Ontogenetic trajectories and hind tibia geometric morphometrics of Holymenia clavigera (Herbst) and Anisoscelis foliacea marginella (Dallas) (Hemiptera: Coreidae)

Abstract

Holymenia clavigera (Herbst) and Anisoscelis foliacea marginella (Dallas) (Hemiptera: Coreidae) are distributed in southern Brazil and belong to the poorly studied tribe Anisoscelini. Preliminary observations indicate an ample coexistence of these species in terms of host-plant use. There is also a strong similarity regarding egg and nymph morphology. We characterized and compared their ontogenetic trajectories by means of growth curves and multivariate ontogenetic allometry, since the only apparent difference between these species is a remarkable growth in the hind tibia of A. foliacea marginella. Because their hind tibia is similar in the early instars, the shape variation of this structure was quantified by the thin plate splines function with the relaxed algorithm for semilandmarks. H. clavigera was significantly larger than A. foliacea marginella in all stages. Their ontogenetic trajectories were significantly different, and the allometric vectors did not present a significant correlation. Hind tibia shape was not statistically different in the first instar, but was different in the second instar. In the third instar, this difference became visually apparent. Thus, although these bugs are almost morphologically identical in the immature stages, their growth patterns and general size are different. We found size to be a useful parameter for species differentiation at these stages.