Genera and Allometry in the Stag Beetle Family Lucanidae, Coleoptera

Abstract

Analyses of intraspecific and interspecific mandible allometry and dimorphism for natural population samples of 45 species in 3 representative genera of the stag beetle family Lucanidae confirmed that conventional taxonomists have been identifying groups of species sharing the same intraspecific allometry and dimorphism as a genus. Although there was extensive variation, both intraspecific and interspecific, in male mandible morphology, covariance analyses indicated that a high proportion (87, 89, and 91% in the 3 genera studied) of the mandible length, variance of all the individuals of all the species within the same genus was accounted for by the common generic allometry and dimorphism. This highly parallel nature of intraspecific allometry and dimorphism with the interspecific variation within the same genus suggests that each genus of Lucanidae is characterized by its own basic allometric and dimorphic program, and all the variations within genus, whether they are intraspecific or interspecific, follow this basic program. In stag beetles, where an individual adult morphology is fixed and mostly determined by the length and nutritional condition of the larval period, the broad sequential and dimorphic variation in male adult mandibles, seen within a given intraspecific population as a static allometry, may be also considered as an expression of the species ontogenetic program observable in a static form. The abundance of shared morphological traits among species of the same genus suggests the possibility of ontogeny functioning as a phylogenetic constraint. Genera in the Lucanidae are quantitatively describable and possibly developmentally definable, biological entities.