Species richness is one of the fundamental metrics of biodiversity. Estimating species richness helps spotlight taxonomic groups that are particularly under-studied, such as the highly diverse Darwin wasps. The only available estimate of the number of Darwin wasps in the Afrotropics proposed almost 11,000 species, compared to the 2,322 recorded species. However, it relied exclusively on the ratio of morphospecies to described species in Henry Townes’ personal collection. We provide an updated estimate of the Afrotropical Darwin wasp species, using empirical data from multiple sources, including the increase in species numbers following generic revisions, morphospecies sorting in natural history collections, and diversity patterns of better-studied insects (butterflies) for extrapolation. Our analyses suggest that our knowledge of Darwin wasps is highly incomplete, with only 13–22% of species known in the five most extensively studied countries in the Afrotropics. We estimate 9,206–15,577 species of Darwin wasps within the entire Afrotropics, with the highest concentration expected in the Equatorial Afrotropics and Madagascar. Due to data constraints, our approach tends to underestimate diversity at each step, rendering the upper estimate (15,577 species) more realistic. We highlight reasons contributing to the gap between recorded and estimated species richness, including logistical and financial factors, as well as post-colonial influences.

Biogeography attempts to find explanations for the distributions of species, based on their past histories and present environmental conditions. Historically, biogeographic studies were modelled on intuitive and expert knowledge, whereas recent studies have advanced with the aid of digitised natural history collections, computational power and repeatable methods. In South Africa, biogeographical studies on insects are greatly lacking and very little is known about the zoogeographic patterns for many insect groups in the region. South Africa has a high level of diversity and endemism of orthopterans (> 800 species), making them an ideal group to investigate zoogeographic patterns. The aim of this study was to identify and describe the zoogeographical patterns of South Africa’s orthopteran species, based on the distributions and levels of diversity of all major families. Point locality data was used to conduct a hierarchical cluster analysis based on the shared presence of species to delimit zoogeographical centres. In addition, delimited centres were compared to plant-based biomes and phytogeographic regions. Results showed that orthopteran species richness was evenly distributed across the region and clustered into six zoogeographical centres. There was a primary split, separating species into a western winter-rainfall and an eastern summer-rainfall group. The western and eastern regions contained three centres each, with the east being less diverse and taxonomically distinctive than the west. Strong consensus was seen between orthopterans and the Greater Cape Floristic Region, and between orthopterans and the Cape zoogeographic region for butterflies, reinforcing the notion that this region is representative of a biochorion. In addition, this region had the greatest numbers of orthopteran families, highlighting its importance for orthopteran diversification.

The genus Bullacris in the family Pneumoridae was most recently revised by Dirsh in 1965 based on morphological comparisons between species. However, since that time, new information about the genus and the family has come to light, necessitating a revision of the genus. In addition, the species B. boschimana was originally described based on a single female specimen. Here we present and describe the male of the species for the first time. The aim of this study was to update the current species descriptions by including additional specimens and incorporating additional methods for a more comprehensive comparison. Analyses consisted of morphometric measurements from high-quality images of type specimens, existing South African museum specimens, as well as personally collected specimens. Acoustic signals are also presented and compared between species. In addition, phylogenetic analyses were conducted on the barcoding mitochondrial gene COI and two nuclear genes, namely ITS and 18S. Results show that according to morphological, acoustic and genetic data, B. discolor and B. serrata as well as B. intermedia and B. membracioides share notable similarities. Bullacris discolor and B. serrata share similar phenotypic traits, in which B. discolor can either appear uniform in colour or have a speckled variation that is very similar in appearance to B. serrata. Bullacris intermedia and B. membracioides have a 5% mitochondrial DNA pairwise distance, suggesting that they may have not be fully diverged; however, morphological analysis shows that these species are morphologically distinguishable. It is suggested that these species may have undergone spatial separation at one point; however, further investigation is required. Additional sampling across a wider geographic range is essential to clarify the relationships between B. discolor and B. serrata, as well as between B. intermedia and B. membracioides.