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—Oenotherasect.Pachylophushas proven to be a valuable system in which to study plant-insect coevolution and the drivers of variation in floral morphology and scent. Current species circumscriptions based on morphological characteristics suggest that the section consists of five species, one of which is subdivided into five subspecies. Previous attempts to understand species (and subspecies) relationships at a molecular level have been largely unsuccessful due to high levels of incomplete lineage sorting and limited phylogenetic signal from slowly evolving gene regions. In the present study, target enrichment was used to sequence 322 conserved protein-coding nuclear genes from 50 individuals spanning the geographic range ofOenotherasect.Pachylophus, with species trees inferred using concatenation and coalescent-based methods. Our findings concur with previous research in suggesting thatO. psammophilaandO. harringtoniiare nested within a paraphyleticOenothera cespitosa. By contrast, our results show clearly that the two annual species (O. cavernaeandO. brandegeei) did not arise from theO. cespitosalineage, but rather from a common ancestor ofOenotherasect.Pachylophus. Budding speciation as a result of edaphic specialization appears to best explain the evolution of the narrow endemic speciesO. harringtoniiandO. psammophila. Complete understanding of possible introgression among subspecies ofO. cespitosawill require broader sampling across the full geographical and ecological ranges of these taxa.

Oenothera sect. Calylophus is a North American group of 13 recognized taxa in the evening primrose family (Onagraceae) with an evolutionary history that may include independent origins of bee pollination, edaphic endemism, and permanent translocation heterozygosity. Like other groups that radiated relatively recently and rapidly, taxon boundaries within Oenothera sect. Calylophus have remained challenging to circumscribe. In this study, we used target enrichment, flanking noncoding regions, gene tree/species tree methods, tests for gene flow modified for target-enrichment data, and morphometric analysis to reconstruct phylogenetic hypotheses, evaluate current taxon circumscriptions, and examine character evolution in Oenothera sect. Calylophus. Because sect. Calylophus comprises a clade with a relatively restricted geographic range, we were able to extensively sample across the range of geographic, edaphic, and morphological diversity in the group. We found that the combination of exons and flanking noncoding regions led to improved support for species relationships. We reconstructed potential hybrid origins of some accessions and note that if processes such as hybridization are not taken into account, the number of inferred evolutionary transitions may be artificially inflated. We recovered strong evidence for multiple evolutionary origins of bee pollination from ancestral hawkmoth pollination, edaphic specialization on gypsum, and permanent translocation heterozygosity. This study applies newly emerging techniques alongside dense infraspecific sampling and morphological analyses to effectively reconstruct the recalcitrant history of a rapid radiation. [Gypsum endemism; Oenothera sect. Calylophus; Onagraceae; phylogenomics; pollinator shift; recent radiation; target enrichment.]

Land-use change is among the top drivers of global biodiversity loss, which impacts the arrangement and distribution of suitable habitat for species. Population-level effects include increased isolation, decreased population size, and changes to mutualistic and antagonistic interactions. However, the extent to which species are impacted is determined by life history characteristics including dispersal. In plants, mating dynamics can be changed in ways that can negatively impact population persistence if dispersal of pollen and/or seed is disrupted. Long-distance dispersal has the potential to buffer species from the negative impacts of land-use change. Biotic vectors of long-distance dispersal have been less frequently studied, though specific taxa are known to travel great distances. Here, we describe population genetic diversity and structure in a sphingophilous species that is experiencing habitat fragmentation through land-use change, Oenothera harringtonii W. L. Wagner, Stockh. & W. M. Klein (Onagraceae). We use 12 nuclear and four plastid microsatellite markers and show that pollen dispersal by hawkmoths drives high gene flow and low population differentiation despite a range-wide gradient of land-use change and habitat fragmentation. By separating the contributions of pollen and seed dispersal to gene flow, we show that most of the genetic parameters are driven by hawkmoth-facilitated long-distance pollen dispersal, but populations with small, effective population sizes experience higher levels of relatedness and inbreeding. We discuss considerations for conservation efforts for this and other species that are pollinated by long-distance dispersers.

Oenothera sect. Calylophus is a North American group of 13 recognized taxa in the evening primrose family (Onagraceae) with an evolutionary history that may include independent origins of bee pollination, edaphic endemism, and permanent translocation heterozygosity. Like other groups that radiated relatively recently and rapidly, taxon boundaries within Oenothera sect. Calylophus have remained challenging to circumscribe. In this study, we used target enrichment, flanking non-coding regions, summary coalescent methods, tests for gene flow modified for target-enrichment data, and morphometric analysis to reconstruct phylogenetic hypotheses, evaluate current taxon circumscriptions, and examine character evolution in Oenothera sect. Calylophus. Because sect. Calylophus comprises a clade with a relatively restricted geographic range, we were able to extensively sample across the range of geographic and morphological diversity in the group. We found that the combination of exons and flanking non-coding regions led to improved support for species relationships. We reconstructed potential hybrid origins of some accessions and note that if processes such as hybridization are not taken into account, the number of inferred evolutionary transitions may be artificially inflated. We recovered strong evidence for multiple origins of the evolution of bee pollination from ancestral hawkmoth pollination, the evolution of edaphic specialization on gypsum, and permanent translocation heterozygosity. This study applies newly emerging techniques alongside dense infraspecific sampling and morphological analyses to effectively address a relatively common but recalcitrant problem in evolutionary biology.

