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Ants (Formicidae) in Mexico have usually been undersampled despite their ecological significance and their utility as environmental service providers and bioindicators. This study estimates the species richness and the narrow endemic species number of ants across Mexico. It also documents the presence of one species newly recorded in Mexico and 19 new state-based records of 14 species from central and north Mexico. No surveys have been performed in most of the localities where we report those records, suggesting the need for a higher sampling effort across the country. We present an ant species richness estimation and a narrow endemic ant species estimation in a grid of 0.5 degrees in Mexico. Stenamma schmitii is recorded for the first time from Mexico. Additionally, new state-based records of Azteca velox, Dorymyrmex insanus, Camponotus coruscus, Camponotus striatus, Formica propatula, Lasius latipes, Neivamyrmex melanocephalus, Neivamyrmex rugulosus, Syscia augustae, Atta texana, Cephalotes scutulatus, Crematogaster crinosa and Temnothorax andrei are recorded.

The synthesis of comprehensive databases on the identity and distributions of alien organisms is a critical step to developing informed invasion management plans and identifying areas that are data-deficient. Here, we assembled all available records of alien ant distributions for Mexico, based on the literature, databases and unpublished data for a period ranging from 1855 to 2019; we compiled 967 records for 42 ant species non-native to Mexico, distributed across 438 localities. For the first time, we present mapped records and the distribution database of alien ants which is available through The Global Ant Biodiversity Informatics database at www.antmaps.org . The most commonly recorded species were Paratrechina longicornis, Monomorium pharaonis and Anoplolepis gracilipes. The states with the most records were Veracruz, Chiapas, Jalisco and Quintana Roo. The alien ants were most frequently encountered in urban areas (372 records) and in deciduous forest habitats (220). We provide summary of their distribution patterns and other related information useful for the control of these species in Mexico.

AIM: The latitudinal diversity gradient is the dominant pattern of life on Earth, but a consensus understanding of its origins has remained elusive. The analysis of recently diverged, hyper-rich invertebrate groups provides an opportunity to investigate latitudinal patterns with the statistical power of large trees while minimizing potentially confounding variation in ecology and history. Here, we synthesize global phylogenetic and macroecological data on a hyperdiverse (>1100 species) ant radiation, Pheidole , and evaluate the roles of three general explanations for the latitudinal gradient: variation in diversification rate, tropical conservatism, and ecological regulation. LOCATION: Global. TIME PERIOD: The past 35 million years. MAJOR TAXA STUDIED: The hyperdiverse ant genus Pheidole Westwood. METHODS: We assembled geographic data for 1499 species and morphospecies, and inferred a dated phylogeny of Pheidole of 449 species, including 150 species newly sequenced for this study. We tested correlations between diversification rate and latitude with BAMM, HiSSE, GeoSSE, and FiSSE, and examined patterns of diversification as Pheidole spread around the globe. RESULTS: We found that Pheidole diversification occurred in series of bursts when new continents were colonized, followed by a slowdown in each region. There was no evidence of systematic variation of net diversification rates with latitude across any of the methods. Additionally, we found latitudinal affinity is moderately conserved with a Neotropical ancestor and phylogenetic inertia alone is sufficient to produce the gradient pattern. MAIN CONCLUSIONS: Overall our results are consistent with tropical conservatism explaining the diversity gradient, while providing no evidence that diversification rate varies systematically with latitude. There is evidence of ecological regulation on continental scales through the pattern of diversification after colonization. These results shed light on the mechanisms underlying the diversity gradient, while contributing toward a much-needed invertebrate perspective on global biodiversity dynamics.

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In our recent publication (Sharma et al., 2017), we tested the hypothesis that eggs attached to the legs of male Podoctidae (Opiliones, Laniatores) constituted a case of paternal care, using molecular sequence data in tandem with multiple sequence alignments to test the prediction that sequences of the eggs and the adults that carried them would indicate conspecific identity. We discovered that the sequences of the eggs belonged to spiders, and thus rejected the paternal care hypothesis for these species. Machado and Wolff (2017) recently critiqued our work, which they regarded as a non-critical interpretation and over-reliance on molecular sequence data, and defended the traditional argument that the eggs attached to podoctids are in fact harvestman eggs. Here we show that additional molecular sequence data also refute the identity of the eggs as conspecific harvestman eggs, using molecular cloning techniques to rule out contamination. We show that individual gene trees consistently and reliably place the egg and adult sequences in disparate parts of the tree topology. Phylogenetic methods consistently place all egg sequences within the order Araneae (spiders). We submit that evidence for the paternal care hypothesis based on behavioral, morphological, and natural history approaches is either absent or insufficient for concluding that the eggs of podoctids are conspecific.

The Malay Archipelago and the tropical South Pacific (hereafter the Indo-Pacific region) are considered biodiversity hotspots, yet a general understanding of the origins and diversification of species-rich groups in the region remains elusive. We aimed to test hypotheses for the evolutionary processes driving insect species diversity in the Indo-Pacific using a higher-level and comprehensive phylogenetic hypothesis for an ant clade consisting of seven genera. We estimated divergence times and reconstructed the biogeographical history of ant species in the Prenolepis genus-group (Formicidae: Formicinae: Lasiini). We used a fossil-calibrated phylogeny to infer ancestral geographical ranges utilizing a biogeographic model that includes founder-event speciation. Ancestral state reconstructions of the ants' ecological preferences, and diversification rates were estimated for selected Indo-Pacific clades. Overall, we report that faunal interchange between Asia and Australia has occurred since at least 20–25 Ma, and early dispersal to the Fijian Basin happened during the early and mid-Miocene (ca. 10–20 Ma). Differences in diversification rates across Indo-Pacific clades may be related to ecological preference breadth, which in turn may have facilitated geographical range expansions. Ancient dispersal routes suggested by our results agree with the palaeogeography of the region. For this particular group of ants, the rapid orogenesis in New Guinea and possibly subsequent ecological shifts may have promoted their rapid diversification and widespread distribution across the Indo-Pacific.

Mexico is one of the most biodiverse countries in the world, with an important proportion of endemism mainly because of the convergence of the Nearctic and Neotropical biogeographic regions, which generate great diversity and species turnover at different spatial scales. However, most of our knowledge of the Mexican ant biota is limited to a few well-studied taxa, and we lack a comprehensive synthesis of ant biodiversity information. For instance, most of the knowledge available in the literature on Mexican ant fauna refers only to species lists by states, or is focused on only a few regions of the country, which prevents the study of several basic and applied aspects of ants, from diversity and distribution to conservation. Our aims in this data paper are therefore (1) to compile all the information available regarding ants across the Mexican territory, and (2) to identify major patterns in the gathered data set and geographic gaps in order to direct future sampling efforts. All records were obtained from raw data, including both unpublished and published information. After exhaustive filtering and updating information and synonyms, we compiled a total of 21,731 records for 887 ant species distributed throughout Mexico from 1894 to 2018. These records were concentrated mainly in the states of Chiapas (n = 6,902, 32.76%) and Veracruz de Ignacio de la Llave (n = 4,329, 19.92%), which together comprise half the records. The subfamily with the highest number of records was Myrmicinae (n = 10,458 records, 48.12%), followed by Formicinae (n = 3,284, 15.11%) and Ponerinae (n = 1,914, 8.8%). Most ant records were collected in the Neotropical region of the country (n = 12,646, 58.19%), followed by the Mexican transition zone (n = 5,237, 24.09%) and the Nearctic region (n = 3,848, 17.72%). Native species comprised 95.46% of the records (n = 20,745). To the best of our knowledge, this is the most complete data set available to date in the literature for the country. We hope that this compilation will encourage researchers to explore different aspects of the population and community research of ants at different spatial scales, and to aid in the establishment of conservation policies and actions. There are no copyright restrictions. Please cite this data paper when using its data for publications or teaching events.

