Nomenclature and Morphology of Ostertagia trifurcata Ransom, 1907, with Data on Spicule Lengths of Five Stomach Worms of Ruminants

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 Parasite Faunal Diversity

“…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. Generally the differences that distinguish the minor morphotypes of T. boreoarcticus parallel those demonstrated for the T. trifurcata and T. davtiani morphotypes in association with T. (96) 6.8-9 (7.8 ± 0.5) (58) 6.6-9.1 (7.7 ± 0.5) (13) 6.5-8.8 (7.5 ± 0.6) circumcincta sensu stricto (e.g., Becklund and Walker, 1971). In specimens of T. boreoarcticus f. minor B, the ''7'' papillae are narrowly spaced distally and protrude from the postero-ventral margin of the Sjö berg's organ.…”

“…Although Becklund (1962) and Becklund and Walker (1971) examined numerous specimens attributed at that time to T. davtiani in domestic sheep and free-ranging ungulates (78 specimens in 7 host species), they did not specify the origins of particular lots of worms relative to hosts or geographic site of collection. The range for spicule length was reported as 156-238 mm (mean 5 196).…”

“…Hoberg et al (1999) suggested that T. boreoarcticus either differed from T. circumcincta (with a major and 2 minor male morphotypes) or that the putative third male morphotype should eventually be discovered (Dró z_dz_, 1995). As a basis for comparison, the morphology and identity of the respective minor morphotypes for T. circumcincta were resolved in studies by Becklund and Walker (1971).…”

Insight into species diversity of the Trichostrongylidae Leiper, 1912 (Nematoda: Strongylida) in ruminants

“…Initially T. circumcincta (Stadleman, 1894) was characterized by slender spicules, in comparison with the shorter and stouter spicules of T. trifurcata (Ransom, 1907) and T. davtiani Andreev & Satubaldin, 1954. The latter two species were differentiated by morphological variation of the genital cone (Becklund & Walker, 1971). Later, some authors (Andrews & Beveridge, 1990; Suarez & Cabaret, 1992; Lichtenfels & Hoberg, 1993; Stevenson et al , 1996) suggested that T. trifurcata and T. davtiani are in fact morphotypes of T. circumcincta , because: (i) males of all three morphotypes appeared always to occur together, with T. circumcincta constituting the major proportion of the population (Lancaster & Hong, 1981; Lichtenfels & Hoberg, 1993; Craig et al , 2006); (ii) no differences in female worm morphology have been identified within populations containing the male morphotypes (Lichtenfels & Hoberg, 1993); and (iii) cross-breeding experiments have produced males of different morphotypes, either from a cross between female T. circumcincta (monomorphic laboratory strain) and male T. trifurcata , or from unknown female Teladorsagia mating with males of one of the morphotypes (Suarez & Cabaret, 1992; Lichtenfels & Hoberg, 1993).…”

“…The presence of cryptic species is assumed especially within the subfamily Ostertagiinae, which contains many of the gastrointestinal parasites of ruminants. Precise designation of these parasites is based primarily on morphological and morphometric features (Becklund & Walker, 1971; Gibbons & Khalil, 1982; Lichtenfels et al , 1988a, 1997; Lichtenfels & Hoberg, 1993; Dróżdż, 1995). The increasing use of molecular techniques, sometimes in combination with advanced morphological analysis, have allowed the traditionally regarded species to be examined more closely.…”