BackgroundPlant volatiles play an important role in both plant-pollinator and plant-herbivore interactions. Intraspecific polymorphisms in volatile production are ubiquitous, but studies that explore underlying differential gene expression are rare. Oenothera harringtonii populations are polymorphic in floral emission of the monoterpene (R)-(-)-linalool; some plants emit (R)-(-)-linalool (linalool+ plants) while others do not (linalool-plants). However, the genes associated with differential production of this floral volatile in Oenothera are unknown. We used RNA-Seq to broadly characterize differential gene expression involved in (R)-(-)-linalool biosynthesis. To identify genes that may be associated with the polymorphism for this trait, we used RNA-Seq to compare gene expression in six different Oenothera harringtonii tissues from each of three linalool+ and linalool-plants.ResultsThree clusters of differentially expressed genes were enriched for terpene synthase activity: two were characterized by tissue-specific upregulation and one by upregulation only in plants with flowers that produce (R)-(-)-linalool. A molecular phylogeny of all terpene synthases identified two putative (R)-(-)-linalool synthase transcripts in Oenothera harringtonii, a single allele of which is found exclusively in linalool+ plants.ConclusionsBy using a naturally occurring polymorphism and comparing different tissues, we were able to identify genes putatively involved in the biosynthesis of (R)-(-)-linalool. Expression of these genes in linalool-plants suggests a regulatory polymorphism, rather than a population-specific loss-of-function allele. Additional terpene biosynthesis-related genes that are up-regulated in plants that emit (R)-(-)-linalool may be associated with herbivore defense, suggesting a potential economy of scale between plant reproduction and defense.

The California seed harvester ant Pogonomyrmex californicus exhibits striking differences in queen behavior and colony organization throughout its range. Most populations show the likely ancestral condition of single-queen colonies (monogyny). However, in one known population, cooperation between queens during colony founding (pleometrosis) occurs, and is suspected to persist to the mature colony stage (primary polygyny). To better understand this variation in social phenotype, we estimate relatedness among co-foundresses, measure the frequency of polygyny in adult colonies across three focal populations, and assess population genetic structure between populations. We additionally measure queen mating frequency (polyandry) across focal populations. With few possible exceptions, queens within pleometrotic associations are unrelated. We demonstrate a correlation between pleometrosis in incipient colonies and polygyny in adult colonies at the population level. Nuclear microsatellites and mtDNA barcoding indicate significant structure between focal populations. Queens from all three focal populations engage in relatively high levels of polyandry. These findings, when examined with previous data demonstrating that pleometrosis leads to polygynous colonies in the laboratory, strongly suggest that the same occurs in nature. However, the possibility of additional queen adoption in adult colonies (secondary polygyny) is not excluded. Thus, polygynous P. californicus colonies potentially represent long-term associations of unrelated family groups, containing multiple unrelated queens and their mixed-paternity offspring. Due to its pronounced variation in social behavior, P. californicus provides a unique opportunity to examine the evolutionary history and genetic underpinnings of cooperation among non-relatives, a strategy of intense interest in behavioral ecology.

Insect herbivores and their hostplants constitute much of Earth’s described diversity, but how these often-specialized associations evolve and generate biodiversity is still not fully understood. We combined detailed hostplant data and comparative phylogenetic analyses of the lepidopteran family Momphidae to explore how shifts in the use of hostplant resources, not just hostplant taxonomy, contribute to the diversification of phytophagous insect lineages. We generated two phylogenies primarily from momphid species in the nominate genus,MomphaHübner. A six-gene phylogeny was constructed with exemplars from Onagraceae hosts in western and southwestern USA and a cytochromecoxidase subunit 1 (COI) phylogeny utilized both our collected sequences and publicly available accessions from the Barcode of Life Data System. Coalescent-based analyses combined with morphological data revealed ca. 56 undescribedMomphaspecies-level taxa, many of which are hostplant specialists on southwestern USA Onagraceae. Our phylogenetic reconstructions identified four major momphid clades: 1) an Onagraceae flower- and fruit-feeding clade, 2) a Melastomataceae galling clade, 3) an Onagraceae and Rubiaceae leafmining clade, and 4) a heterogeneous clade associated with multiple hostplant families, plant tissues, and larval feeding modes. Ancestral trait reconstructions on the COI tree identified leafmining on Onagraceae as the ancestral state for Momphidae. Cophylogenetic analyses detected loose phylogenetic tracking of hostplant taxa. Our study finds that shifts along three hostplant resource axes (hostplant taxon, plant tissue type, and larval feeding mode) contributed to the evolutionary success and diversification ofMompha. More transitions between exploited host tissue types than between hostplant families indicated that exploited host tissue (without a change in host) played an unexpectedly large role in the diversification of these moths.

In this study we revise the taxonomy of the genus Prionopelta for the Malagasy region, treating seven species, six of which are newly described (Prionopelta laurae sp. n., Prionopelta seychelles sp. n., Prionopelta subtilis sp. n., Prionopelta talos sp. n., Prionopelta vampira sp. n., Prionopelta xerosilva sp. n.), and one redescribed (Prionopelta descarpentriesi Santschi). One species, Prionopelta seychelles, is restricted to Seychelles, while the six remaining species treated are endemic to Madagascar.

The North American little black ant, Monomorium sp. AZ-02 (subfamily Myrmicinae), displays a dimorphism that consists of alate (winged) and ergatoid (wingless) queens. Surveys at our field site in southcentral Arizona, USA, demonstrated that only one queen phenotype (alate or ergatoid) occurred in each colony during the season in which reproductive sexuals were produced. A morphometric analysis demonstrated that ergatoid queens retained all specialized anatomical features of alate queens (except for wings), and that they were significantly smaller and had a lower mass than alate queens. Using eight morphological characters, a discriminant analysis correctly categorized all queens (40 of 40) of both phenotypes. A molecular phylogeny using 420 base pairs of the mitochondrial gene cytochrome oxidase I demonstrated that alate and ergatoid queens are two alternative phenotypes within the species; both phenotypes were intermixed on our phylogeny, and both phenotypes often displayed the same haplotype. A survey of the genus Monomorium (358 species) found that wingless queens (ergatoid queens, brachypterous queens) occur in 42 of 137 species (30.6%) in which the queen has been described. These wingless queen species are geographically and taxonomically widespread as they occur on several continents and in eight species groups, suggesting that winglessness probably arose independently on many occasions in the genus.

