Location: Animal Parasitic Diseases
Title: Diversity at the Holarctic nexus: species of Arostrilepis (Eucestoda: Hymenolepididae) in arvicoline rodents (Cricetidae: Arvicolinae) from greater Beringia Authors
Submitted to: Zootaxa
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 24, 2012
Publication Date: February 23, 2013
Citation: Makarikov, A.A., Galbreath, K.E., Hoberg, E.P. 2013. Diversity at the Holarctic nexus: species of Arostrilepis (Eucestoda: Hymenolepididae) in arvicoline rodents (Cricetidae: Arvicolinae) from greater Beringia. Zootaxa. 3608:401-439. Interpretive Summary: Defining and understanding patterns of parasite diversity, relative to hosts and geographic occurrence, is fundamental to broader descriptions of structure and history of the biosphere and the processes (biotic and abiotic) that have been determinants of complex faunal distributions. Although extensive documentation of complex host-parasite assemblages across the Northern Hemisphere has been conducted, we continue to discover remarkable patterns of diversity, and in particular, what are regarded as "complexes" of otherwise cryptic species (closely related species that cannot be easily differentiated based on structural characters). Resolution of diversity across multiple groups of parasites is a first step in developing a comprehensive picture of history, and the forces that have structured faunas in space and time. We demonstrate this concept with discovery of additional new species in the tapeworm genus Arostrilepis (previously considered to represent a single species, this group now includes 12 nominal taxa) based on studies integrating broad-based field investigations in North America and Siberia, museum collections, morphology and molecular approaches). Significantly, we demonstrate complete concordance between obscure morphological characters and DNA sequences that are diagnostic for identification. We also identify the emerging generality for geographic expansion, and colonization under regimes of episodic changes in climate as primary mechanisms involved in speciation and biogeography for this assemblage; this contributes substantially to a general model for these processes in the evolution of complex parasite faunas in ungulates and other mammals. The study is important at many levels: (1) for those working in parasite speciation and biogeography; (2) for taxonomists dealing with the nuances of cryptic species; and (3) those exploring the influence of climate perturbations on the structure of parasite faunas, and emergence of disease. We anticipate that the results of our study will be applied by wildlife disease ecologists, parasite biologists, historical biogeographers and museum curators in academic and government research in the U.S. and more broadly in North America and globally.
Technical Abstract: 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, Chukhotka Autonomous Okrug, and Magadanskaya Oblast’, Russian Far East (western Beringia); Arostrilepis cooki sp. n. is named for cestodes in Myodes gapperi from British Columbia, Canada and Montana, U.S.A.; and Arostrilepis 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, U.S.A. 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 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) and A. macrocirrosa Makarikov, Gulyaev & Kontrimavichus, 2011 in red backed voles (species of Myodes) and less often other rodent host species.