa of mule deer (Odocoileus hemionus) and domestic sheep (Ovis aries) in regions of sympatry for pronghorn and these artiodactyl hosts.     

A new lungworm in muskoxen: an exploration in Arctic parasitology

Ruminants are vital elements of the Holarctic ecosystem. Little is known, however, of the structure or biology of their parasite fauna, particularly in North America. Global warming, coupled with increasing human activity in the Arctic, requires enhanced international interdisciplinary efforts to better understand the many factors, including parasites, that influence the population health of caribou, reindeer, muskoxen and wild sheep. The discovery of an unusual new genus of protostrongylid lung nematode in muskoxen from the central Canadian Arctic is described, and the intricacies of the parasite's relationship with its muskoxen definitive hosts, its gastropod intermediate hosts and the arctic environment are discussed.     

Hamulonema gen. nov. for Teladorsagia hamata and Ostertagia kenyensis in the ostertagiine fauna (Nematoda: Trichostrongyloidea) from African ungulates

Hamulonema gen. nov. is proposed for Teladorsagia hamata and Ostertagia kenyensis in the ostertagiine nematode fauna found in artiodactyl hosts from Africa. Monomorphic species representing this genus are characterized by a bilaterally symmetrical and parallel synlophe in males and females, a 2-2-1 bursal formula, an accessory bursal membrane that is strongly cuticularized and reduced, a strongly reduced dorsal lobe and ray, and robust spicules with a simple, weakly pointed, ventral process, and curved, hooklike dorsal process. Species referred to Hamulonema nov. gen. are immediately distinguished from those of Camelostrongylus, Longistrongylus, Marshallagia, Orloffia, Ostertagia, and Pseudomarshallagia in which the bursal formula is 2-1-2 in males. Hamulonema nov. gen. is distinguished from those genera having a 2-2-1 bursa, including Africanastrongylus, Cervicaprastrongylus, Hyostrongylus, Mazamastrongylus, Sarwaria, Spiculopteragia, and Teladorsagia by the structure of the synlophe, bursa, genital cone, "0" and "7" papillae, dorsal lobe, and spicules in specific instances. In the global fauna, 4 of 14 ostertagiine genera are endemic to Africa. African genera may represent morphologically divergent and discrete or historically isolated lineages reflecting a pattern of geographic and host colonization as a driver for diversification since the Miocene.     

Age distribution and seasonal dynamics of abomasal helminths in wild red deer from central Spain

A study on age distribution and seasonal dynamics of abomasal helminths in wild red deer was conducted in central Spain, by monthly samplings of fawns (<1 yr), subadult (1-2 yr), and adult (>2 yr) animals. Both intensity and prevalence of abomasal parasitism were higher in older animals, particularly in males. A bimodal pattern for intensity of infection by gastrointestinal parasites was observed. Maximum values attained in winter and summer may be related to variation in climate and the shifting availability of forage resources. The pattern was largely due to the contribution of Spiculopteragia asymmetrica/Spiculopteragia quadrispiculata, whereas the other species found (Ostertagia leptospicularis/Ostertagia kolchida and Ostertagia drozdzi/Ostertagia ryjikovi) occurred with lower prevalence and intensity of infection. Among these ostertagiines, the ratio for major and minor morphotypes of males of respective species and the relative abundance of males and females were stable through the annual cycle.     

Bionomics of larvae of Parelaphostrongylus odocoilei (Nematoda: Protostrongylidae) in experimentally infected gastropod intermediate hosts

Parelaphostrongylus odocoilei is a protostrongylid parasite that has recently been recognized at several locations in sub-Arctic, but not Arctic, North America. We investigated factors that may determine the distribution of P. odocoilei, including suitable gastropod intermediate hosts, temperature requirements for larval development in gastropods, and larval emergence facilitating overwinter transmission. We collected and experimentally infected gastropods from a site in the sub-Arctic where P. odocoilei is at the northern limit of its distribution. Deroceras laeve, Catinella sp., and Euconulus cf fulvus, but not members of the Pupillidae, were suitable intermediate hosts. We describe bionomics of larvae of P. odocoilei in D. laeve and Catinella sp. Infective larvae emerged from all slugs (D. laeve) and 60% of Catinella sp. snails, and emergence from D. laeve was intensity dependent. Emerged infective larvae survived up to 6 mo under conditions approximating that of the subnivean environment. In D. laeve, there was a direct relationship between temperature and development rate of larvae of P. odocoilei. Larvae of P. odocoilei did not develop to infective stage below the theoretical threshold (8.5 C), and required a minimum of 163 degree days to complete development. These developmental parameters can be incorporated into a model to predict larval development in the field. Knowledge of the factors influencing larval bionomics provides the foundation for predicting temporal and spatial patterns of parasite distribution, abundance, and transmission.     