Research on the evolution of cooperative groups tends to explore the costs and benefits of cooperation, with less focus on the proximate behavioral changes necessary for the transition from solitary to cooperative living. However, understanding what proximate changes must occur, as well as those pre-conditions already in place, is critical to understand- ing the origins and evolution of sociality. The California harvester ant Pogonomyrmex californicus demonstrates population-level variation in colony founding over a close geographic range. In adjacent populations, queens either found nests as single individuals (haplometrosis) or form cooperative groups of nonrelatives (pleometrosis). We com- pared aggregation, aggression, and tolerance of queens from one pleometrotic and two haplometrotic populations during nest initiation, to determine which behaviors show an evolu- tionary shift and which are present at the transition to pleometrosis. Surprisingly, within-nest aggregative behavior was equally present among all populations. In nesting boxes with multiple available brood-rearing sites, both queen types readily formed and clustered around a single common brood pile, suggesting that innate attraction to brood (offspring) facilitates the transition to social aggregation. In contrast, queens from the three populations differed in their probabili- ties of attraction on the ground to nest sites occupied by other queens and in levels of aggression. Our results suggest that

Colony size is a fundamental attribute of insect societies that appears to play an important role in their organization of work. In the harvester ant Pogonomyrmex californicus, division of labor increases with colony size during colony ontogeny and among unmanipulated colonies of the same age. However, the mechanism(s) integrating individual task specialization and colony size is unknown. To test whether the scaling of division of labor is an emergent epiphenomenon, as predicted by self-organizational models of task performance, we manipulated colony size in P. californicus and quantified short-term behavioral responses of individuals and colonies. Variation in colony size failed to elicit a change in division of labor, suggesting that colony-size effects on task specialization are mediated by slower developmental processes and/or correlates of colony size that were missing from our experiment. In contrast, the proportional allocation of workers to tasks shifted with colony size, suggesting that task needs or priorities depend, in part, on colony size alone. Finally, although task allocation was flexible, colony members differed consistently in task performance and spatial tendency across colony size treatments. Sources of interindividual behavioral variability include worker age and genotype (matriline).

The diversity of floral forms in angiosperms is frequently attributed to pollinators but herbivores can be just as important. Here we examine the role of a flower-feeding caterpillar, Mompha, in driving floral trait evolution and subsequent pollinator-shifts in a recently radiated clade of flowering plants, Oenothera sect. Calylophus (Onagraceae). Longer-tubed, hawkmoth flowers had substantially greater damage compared to smaller bee-pollinated flowers. Mompha's preference for longer-tubed flowers, which is evident even within populations of some species, may have played an important role in driving the morphological changes associated with shifts from hawkmoth to bee pollination., Floral trait evolution is frequently attributed to pollinator-mediated selection but herbivores can play a key role in shaping plant reproductive biology. Here we examine the role of florivores in driving floral trait evolution and pollinator shifts in a recently radiated clade of flowering plants, Oenothera sect. Calylophus. We compare florivory by a specialist, internal feeder, Mompha, on closely related hawkmoth- and bee-pollinated species and document variation in damage based on floral traits within sites, species and among species. Our results show that flowers with longer floral tubes and decreased floral flare have increased Mompha damage. Bee-pollinated flowers, which have substantially smaller floral tubes, experience on average 13% less Mompha florivory than do hawkmoth-pollinated flowers. The positive association between tube length and Mompha damage is evident even within sites of some species, suggesting that Mompha can drive trait differentiation at microevolutionary scales. Given that there are at least two independent shifts from hawkmoth to bee pollination in this clade, florivore-mediated selection on floral traits may have played an important role in facilitating morphological changes associated with transitions from hawkmoth to bee pollination.

Ants are some of the most abundant and familiar animals on Earth, and they play vital roles in most terrestrial ecosystems. Although all ants are eusocial, and display a variety of complex and fascinating behaviors, few genomic resources exist for them. Here, we report the draft genome sequence of a particularly widespread and well-studied species, the invasive Argentine ant ( Linepithema humile ), which was accomplished using a combination of 454 (Roche) and Illumina sequencing and community-based funding rather than federal grant support. Manual annotation of >1,000 genes from a variety of different gene families and functional classes reveals unique features of the Argentine ant's biology, as well as similarities to Apis mellifera and Nasonia vitripennis . Distinctive features of the Argentine ant genome include remarkable expansions of gustatory (116 genes) and odorant receptors (367 genes), an abundance of cytochrome P450 genes (>110), lineage-specific expansions of yellow/major royal jelly proteins and desaturases, and complete CpG DNA methylation and RNAi toolkits. The Argentine ant genome contains fewer immune genes than Drosophila and Tribolium , which may reflect the prominent role played by behavioral and chemical suppression of pathogens. Analysis of the ratio of observed to expected CpG nucleotides for genes in the reproductive development and apoptosis pathways suggests higher levels of methylation than in the genome overall. The resources provided by this genome sequence will offer an abundance of tools for researchers seeking to illuminate the fascinating biology of this emerging model organism.

A reproductive division of labor between subordinates and established reproductives is a hallmark of eusociality. In most groups, however, workers retain some reproductive capabilities. Across insect societies, measures of successful worker reproduction in the presence of a queen, with few exceptions, indicate that worker reproduction is kept at very low levels. There are, however, certain colony-level characteristics that may influence the degree to which worker reproduction is promoted, such as queen number, queen mating frequency, and physical presence of a queen in species with multiple nesting sites (polydomy). In this study, the level of worker reproduction in field colonies of the ant species Aphaenogaster cockerelli was measured. A. cockerelli is a monogynous and polydomous species, so worker reproduction across nesting sites was investigated. None of the 297 males sampled provided any evidence of worker reproduction. Worker reproduction would have been detectable if it was present at or above a level of 1.5 % of the total males per colony. An effective mating frequency for queens of this species was found to be 1.03. Although A. cockerelli colonies have many colony-level factors potentially promoting worker reproduction (workers with active, trophic egg-producing ovaries, a single singly-mated queen, workers who are physically separated from the queen), it is evident that worker reproduction is highly regulated. Synthesizing the extensive amount of policing and fertility signaling data previously reported on this species, A. cockerelli is presented as case study for how worker reproduction is repressed and cooperation is maintained in insect societies.

