The Cetoniidae, the showiest of scarabs, comprises some 3900 species in 515 genera, distributed worldwide except for subpolar areas and some offshore New Zealand islands. Parsimony analysis of 76 larval and adult characters and 42 terminal taxa supports the monophyly of Cetoniidae (sensu Krikken, 1984), but not of the traditionally considered subfamilies Cetoniinae and Trichiinae (sensu Krikken, 1984). In the study taxon, larval characters are shown to be more informative than those of adults for deeper phylogeny. The evolution of some larval characters (head and legs) in relation to feeding habits is discussed on the basis of phylogenetic analysis. The results show an evolutionary shift from wood associations to a higher ecological plasticity that allows the larvae to feed on wide sources of organic matter (including compost, dung, gopher burrows, packrat middens, ant debris piles, etc.).

No abstract

No abstract

Sexual size dimorphism (SSD) is widespread among animals, but its developmental mechanisms are not fully undestood. We investigated the proximate causes of SSD in three male-larger and one monomorphic scarab beetles using detailed monitoring of growth in individual instars. Apart from the finding that SSD in all three male-larger species started to develop already in the first larval instar, we generally found a high variability in SSD formation among the species as well as among instars. Overall, sexual differences in developmental time, average growth rate, as well as in the shape of the growth trajectory seem to be the mechanisms responsible for SSD ontogeny in scarab beetles. In the third instar, when the larvae attain most of their mass, the males had a similar or even lower instantaneous growth rate than females and SSD largely developed as a consequence of a longer period of rapid growth in males even in cases when the sexes did not differ in the total duration of this instar. Our results demonstrate that a detailed approach, examining not only the average growth rate and developmental time, but also the shape of the growth trajectory, is necessary to elucidate the complex development of SSD.

Immature stages of I. pulverulenta (Olivier, 1789) (Coleoptera: Scarabaeidae: Cetoniinae: Incini) are described for the first time, and those of I. bonpalandi (Gyllenhal, 1827) and I. clathrata sommeri Westwood, 1845 are redescribed. A key to the third instar of Incini is presented, notes on Inca larval characters in the phylogenetic context of Cetoniinae and on scarab pupal morphology are also given.