Aim The fundamental biogeographical processes of colonization, speciation and extinction shape island biotas in space–time. On oceanic islands, area and isolation affect these processes and resulting biodiversity patterns. In the Anthropocene, a new human-mediated colonization dynamic is altering insular ecosystems world-wide. Here, we test predictions about the roles of archipelago area and isolation in structuring ant diversity patterns through effects on both natural and anthropogenic biogeographical processes. Location Tropical Pacific islands. Methods We compiled a comprehensive data set of ant faunal compositions across tropical Pacific archipelagos. Using regression analysis we evaluated the bivariate and interactive effects of area and isolation on the number of colonizing lineages, native species, endemic species, exotic species and total richness in the archipelago. Results There is a strong species–area effect and a much more modest isolation effect on total ant species richness across the Pacific archipelagos. The number of colonizing lineages of each archipelago is strongly driven by the isolation of the archipelago. Endemic species are present in large archipelagos of low and intermediate isolation. The most remote archipelagos are nearly devoid of endemic lineages and their ant faunas are largely composed of Pacific Tramp species and exotics brought from outside the Pacific region. Main conclusions The prominent species–area curve in Pacific ants emerged over time through multiple processes. The colonization of lineages is determined primarily by isolation, with few or no lineages reaching remote archipelagos. Cladogenesis mediates the isolation effect and increases the area effect through the differential radiation of lineages in large archipelagos. In the Anthropocene, the assembly of the species–area relationship has accelerated dramatically through human-mediated colonization. Overall, our results support a view that species–area curves reflect regulating limits on species richness that scale with area, but that multiple biogeographical processes can occur to achieve these limits.

AimThe latitudinal diversity gradient is the dominant pattern of life on Earth, but a consensus understanding of its origins has remained elusive. The analysis of recently diverged, hyper-rich invertebrate groups provides an opportunity to investigate latitudinal patterns with the statistical power of large trees while minimizing potentially confounding variation in ecology and history. Here, we synthesize global phylogenetic and macroecological data on a hyperdiverse (>1100 species) ant radiation, Pheidole, and evaluate the roles of three general explanations for the latitudinal gradient: variation in diversification rate, tropical conservatism, and ecological regulation.LocationGlobal.Time PeriodThe past 35 million years.Major taxa studiedThe hyperdiverse ant genus Pheidole Westwood.MethodsWe assembled geographic data for 1499 species and morphospecies, and inferred a dated phylogeny of Pheidole of 449 species, including 150 species newly sequenced for this study. We tested correlations between diversification rate and latitude with BAMM, HiSSE, GeoSSE, and FiSSE, and examined patterns of diversification as Pheidole spread around the globe.ResultsWe found that Pheidole diversification occurred in series of bursts when new continents were colonized, followed by a slowdown in each region. There was no evidence of systematic variation of net diversification rates with latitude across any of the methods. Additionally, we found latitudinal affinity is moderately conserved with a Neotropical ancestor and phylogenetic inertia alone is sufficient to produce the gradient pattern.Main ConclusionsOverall our results are consistent with tropical conservatism explaining the diversity gradient, while providing no evidence that diversification rate varies systematically with latitude. There is evidence of ecological regulation on continental scales through the pattern of diversification after colonization. These results shed light on the mechanisms underlying the diversity gradient, while contributing toward a much-needed invertebrate perspective on global biodiversity dynamics.

Highly seasonal conditions of tropical dry forests determine the temporal patterns of insect abundance. However, density-independent factors such as natural disturbances can abruptly change environmental conditions, affecting insect populations. We address the effects of the Hurricane Patricia (category 5) on species density and abundance of three feeding guilds of herbivorous insects (sap-sucking, folivorous beetles and xylophagous) and predatory beetles associated to the canopy of a tropical dry forest. Hurricane Patricia has been the strongest tropical hurricane ever reported in the Western Hemisphere. Herbivorous insects (sap-sucking and xylophagous) and predatory beetles increased in species density and abundance in the following months after the hurricane, compared to samples before it. The positive response of sap-sucking insects to Hurricane Patricia was probably related to an increase in the availability of new shoots and leaf meristems after the natural coppicing by the hurricane, while xylophagous guild seems to have been positively affected by the increase in the amount and diversity of deadwood resources. The positive response of predatory beetles may be the result of a bottom-up effect due to a greater availability of arthropod preys after the hurricane. We demonstrated that catastrophic hurricane disturbances could be important events that temporarily increase the species density and abundance of insects in tropical dry forests.

Aim We sought to reconstruct the biogeographical structure and dynamics of a hyperdiverse ant genus, Pheidole, and to test several predictions of the taxon cycle hypothesis. Using large datasets on Pheidole geographical distributions and phylogeny, we (1) inferred patterns of biogeographical modularity (clusters of areas with similar faunal composition), (2) tested whether species in open habitats are more likely to be expanding their range beyond module boundaries, and (3) tested whether there is a bias of lineage flow from high- to low-diversity areas. Location The Old World. Methods We compiled and jointly analysed a comprehensive database of Pheidole geographical distributions, the ecological affinities of different species, and a multilocus phylogeny of the Old World radiation. We used network modularity methods to infer biogeographical structure in the genus and comparative methods to evaluate the hypotheses. Results The network analysis identified eight biogeographical modules, and a suite of species with anomalous ranges that are statistically more likely to occur in open habitat, supporting the hypothesis that open habitats promote range expansion. Phylogenetic analysis shows evidence for a cascade pattern of colonization from Asia to New Guinea to the Pacific, but no ‘upstream’ colonization in the reverse direction. Main conclusions The distributions of Pheidole lineages in the Old World are highly modular, with modules generally corresponding to biogeographical regions inferred in other groups of organisms. However, some lineages have expanded their ranges across module boundaries, and these species are more likely to be adapted to open habitats rather than interior forest. In addition, there is a cascade pattern of dispersal from higher to lower diversity areas during these range expansions. Our findings are consistent with the taxon cycle hypothesis, although they do not rule out alternative interpretations.

