A Morphometric Analysis of the \u3cem\u3eIxodes ricinus\u3c/em\u3e Complex (Acari: Ixodida: Ixodidae)

The research presented herein is a morphological analysis of adult male and female tick species that compose the Ixodes ricinus complex along with Ixodes spinipalpis and Ixodes dentatus. Morphological characters of 20 males and 20 females for each species from various geographical locations were measured. They included the palps, basis capituli, scutum, tarsus I, spiracle (males), hypostome, toothed portion of hypostome, coxa I, coxa I spur, median plate (males), adanal plate (males), porose area (females), and interporose area (females). Data were extrapolated to compare morphological differences among species. Comparisons of individual characters among species for each sex were calculated separately by conducting a one-way analysis of variance (ANOVA). Multivariate analysis (MANOVA) was performed to analyze overall differences in morphology among species for each sex. Principal Component Analysis (PCA) was also conducted using linear combinations of the original variables. This explained as much of the variation among the original variable measurements as possible and facilitated comparisons using multivariate data. The latter were represented by a scatter plot diagram. Data from ANOVA, MANOVA and PCA analysis indicated that there is a significant difference among all species. These data illustrate that I. dentatus and /. spinipalpis possess great variation in shape and size when compared to species belonging to the I. ricinus complex. Results also indicated that tick species within the I. ricinus complex have significant differences among species; however, these findings also show that some species are more closely related to each other than to other members in this group