The harvester ants Pogonomyrmex barbatus and P. rugosus serve as hosts for the parasitic ants P. anergismus and P. colei. Recent molecular studies demonstrated that morphology is unreliable for identification of hosts because the hosts contain cryptic species. Using mitochondrial-DNA sequences, we determined identity of 15 of 16 known populations of hosts, and in 9 instances, the identity of the particular host colony. Hosts are composed of 6 reproductively isolated lineages. While P. colei is known only from a single host, P. anergismus occurs in five distinct hosts and appears to have a much broader geographic range. We report seven new locality records for P. anergismus. Range extensions for P. anergismus in the United States consist of southwestern Texas including Big Bend National Park, northwestern Texas, central New Mexico, and south-central Arizona. We discuss factors that may influence dispersal of parasitic ants and host-parasite co-evolution.

Pogonomyrmex magnacanthus Cole was described as a distinct species; unusually large eyes and a high ocular index (maximum eye diameter/head width) were listed as diagnostic characters. However, examination of numerous series of P. magnacanthus revealed that both characters were highly variable, and that these series consisted of P. magnacanthus plus an undescribed species, Pogonomyrmex hoelldobleri Johnson, OversonMoreau sp. nov. This paper describes all three castes of P. hoelldobleri as well as the alate queen of P mohavensis, which is very similar to that of P. hoelldobleri. A molecular phylogeny that consisted of 3,703 bp from one mitochondrial and five nuclear gene fragments-supported the monophyly of P. hoelldobleri, P. magnacanthus, and P mohavensis. Pogonomyrnex inagnacanthus can be separated from other P. californicus group species based on: (1) its unusually large eyes, (2) a high ocular index, and (3) a malar ratio that is typicallyor = 1.0. Pogonomyrmex hoelldobleri can be separated from other P. californicus group species based on the combination of: (1) eyes not unusually large, (2) cephalic rugae not forming circumocular whorls, but rather converging posterior to the eyes, usually near the vertex, (3) mandible with seven teeth, and (4) interrugal spaces on pronotal sides moderately to strongly granulate, dull to weakly shining. Pogonomyrmex mohavensis can be separated from other P. californicus group species based on the combination of: (1) eyes not unusually large, (2) cephalic rugae not forming circumocular whorls, but rather extending more or less directly to the vertex or converging only slightly near the vertex, (3) mandible with six teeth (a seventh sometimes occurs as a denticle between the basal and sub-basal teeth), and (4) interrugal spaces on pronotal sides smooth and shining to weakly punctate and moderately shining. We also provide field observations and distribution maps for P. magnacanthus, P. hoelldobleri, and P. mohavensis, and an updated key to P californicus group species that occur in central and western North America.