The relationship between levels of dominance and species richness is highly contentious, especially in ant communities. The dominance-impoverishment rule states that high levels of dominance only occur in species-poor communities, but there appear to be many cases of high levels of dominance in highly diverse communities. The extent to which dominant species limit local richness through competitive exclusion remains unclear, but such exclusion appears more apparent for non-native rather than native dominant species. Here we perform the first global analysis of the relationship between behavioral dominance and species richness. We used data from 1,293 local assemblages of ground-dwelling ants distributed across five continents to document the generality of the dominance-impoverishment rule, and to identify the biotic and abiotic conditions under which it does and does not apply. We found that the behavioral dominance–diversity relationship varies greatly, and depends on whether dominant species are native or non-native, whether dominance is considered as occurrence or relative abundance, and on variation in mean annual temperature. There were declines in diversity with increasing dominance in invaded communities, but diversity increased with increasing dominance in native communities. These patterns occur along the global temperature gradient. However, positive and negative relationships are strongest in the hottest sites. We also found that climate regulates the degree of behavioral dominance, but differently from how it shapes species richness. Our findings imply that, despite strong competitive interactions among ants, competitive exclusion is not a major driver of local richness in native ant communities. Although the dominance-impoverishment rule applies to invaded communities, we propose an alternative dominance-diversification rule for native communities.

Nonequilibrium dynamics and non-neutral processes, such as trait-dependent dispersal, are often missing from quantitative island biogeography models despite their potential explanatory value. One of the most influential nonequilibrium models is the taxon cycle, but it has been difficult to test its validity as a general biogeographical framework. Here, we test predictions of the taxon cycle model using six expected phylogenetic patterns and a time-calibrated phylogeny of Indo-Pacific Odontomachus (Hymenoptera: Formicidae: Ponerinae), one of the ant genera that E.O. Wilson used when first proposing the hypothesis. We used model-based inference and a newly developed trait-dependent dispersal model to jointly estimate ancestral biogeography, ecology (habitat preferences for forest interiors, vs. "marginal" habitats, such as savannahs, shorelines, disturbed areas) and the linkage between ecology and dispersal rates. We found strong evidence that habitat shifts from forest interior to open and disturbed habitats increased macroevolutionary dispersal rate. In addition, lineages occupying open and disturbed habitats can give rise to both island endemics re-occupying only forest interiors and taxa that re-expand geographical ranges. The phylogenetic predictions outlined in this study can be used in future work to evaluate the relative weights of neutral (e.g., geographical distance and area) and non-neutral (e.g., trait-dependent dispersal) processes in historical biogeography and community ecology.

Ronald M. Clouse, Benjamin D. Blanchard, Rebecca Gibson, Ward C. Wheeler, Milan Janda (2016): Taxonomic updates for some confusing Micronesian species of Camponotus (Hymenoptera: Formicidae: Formicinae). Myrmecological News 23: 139-152, DOI: 10.5281/zenodo.164974

Camponotus tol sp.n. GIBSON & CLOUSE (Figs. 30 ­ 35) Type material: Holotype major worker. Federated States of Micronesia: Chuuk, Tol Island at 120 m (7o 19' 27.3" N, 151o 36' 50.6" E), leg. R. Clouse, P. Sharma, and Techuo family. Paratypes, (3 major workers, 9 minor workers), same collection data as holotype. Twelve additional minors stored in 95% EtOH, as well as two minors each with one leg removed and used for DNA extraction, also same collection data as holotype. All specimens are deposited in the Museum of Comparative Zoology, Harvard University, Massachusetts, USA. Description of holotype major worker (Figs. 30 ­ 32): EL 0.48, EW 0.30, FCL 1.05, HL 2.05, HW 1.84, ML 2.51, MTL 1.54, PH 0.54, PL 0.60, SL 1.77; CI 90, SI 96. Mandible outer margin gently curved to an apex of about 75 degrees, the masticatory margin straight in front view. Mandibles tightly closed, masticatory margin with five visible teeth that gradually diminish in size from apex. Clypeus continuing anteriorly past mandibular insertions a distance slightly less than length of apical tooth, then straight across. Posterior clypeus curved anteriorly forming bilobed appearance, antennal insertions separated from clypeus by a distance almost equal to the distance from nearest clypeal margin to clypeal midpoint. Head slightly longer than wide. Vertex weakly concave. In frontal view eyes located halfway between posterior clypeal margin and vertex; inner margins halfway between frontal lobes and sides of head; eyes not extending past lateral edge. Antennae 12­segmented. Antennal scape length extending past the vertex by a distance of 2 ­ 3 times the width of the scape at the apex. Mesosoma in profile gently sloping from anterior pronotum to dorsal propodeum, with moderate propodeal declivity. Color: Distinct bicoloration: head mostly glossy brown, mesosoma uniform light yellow­brown, gaster glossy brown. Gradual lightening from vertex down to mandibles. Vertex to posterior clypeus same glossy brown as gaster. Black outlining along frontal carina. Anterior clypeus to mandibular insertions light yellow­brown. Mandibles lighter brown than vertex down to posterior clypeus. Teeth of mandibles, scrobes, sutures, and joints on the head darker than surrounding cuticle. Each gastral tergite with hyaline margin along posterior fifth. Pilosity: Layer of short, recumbent, light hairs all over head. Long, yellow, standing hairs numerous on front, back, and sides of head. In frontal view, area between eyes and frontal carina with two rows of long, standing hairs extending from vertex to mid­clypeus. Row of long hairs extending across anterior clypeal edge. From dorsal view, mesosoma with two side­by­side groups of standing hairs on pronotum, four long hairs with some small hairs per group; one group of standing hairs on mesonotum, with three long hairs and some small hairs; two groups of standing hairs clustered on propodeum, with three long hairs per group; layer of short recumbent hairs all over each appendage, decreasing in length from trochanter to tarsus. Propleuron standing hairs indistinct but present. Each gastral tergite with 20 to 30 long, yellow, standing hairs encircling tergite immediately before hyaline margin along posterior edge; 10 to 20 longer standing hairs encircling tergite halfway between hyaline margin and posterior edge of previous tergite. Standing hairs on hind femur indistinct but present. Sculpturing: Head and gaster surface glossy; genae weakly punctured. Mesosoma surface smooth and shiny, although not glossy. Description of paratypes: Majors closely resembling holotype except vertex and mandibles more reddish­brown; overall slightly larger (ML 2.6 ­ 2.75 and HW 1.88 ­ 1.95); CI same (90) but SI smaller (87 ­ 92), indicating consistency in head shape and scape absolute length in larger specimens. Minors closely resembling majors in coloration and pilosity. Slightly smaller than majors (ML 2.00 ­ 2.25) and with significantly narrower heads and longer, more variable scapes (CI 76 ­ 80, SI 157 ­ 172). Scapes extending beyond vertex by a range of 25% ­ 50% of total scape length. Posterior clypeus lighter brown than holotype. Eyes extending past lateral outline of head. One minor with open mandibles has six visible teeth on masticatory margin that gradually diminish in size from the apex. Measurements of minor collected with holotype and pictured in Figures 33 ­ 35: EL 0.45, EW 0.33, FCL 0.82, HL 1.34, HW 1.05, ML 2.08, MTL 1.31, PH 0.45, PL 0.45, SL 1.73; CI 78, SI 165. Differential diagnosis: The only specimens from Chuuk that might be mistaken for Camponotus tol sp.n. are very dark, small C. micronesicus sp.n., but C. tol sp.n. has hairs on the propleuron and hind femur, and C. micronesicus sp.n. does not. Among other similar species in Micronesia, C. tol sp.n. is not as starkly bicolorous as C. eperiamorum, and it is approximately 75% the overall size of C. kubaryi stat. rev. Habitat: This species was collected from low­elevation, mixed agroforest (120 m a.s.l.) on Tol Island in Chuuk Lagoon. This island is the largest in the region, and reaches a maximum elevation of 439 m, but it shows evidence of agroforesty and agro­native mixed forest at all elevations. Specimens were collected from one colony and appeared to be less abundant on the island than Camponotus micronesicus sp.n. Etymology: The specific epithet is a noun in apposition to the genus that refers to the type locality, Tol Island (pronounced " tōl," as in the common word "toll"). Tol is the largest island inside the main atoll and island group of Chuuk State in the Federated States of Micronesia. The island is sometimes written as "Ton," as the phonemes "l" and "n" are not distinct in Chuukese. Comments: Camponotus tol is part of a larger clade in the molecular phylogeny (Clade IV; Fig. 2) that includes C. chloroticus, C. kubaryi stat. rev., an undescribed species collected in Papua New Guinea and Indonesia, and an endemic species found on the nearby Micronesian island of Pohnpei, C. eperiamorum (CLOUSE 2007b, CLOUSE & al. 2015). These species are all larger than C. tol, and they are also distinguished by their coloration: C. chloroticus and the unnamed species are lighter, C. kubaryi stat. rev. is darker, and C. eperiamorum contrasts more in shade among the mesosoma, head, and gaster. All of these species have the distinctive hairs on the propleuron and hind femur, but only C. tol sp.n. has such a distinctive double row of long hairs down the front of the head. Overall, C. tol sp.n. is distinct as a dusky, small, member of the Camponotus maculatus ­like species in the Pacific.

