A time scale for scales : reconciling neontology and paleontology in Coccoidea (Hemiptera)

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Scale insects (Hemiptera: Coccoidea), with 8,000 species, 33 Recent and 19 extinct families, are amongst the most destructive insects in agriculture. Perhaps 98% of the species feed on angiosperms. The superfamily is traditionally divided into the primitive archaeococcoids and the derived neococcoids, the latter with 90% of the species. The neococcoids were hypothesized to have diversified in response to the radiation of angiosperms ca. 100 Ma. Despite a sophisticated taxonomy based almost exclusively on the conspicuous neotenic adult females, there is a paucity of higher-level phylogenetic studies, and this compromises evolutionary understanding. Fossil scale insects are diverse in ambers around the world, 135 to 20 Ma, but are preserved mostly asthe highly dissimilar winged adult males, adding a challenge in understanding the relationships of fossil taxa. My dissertation is aimed at reconciling paleontology and neontology in Coccoidea and testing whether the neococcoids diversified as a result of the angiosperm radiations.My approach was to first assess whether fossil scale insects could be incorporated in a phylogenetic framework. To begin, I used the Ortheziidae (ensign scale insects), a morphologically well-defined family, where morphological features and fossil evidence suggests an early origin of the family in Coccoidea evolution. Based on 69 morphological characters of female ortheziids and using 39 exemplar Recent species, I provide the first analytical assessment of relationships among Recent and extinct genera of the family. Fossils included eight species, based on complete, well-preserved specimens in amber from 125-20 Ma (unlike other coccoid groups, ortheziids are fossilized mostly as females). Five new species and one new genus of fossil ensign scales are described from three amber deposits. Second, it was necessary to understand macropterous male morphology. However, because adult male Coccoidea do not feed and rarely live more than three or four days, they are seldom collected and their morphology has been little studied. In the Ortheziidae, for example, males of only four extant and three fossil species were known, in a family of over 200 species. Herein, the detailed male morphology of seven previously described species is provided, which, by knowing males of three additional genera, provides significantly better understanding of male morphological variation in Ortheziidae. The utility of laser confocal microscopy for the study of old, rare, uncleared collection slide preparations is shown to allow better visibility of macrostructures, but not for minute structures such as pores. A comprehensive study was made of macropterous males in four amber deposits: Eocene of the Baltic region and India (Cambay amber), mid-Cretaceous of Myanmar, and Early Cretaceous of Lebanon. Descriptions of 16 new species, 11 new genera, and three new families are provided, including very important records for six Recent families, such as the first fossil Margarodidae (Cambay amber) and another definitive Cretaceous neococcoid (in Burmese amber). These fossils are then discussed in a phylogenetic framework, obtained from analyzing 123 Recent and fossil taxa for 169 morphological characters. Finally, I assess whether fossil information can help resolve deep-node relationships in Coccoidea. Estimates of divergence times of the major lineages are made based on morphological and molecular data, and lineage ages are discussed with major biotic events in earth history. This study presents the first total-evidence (vs. nodecalibrated) approach to phylogenetic assessment for the Coccoidea, using 169 morphological characters and regions of the 18S, 28S and EF-1a genes. The taxon sampling includes 73 Recent and 43 fossil terminals covering 48 of the 54 recognized families in Coccoidea. Despite the large proportion of missing data and a very heterogeneous dataset, results indicate that most of the Recent families of Coccoidea were established by 100 Ma, revealing that the divergence of neoccoccoid families may have not affected by the angiosperm radiations. The origin of Coccoidea is estimated as Late Triassic, ca. 220 Ma.
xiv, 445, [1] leaves) : illustrations (some color)
Scale insects--Phylogeny.