Pogonomyrmex hoelldobleri Johnson, Overson & Moreau, NEW SPECIES (Figures 2, 6-8) Pogonomyrmex magnacanthus Cole, 1968: 133 [part]. Worker Diagnosis. Pogonomyrmex hoelldobleri is characterized by: (1) eye not unusually large (MOD usually 1.05 (Figure 3), (2) mandible with seven teeth, (3) cephalic rugae converge posterior to eyes, usually near vertex, but not forming circumocular whorls, (4) interrugal spaces on pronotal sides moderately to strongly granulate, dull to weakly shining (see Figures 2, 6), and (5) gaster concolorous with head and mesosoma. Measurements (mm)-holotype (n = 75 [15 paratypes, 43 non-types, 16 P. magnacanthus Paratypes]). HL 1.57 (1.24-1.76); HW 1.55 (1.17-1.84); MOD 0.36 (0.30-0.42); OMD 0.42 (0.35-0.72); SL 1.20 (0.94-1.34); PNW 0.91 (0.77-1.11); HF 1.67 (1.19-1.89); ML 1.84 (1.35-2.03); PW 0.34 (0.27-0.46): PPW 0.51 (0.38-0.59). Indices: SI 77.42 (66.25-87.18); CI 98.73 (93.98-115.79); OI 23.23 (21.12-29.01); HFI 107.74 (84.97-117.93). Description. Head subquadrate to quadrate (CI = 93.98-115.79), broadest just posterior to eye; posterior margin flat in full-face view. Longitudinal cephalic rugae prominent, in full-face view median rugae usually diverging toward posterior corners near posterior margin of head. In side view, rugae converging slightly near vertex, occasionally becoming faint between posterior margin of eye and vertex. Vertex faintly to strongly rugose, occasionally mostly smooth to weakly granulate, sub-shining to shining. Cephalic interrugal spaces moderately punctate, sub-shining to smooth and shining. Anterior margin of clypeus slightly concave. Mandible with seven teeth; mandibular dorsum coarsely striate. In profile, eyes not unusually large, MOD ranging from 0.22-0.29x HL, OI = 21.12-29.01, MR usually> 1.05; eye situated near middle of head. Antennal scapes moderately long (SI = 66.25-87.18), failing to reach vertex by less than length of basal funicular segment. Basal flange of antennal scape flattened and well developed, margin weakly carinate. Psammophore well developed. Mesosomal profile convex. All mesosomal surfaces with prominent parallel/subparallel rugae. Dorsum of promesonotum with transverse rugae that curve obliquely to posterior on pronotal sides, rugae on pronotal sides often slightly less distinct than on other portions of mesosoma; rugae usually oblique to longitudinal on anterior portion of mesonotum. Mesopleura with subparallel rugae angling posterodorsally. Propodeum lacking spines or teeth; in side view, juncture of propodeum and propodeal declivity evenly convex to weakly angulate; rugae on propodeal dorsum transverse, declivitous face smooth and shining. Propodeal spiracles narrowly ovate. Interrugal spaces on mesosoma moderately granulate-punctate, sub-shining to smooth and shining; interrugal spaces on pronotal sides usually more densely granulate than other portions of mesosoma. Legs moderately to strongly shining. Petiolar peduncle long, ventral margin straight. In side view, posterior face of petiole slightly convex; petiolar node asymmetrical with anterior surface slightly shorter than posterior surface. Apex of node weakly to strongly angulate, posterior surface sometimes curved upward near anterior margin. In dorsal view, petiolar node longer than broad, sides subparallel or diverging slightly toward the smoothly rounded to weakly angulate anterior margin. Sides and dorsum of petiolar node strongly granulate-punctate, dull to sub-shining to smooth and shining, occasionally with several longitudinal to oblique rugae that are restricted to posterior one-third of petiole. Dorsum of postpetiole convex in profile; in dorsal view, widest at or near posterior margin and tapering to anterior margin, maximal width about equal to length, weakly to moderately granulate, dull to sub-shining. Gaster smooth and strongly shining. Erect to suberect white pilosity moderately abundant on head, short to medium in length, often with one to few longer hairs, none exceeding MOD. Moderately abundant semidecumbent to decumbent pilosity on scape, abundant semidecumbent to decumbent hairs on funicular segments. Legs with moderately abundant suberect to semidecumbent white setae. Mesosoma, petiole, and postpetiole with a lower density of mostly longer, flexuous hairs mostly concentrated on dorsal surface, longest distinctly shorter than MOD; gastric tergites with moderately abundant, medium length suberect hairs. Entire body concolorous light to dark ferruginous orange, posterior portion of gaster sometimes slightly darker (Figure 6). Queen Diagnosis. As in worker diagnosis, but with caste-specific structures related to wing-bearing and presence of small ocelli on head. Mandible with seven teeth. Eye not unusually large (MOD 1.05). All mesosomal surfaces except for mesoscutum and mesoscutellum with prominent rugae; sculpturing absent on mesoscutum and mesoscutellum except for scattered punctures and occasional faint longitudinal striae (Figure 7). Posterior face of petiole and dorsum of postpetiole weakly to moderately granulate or with weak tranverse rugae. Base of scape rounded; superior and inferior lobes poorly developed, no wider than width of scape base. Measurements (mm)-(n = 8). HL 1.36-1.66; HW 1.44-1.79; MOD 0.40-0.45; OMD 0.40-0.50; SL 0.97- 1.23; PNW 1.24-1.54; HFL 1.38-1.67; ML 2.18-2.62; PW 0.45-0.57; PPW 0.61-0.73. Indices: SI 65.52-72.12; CI 100.00-114.10; OI 22.47-28.47; HFI 83.64-109.03. Description. As in worker diagnosis, but with caste-specific structures related to wing-bearing, presence of small ocelli on head, and as illustrated in Figure 7. Small, only slightly larger than conspecific workers. In full-face view, head quadrate to broader than long, posterior margin flat. Dorsum and sides of head conspicuously rugose, in side view rugae forming circumocular whorls posterior to eyes or rugae converging near vertex, interrugal spaces smooth and strongly shining. Mandible with seven teeth, dorsal surface coarsely rugose, strongly shining. Eyes not large (OI = 22.47-28.47), MR usually> 1.05, MOD ranging from 0.25-0.30x HL. Base of scape not flattened; superior and inferior lobes poorly developed, no wider than width of base of scape. Mesosoma as described above, propodeum unarmed; in side view, juncture of propodeum and propodeal declivity rounded to subangulate, sides and dorsal surface rugose or rugae absent near mid-line, shining, posterior surface smooth and strongly shining. Petiolar peduncle long, ventral margin straight. In side view, petiolar node asymmetrical with anterior surface shorter than posterior surface. Apex of node moderately to strongly angulate, anterior edge of posterior face sometimes curved upward forming a crest. Postpetiole broader than long. Posterior face of petiole and dorsum of postpetiole weakly to moderately granulate or with weak transverse rugae, sub-shining to shining. Gastric tergites smooth and shining. Most body surfaces with moderately abundant coarse suberect to erect setae. Entire body concolorous light to dark ferruginous orange, except for incomplete to complete darker transverse bands on one or more gastric tergites. Male Diagnosis. Mandible with four teeth on suboblique cutting margin. Mandibular dorsum, clypeus, and antennal scapes lacking sculpture (mandibular dorsum occasionally with faint striae), mostly smooth and shining except for scattered punctures; anterior margin of clypeus weakly concave, lateral lobes indistinct. Eye not unusually large (MOD 0.38) (Figure 8). Measurements (mm)-(n = 2). HL 1.15-1.25; HW 1.27-1.30; MOD 0.49-0.50; OMD 0.19-0.20; SL 0.54- 0.56; HFL 1.43-1.56; ML 2.08-2.26; PW 0.54-0.58; PPW 0.65-0.73. Indices: SI 42.52-43.08; CI 104.00-110.43; OI 37.69-39.37; HFI 112.60-120.00. Description. Mandible with four teeth on suboblique cutting margin; tip of sub-apical tooth sometimes weakly bifid; basal tooth not offset; mandibular dorsum as described above. Anterior margin of clypeus broadly and shallowly concave, mostly smooth and shining except for scattered punctures, lateral lobes indistinct. Antennal scapes reaching to or near posterior margin of eye, mostly smooth and shining. Cephalic rugae fine and close, slightly wavy to irregular, interrugae weakly punctate, moderately shining. In profile, anterior face of mesonotum forming a mostly straight line with pronotum, slightly less than one-half as long as dorsal surface. In side view, juncture between propodeum and propodeal declivity subangulate, without spines or denticles. Sides of pronotal collar superficially rugoreticulate to punctate-granulate; katepisternum partially to largely covered by very fine wavy to irregular longitudinal striae, sub-shining to shining. Mesonotum shiny with piligerous punctures, notauli weakly impressed. Propodeum mostly smooth and shining to microrugoreticulate, granulate, sub-shining. Ventral margin of petiolar peduncle straight. In side view, petiolar node broadly rounded, anterior surface longer than posterior surface, forming a mostly straight continuous to slightly curved profile with dorsal surface of petiolar peduncle. Dorsal surface of petiole smooth and shining with scattered punctures to microrugoreticulate, sub-shining. Postpetiole broader than long, dorsal surface mostly smooth, sub-shining to shining. Head, mesosoma, petiole, and postpetiole with moderately abundant flexuous white hairs, often similar in length to MOD. Gastric tergites smooth and shining, hairs shorter and less dense than on rest of body. Head and mesosoma brownish-orange, gaster a lighter ferruginous orange (Figure 8). Type material: Holotype (worker) plus 27 paratypes. UNITED STATES: Arizona: Yuma Co.: 0.2 km S Tacna, 125 m (22 o 6.4'S 65 o 36.8'W), May 14, 2010, leg. R.A. Johnson #4500. Nests were in Sonoran Desert habitat that was dominated by scattered individuals of Larrea tridentata and Ambrosia dumosa. The holotype is deposited in the MCZ. Paratypes (n = 27 workers) all from the same locality and date as the holotype and leg. R.A. Johnson #4500 are distributed as follows: MCZ (6w), LACM (3w), UCDC (3w), USNM (6w), WPMC (3w), RAJC (6w). Additional paratype series (RAJC), collected on June 24, 2009, include RAJ #4253 (6w) and RAJ#4255 (9w): all series have additional workers in ethanol. Additional material examined. UNITED STATES: Arizona: Maricopa Co.: 12 mi E Sentinel, Jul 30, 1960, AC Cole AZ-519 (26w PARATYPES of P. magnacanthus, LACM). Mohave Co.: Golden Shores, Sep 5, 1995, RA Johnson RAJ#691 (8w, RAJC); 0.3 mi W Golden Shores, May 18, 2010, 620', RA Johnson RAJ#4490 (6w, RAJC). Yuma Co.: I-8 at Aztec Road, 490', Apr 26, 2012, RA Johnson #4919 (6w, RAJC). California: Imperial Co.: Coyote Wells, Jul 29, 1957, AC Cole CAL-305 (17w, LACM); El Centro to Jacumba, Jul 10, 1956, AC Cole CAL- 11 (3w PARATYPES of P magnacanthus, LACM), CAL-12 (3w PARATYPES of P magnacanthus, LACM); 14 mi W Winterhaven, Jul 28, 1959, AC Cole CAL-334A (6w PARATYPES of P. magnacanthus, LACM); 15 mi E Holtville, Jul 27, 1961, AC Cole CAL-394 (24w PARATYPES of P. magnacanthus, LACM). Inyo Co.: Death Valley National Monument at Ashford Mill, 0', Apr 28, 1952, WS Creighton no number (16w, 5aq, LACM), CR-226 (10w, 1aq, 1m, LACM), CR-417 (11w, 1aq, LACM), CR-618 (15w, 1aq, 1m, LACM); Death Valley National Park, Spring 2000, KE Anderson KEA#550 (3w, RAJC); 9.05 km W Panamint Springs, 4450', May 30, 2006, RR Snelling #06-006 (1w, RAJC); Riverside Co.: 21 mi E Indio, 1600', Apr 8, 1952, WS Creighton CR-324 (19w PARATYPES of P. magnacanthus, LACM). San Bernardino Co.: Needles, May 1905, WM Wheeler (3w, LACM); 3.5 mi N Pisgah Crater, 2270', May 11, 2010, RA Johnson RAJ#4488 (6w, RAJC), RAJ#4489 (6w, RAJC); 5.5 mi NW Pisgah Crater, 1890', May 4, 2010, RA Johnson RAJ#4493 (3w, RAJC), RAJ#4494 (5w, 1aq, RAJC); I-40 at Goffs Road, 2040', Sep 16, 2011, RA Johnson RAJ#4808 (6w, RAJC). San Diego Co.: Anza Borrego State Park, Palm Canyon, Apr 17, 1952, WS Creighton CR-559 (6w, LACM); Ocotillo Well, Aug 8, 1960, AC Cole CAL-366 (4w PARATYPES of P. magnacanthus, LACM). Nevada: Clark Co.: 7 mi W Echo Bay, 1800', Apr 5, 1976, G & J Wheeler NEV-725 (3w, LACM); 4 mi SW Riverside, 1500', Apr 2, 1970, G & J Wheeler NEV#707 (3w, LACM); 5 km E Jean, Apr 26, 2009, 2780', RA Johnson RAJ#4222 (3w, RAJC), RAJ#4223 (3w, RAJC); Valley of Fire, 2100', Mar 14, 1970, G & J Wheeler NEV#640 (3w, LACM), NEV#631 (3w, LACM); Valley of Fire, 2000', NEV#645 (2w, LACM); W base of Mormon Mesa, 1500', Apr 3, 1970, G & J Wheeler NEV#720 (3w, LACM), NEV#716 (3w, LACM); 3 mi W Cottonwood Cove, 1200', Dec 10, 1970, G & J Wheeler NEV-1498 (3w, LACM). Nye Co.: Mercury, Jul 11, 1961, #5AA1C (1w, LACM), May 24, 1961, #5EA7C (1w, LACM); Pahrump, spring 2000, KE Anderson KEA#532 (3w, RAJC); 2 mi N Pahrump, 2700', Apr 4, 1970, G & J Wheeler NEV-740 (2w, LACM); Beatty, Jul 17, 1954, AC Cole, NEV-374 (6w, LACM), NEV-375 (4w, LACM), NEV-376 (6w, LACM), NEV-377 (22w, LACM), NEV-380 (2w, LACM); Hwy 95 at 4.0 mi NW Lathrop Wells, 2610', Apr 17, 2009, RA Johnson RAJ#4216 (6w, RAJC), RAJ#4217 (9w, RAJC); Rock Valley, 9 mi ENE Lathrop Wells, Apr 14, 1970, G & J Wheeler, NEV-781 (9w, LACM). MEXICO: Baja California: Valle San Felipe, May 10, 1998, RA Johnson RAJ#BC 1376 (9w, RAJC), RAJ#BC 1377 (9w, RAJC). Sonora: Pinacate Desert, no date, 1982, IR Lopez Moreno #F-11 (2w, LACM), #F-16 (8w, LACM); Puerto Penasco, 50', Jul 15, 1950, WS Creighton #308 (30w, LACM), #304 (3w, LACM); 11.5 mi E Puerto Penasco, July 17, 2009, RA Johnson RAJ#4274 (9w, RAJC), RAJ#4278 (3w, RAJC), RAJ#4281 (9w, RAJC). Etymology. The specific epithet honors Prof. Dr. Bert H��lldobler, who was an "ant god" during the tenure of RAJ in graduate school and beyond-and who now is a good friend, colleague, collaborator, and supporter who is dedicated to understanding all aspects of ant biology. His continued child-like enthusiasm for learning about ants and his earnest interest in helping students invigorate all of those around him. Discussion. Pogonomyrmex hoelldobleri is most likely to be confused with P. magnacanthus, especially given the large number of series that A.C. Cole erroneously identified as P. magnacanthus. The two species occur sympatrically in several locales. The significantly larger eye (MOD and OI) separates P. magnacanthus from P hoelldobleri (Figures 2-3). OI is the best character to separate the two species because it is consistently higher for P. magnacanthus (OI = 27.22-33.61) than for P. hoelldobleri (OI rarely> 27.50)(Figure 3). The malar ratio is usually 1.05 for P. hoelldobleri (Figure 3). Pogonomyrmex hoelldobleri also occurs in sympatry with P. californicus and is likely to occur in sympatry with P. mohavensis, but it has a low likelihood of co-occurring with P. maricopa. Pogonomyrmex hoelldobleri can be distinguished from P. mohavensis based on the following characters: (1) P. hoelldobleri has seven teeth, (2) the interrugal spaces on the pronotal shoulders are weakly to strongly punctate/granulate, dull to sub-shining, and (3) the cephalic rugae typically converge near the vertex. In P. mohavensis, the mandible has six teeth (a seventh sometimes occurs as a denticle between the basal and sub-basal teeth), interrugal spaces on the pronotal shoulders are smooth and shining, and the cephalic rugae extend more or less directly to the vertex or converge only slightly near the vertex. Two other P. californicus group species (P. anzensis and P. snellingi) also occur in the Sonoran and Mohave Deserts, but it is doubtful that P. hoelldobleri occurs sympatrically with either species; P. anzensis occurs in unproductive, rocky hillside habitats unlike any sites that are known to be occupied by P. hoelldobleri, while P. snellingi is well removed from the probable geographic distribution of P. hoelldobleri. Regardless, the absence of circumocular whorls separates P. hoelldobleri from both species., Published as part of ROBERT A. JOHNSON, RICK P. OVERSON & CORRIE S. MOREAU, 2013, A New Species of Seed-harvester Ant, Pogonomyrmex hoelldobleri (Hymenoptera: Formicidae), from the Mohave and Sonoran Deserts of North America, pp. 201-227 in ZOOTAXA 3646 (3) on pages 213-217, DOI: 10.11646/zootaxa.3646.3.1