Camponotus micronesicus sp.n. BLANCHARD & CLOUSE (Figs. 21 �� 29; Tab. 4) Type material: Holotype major worker, Federated States of Micronesia: Pohnpei Island, Nah Islet, 1 m a.s.l. (6�� 51' 11.2" N, 158�� 21' 16.3" E), 15. IX. 2010, leg. R. Clouse and P. Sharma. Paratypes (8 major workers, 8 minor workers), detailed collection information provided in Table 4. All specimens are deposited in the Museum of Comparative Zoology, Harvard University, Massachusetts, USA. Description of holotype major worker (Figs. 21 �� 23): EL 0.55, EW 0.40, FCL 1.30, HL 2.50, HW 2.25, ML 3.00, MTL 1.80, PH 0.85, PL 0.65, SL 1.95; CI 90, SI 87. Masticatory margin with six teeth that diminish in size unevenly from the apical tooth; teeth 2 �� 5 similar in size, sixth tooth (not visible when mandibles closed) distinctly smaller. Clypeus continuing anteriorly past mandibular insertions one fourth its total height, then slightly convex. Posterior margin of clypeus straight to slightly concave, antennal insertions separated from clypeus by a distance almost equal to the distance from nearest clypeal margin to clypeal midpoint. Posterior head margin weakly concave to nearly flat. In frontal view: eyes located halfway between posterior clypeal margin and vertex; inner eye margins halfway between frontal lobes and sides of head; eyes not extending past lateral margin of head. Antennae 12�� segmented. Antennal scape reaching past the posterior margin of head by a distance 1 �� 2 times the width of the scape at its apex. Mesosoma in profile gently sloping from anterior pronotum to dorsal propodeum, with slightly steep�� er propodeal declivity. Petiolar node sloping evenly up to and down from its apex. Color: Gaster and mesosoma uniformly yellow��orange, the head ranging from slightly to considerably darker orange��brown. Vertex to posterior frons and anterior frontal lobes orange brown, anterior frons and clypeus yelloworange; central posterior head and frontal carina dark orange brown. Mandibles dark reddish brown, lighter at insertions, mandibular teeth black. Each gastral tergite with hyaline margin along posterior fifth. Pilosity: Layer of small, recumbent, light hairs all over head. Longer, standing hairs numerous on front, back, and sides of head, longer at vertex and more dense on clypeus. From frontal view, area between eyes and frontal carina, two rows of long, standing hairs extending from vertex to mid��clypeus. Dorsal pronotum, mesonotum and vertex of propodeal angle with long standing hairs. Propleuron standing hairs lacking. Each gastral tergite with 10 to 20 long standing hairs encircling tergite immediately before hyaline margin along posterior edge; 5 to 10 longer standing hairs encircling tergite halfway between hyaline margin and posterior edge of previous tergite. Hind femur standing hairs lacking. Sculpturing: Head, mesosoma, and gaster surface glossy; genae, clypeus, and mandibles weakly punctured. Description of paratypes: Majors resembling holotype in coloration and pilosity, mesosoma ranging from light yellow to orange��yellow, heads sometimes distinctly darker than mesosoma but not brown. Generally same size or smaller than holotype (ML 2.65 �� 3.00, HW 1.85 �� 2.30), with similar head shapes (CI 86 �� 92). Relative scape lengths more variable (SI 83 �� 98). Minors approximately 15% �� 20% smaller than majors (ML 2.2 �� 2.5) but with much narrower heads (CI 67 �� 74) and proportionally longer, more variable scapes (SI 175 �� 191). Mesosoma coloration more consistently light yellow with similar or only slightly darker heads. Occipital carina always present. Measurements of minor worker collected with holotype and shown in Figs. 24 �� 26: EL 0.40, EW 0.30, FCL 0.95, HL 1.35, HW 1.00, ML 2.30, MTL 1.50, PH 0.51, PL 0.50, SL 1.85; CI 74, SI 185. Differential diagnosis: In Micronesia there are four closely related Camponotus species that resemble C. maculatus (characters for which are described and illustrated in MCARTHUR & LEYS 2006): C. micronesicus sp.n., C. eperiamorum, C. kubaryi stat. rev., and C. tol sp.n. Of these species, only C. micronesicus sp.n. is mostly concolorous yellow��orange, and with the other three species being island endemics, C. micronesicus sp.n. can be collected alongside only one of them at a time (CLOUSE 2007a). In Melanesia collections of C. micronesicus sp.n. are near those of three other described C. maculatus ��like species: C. choloroticus, C. novaehollandiae, and C. humilior. However, only the latter two share the lack of propleuron and hind femur standing hairs with C. micronesicus sp.n., and although uniformly yellow��orange specimens of C. humilior and C. novaehollandiae are occasionally seen, both species tend to be strongly bicolorous. Moreover, the head length and width measurements for both majors and minors of C. novaehollandiae are approximately 25% larger than those of C. micronesicus sp.n., and we have no evidence that the ranges of these species overlap exactly with C. micronesicus sp.n. (C. humilior and C. novaehollandiae enter New Guinea only along the southern coast, where we have no C. micronesicus sp.n. collections). The most difficult cases of identification will be between Camponotus micronesicus sp.n. and C. chloroticus specimens collected from Vanuatu, where they are sympatric and look nearly identical. Our best advice for identification is to check for hairs on the propleuron and hind femur, which should be absent in C. micronesicus sp.n. and present in C. chloroticus. In addition, C. chloroticus minors usually have a larger cephalic index (74 �� 8 2 vs.67 �� 74) and smaller scape index (123 �� 154 vs. 175 �� 191), both resulting from having a wider head; majors show the same trend, although those of C. chloroticus are highly variable (Tab. 2). Habitat: This species is found in disturbed forest, both natural (e.g., reef islets, which are washed over during heavy storms) and anthropogenic (e.g., agroforest at low and middle elevations). Etymology: This species is named for Micronesia, the predominant region where it is found. Comments: All paratypes are listed in Table 4 by their terminal name in CLOUSE & al. (2015). A sample of some of the variation in head shape of major workers from across Micronesia is shown in Figures 27 �� 29., Published as part of Ronald M. Clouse, Benjamin D. Blanchard, Rebecca Gibson, Ward C. Wheeler & Milan Janda, 2016, Taxonomic updates for some confusing Micronesian species of Camponotus (Hymenoptera: Formicidae: Formicinae), pp. 139-152 in Myrmecological News 23 on pages 147-149, DOI: 10.5281/zenodo.164974, {"references":["MCARTHUR, A. J. & LEYS, R. 2006: A morphological and molecular study of some species in the Camponotus maculatus group (Hymenoptera: Formicidae) in Australia and Africa, with a description of a new Australian species. - Myrmecologische Nachrichten 8: 99 - 110.","CLOUSE, R. 2007 a: The ants of Micronesia (Hymenoptera: Formicidae). - Micronesica 39: 171 - 295.","CLOUSE, R. M., JANDA, M., BLANCHARD, B., SHARMA, P., HOFFMANN, B. D., ANDERSEN, A. N., CZEKANSKI- MOIR, J. E., KRUSHELNYCKY, P., RABELING, C., WILSON, E. O., ECONOMO, E. P., SARNAT, E. M., GENERAL, D. M., ALPERT, G. D. & WHEELER, W. C. 2015: Molecular phylogeny of Indo-Pacific carpenter ants (Hymenoptera: Formicidae, Camponotus) reveals waves of dispersal and colonization from diverse source areas. - Cladistics 31: 424 - 437."]}

