Abstract
The morphological characters of the prescutum and scutellum of representative species of twenty-three genera of Hylesinini and Scolytini (Coleoptera: Curculionidae: Scolytinae), and two genera of outlier tribes of similar ecological habits, were examined by scanning electron microscopy. Characters involving the prescutum formed three groups: shape, setae, and surface features. Characters of the scutellum involved its shape and attachment to the prescutum. This study uncovered a range of morphological characters, rivaling the traditional antennal characters, useful support to the study of the classification, phylogeny and biology of two tribes of Scolytinae. All taxa studied had a shield-shaped prescutum, except the outlier Platypus (Platypodinae: Platypodini). Hylesinini differed significantly from Scolytini in having a greater number of setae with multiple stems and proportionately more genera with a smooth prescutum surface. More stems of the scutellum of Scolytini were tapered than were those of other studied taxa. Comparison of three pairs of sibling species of Dendroctonus Erichson indicated that intraspecific morphological characters exhibit differences potentially useful in helping resolve cases of questioned synonymy. The phloeophagous outlier Pissodes Germar (Curculionidae: Molytinae) fell within variation present in Hylesinini whereas outlier xylophagous Platypus did not resemble any other genus herein.