The ant subfamily Pseudomyrmecinae comprises three genera of hyperoptic, arboreal ants, widely distributed in tropical and subtropical regions: Pseudomyrmex ($200 species, New World), Myrcidris (two species, South America) and Tetraponera ($100 species, Palaeotropics). The phylogenetic relationships among these ants were investigated using DNA sequence data ($5.2 kb from 18S rDNA, 28S rDNA, wingless, abdominal-A, and long-wavelength rhodopsin genes) and 144 morphological characters, both separately and in combination. Data were gathered from a representative set of forty-nine pseudomyrmecine species, plus eighteen species from various outgroups. There was substantial agreement among the results obtained from different datasets, and from different methods of phylogenetic inference (parsimony, Bayesian inference). The monophyly of the following groups is strongly supported (100% bootstrap support and 1.00 posterior probability in the molecular dataset): Pseudomyrmecinae, Pseudomyrmex, and Pseudomyrmex þ Myrcidris. The status of the genus Tetraponera is less clear: the DNA sequence data indicate that the genus is paraphyletic, but morphological features and a unique insertion in the 28S gene support the monophyly of this taxon. Seven of nine Pseudomyrmex species groups, established previously on the basis of morphology alone, are strongly upheld, but monophyly is rejected for the P. pallens group and the P. viduus group. In the latter case, molecular evidence indicates the existence of two independent clades, associated with the ant-plants Triplaris and Tachigali, respectively, whose convergent morphological features had caused them to be placed erroneously in the same species group. The present results confirm an earlier assertion that obligate associations with domatia-bearing plants have arisen at least twelve times in the subfamily. Molecular and morphological data support the hypothesis of a sister-group relationship between Pseudomyrmecinae and Myrmeciinae (84% parsimony bootstrap, combined dataset), which implies a Cretaceous origin of the stem-group pseudomyrmecines in the southern hemisphere. Pseudomyrmecines appear to have arisen in the Palaeotropics and later dispersed from Africa to South America, where they experienced a pronounced burst of diversification.

Abstract. Mealybugs (Hemiptera: Pseudococcidae) are small, plant‐sucking insects which comprise the second largest family of scale insects (Coccoidea). Relationships among many pseudococcid genera are poorly known and there is no stable higher level classification. Here we review previous hypotheses on relationships and classification and present the first comprehensive phylogenetic study of the Pseudococcidae based on analysis of nucleotide sequence data. We used three nuclear genes, comprising two noncontiguous fragments of elongation factor 1α (EF‐1α 5′ and EF‐1α 3′), fragments of the D2 and D10 expansion regions of the large subunit ribosomal DNA gene (28S), and a region of the small subunit ribosomal DNA gene (18S). We sampled sixty‐four species of mealybug belonging to thirty‐five genera and representing each of the five subfamilies which had been recognized previously, and included four species of Puto (Putoidae) and one species each of Aclerda (Aclerdidae) and Icerya (Margarodidae), using Icerya as the most distant outgroup. A combined analysis of all data found three major clades of mealybugs which we equate to the subfamilies Pseudococcinae, Phenacoccinae and Rhizoecinae. Within Pseudococcinae, we recognize the tribes Pseudococcini (for Pseudococcus, Dysmicoccus, Trionymus and a few smaller genera), Planococcini (for Planococcus and possibly Planococcoides) and Trabutinini (represented by a diverse range of genera, including Amonostherium, Antonina, Balanococcus, Nipaecoccus and non‐African Paracoccus), as well as the Ferrisia group (for Ferrisia and Anisococcus), some ungrouped African taxa (Grewiacoccus, Paracoccus, Paraputo and Vryburgia), Chaetococcus bambusae and Maconellicoccus. The ‘legless’ mealybugs Antonina and Chaetococcus were not closely related and thus we confirmed that the Sphaerococcinae as presently constituted is polyphyletic. In our analyses, the subfamily Phenacoccinae was represented by just Phenacoccus and Heliococcus. The hypogeic mealybugs of the Rhizoecinae usually formed a monophyletic group sister to all other taxa. Our molecular data also suggest that the genera Pseudococcus, Dysmicoccus, Nipaecoccus and Paracoccus are not monophyletic (probably polyphyletic) and that Phenacoccus may be paraphyletic, but further sampling of species and genes is required. We compare our phylogenetic results with published information on the intracellular endosymbionts of mealybugs and hypothesize that the subfamily Pseudococcinae may be characterized by the possession of β‐Proteobacteria (primary endosymbionts) capable of intracellular symbiosis with γ‐Proteobacteria (secondary endosymbionts). Furthermore, our data suggest that the identities of the secondary endosymbionts may be useful in inferring mealybug relationships. Finally, cloning polymerase chain reaction products showed that paralogous copies of EF‐1α were present in at least three taxa. Unlike the situation in Apis and Drosophila, the paralogues could not be distinguished by either the presence/absence or position of an intron.

