Out of the desert: Paleoclimatic changes drove the diversification of arid-adapted Ocymyrmex ants in southern Africa.

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 (∼12.5 Ma) and Pleistocene (∼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.

Now you see me, now you don't: verifying the absence of alien invasive yellow crazy ant Anoplolepis gracilipes in South Africa.

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.

Morphology and life history of an ant parasitoid, Psilocharis afra (Hymenoptera: Eucharitidae).

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.