Pogonomyrmex magnacanthus Cole (Figures 1-2, 4-5) Pogonomyrmex (Pogonomyrmex) magnacanthus Cole, 1968 [part]: 133, pl. 2, fig. 5; pl. 3, fig. 12; pl. 4, fig. 10; pl. 6, fig. 9; pl. 7, fig. 16; pl. 8, fig. 10; pl. 11, fig. 10 (worker, queen, male). Holotype examined [LACM, Cole No. Cal-378]; Palm Springs, California, USA (by A.C. Cole, Jr., on 8 August, 1960); Taber, Cokendolpher & Francke, 1988: 51 (karyotype) (2n = 32). See also Ward (2005). Worker Diagnosis. Pogonomyrmex magnacanthus is a small species (HW = 1.15-1.80 mm) that is identified by: (1) its unusually large eyes (MOD = 0.33-0.49 mm; OI = 27.22-33.61; malar ratio (MOD/OMD) usually 0.53, OI> 42.5, MR 1.05 for P. hoelldobleri (Figure 3). Pogonomyrmex magnacanthus occurs sympatrically with P. californicus, but it has a low likelihood of co-occurring with P. maricopa and P. mohavensis. Two other P. californicus group species (P. anzensis and P. snellingi) also occur in the Sonoran Desert, but it is doubtful that P. magnacanthus occurs sympatrically with either species; P. anzensis inhabits unproductive, rocky hillsides that are unlike any sites known to be occupied by P. magnacanthus, while P. snellingi is well removed from the probable geographic distribution of P. magnacanthus. Pogonomyrmex magnacanthus can be distinguished from all of these species using the characters described above., Published as part of ROBERT A. JOHNSON, RICK P. OVERSON & CORRIE S. MOREAU, 2013, A New Species of Seed-harvester Ant, Pogonomyrmex hoelldobleri (Hymenoptera: Formicidae), from the Mohave and Sonoran Deserts of North America, pp. 201-227 in ZOOTAXA 3646 (3) on pages 205-213, DOI: 10.11646/zootaxa.3646.3.1