Camponotus kubaryi stat. rev. MAYR , 1876 (Figs. 11, 12, 14; Tab. 2) Combination in Camponotus (Myrmoturba): FOREL 1914. Combination in Camponotus (Tanaemyrmex): EMERY 1925. Subspecies of Camponotus maculatus: EMERY 1896. Subspecies of Camponotus irritans: EMERY 1920, KARAVAIEV 1929. Comments: MAYR' S (1876) description of this species consists of a few lines that describe it as 7.5 �� 9.5 mm long, reddish��brown, and with a darker head, mandibles, and antennae, plus some description of characters that do little to distinguish it beyond being in the genus Camponotus. Although this species is restricted to the islands of the Republic of Palau, which constitute an area of less than 500 km 2 over 800 km away from any major landmass, it still shows noticeable morphological variation (for example, the head shapes and colors of syntypes shown in Figs. 11, 12). This may be due to the fact that the country is comprised of over 200 small limestone islands, which may divide this species into many somewhat isolated populations. Nonetheless, despite variation in tone and shade, and the degree to which the head is tapered and the vertex concave, it is the only Camponotus in Micronesia with a large, dark head, and its restriction to Palau makes identification straightforward. Still, we add to the original description this summary from our morphological examinations, combining syntypes and modern specimens. Majors: EL 0.59 (range 0.56 �� 0.60), EW 0.43 (0.40 �� 0.45), FCL 1.49 (1.45 �� 1.55), HL 2.75 (2.56 �� 2.95), HW 2.60 (2.40 �� 2.75), ML 3.35 (3.16 �� 3.55), MTL 2.02 (1.97 �� 2.10), PH 0.96 (0.73 �� 1.10), PL 0.72 (0.56 �� 0.85), SL 2.15 (2.10 �� 2.20); CI 94 (93 �� 96), SI 83 (80 �� 88); mesosoma medium yellow, head and gaster much darker, approaching black; head tapering and vertex distinctly concave; standing hairs present on propleuron and hind femur. Minors: EL 0.46 (0.45 �� 0.46), EW 0.36 (0.35 �� 0.36), FCL 1.17 (1.1 0 �� 1.24), HL 1.71 (1.60 �� 1.82), HW 1.35 (1.20 �� 1.50), ML 2.73 (2.45 �� 3.00), MTL 2.09 (1.70 �� 2.48), PH 0.77 (0.70 �� 0.84), PL 0.48 (0.36 �� 0.60), SL 2.01 (2.00 �� 2.02); CI 79 (75 �� 82), SI 150 (134 �� 167); mesosoma light yellow, head and gaster much darker, approaching black; head tapering and vertex convex. These characters match those of three other specimens not used in this study but described in CLOUSE (2007 a) un�� der the species code "sp. 1945 ". One of the majors is shown in Figure 14, and the specimens can now be securely identified as C. kubaryi stat. rev. The two majors had total lengths of 8.2 and 7.9 mm, matching MAYR' S original description, and the following other measurements are very similar to those of the specimens we examined here: HL 3.00, HW 2.83, SL 2.30, CI 94, and SI 81 for the larger specimen, and HL 2.73, HW 2.63, SL 2.07, CI 96, and SI 87 for the smaller. Likewise, the minor specimen of "sp. 1945 " is very similar to the ones here: HL 1.77, HW 1.33, SL 1.77, CI 75, and SI 133., Published as part of Ronald M. Clouse, Benjamin D. Blanchard, Rebecca Gibson, Ward C. Wheeler & Milan Janda, 2016, Taxonomic updates for some confusing Micronesian species of Camponotus (Hymenoptera: Formicidae: Formicinae), pp. 139-152 in Myrmecological News 23 on page 147, DOI: 10.5281/zenodo.164974, {"references":["MAYR, G. 1876: Die australischen Formiciden. - Journal des Museum Godeffroy 12: 56 - 115.","CLOUSE, R. 2007 a: The ants of Micronesia (Hymenoptera: Formicidae). - Micronesica 39: 171 - 295."]}

The taxonomy and systematics of the armored harvestmen (suborder Laniatores) are based on various sets of morphological characters pertaining to shape, armature, pedipalpal setation, and the number of articles of the walking leg tarsi. Few studies have tested the validity of these historical character systems in a comprehensive way, with reference to an independent data class, i.e., molecular sequence data. We examined as a test case the systematics of Podoctidae, a family distributed throughout the Indo-Pacific. We tested the validity of the three subfamilies of Podoctidae using a five-locus phylogeny, and examined the evolution of dorsal shape as a proxy for taxonomic utility, using parametric shape analysis. Here we show that two of the three subfamilies, Ibaloniinae and Podoctinae, are non-monophyletic, with the third subfamily, Erecananinae, recovered as non-monophyletic in a subset of analyses. Various genera were also recovered as non-monophyletic. As first steps toward revision of Podoctidae, the subfamilies Erecananinae Roewer, 1912 and Ibaloniinae Roewer, 1912 are synonymized with Podoctinae Roewer, 1912 new synonymies, thereby abolishing unsubstantiated subfamilial divisions within Podoctidae. We once again synonymize the genus Paralomanius Goodnight & Goodnight, 1948 with Lomanius Roewer, 1923 revalidated. We additionally show that eggs carried on the legs of male Podoctidae are not conspecific to the males, falsifying the hypothesis of paternal care in this group.

