© CSIRO 2003 10.1071/IS02004 1445-5226/03/020349 www.publish.csiro.au/journals/is Invertebrate Systematics, 2003, 17, 349–358 CSIRO PUBLISHING Morphometric variation between populations of Kampimodromus aberrans (Oudemans) (Acari:Phytoseiidae): implications for the taxonomy of the genus M.-S. Tixier A,B , S. Kreiter A , B. Cheval A and P. Auger A A Ecole Nationale Supérieure Agronomique / Institut National de la Recherche Agronomique, UP d’Ecologie Animale et de Zoologie Agricole, Laboratoire d’Acarologie, 2, Place Pierre Viala, 34060 Montpellier cedex 01, France. B To whom correspondance should be addressed. Email: garcin@ensam.inra.fr Abstract. This study reports variation between populations of the phytoseiid mite Kampimodromus aberrans (Oudemans). The influence of seasons (summer and winter), different host plants, and localities on morphological variation was investigated to determine the reliability of the parameters usually used to distinguish species in the genus Kampimodromus. This study was conducted in southern France. The specimens examined consisted of three summer and three winter populations each collected from Celtis australis L., Quercus pubescens Willdenow (referred as Q. pubescens no. 1 in the text) and Corylus avellanae L., and three additional summer populations collected from each of Q. pubescens (referred as Q. pubescens no. 2 in the text), Vitis vinifera cv. Carignan and Vitis vinifera cv. Cabernet-Sauvignon. Significant differences were observed between the winter and summer populations. Females of summer populations had longer setae than females of winter populations. However, these differences are usually very small. Greatest differences were observed within the population collected in summer on Q. pubescens no. 1 from which two distinct groups of specimens were distinguished. To determine if more than one species of Kampimodromus were present on this plant, measurements of other closely related species were also included in the analysis. It was concluded that all the females studied belong to K. aberrans. However, the setal variations observed raised the following questions. (i) What is the validity of other closely related species whose setal lengths differ only slightly from those of K. aberrans? (ii) Are setal lengths useful characters to distinguish between closely related species in the genus Kampimodromus? Additional keywords: intraspecific variation, seasonal variations, setal length Introduction Phytoseiid mites are important predators involved in the control of phytophagous mites on various crops (Ivancich- Gambarro 1973; Duso 1992; McMurtry and Croft 1997). Kampimodromus aberrans (Oudemans) is a very common phytoseiid species in Europe on cultivated (apple orchards and vineyards) and wild plants (Duso 1992; Ragusa et al. 1995; Ragusa and Tsolakis 1996; Schausberger 1997; Kreiter et al. 2000; Tixier et al. 2000b). It lives primarily on trees and shrubs with hairy leaves and domatia (Barret and Kreiter 1992; Camporese and Duso, 1996; Duso et al. 1997; Tixier et al. 2000b; Kreiter et al. 2002). It has been found to feed on several prey species, particularly Eotetranychus carpini (Oudemans) in vineyards in southern Europe (especially France and Italy) (Duso 1992; Kreiter et al. 2002). Exact diagnosis of this species is important for both scientific and applied agronomic purposes. Dorsal setae are important characters in phytoseiid mite systematics. A few studies deal with the variation in length of the dorsal setae of K. aberrans between seasons. Chant (1955) showed that summer populations have longer, thicker and more serrated dorsal setae than overwintering populations. These differences were sufficiently noticeable for Oudemans (1930) to report winter and summer populations as two different species, K. aberrans and K. elongatus (Oudemans) respectively, the latter of which was described by Nesbitt (1951) as the type of the genus. Chant (1955), Chant and Yoshida-Shaul (1995) and Ragusa and Tsolakis (1994) considered K. elongatus to be a junior synonym of K. aberrans. Swirski and Amitai (1965) reported large variations in setal lengths between populations of a species then identified as K. aberrans from Israel, Algeria and Europe. In a later publication, Swirski and Amitai (1997) re-identified those