A macroevolutionary mosaic: episodic host-switching, geographical colonization and diversification in complex host–parasite systems

Aim  To integrate ecological fitting, the oscillation hypothesis and the taxon pulse hypothesis into a coherent null model for the evolution of complex host–parasite associations.
Location  Global.
Methods  This paper reviews and synthesizes literature that focuses on phylogenetic analyses and reciprocal mapping of a model system of hosts and their parasites to determine patterns of host–parasite associations and geographical distributions through time.
Results  Host-switching and geographical dispersal of parasites are common phenomena, occurring on many temporal and spatial scales. Diversification involving both co-evolution and colonization explains complex host–parasite associations. Across the expanse of Earth history, the major radiations in host–parasite assemblages have been preceded by ecological disruption, ecological breakdown and host-switching in a context that can be defined by the concept of ecological fitting. This cyclical process sets the stage for co-diversification during periods of relative stability, punctuated by host-switching during episodes of regional to global environmental disruption and climatological change.
Main conclusions  Most observed host–parasite associations can be explained by an historical interaction between ecological fitting, oscillation (episodes of increasing host range alternating with isolation on particular hosts) and taxon pulses (cyclical episodes of expansion and isolation in geographical range). Major episodes of environmental change appear to be the main drivers for both the persistence and diversification of host–parasite systems, creating opportunities for host-switching during periods of geographical expansion and allowing for co-evolution and co-speciation during periods of geographical isolation.     

Muscleworms, Parelaphostrongylus andersoni (Nematoda: Protostrongylidae), discovered in Columbia white-tailed deer from Oregon and Washington: implications for biogeography and host associations

Parelaphostrongylus andersoni is considered a characteristic nematode infecting white-tailed deer (Odocoileus virginianus). Host and geographic distribution for this parasite, however, remain poorly defined in the region of western North America. Fecal samples collected from Columbia white-tailed deer (O. v. leucurus) in a restricted range endemic to Oregon and Washington, USA, were examined for dorsal-spined larvae characteristic of many protostrongylid nematodes. Multilocus DNA sequence data (internal transcribed spacer 2 and cytochrome c oxidase subunit 1) established the identity and a new record for P. andersoni in a subspecies of white-tailed deer previously unrecognized as hosts. Populations of P. andersoni are now recognized along the basin of the lower Columbia River in Oregon and Washington and from south-central Oregon on the North Umpqua River. Current data indicate a potentially broad zone of sympatry for P. andersoni and Parelaphostrongylus odocoilei in the western region of North America, although these elaphostrongylines seem to be segregated, respectively, in white-tailed deer or in black-tailed and mule deer (Odocoileus hemionus) at temperate latitudes. The geographic range for P. andersoni in white-tailed deer is extended substantially to the west of the currently defined limit in North America, and we confirm an apparently extensive range for this elpahostrongyline. These observations are explored in the broader context of host and geographic associations for P. andersoni and related elaphostrongylines in North American cervids.     

Trichinella britovi etiological agent of sylvatic trichinellosis in the Republic of Guinea (West Africa) and a re-evaluation of geographical distribution for encapsulated species in Africa

In West Africa, Trichinella infection was documented in humans and animals from Senegal in the 1960s, and the biological characters of one isolate showed a lower infectivity to domestic pigs and rodents when compared with that of a Trichinella spiralis pig isolate from Europe. To identify the Trichinella species present in West Africa, a survey was conducted in a total of 160 wild animals in the Republic of Guinea. Three Viverridae, one true civet (Viverra civetta) and two African palm civets (Nandinia binotata) from the Fouta Djallon Massif, Pilimini Subprefecture, were found positive by artificial digestion of muscle samples. Trichinella larvae from these three viverrids were identified as Trichinella britovi and no difference was detected in three examined sequences from these African isolates and the reference strain of T. britovi from Europe, indicating common ancestry, an historically continuous geographic distribution, and recent isolation for African and European populations. The detection of T. britovi in West Africa modifies our knowledge about the distribution of encapsulated species of Trichinella in Africa. Thus, Trichinella nelsoni is now considered to have a distribution limited to the Eastern part of the Afrotropical region from Kenya to South Africa. This provides a plausible explanation for the presence of Trichinella T8 in Namibia and South Africa, and further suggests that T. britovi could be the Trichinella species circulating among wild animals of Northern Africa.