John S. LaPolla

Phylogeny and taxonomy of the Prenolepis genus‐group of ants (Hymenoptera: Formicidae)

Abstract. We investigated the phylogeny and taxonomy of the Prenolepis genus‐group, a clade of ants we define within the subfamily Formicinae comprising the genera Euprenolepis, Nylanderia, gen. rev., Paraparatrechina, gen. rev. & stat. nov., Paratrechina, Prenolepis and Pseudolasius. We inferred a phylogeny of the Prenolepis genus‐group using DNA sequence data from five genes (CAD, EF1αF1, EF1αF2, wingless and COI) sampled from 50 taxa. Based on the results of this phylogeny the taxonomy of the Prenolepis genus‐group was re‐examined. Paratrechina (broad sense) species segregated into three distinct, robust clades. Paratrechina longicornis represents a distinct lineage, a result consistent with morphological evidence; because this is the type species for the genus, Paratrechina is redefined as a monotypic genus. Two formerly synonymized subgenera, Nylanderia and Paraparatrechina, are raised to generic status in order to provide names for the other two clades. The majority of taxa formerly placed in Paratrechina, 133 species and subspecies, are transferred to Nylanderia, and 28 species and subspecies are transferred to Paraparatrechina. In addition, two species are transferred from Pseudolasius to Paraparatrechina and one species of Pseudolasius is transferred to Nylanderia. A morphological diagnosis for the worker caste of all six genera is provided, with a discussion of the morphological characters used to define each genus. Two genera, Prenolepis and Pseudolasius, were not recovered as monophyletic by the molecular data, and the implications of this result are discussed. A worker‐based key to the genera of the Prenolepis genus‐group is provided.

Ants and the Fossil Record

The dominance of ants in the terrestrial biosphere has few equals among animals today, but this was not always the case. The oldest ants appear in the fossil record 100 million years ago, but given the scarcity of their fossils, it is presumed they were relatively minor components of Mesozoic insect life. The ant fossil record consists of two primary types of fossils, each with inherent biases: as imprints in rock and as inclusions in fossilized resins (amber). New imaging technology allows ancient ant fossils to be examined in ways never before possible. This is particularly helpful because it can be difficult to distinguish true ants from non-ants in Mesozoic fossils. Fossil discoveries continue to inform our understanding of ancient ant morphological diversity, as well as provide insights into their paleobiology.

The Importance of Using Multiple Approaches for Identifying Emerging Invasive Species: The Case of the Rasberry Crazy Ant in the United States

In the past decade, Houston, Texas has been virtually overrun by an unidentified ant species, the sudden appearance and enormous population sizes and densities of which have received national media attention. The Rasberry Crazy Ant, as it has become known due to its uncertain species status, has since spread to neighboring states and is still a major concern to pest control officials. Previous attempts at identifying this species have resulted in widely different conclusions in regards to its native range, source, and biology. We identify this highly invasive pest species as Nylanderia fulva (Mayr) using morphometric data measured from 14 characters, molecular sequence data consisting of 4,669 aligned nucleotide sites from six independent loci and comparison with type specimens. This identification will allow for the study and control of this emerging pest species to proceed unencumbered by taxonomic uncertainty. We also show that N. fulva has a much wider distribution than previously thought and has most likely invaded all of the Gulf Coast states.

Leaf litter ant diversity in Guyana

Leaf litter ants are an important group of organisms for informing conservation planning. This study presents the beginning of a leaf litter ant dataset for Guyana. Following the ants of the leaf litter protocol, ants were extracted from sifted leaf litter sampled along eight transects from across Guyana. A total of 230 species were collected from 44 genera. Of those 230 species, 122 species (ca. 53%) were found at only one site. Out of the 122 species found at only one site, 43 species (ca. 19%) were singletons, being known from only one specimen. Using a cluster analysis, faunistic composition was compared among sites. While the lowland sites accounted for the highest species richness, Mt. Ayanganna possessed an especially distinctive ant fauna and may represent a center of endemism. Three leaf litter ant communities were identified: lowland and two Mt. Ayanganna communities, mid-elevation and upper elevation. Recent mining operations on Mt. Ayanganna threaten its pristine nature and this study confirms the need for further biological study of the area. With upwards of 70% of its area still forested Guyana has the opportunity to preserve its biological heritage before widespread deforestation occurs. If expanded, this leaf litter ant dataset will be increasingly useful for country-wide conservation planning.

