“…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).…”