Discovery and Description of the "Davtiani" Morphotype for Teladorsagia boreoarcticus (Trichostrongyloidea: Ostertagiinae) Abomasal Parasites in Muskoxen, Ovibos moschatus, and caribou, Rangifer tarandus, from the North American Arctic: Implications for P

Collections to explore helminth diversity among free-ranging ungulates in the North American Arctic revealed the occurrence of a third male, or ‘‘davtiani,’’ morphotype for Teladorsagia boreoarcticus. Designated as T. boreoarcticus forma (f.) minor B, the males occurred with T. boreoarcticus f. major and T. borearcticus f. minor A in endemic populations of muskoxen (Ovibos moschatus wardi) and barrenground caribou (Rangifer tarandus groenlandicus) on Victoria Island, Nunavut, Canada, and in muskoxen and Peary caribou (Rangifer tarandus pearyi) on Banks Island, Northwest Territories, Canada. These specimens differ from conspecific morphotypes in the structure of the genital cone and Sjöberg’s organ. Relative to T. boreoarcticus f. minor A, specimens of T. boreoarcticus f. minor B are consistently smaller, and mean dimensions for the bursa and spicules do not overlap. The robust spicules are similar in form, particularly in the relative length of the dorsal and ventral processes, but mean total length is substantially less in specimens of T. boreoarcticus f. minor B. Differences that distinguish the minor morphotypes of T. boreoarcticus parallel those demonstrated for the T. trifurcata and T. davtiani morphotypes in association with T. circumcincta sensu stricto. New host and geographic records include the 3 morphotypes of T. boreoarcticus in muskoxen and Peary caribou from Banks Island and in barrenground caribou from Victoria Island. Recognition of the ubiquitous nature of cryptic species emphasizes the need to effectively develop and use our collections-based resources and museum archives to build a robust understanding of the biosphere. Field inventory should include provisions for integrative approaches that preserve specimens suitable for comparative morphology, multifaceted molecular investigations, and population genetics. Teladorsagia circumcincta (Stadelman, 1894) and T. boreoarcticus Hoberg, Monsen, Kutz and Blouin, 1999 have been shown to represent a potentially diverse complex of cryptic polymorphic species distributed, and probably partitioned, among domestic and free-ranging ungulates across the Holarctic (Hoberg et al., 1999; Leignel et al., 2002; Grillo et al., 2007). In the restricted sense, T. circumcincta/T. trifurcata (Ransom, 1907)/T. davtiani Andreeva and Satubaldin, 1954 (in the taxonomic notation used to designate nominal polymorphic forms representing a single species in Ostertagiinae) is a characteristic polymorphic species of small domestic ruminants, particularly sheep, Ovis aries L. (e.g., Dróz_dz_, 1995). Some populations of nematodes restricted to goats, Capra hircus L., represent another putative species within T. circumcincta that has not yet been fully characterized, further supporting the concept for a diverse assemblage (Gasnier et al., 1997; Leignel et al., 2002). Subsequent to putative origins in Eurasia, T. circumcincta has been translocated and disseminated globally coincidental initially with expansion of agriculture and later European exploration after the 1500s (e.g., Hoberg, 1997; Hoberg et al., 2001). Thus, T. circumcincta has been widely introduced and is an important element of mosaic nematode faunas (containing both introduced and endemic species) occurring among ungulates (Hoberg et al., 1999, 2001, 2008a; Hoberg, 2010). Diversity and species limits within the T. circumcincta complex have yet to be adequately, or completely, delineated either in domestic or in free-ranging hosts. New geographically extensive surveys in conjunction with integrated approaches linking morphology and molecular systematics are thus required (Gasnier et al., 1997; Hoberg et al., 1999; Leignel et al., 2002; Grillo et al., 2007). Clear definitions of nematode diversity are increasingly important in the context of ecotones at the borderlands of both managed and wild ecosystems. As part of baselines, they are essential in understanding patterns and history for faunal structure, including the potential exchange of parasites among domestic and free-ranging host species in zones of contact (Hoberg et al., 1999; Cerutti et al., 2010). Furthermore, translocations involving multiple species and subspecies of free ranging hosts (and their parasites) will serve to influence patterns of faunal diversity and the distribution and relationships for parasite populations in newly developed zones of sympatry. Recognition of species limits within the cryptic complex have additional ramifications, because biology, life history, development, population structure, host associations, and responses to environmental change may vary according to the history, evolution, and biogeography for different assemblages of parasites (Suarez and Cabaret, 1991; Hoberg et al., 1999, 2008a;