The chaetotactic nomenclature proposed by Lindquist and Evans (1965) for the Gamasina, using the family Ascidae as examplar, is adopted for use in the family Phytoseiidae. Probable setal homologies were determined by: examining and comparing ontogenetic relationships in both the Phytoseiidae and Ascidae; standardizing the shape and size of the dorsal shield of exemplars from 7 genera of Phytoseiidae and one of Ascidae in order to compare standardized, transformed setal positions; examining the spatial relationships between setal and pore positions. The technique used to standardize the shape and size of the dorsal shield is described. The setal nomenclature adopted for each of the genera of Phytoseiidae is discussed and presented in diagrammatic form. Ventral chaetotaxy in the Ascidae and Phytoseiidae is also discussed.
The ontogenetic development of setae on the dorsum and venter of the idiosoma and on the legs is described for the following four species of Phytoseiidae: Amblyseius andersoni (Chant). Amblyseius degenerans (Berlese), Phytoseiulus persimilis Athias-Henriot, and Typhlodromus pyri Scheuten. Homologous setal relationships between successive instars are discussed. The larvae of additional species were examined to determine if there are consistent patterns of setal development in the Phytoseiidae. A standard system of nomenclature for the setae on the idiosoma is applied to the immature instars.
The taxonomic history of the family Phytoseiidae is briefly reviewed. The taxonomic structure of the family is analysed using the methods of numerical taxonomy, with 221 morphological characters in 93 species covering the major taxonomic groups that have been proposed within the family. Both weighted and unweighted character analyses are used. It is shown that definite gaps separate groups of species within this family. At the level of major hierarchical separations both the unweighted and weighted character analyses are similar. A classification based on these major hierarchical separations is proposed. It is demonstrated that neither the classical system, based mainly on dorsal chaetotaxy, nor the numerical system alone provides a completely acceptable classification of the family, but that numerical taxonomic analyses are useful as a tool in helping to determine the hierarchical organization of the group.
Variation in morphological characters between Canadian populations of Typhlodromus caudiglans Schuster (Acarina: Phytoseiidae) was examined by the methods of numerical taxonomy. Western populations are separated from the other populations when multivariate tests are used. Two subspecies are proposed, and Typhlodromella nodosus De Leon is synonymized with Typhlodromus caudiglans. Morphological variations between northern and eastern populations are correlated with climatic variables and with host plants.
Morphological characteristics common to both sexes in 46 species, including exemplars from six genera and four tribes, of the family Phytoseiidae were compared interspecifically, intergenerically, and intertribally. The relationships between the sexes were quantified in terms of correlation coefficients and model II linear regression analyses, comparing the same set of morphological characters in both sexes. It is shown that there is a high degree of association between the males and females of a species despite their obvious morphological differences and that these relationships vary among some systematic groupings. The quantified differences shown between some taxa permit speculation on the phylogenetic relationships between the species studied. The quantitative relationships between the sexes in most cases are shown to be unique for males and females of the same species, offering a numerical method of identifying unknown male specimens. Many morphological characteristics are shown to be consistently shared by both sexes.
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