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United States Department of Agriculture

Agricultural Research Service

Title: Phylogeny for Genera of Nematodirinae (Nematoda Trichostronylina)

Authors
item Hoberg, Eric
item Lichtenfels, James
item Rickard, L - MISSISSIPPI STATE U

Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 7, 2004
Publication Date: February 8, 2005
Citation: Hoberg, E.P., Lichtenfels, J.R., Rickard, L.G. 2005. Phylogeny for genera of Nematodirinae (Nematoda: Tichostronoylina). Journal of Parasitology. 91:382-389.

Interpretive Summary: Nematodirine nematodes globally represent serious pathogens in wild mammals and domestic stock. The speciose genus, Nematodirus contains an array of helminth pathogens that infect ruminants throughout the world, and species such as N. battus continue to be regarded as the most economically significant parasites in domestic sheep, Ovis aries Linnaeus, across the Northern Hemisphere. Although there has been considerable effort and research to define epizootiology, and the host-parasite interface for species of Nematodirus, our understanding of the broader evolution and history for these and related nematodes remains to be fully elucidated. We conducted the first phylogenetic studies of the Nematodirinae. Monophyly for the Nematodirinae, with 5 inclusive genera, Murlieus, Rauschia, Nematodiroides, Nematodirus and Nematodirella was confirmed based on comparative morphology and phylogenetic analysis of structural characters. This concept for the nematodirines excludes the monotypic Lamanema chavezi, but otherwise corroborates inclusive generic-level diversity as defined in prior studies. Phylogenetic hypotheses are foundations for understanding the history and structure of biotas. Knowledge of the history and distribution of this fauna promotes examination and prediction for responses by hosts and parasites to global change and ecological perturbation at temperate, Boreal and Arctic latitudes.

Technical Abstract: Monophyly for the Nematodirinae, with 5 inclusive genera, Murlieus, Rauschia, Nematodiroides, Nematodirus and Nematodirella was confirmed based on comparative morphology and phylogenetic analysis of structural characters. This concept for the nematodirines excludes the monotypic Lamanema chavezi, but otherwise corroborates inclusive generic-level diversity as defined in prior studies. Exhaustive analysis,resulted in one most parsimonious tree (37 steps; CI= 0.95; HI= 0.08; RI= 0.92; RC= 0.87; excluding phylogenetically uninformative characters, CI= 0.92; HI= 0.08). As an inclusive group, Nematodirinae was diagnosed by 7 synapomorphies: (i) large eggs; (ii.) long filiform spicules; (iii) basal division of the dorsal ray; (iv) symmetrical membrane enveloping the spicules; (v) fused structure of the spicule tips; (vi) absence of the gubernaculum; and (vii) development of the third stage larva within the egg. Exclusion of Lamanema indicates that hypotheses for the coevolution and historical biogeography for the nematodirinae will require revision.

Last Modified: 7/30/2014