Summary 1. Species diversity of arboreal arthropods tends to increase during rainforest succession so that primary forest communities comprise more species than those from secondary vegetation, but it is not well understood why. Primary forests differ from secondary forests in a wide array of factors whose relative impacts on arthropod diversity have not yet been quantified. 2. We assessed the effects of succession-related determinants on a keystone ecological group, arboreal ants, by conducting a complete census of 1332 ant nests from all trees with diameter at breast height ‡ 5 cm occurring within two (unreplicated) 0AE32-ha plots, one in primary and one in secondary lowland forest in New Guinea. Specifically, we used a novel rarefaction-based approach to match number, size distribution and taxonomic structure of trees in primary forest communities to those in secondary forest and compared the resulting numbers of ant species. 3. In total, we recorded 80 nesting ant species from 389 trees in primary forest but only 42 species from 295 trees in secondary forest. The two habitats did not differ in the mean number of ant species per tree or in the relationship between ant diversity and tree size. However, the between-tree similarity of ant communities was higher in secondary forest than in primary forest, as was the between-tree nest site similarity, suggesting that secondary trees were more uniform in providing nesting microhabitats. 4. Using our rarefaction method, the difference in ant species richness between two forest types was partitioned according to the effects of higher tree density (22AE6%), larger tree size (15AE5%) and higher taxonomic diversity of trees (14AE3%) in primary than in secondary forest. The remaining difference (47AE6%) was because of higher beta diversity of ant communities between primary forest trees. In contrast, difference in nest density was explained solely by difference in tree density. 5. Our study shows that reduction in plant taxonomic diversity in secondary forests is not the main driver of the reduction in canopy ant species richness. We suggest that the majority of arboreal species losses in secondary tropical forests are attributable to simpler vegetation structure, combined with lower turnover of nesting microhabitats between trees.

What forces structure ecological assemblages? A key limitation to general insights about assemblage structure is the availability of data that are collected at a small spatial grain (local assemblages) and a large spatial extent (global coverage). Here, we present published and unpublished data from 51 ,388 ant abundance and occurrence records of more than 2,693 species and 7,953 morphospecies from local assemblages collected at 4,212 locations around the world. Ants were selected because they are diverse and abundant globally, comprise a large fraction of animal biomass in most terrestrial communities, and are key contributors to a range of ecosystem functions. Data were collected between 1949 and 2014, and include, for each geo-referenced sampling site, both the identity of the ants collected and details of sampling design, habitat type, and degree of disturbance. The aim of compiling this data set was to provide comprehensive species abundance data in order to test relationships between assemblage structure and environmental and biogeographic factors. Data were collected using a variety of standardized methods, such as pitfall and Winkler traps, and will be valuable for studies investigating large-scale forces structuring local assemblages. Understanding such relationships is particularly critical under current rates of global change. We encourage authors holding additional data on systematically collected ant assemblages, especially those in dry and cold, and remote areas, to contact us and contribute their data to this growing data set.

Ants are extremely abundant in lowland tropical forests where they are important predators, plant mutualists, and herbivores. Their complex role in tropical plant-insect food webs can be best assessed by experimental manipulation of their abundance. Historically, ant exclusion experiments have had a small-scale focus, such as single trees. Here, we test a new 'whole-forest' method of ant exclusion, using treated canopy bait stations, in a diverse tropical rainforest in New Guinea. 2. We conducted a 10-month manipulative experiment in primary and secondary rainforests. In each forest type, a 625 m 2 treatment plot was isolated from the sur- rounding forest and 135 bait stations treated with fipronil, S-methoprene, and hydram- ethylnon were placed in trees to suppress ants. Ant activity was monitored in the forest canopy and understorey with an additional 65 stations in treatment and control plots. 3. We achieved a dramatic decline in ant abundance in treatment plots compared with controls in both forest types, with an average decrease in ant numbers per station of 82.4% in primary and 91.2% in secondary forest. In particular, native dominant species Oecophylla smaragdina, Anonychomyrma cf. scrutator in primary forest, and invasive Anoplolepis gracilipes in secondary forest were greatly affected. In contrast, Tapinoma melanocephalum flourished in treatment plots, perhaps benefiting from reduced competition from other ant species. 4. Our study demonstrates that it is possible to selectively eradicate most of the foraging ants in a structurally complex tropical forest. We propose whole-forest manip- ulation as a novel tool for studying the role of ants in shaping plant-insect food webs.

The ant assemblages in two common tree species in primary lowland forest of New Guinea were explored using direct canopy access and tuna bait traps. The 19 trees investigated were occupied by 21 ant species of which 18 were canopy inhabitants. On average only 3.6 ant species per tree and 3 species per bait were found. Height of bait position was positively related to ant species richness, with the upper parts of the canopy being occupied by the highest number of species. On the other hand, tree species and study site did not have any effect on ant species richness nor on structure of the ant assemblages. Ant species appeared to be distributed randomly and we did not detect any effect of distance on similarity of ant assemblage occurring on the trees. The dominant species (Crematogaster polita) had certain negative effects on the presence of some species at food sources co-occurring at the same tree, but it did co-occur with the other ants to some extent as well. The majority of species found in the canopy were generalist omnivores (depending mainly on trophobionts or plant exudates).

A central focus of ecology and biogeography is to determine the factors that govern spatial variation in biodiversity. Here, we examined patterns of ant diversity along climatic gradients in three temperate montane systems: Great Smoky Mountains National Park (USA), Chiricahua Mountains (USA), and Vorarlberg (Austria). To identify the factors which potentially shape these elevational diversity gradients, we analyzed patterns of community phylogenetic structure (i.e. the evolutionary relationships among species coexisting in local communities). We found that species at low-elevation sites tended to be evenly dispersed across phylogeny, suggesting that these communities are structured by interspecific competition. In contrast, species occurring at high-elevation sites tended to be more closely related than expected by chance, implying that these communities are structured primarily by environmental filtering caused by low temperatures. Taken together, the results of our study highlight the potential role of niche constraints, environmental temperature, and competition in shaping broad-scale diversity gradients. We conclude that phylogenetic structure indeed accounts for some variation in species density, yet it does not entirely explain why temperature and species density are correlated.