Evidence of niche shift and global invasion potential of the Tawny Crazy ant, Nylanderia fulva

Abstract Analysis of an invasive species niche shift between native and introduced ranges, along with potential distribution maps, can provide valuable information about its invasive potential. The tawny crazy ant, Nylanderia fulva, is a rapidly emerging and economically important invasive species in the southern United States. It is originally from east‐central South America and has also invaded Colombia and the Caribbean Islands. Our objectives were to generate a global potential distribution map for N. fulva, identify important climatic drivers associated with its current distribution, and test whether N. fulvas realized climatic niche has shifted across its invasive range. We used MaxEnt niche model to map the potential distribution of N. fulva using its native and invaded range occurrences and climatic variables. We used principal component analysis methods for investigating potential shifts in the realized climatic niche of N. fulva during invasion. We found strong evidence for a shift in the realized climatic niche of N. fulva across its invasive range. Our models predicted potentially suitable habitat for N. fulva in the United States and other parts of the world. Our analyses suggest that the majority of observed occurrences of N. fulva in the United States represent stabilizing populations. Mean diurnal range in temperature, degree days at ≥10°C, and precipitation of driest quarter were the most important variables associated with N. fulva distribution. The climatic niche expansion demonstrated in our study may suggest significant plasticity in the ability of N. fulva to survive in areas with diverse temperature ranges shown by its tolerance for environmental conditions in the southern United States, Caribbean Islands, and Colombia. The risk maps produced in this study can be useful in preventing N. fulvas future spread, and in managing and monitoring currently infested areas.

Systematics of the mealybug tribe Xenococcini (Hemiptera: Coccoidea: Pseudococcidae), with a discussion of trophobiotic associations with Acropyga Roger ants

The mealybug tribe Xenococcini (Hemiptera: Pseudococcidae) comprises three genera, Eumyrmococcus Silvestri, Neochavesia Williams & Granara de Willink and Xenococcus Silvestri, trophobiotically associated with ants of the genus Acropyga Roger (Hymenoptera: Formicidae). Alate Acropyga queens vertically transmit trophobionts by carrying them along on the nuptial flight, a unique behaviour termed trophophoresy. Xenococcine mealybugs have never been collected without ant associates, and putatively only associate with Acropyga. Xenococcine mealybugs are characterized by the absence of dorsal ostioles, presence of distally cup‐shaped circuli and a female pupal instar rather than a third feeding instar. The phylogeny of this tribe is derived for the first time using morphological data from adult females (53 characters) through Bayesian inference and maximum parsimony methods. Monophyly of the clade is strongly supported and a discussion of their taxonomy is included. The Neotropical genus Neochavesia was recovered as monophyletic. Eumyrmococcus, as previously defined, was recovered as paraphyletic, and thus two species are transferred to Xenococcus: Xenococcus kinomurai (Williams & Terayama) comb.n. and Xenococcus neoguineensis (Williams) comb.n. Two species groups are recognized within Eumyrmococcus: the Eumyrmococcus scorpioides species group, restricted to the eastern Mediterranean and Afrotropics, and the Eumyrmococcus smithii species group, restricted to the Orient and Indo‐Australasia. Six new species are described: Eumyrmococcus adornocapillussp.n. from Australia; Eumyrmococcus sarnatisp.n. from Fiji; Eumyrmococcus ordinotersussp.n. and Xenococcus baryglobosussp.n. from the Solomon Islands; Neochavesia cephalonodussp.n. from French Guiana; and Neochavesia linealumasp.n. from Guyana. The systematics and biology of the xenococcine mealybugs is discussed in the context of obligate ant symbiosis.

Phylogenomics, biogeography and diversification of obligate mealybug-tending ants in the genus Acropyga.

