Small organisms tend to lose water more rapidly than larger ones because of their high surface area relative to their body volume. In hot arid regions, desiccation resistance is an important trait for these organisms as they are exposed to high day temperatures and scarcity of water. For instance, Ocymyrmex ants have evolved physiological adaptations that enable them to survive the dry environments in which they live. These ants are adapted to forage at ground temperatures exceeding 50 degrees C. In this study, we investigated the physiological traits that enhance thermo-tolerance across selected Ocymyrmex species, collected from different climatic zones in South Africa. We measured and compared desiccation resistance, critical thermal limits, and cuticular hydrocarbon composition of these ants and tested whether these traits are evolutionary conserved or labile. We also investigated whether these adaptations are maintained by evolutionary constraints or environmental factors. Our results demonstrated that these ants have high thermal limits, are resistant to desiccation, and that their cuticular hydrocarbons are composed of long chains dominated by linear alkanes, which are believed to be beneficial for waterproofing. The results also showed a strong phylogenetic signal for desiccation tolerance, which could indicate that desiccation tolerance is an ancestral trait in this group of ants. In contrast, there was weak evidence for phylogenetic signal in critical thermal limits across all species, which could indicate that these traits are ubiquitous rather than varying across species from different environments.

A highly endemic ant fauna is found in the arid regions of southern Africa, including species in the genus Ocymyrmex. This genus of ants has higher species richness in the western arid regions of southern Africa compared to tropical and subtropical parts of the continent. The processes that have produced these patterns of diversity and distribution of arid adapted ants in southern Africa have never been investigated. The diversification of many other taxa in the region has been associated with past climate fluctuations that occurred during the Miocene epoch. In this study, the nature and timing of historical processes that may have led to the diversification within Ocymyrmex were assessed. We hypothesized that past climate oscillations, characterized by long periods of aridification, have driven the current distribution of Ocymyrmex species that resulted in the highest species richness of the genus in the Deserts & xeric shrublands biome in southern Africa. Ninety-four Ocymyrmex worker specimens from Botswana, Kenya, Namibia, South Africa, Tanzania and Zimbabwe, representing 21 currently described species and six morphospecies, were included in a phylogenomic analysis. Phylogenies for the genus, based on next generation sequencing data from ultraconserved elements, were inferred using Maximum Likelihood, and a dating analysis was performed using secondary age estimates as calibration points. A distribution database of Ocymyrmex records was used to assign species ranges, which were then coded according to major biomes in southern Africa and used as input for biogeographical analysis. We explored the phylogenomic relationships of Ocymyrmex and analysed these within a biogeographical and paleoclimatic framework to disentangle the potential processes responsible for diversification in this group. Dating analyses estimated that the crown age of Ocymyrmex dates to the Oligocene, around 32 Ma. Diversification within this group occurred between the mid-Miocene (similar to 12.5 Ma) and Pleistocene (similar to 2 Ma). Our biogeographic analyses suggest that Ocymyrmex species originated in the south-western region of southern Africa, which is now part of the Deserts & xeric shrublands biome and diversified into eastern subtropical areas during the Pliocene. Paleoclimatic changes resulting in increased aridity during the Miocene likely drove the diversification of the genus Ocymyrmex. It is most likely that the diversification of grasslands, because of historical climate change, facilitated the diversification of these ants to the eastern parts of southern Africa when open grasslands replaced forests during the early Miocene.

Anoplolepis gracilipes is an invasive species that is a major threat to native ecosystems worldwide. It has been listed as one of the top 100 worst invasive species in the world and is well known for its negative impact on native arthropods and some vertebrates. This study aimed to confirm the presence or absence of A. gracilipes in some major South African harbours. We did so by surveying four harbours in the Western Cape and KwaZulu-Natal provinces, using pitfall trapping, yellow pan traps, and baiting. In addition, ant collections from Iziko Museums of South Africa (Cape Town, South Africa), University of KwaZulu-Natal (Pietermaritzburg campus, South Africa), Iimbovane Outreach Project (Stellenbosch University, South Africa), and AfriBugs CC (Pretoria, South Africa) were examined for specimens of A. gracilipes . The invasive species A. gracilipes was not detected from any of the sampled harbours during this study, nor in the main ant collections in South Africa. The only, and potentially erroneous published record of A. gracilipes in South Africa, is from Durban harbour and subsequent possibly erroneous citizen science observations are from other coastal sites such as Gansbaai, Knysna, Table Bay, and Kalk Bay. This is a positive outcome for conservation authorities as this species is highly invasive and, if introduced, will likely outcompete native fauna and result in ecosystem collapse. Although A. gracilipes was not detected in the samples from this study, early detection and eradication of this species should be prioritised. This can be achieved through existing pest monitoring programs at harbours, and continued border biosecurity measures.