Range expansions through human introductions have increased with global commerce and have led to the extinction of native species, alterations in community structure and pest status of the invasive species. Inferring the evolutionary history of invasive species can help to build a firmer footing for management tactics. This study used mitochondrial DNA (mtDNA) sequence comparisons of samples collected from the native and introduced ranges of a pest herbivore of cultivated grapes, grape phylloxera (Daktulosphaira vitifoliae Fitch, Phylloxeridae) to infer the sources and pattern of introductions into worldwide viticulture. Introductions into viticulture from its native North American range first occurred in the mid-19th century. The pattern of spread has suggested a focus of introduction into France, but independent introductions may have occurred elsewhere. The results show that the introduced population represents a limited subsample of the native genetic diversity. The data suggest that most grape phylloxera in viticulture, including all European, have originated in the northeastern USA where the grape species Vitis riparia dominates. There was evidence for independent introductions into South Africa and California. Most California haplotypes were most closely related to native grape phylloxera from the Atlantic Coast on V. vulpina. It is likely that subsequent spread from California into Australia, New Zealand and Peru has occurred.

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There are many examples of cryptic species that have been identified through DNA‐barcoding or other genetic techniques. There are, however, very few confirmations of cryptic species being reproductively isolated. This study presents one of the few cases of cryptic species that has been confirmed to be reproductively isolated and therefore true species according to the biological species concept. The cryptic species are of special interest because they were discovered within biological control agent populations. Two geographically isolated populations of Eccritotarsus catarinensis (Carvalho) [Hemiptera: Miridae], a biological control agent for the invasive aquatic macrophyte, water hyacinth, Eichhornia crassipes (Mart.) Solms [Pontederiaceae], in South Africa, were sampled from the native range of the species in South America. Morphological characteristics indicated that both populations were the same species according to the current taxonomy, but subsequent DNA analysis and breeding experiments revealed that the two populations are reproductively isolated. Crossbreeding experiments resulted in very few hybrid offspring when individuals were forced to interbreed with individuals of the other population, and no hybrid offspring were recorded when a choice of mate from either population was offered. The data indicate that the two populations are cryptic species that are reproductively incompatible. Subtle but reliable diagnostic characteristics were then identified to distinguish between the two species which would have been considered intraspecific variation without the data from the genetics and interbreeding experiments. These findings suggest that all consignments of biological control agents from allopatric populations should be screened for cryptic species using genetic techniques and that the importation of multiple consignments of the same species for biological control should be conducted with caution.

Abstract. Studies of patterns of molecular variation in natural populations can provide important insights into a number of evolutionary problems. Among these, the question of whether geographic factors are more important than ecological factors in promoting population differentiation and ultimately speciation has been an important and contentious area in evolutionary biology. Systems involving herbivorous insects have played a leading role in this discussion. This study examined the distribution of molecular variation in a highly specialized gall-forming insect, grape phylloxera (Daktulosphaira vitifoliae Fitch), that is found on both sympatric and allopatric host-plant species of the genus Vitis. In addition, the relationship of insects in the introduced range in the United States to ancestral populations in the native range was examined. Evidence for differentiation along host-plant lines from both nuclear (RAPD) and mitochondrial (COI) DNA was confounded with the effect of geography. Differentiation was found where hosts were allopatric or parapatric, but no evidence was found for such differentiation on two hosts, V. vulpina and V. aestivalis, that are broadly sympatric. The question of population differentiation onto these sympatric hosts can be considered to be resolved-it has not occurred in spite of a long history of association. Evidence was equivocal, but suggestive of a period of divergence in allopatry prior to reestablishment of contact, for insects associated with another host plant species, V. cinerea, found in both sympatric and parapatric populations. A low level of diversity and placement of samples collected from the grape species V. riparia at the tip of a phylogenetic tree supports the hypothesis that this host has been recently colonized from populations from the Mississippi Valley. A polyphyletic origin for biotype B grape phylloxera was supported: Although most samples collected from vineyards in the introduced range in California had similar haplotypes, they were closely related to natives on V. vulpina from the Atlantic CoastPiedmont region. All samples collected from vineyards in Oregon and Washington were closely related to natives on V. riparia in the northern United States.Key words. Biotypes, cytochrome oxidase I, geographic distribution, grape phylloxera, herbivorous insects, hostplant variation, sympatric divergence, Vitis. Geographical features of the environment of organisms that prevent or reduce gene flow are widely considered to be better predictors of genetic differentiation of populations than are ecological factors (Dobzansky 1937;Mayr 1963;Futuyma and Mayer 1980;Patterson 1981;Templeton 1981;Carson 1982;Barton and Charlesworth 1984;Lynch 1989;Allmon 1992;Avise 2000;Barraclough and Vogler 2000), but the consensus on this issue is far from complete. Increasing theoretical support for the sympatric model of speciation has accumulated over the years and many evolutionary biologists now feel quite comfortable with this model (Maynard

Complementary nuclear (28S rRNA) and mitochondrial (COI) genes were sequenced from blowflies that phenotypically resembled Lucilia cuprina (W.), Lucilia sericata (Meigen) or exhibited characters of both species. The aim was to test a long-held hypothesis that these species hybridize under natural conditions in South Africa (Ullyett, 1945). Blowflies were obtained predominantly from the Cape Town metropolitan area, but reference samples were acquired for L. sericata from Pretoria. Several L. cuprina-like flies were shown to possess a conflicting combination of nuclear and mitochondrial genes that has also been seen in Hawaiian specimens. Homoplasy, sampling of pseudogenes, hybridization and incomplete lineage sorting are discussed as possible hypotheses for the pattern and the latter is concluded to represent the most likely explanation.

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