Leptogenopapus mirabilis, gen. n., sp. n. is described based on the single male collected from foraging colony of Leptogenys breviceps Viehmeyer in Papua New Guinea. The genus is a member of the tribe Lomechusini (Coleoptera: Staphylinidae, Aleocharinae) and is most closely related to Leptogenoxenus Kistner. The list of all Staphylinidae associated with the ant genus Leptogenys Roger is given.

Ants in the genera Anochetus and Odontomachus belong to one of the largest clades in the subfamily Ponerinae, and are one of four lineages of ants possessing spring-loaded "trap-jaws." Here we present results from the first global species-level molecular phylogenetic analysis of these trap-jaw ants, reconstructed from one mitochondrial, one ribosomal RNA, and three nuclear protein-coding genes. Bayesian and likelihood analyses strongly support reciprocal monophyly for the genera Anochetus and Odontomachus. Additionally, we found strong support for seven trap-jaw ant clades (four in Anochetus and three in Odontomachus) mostly concordant with geographic distribution. Ambiguity remains concerning the closest living non-trap-jaw ant relative of the Anochetus+Odontomachus clade, but Bayes factor hypothesis testing strongly suggests that trap-jaw ants evolved from a short mandible ancestor. Ponerine trap-jaw ants originated in the early Eocene (52.5Mya) in either South America or Southeast Asia, where they have radiated rapidly in the last 30million years, and subsequently dispersed multiple times to Africa and Australia. These results will guide future taxonomic work on the group and act as a phylogenetic framework to study the macroevolution of extreme ant mouthpart specialization.

Insects are a major force in most ecosystems, yet in studies of biodiversity they often receive less attention than birds, mammals and plants. Two papers this week redress the balance. Novotny et al. studied some 500 species of lepidopteran caterpillars, beetles and fruit flies across 75,000 km2 of rain forest in Papua New Guinea. They found that most species of herbivorous insects were widely distributed. Species richness was high, as expected in the tropics, but the species found did not alter much even over hundreds of kilometres. Dyer et al. reached rather different conclusions from their work on hundreds of thousands of host-specificity feeding records for butterfly and moth caterpillars from areas ranging from Canada to Brazil. They found that the average number of tree species on which an insect species feeds was fewer in the tropics than in temperate parts of the New World, a confirmation of the latitudinal gradient in ecological specialization much discussed by biologists since the time of Darwin and Wallace. With apparently contradictory results such as these two reports, though, the discussion may run and run. A study of about 500 species of lepidopteran caterpillars, beetles and fruit flies details that that most species of herbivorous insects are widely distributed over 75,000 km2 of contiguous lowland rain forest in Papua New Guinea. Thus, although species richness was high, the species found did not alter much even over hundreds of kilometres despite habitat discontinuities and different geological terrains. Recent advances in understanding insect communities in tropical forests1,2 have contributed little to our knowledge of large-scale patterns of insect diversity, because incomplete taxonomic knowledge of many tropical species hinders the mapping of their distribution records3. This impedes an understanding of global biodiversity patterns and explains why tropical insects are under-represented in conservation biology. Our study of approximately 500 species from three herbivorous guilds feeding on foliage (caterpillars, Lepidoptera), wood (ambrosia beetles, Coleoptera) and fruit (fruitflies, Diptera) found a low rate of change in species composition (beta diversity) across 75,000 square kilometres of contiguous lowland rainforest in Papua New Guinea, as most species were widely distributed. For caterpillars feeding on large plant genera, most species fed on multiple host species, so that even locally restricted plant species did not support endemic herbivores. Large plant genera represented a continuously distributed resource easily colonized by moths and butterflies over hundreds of kilometres. Low beta diversity was also documented in groups with differing host specificity (fruitflies and ambrosia beetles), suggesting that dispersal limitation does not have a substantial role in shaping the distribution of insect species in New Guinea lowland rainforests. Similar patterns of low beta diversity can be expected in other tropical lowland rainforests, as they are typically situated in the extensive low basins of major tropical rivers similar to the Sepik–Ramu region of New Guinea studied here.

Phylogeny of ants of the tribe Lasiini ( Lasius , Acanthomyops , Prenolepis , Euprenolepis , Paratrechina , Pseudolasius , and Myrmecocystus ) was analysed using 81 morphological, ecological, and behavioural characters (for 41 species) and mitochondrial DNA sequences (COI, COII, tRNA-Leu; for 19 species). The free-living subgenus Lasius s. str. is paraphyletic with respect to the rest of genus; the traditional “genus” Acanthomyops should be considered a part of Lasius s. lat.; free-living subgenus Cautolasius is a member of the clade of socially parasitic Lasius ants (= Chtonolasius + Acanthomyops + Austrolasius + Dendrolasius ). The tree topology is congruent with two alternative scenarios of origin of the temporary social parasitism: (i) a single origin of the parasitic strategy in a derived subclade of Lasius and a secondary loss of this trait in Cautolasius , (ii) a parallel origin of the social parasitism within the clade of hypogeic Lasius ants (in Chtonolasius , and in Acanthomyops + Dendrolasius + Austrolasius ). Emery’s rule in the strict sense does not apply to this group because most parasites exploit any ecologically available, even phylogenetically distant host species. The parasitic strategy in Lasius could have originated from the aggressive interactions between cofounding queens during pleometric colony founding and/or from the secondary queen adoption.

We characterized a plant–caterpillar food web from secondary vegetation in a New Guinean rain forest that included 63 plant species (87.5% of the total basal area), 546 Lepidoptera species and 1679 trophic links between them. The strongest 14 associations involved 50% of all individual caterpillars while some links were extremely rare. A caterpillar randomly picked from the vegetation will, with ‡ 50% probability, (1) feed on one to three host plants (of the 63 studied), (2) feed on < 20% of local plant biomass and (3) have ‡ 90% of population concentrated on a single host plant species. Generalist species were quantitatively unimportant. Caterpillar assemblages on locally monotypic plant genera were distinct, while sympatric congeneric hosts shared many caterpillar species. The partitioning of the plant–caterpillar food web thus depends on the composition of the vegetation. In secondary forest the predominant plant genera were locally monotypic and supported locally isolated caterpillar assemblages.

