Comparison of the head patterns in the Tylenchoidea (Nematoda)

In the order Tylenchida a differentiation is made between the primitive head and the nonprimitive head. Primitive heads are found in all suborders, e.g. in the Tylenchoidea (suborder Tylenchina) primitive heads are present in the Anguinidae. In the other families of the Tylenchoidea definite patterns are found that help to characterize the several families. A lateral elongation of the pattern is found in the Tylenchidae and the Belonolaimidae; a dorso-ventral elongation in the Pratylenchidae. The subfamily Meloidogyninae has the same head end-on view as the Pratylenchidae and the subfamily Heteroderinae has the same head as the family Hoplolaimidae.