Acropyga ants are a widespread clade of small subterranean formicines that live in obligate symbiotic associations with root mealybugs. We generated a data set of 944 loci of ultraconserved elements (UCEs) to reconstruct the phylogeny of 41 representatives of 23 Acropyga species using both concatenation and species-tree approaches. We investigated the biogeographic history of the genus through divergence dating analyses and ancestral range reconstructions. We also explored the evolution of the Acropyga-mealybug mutualism using ancestral state reconstruction methods. We recovered a highly supported species phylogeny for Acropyga with both concatenation and species-tree analyses. The age for crown-group Acropyga is estimated to be around 30Ma. The geographic origin of the genus remains uncertain, although phylogenetic affinities within the subfamily Formicinae point to a Paleotropical ancestor. Two main Acropyga lineages are recovered with mutually exclusive distributions in the Old World and New World. Within the Old World clade, a Palearctic and African lineage is suggested as sister to the remaining species. Ancestral state reconstructions indicate that Old World species have diversified mainly in close association with xenococcines from the genus Eumyrmococcus, although present-day associations also involve other mealybug genera. In contrast, New World Acropyga predominantly evolved with Neochavesia until a recent (10-15Ma) switch to rhizoecid mealybug partners (genus Rhizoecus). The striking mandibular variation in Acropyga evolved most likely from a 5-toothed ancestor. Our results provide an initial evolutionary framework for extended investigations of potential co-evolutionary interactions between these ants and their mealybug partners.

Monograph of Nylanderia (Hymenoptera: Formicidae) of the World: An introduction to the systematics and biology of the genus

This paper serves as an introduction to a world monographic series addressing the species-level taxonomy of the ant genus Nylanderia. This series will consist of several regionally based taxonomic revisions. The systematics and biology of Nylanderia are discussed in a global context, and a diagnosis of the genus is given. Several morphological features, which are considered putative synapomorphies for the genus, are provided. Morphological descriptions of all three castes (workers, queens, and males) are provided and discussed.

Isolation and characterization of Nylanderia fulva virus 1, a positive-sense, single-stranded RNA virus infecting the tawny crazy ant, Nylanderia fulva

We report the discovery of Nylanderia fulva virus 1 (NfV-1), the first virus identified and characterized from the ant, Nylanderia fulva. The NfV-1 genome (GenBank accession KX024775) is 10,881 nucleotides in length, encoding one large open reading frame (ORF). Helicase, protease, RNA-dependent RNA polymerase, and jelly-roll capsid protein domains were recognized within the polyprotein. Phylogenetic analysis placed NfV-1 in an unclassified clade of viruses. Electron microscopic examination of negatively stained samples revealed particles with icosahedral symmetry with a diameter of 28.7±1.1 nm. The virus was detected by RT-PCR in larval, pupal, worker and queen developmental stages. However, the replicative strand of NfV-1 was only detected in larvae. Vertical transmission did not appear to occur, but horizontal transmission was facile. The inter-colonial field prevalence of NfV-1 was 52±35% with some local infections reaching 100%. NfV-1 was not detected in limited samples of other Nylanderia species or closely related ant species.

A new ant genus from the Greater Antilles and Central America, Zatania (Hymenoptera: Formicidae), exemplifies the utility of male and molecular character systems

The ant genus Prenolepis (Hymenoptera: Formicidae) is the nominal member of the recently established Prenolepis genus‐group within the subfamily Formicinae. Our molecular phylogenetic analyses using fragments from five nuclear genes (arginine kinase, carbomoylphosphate synthase, elongation factor 1‐alpha F1, elongation factor 1‐alpha F2, wingless) and one mitochondrial gene (cytochrome oxidase I) indicate that this genus is polyphyletic. Although the majority of Prenolepis species was found to belong to the same monophyletic group (Prenolepis sensu stricto), a smaller subset of Prenolepis species, all found in either Central America or the Greater Antilles, was robustly inferred to comprise a distinct lineage that is sister to the Old World genus Paraparatrechina. Here we describe this newly discovered lineage within the larger Prenolepis genus‐group clade. The genus Zatania, gen.n. is composed of five extant species (Zatania albimaculata, Zatania cisipa, Zatania gibberosa, Zatania gloriosa, sp.n. and Zatania karstica) and one Dominican amber fossil species (Zatania electra†, sp.n.). These are medium‐sized ants (generally between 2.5 and 3 mm in total length) that are characterized by having long scapes and legs, and elongated mesosomata. A reliance on worker‐based taxonomy has previously prevented the discovery of this new lineage because of worker convergence consisting of various combinations of elongated mesosomata, long scapes and legs, and a constriction immediately behind the pronotum, observed in several distinct lineages within the Prenolepis genus‐group. However, we did find that male morphology complements our molecular results in revealing important diagnostic and potentially phylogenetically informative characters. Our study highlights the value for ant systematics to expand beyond its traditional foundation of worker‐based morphology and embrace character systems from other castes and molecular data.