Caterpillar assemblages feeding on two alien plants, Piper aduncum and P. umbellatum, were studied in lowland rainforest in Papua New Guinea and compared with assemblages from 69 species of native woody hosts, including congeneric P. macropiper. 2. Species richness of caterpillars feeding on P. aduncum (29 species per 1500 m 2 of foliage) and P. umbellatum (36 species) was higher than the median richness for the 69 native hosts (23 species). 3. The probability that a caterpillar species colonised alien Piper increased with its host range from 3% for the species feeding on a single plant family to 92% for the species with host range >10 plant families. 4. The assemblage on P. aduncum was dominated by a single species (Herpeto- gramma sp. near licarsisalis, Crambidae), which represented 48% of individuals, and also had a high proportion (34%) of rare species, collected as single individ- uals. This community structure was indistinguishable from that of a typical native host. In contrast, the P. umbellatum assemblage was unusual as no species represented >10% of individuals. 5. The aggressive invasion by P. aduncum of early successional vegetation is not explained by a competitive advantage due to low herbivore load, as the abundance of caterpillars feeding on it was comparable to that of native pioneer plants. 6. The caterpillar assemblage on P. aduncum demonstrated that an assemblage indistinguishable from native assemblages in density, species richness, and dominance structure (but not in host specificity) can originate from the existing species pool in lowland rainforests on a recently established tree species in

Ants that resemble Camponotus maculatus (Fabricius, 1782) present an opportunity to test the hypothesis that the origin of the Pacific island fauna was primarily New Guinea, the Philippines, and the Indo-Malay archipelago (collectively known as Malesia). We sequenced two mitochondrial and four nuclear markers from 146 specimens from Pacific islands, Australia, and Malesia. We also added 211 specimens representing a larger worldwide sample and performed a series of phylogenetic analyses and ancestral area reconstructions. Results indicate that the Pacific members of this group comprise several robust clades that have distinctly different biogeographical histories, and they suggest an important role for Australia as a source of Pacific colonizations. Malesian areas were recovered mostly in derived positions, and one lineage appears to be Neotropical. Phylogenetic hypotheses indicate that the orange, pan-Pacific form commonly identified as C. chloroticus Emery 1897 actually consists of two distantly related lineages. Also, the lineage on Hawai‘i, which has been called C. variegatus (Smith, 1858), appears to be closely related to C. tortuganus Emery, 1895 in Florida and other lineages in the New World. In Micronesia and Polynesia the C. chloroticus-like species support predictions of the taxon-cycle hypothesis and could be candidates for human-mediated dispersal. © The Willi Hennig Society 2014.

1. Species diversity of arboreal arthropods tends to increase during rainforest succession so that primary forest communities comprise more species than those from secondary vegetation, but it is not well understood why. Primary forests differ from secondary forests in a wide array of factors whose relative impacts on arthropod diversity have not yet been quantified. 2. We assessed the effects of succession-related determinants on a keystone ecological group, arboreal ants, by conducting a complete census of 1332 ant nests from all trees with diameter at breast height ≥ 5 cm occurring within two (unreplicated) 0·32-ha plots, one in primary and one in secondary lowland forest in New Guinea. Specifically, we used a novel rarefaction-based approach to match number, size distribution and taxonomic structure of trees in primary forest communities to those in secondary forest and compared the resulting numbers of ant species. 3. In total, we recorded 80 nesting ant species from 389 trees in primary forest but only 42 species from 295 trees in secondary forest. The two habitats did not differ in the mean number of ant species per tree or in the relationship between ant diversity and tree size. However, the between-tree similarity of ant communities was higher in secondary forest than in primary forest, as was the between-tree nest site similarity, suggesting that secondary trees were more uniform in providing nesting microhabitats. 4. Using our rarefaction method, the difference in ant species richness between two forest types was partitioned according to the effects of higher tree density (22·6%), larger tree size (15·5%) and higher taxonomic diversity of trees (14·3%) in primary than in secondary forest. The remaining difference (47·6%) was because of higher beta diversity of ant communities between primary forest trees. In contrast, difference in nest density was explained solely by difference in tree density. 5. Our study shows that reduction in plant taxonomic diversity in secondary forests is not the main driver of the reduction in canopy ant species richness. We suggest that the majority of arboreal species losses in secondary tropical forests are attributable to simpler vegetation structure, combined with lower turnover of nesting microhabitats between trees.

Tropical forest canopies house most of the globe's diversity, yet little is known about global patterns and drivers of canopy diversity. Here, we present models of ant species density, using climate, abundance and habitat (i.e. canopy versus litter) as predictors. Ant species density is positively associated with temperature and precipitation, and negatively (or non-significantly) associated with two metrics of seasonality, precipitation seasonality and temperature range. Ant species density was significantly higher in canopy samples, but this difference disappeared once abundance was considered. Thus, apparent differences in species density between canopy and litter samples are probably owing to differences in abundance–diversity relationships, and not differences in climate–diversity relationships. Thus, it appears that canopy and litter ant assemblages share a common abundance–diversity relationship influenced by similar but not identical climatic drivers.

Although many taxa show a latitudinal gradient in richness, the relationship between latitude and species richness is often asymmetrical between the northern and southern hemispheres. Here we examine the latitudinal pattern of species richness across 1003 local ant assemblages. We find latitudinal asymmetry, with southern hemisphere sites being more diverse than northern hemisphere sites. Most of this asymmetry could be explained statistically by differences in contemporary climate. Local ant species richness was positively associated with temperature, but negatively (although weakly) associated with temperature range and precipitation. After contemporary climate was accounted for, a modest difference in diversity between hemispheres persisted, suggesting that factors other than contemporary climate contributed to the hemispherical asymmetry. The most parsimonious explanation for this remaining asymmetry is that greater climate change since the Eocene in the northern than in the southern hemisphere has led to more extinctions in the northern hemisphere with consequent effects on local ant species richness. © 2009 Blackwell Publishing Ltd/CNRS.

Spatial isolation and geological history are important factors in the diversification and population differentiation of species. Here we describe distributional patterns of ants in the genus Acropyga across Papua New Guinea (PNG), a highly biodiverse but little-studied region. We estimate phylogenetic relationships among currently recognised species of Acropyga and assess population genetic structure of the widespread species, A. acutiventris, across lowland areas of the island. We find that species of Acropyga present in PNG diversified during the Pliocene, between six and two million years ago. Most species now exhibit a patchy distribution that does not show a strong signal of geological history. However, the population genetic structure of the widespread species A. acutiventris has been influenced by geography, habitat association and, possibly, historical habitat fragmentation. There is a significant effect of isolation-by-distance within continuous lowland forest, and proximity to Australia has had a larger impact in structuring populations of A. acutiventris in PNG than has the Central Papuan Cordillera. This study is the first to describe population genetic patterns of an ant species in Papua New Guinea.

Despite recent progress in understanding mechanisms of tree species coexistence in tropical forests, a simple explanation for the even more extensive diversity of insects feeding on these plants has been missing. We compared folivorous insects from temperate and tropical trees to test the hypothesis that herbivore species coexistence in more diverse communities could reflect narrow host specificity relative to less diverse communities. Temperate and tropical tree species of comparable phylogenetic distribution supported similar numbers of folivorous insect species, 29.0 ± 2.2 and 23.5 ± 1.8 per 100 square meters of foliage, respectively. Host specificity did not differ significantly between community samples, indicating that food resources are not more finely partitioned among folivorous insects in tropical than in temperate forests. These findings suggest that the latitudinal gradient in insect species richness could be a direct function of plant diversity, which increased sevenfold from our temperate to tropical study sites.

Norton and Didham suggest that differences in plant abundance between tropical and temperate forests may influence the host specificity of herbivores in these forests. We agree in principle but show that this is likely only for very rare plant species in tropical forests. Studies of herbivores hosted by rare plant species would help our understanding of tropical plant-insect interactions.