Eucharissa (Hymenoptera: Eucharitidae) is an enigmatic genus within Chalcidoidea. Adults have at least 16 antennal segments, which is shared only by the closely related genus, Saccharissa, with some species of Eucharissa having as many as 22 antennal segments. At most, other Chalcidoidea have up to 14 segments. Phylogenetic analyses place Eucharissa within the poneromorph-ant attacking clade, but until now, the host and immature stages of this genus were unknown. Eucharissa insolita sp. nov. was discovered in two cocoons of Bothroponera granosa (Ponerinae) from South Africa; one a fully developed male and the other a second-instar larva. The larval exuviae present within the cocoons allowed for description of the life stages and comparison with other members of the poneromorph-attacking clade of Eucharitidae. Morphology of the pupa across Eucharitidae is reviewed, and synapomorphies of the immature stages are identified that support monophyly of the poneromorph-attacking clade within the tribe Eucharitini.

Eucharitidae (Hymenoptera) are specialized ant (Formicidae) parasitoids. As we begin to develop a better understanding of their phylogenetic relationships, it is critical to establish baselines for morphological and biological data. A morphological review and the first report of life history data for Psilocharis afra Heraty is provided based on new material from the Mpumalanga Province of South Africa. Psilocharis Heraty is included in Eucharitinae, but it is unclear whether it is the sister group of all other members of the subfamily, or sister group to Neolosbanus Girault in a monophyletic Psilocharitini, which would in turn be sister group to Eucharitini. The oviposition habits of P. afra differ from those of other Eucharitidae in that eggs are placed among trichomes under bracts at flower bases, instead of either being inserted into cavities formed in plant tissue by an enlarged ovipositor (as in Oraseminae and some Neolosbanus) or inserted into cavities in plant tissue, as in most Eucharitini. The egg and first-instar planidia larva are described, and adult morphology is discussed with reference to Eucharitidae and other parasitoid Hymenoptera.

Ants of the Tetramorium solidum group occur in Africa, with the vast majority of species endemic to the arid regions of southern Africa. The first revision of the genus was published more than 30 years ago and ant surveys have since considerably expanded the number of specimens available for study. The revision of this group reveals five new species, expanding the total number to 19. Almost all the species in this group occur in the southern parts of the Afrotropical region, with the exception of T. setuliferum Emery, 1895 and T. rothschildi (Forel, 1907). These two species have broad distributions within African grasslands and savannas, with T. setuliferum occurring in southern Africa and T. rothschildi in East Africa and the Sahel. Five new species are described in this revision: T. aisha sp. nov., T. brigitteae sp. nov., T. duncani sp. nov., T. lerouxi sp. nov. and T. margueriteae sp. nov. An illustrated key is presented and descriptions of new species are provided, supported by montage images and distribution maps.

This study reviews the taxonomy of the ant genus Nesomyrmex Wheeler, 1910 in the Afrotropical region. Previous revisionary studies are discussed and four species groups are proposed on the basis of external morphology. The N. angulatus group contains seven species that are widely distributed throughout the whole Afrotropical region, with one species also occurring in the Palaearctic and Malagasy regions. The N. cataulacoides group is monotypic, with one morphologically bizarre species found in Equatorial rain forests. The N. humerosus group is also monotypic and occurs in East Africa. The last and by far most species-rich group is the N. simoni group that contains 17 species, all of which are endemic to South Africa. The four groups are defined for the first time for the region, and an illustrated identification key is provided. Furthermore, the N. angulatus group is more thoroughly reviewed. One new species from Mozambique is described, N. inhaca sp. nov., and species accounts for the other six are provided. Also, an illustrated identification key to the species of the N. angulatus group is presented.

The Tetramorium solidum-group occurs in Africa, with the vast majority of species endemic to the arid regions of southern Africa. In the more than 30 years since the first revision of the genus by Bolton (1980), ant surveys have considerably expanded the amount of material available, including surveys conducted specifically for this study. This review, based on both morphological and genetic data, has expanded the number of known species from 14 (Bolton 1980) to 19, constituting an increase of 36%.

Members of the genus Nesomyrmex in southern Africa are small, non-dominant, myrmicine ants that nest either in trees (angulatus-group) or in soil (simoni-group). Of the twenty species recorded from this region, the following 15 are newly described: ontoinetteae, cederbergensis, entabeni, ezantsi, inye, karooensis, koebergensis, larsenae, mcgregori, nanniae, njengelanga, ruani, saasveldensis, tshiguvhoae and vannoorti. All Nesomyrmex species recorded from southern Africa are described and illustrated, with accompanying information on biology and distribution.