Leaf-cutter ants are one of the most important herbivorous insects in the Neotropics, harvesting vast quantities of fresh leaf material. The ants use leaves to cultivate a fungus that serves as the colony's primary food source. This obligate ant-fungus mutualism is one of the few occurrences of farming by non-humans and likely facilitated the formation of their massive colonies. Mature leaf-cutter ant colonies contain millions of workers ranging in size from small garden tenders to large soldiers, resulting in one of the most complex polymorphic caste systems within ants. To begin uncovering the genomic underpinnings of this system, we sequenced the genome of Atta cephalotes using 454 pyrosequencing. One prediction from this ant's lifestyle is that it has undergone genetic modifications that reflect its obligate dependence on the fungus for nutrients. Analysis of this genome sequence is consistent with this hypothesis, as we find evidence for reductions in genes related to nutrient acquisition. These include extensive reductions in serine proteases (which are likely unnecessary because proteolysis is not a primary mechanism used to process nutrients obtained from the fungus), a loss of genes involved in arginine biosynthesis (suggesting that this amino acid is obtained from the fungus), and the absence of a hexamerin (which sequesters amino acids during larval development in other insects). Following recent reports of genome sequences from other insects that engage in symbioses with beneficial microbes, the A. cephalotes genome provides new insights into the symbiotic lifestyle of this ant and advances our understanding of host–microbe symbioses., Author Summary Leaf-cutter ant workers forage for and cut leaves that they use to support the growth of a specialized fungus, which serves as the colony's primary food source. The ability of these ants to grow their own food likely facilitated their emergence as one of the most dominant herbivores in New World tropical ecosystems, where leaf-cutter ants harvest more plant biomass than any other herbivore species. These ants have also evolved one of the most complex forms of division of labor, with colonies composed of different-sized workers specialized for different tasks. To gain insight into the biology of these ants, we sequenced the first genome of a leaf-cutter ant, Atta cephalotes. Our analysis of this genome reveals characteristics reflecting the obligate nutritional dependency of these ants on their fungus. These findings represent the first genetic evidence of a reduced capacity for nutrient acquisition in leaf-cutter ants, which is likely compensated for by their fungal symbiont. These findings parallel other nutritional host–microbe symbioses, suggesting convergent genomic modifications in these types of associations.

