GEOGRAPHICAL VARIATION, CLASSIFICATION, RECONSTRUCTED PHYLOGENY, AND GEOGRAPHICAL HISTORY OF THECICINDELA SEXGUTTATAGROUP (COLEOPTERA: CICINDELIDAE)

Abstract

AbstractA systematic review was conducted for theCicindela sexguttatagroup taxa. Comparative methods of examination were applied to adult structural and ecological characters for purposes of taxa diagnoses, and to establish a basis for the derivation of the group’s history.Based on 13 adult exoskeletal characters and 25 tests on populations throughout the group’s geographical range, a discriminant analysis identifies the most significant characters as being elytral maculation, body size, pilosity of the stipes, and number of sensory setae on the antennal scape. In addition, selected characters of the male and female genitalia are shown to identify all taxa within the group. Among biological comparisons the different number of mature eggs found in adult females ofC.sexguttataFabricius andC.denikeiBrown indicates that their fecundity differs; and the larval burrow ofC.denikeiopens directly beneath rocks and stones, a habit unique inCicindela. Seasonality profiles of taxa appear to be dictated by geographical location, and by phylogeny to a smaller degree. Species–soils associations indicate thatC.sexguttatahas a strong affinity to warm, moist and loamy soils, butC.denikeiis correlated with sandy, silty till. For all species of the group, habitats occupied and limits of distribution to eastern Canada and the United States appear to be governed by soil and forest types.Three species of the group are recognized:C.sexguttataconsisting of geographical populations varying considerably in adult characteristics and the problematic formC.harrisiiLeng which may be considered a cryptic species;C.denikei; andC.patruelaDejean consisting of two subspeciesC.p.patruelaandC.p.consentaneaDejean.A reconstructed phylogeny of theC.sexguttatagroup based on methods of Hennig (1966) alliesC.sexguttataandC.denikeias sister species, andC.patruelaas an earlier lineage. Recognized as a stem group of theC.purpureacomplex, theC.sexguttatagroup is postulated to have had its origins in forested eastern North America during the Late Miocene. Speciations ofC.patruelaand lineageC.sexguttata–C.denikeiare perceived to have occurred in the Pliocene, followed by speciations ofC.sexguttataandC.denikeiin the Late Pleistocene effected by continental ice mass advances and recessions.