We report the draft genome sequence of the red harvester ant, Pogonomyrmex barbatus . The genome was sequenced using 454 pyrosequencing, and the current assembly and annotation were completed in less than 1 y. Analyses of conserved gene groups (more than 1,200 manually annotated genes to date) suggest a high-quality assembly and annotation comparable to recently sequenced insect genomes using Sanger sequencing. The red harvester ant is a model for studying reproductive division of labor, phenotypic plasticity, and sociogenomics. Although the genome of P. barbatus is similar to other sequenced hymenopterans ( Apis mellifera and Nasonia vitripennis ) in GC content and compositional organization, and possesses a complete CpG methylation toolkit, its predicted genomic CpG content differs markedly from the other hymenopterans. Gene networks involved in generating key differences between the queen and worker castes (e.g., wings and ovaries) show signatures of increased methylation and suggest that ants and bees may have independently co-opted the same gene regulatory mechanisms for reproductive division of labor. Gene family expansions (e.g., 344 functional odorant receptors) and pseudogene accumulation in chemoreception and P450 genes compared with A. mellifera and N. vitripennis are consistent with major life-history changes during the adaptive radiation of Pogonomyrmex spp., perhaps in parallel with the development of the North American deserts.

The international conference ‘Social Biomimicry: Insect Societies and Human Design’, hosted by Arizona State University, USA, 18–20 February 2010, explored how the collective behaviour and nest architecture of social insects can inspire innovative and effective solutions to human design challenges. It brought together biologists, designers, engineers, computer scientists, architects and businesspeople, with the dual aims of enriching biology and advancing biomimetic design.

Pogonomyrmex magnacanthus Cole was described as a distinct species; unusually large eyes and a high ocular index (maximum eye diameter/head width) were listed as diagnostic characters. However, examination of numerous series of P. magnacanthus revealed that both characters were highly variable, and that these series consisted of P. magnacanthus plus an undescribed species, Pogonomyrmex hoelldobleri Johnson, Overson & Moreau sp. nov. This paper describes all three castes of P. hoelldobleri as well as the alate queen of P mohavensis, which is very similar to that of P. hoelldobleri. A molecular phylogeny that consisted of 3,703 bp from one mitochondrial and five nuclear gene fragments-supported the monophyly of P. hoelldobleri, P. magnacanthus, and P mohavensis. Pogonomyrnex inagnacanthus can be separated from other P. californicus group species based on: (1) its unusually large eyes, (2) a high ocular index, and (3) a malar ratio that is typically < or = 1.0. Pogonomyrmex hoelldobleri can be separated from other P. californicus group species based on the combination of: (1) eyes not unusually large, (2) cephalic rugae not forming circumocular whorls, but rather converging posterior to the eyes, usually near the vertex, (3) mandible with seven teeth, and (4) interrugal spaces on pronotal sides moderately to strongly granulate, dull to weakly shining. Pogonomyrmex mohavensis can be separated from other P. californicus group species based on the combination of: (1) eyes not unusually large, (2) cephalic rugae not forming circumocular whorls, but rather extending more or less directly to the vertex or converging only slightly near the vertex, (3) mandible with six teeth (a seventh sometimes occurs as a denticle between the basal and sub-basal teeth), and (4) interrugal spaces on pronotal sides smooth and shining to weakly punctate and moderately shining. We also provide field observations and distribution maps for P. magnacanthus, P. hoelldobleri, and P. mohavensis, and an updated key to P californicus group species that occur in central and western North America.

Lowland tropical bryophytes have been perceived as excellent dispersers. In such groups, the inverse isolation hypothesis proposes that spatial genetic structure is erased beyond the limits of short-distance dispersal. Here, we determine the influence of environmental variation and geographic barriers on the spatial genetic structure of a widely dispersed and phylogenetically independent sample of Amazonian bryophytes. Single nucleotide polymorphism data were produced from a restriction site-associated DNA sequencing protocol for 10 species and analyzed through F-statistics and Mantel tests. Neither isolation-by-environment nor the impact of geographic barriers were recovered from the analyses. However, significant isolation-by-distance patterns were observed for 8 out of the 10 investigated species beyond the scale of short-distance dispersal (> 1 km), offering evidence contrary to the inverse isolation hypothesis. Despite a cadre of life-history traits and distributional patterns suggesting that tropical bryophytes are highly vagile, our analyses reveal spatial genetic structures comparable to those documented for angiosperms, whose diaspores are orders of magnitude larger. Dispersal limitation for tropical bryophytes flies in the face of traditional assumptions regarding their dispersal potential, and suggests that the plight of this component of cryptic biodiversity is more dire than previously considered in light of accelerated forest fragmentation in the Amazon. © 2020 The Authors. New Phytologist © 2020 New Phytologist Trust