Southern African Species Research Articles

Morphology, locomotor performance and habitat use in southern African agamids

AbstractUnderstanding the relationships between form and function can help us to understand the evolution of phenotypic diversity in different ecological contexts. Locomotor traits are ecologically relevant as they reflect the ability of an organism to escape from predators, to catch prey or to defend territories. As such, locomotion provides a good model to investigate how environmental constraints may influence an organism’s performance. Here, we investigate the ecomorphological relationships between limb morphology, locomotor performance (sprint speed and endurance) and habitat use in six southern African agamid species. The investigated agamid species showed differences in hind limb and toe lengths. Both of these traits were further correlated with endurance capacity. This association was supported by stepwise multiple regression analyses. However, we demonstrate trade-offs in locomotor performance traits, suggesting that specialization towards speed comes at the detriment of endurance capacity. Overall, the single arboreal species studied had longer hind limbs, a higher exertion capacity and a higher mean speed. However, for a given hind limb length, the arboreal species was slower than the other habitat specialists. This study provides insights into the evolutionary mechanisms that have driven the morphological and functional evolution in southern African agamid lizards.

Bat thermoregulation in the heat: Limits to evaporative cooling capacity in three southern African bats.

High environmental temperatures pose significant physiological challenges related to energy and water balance for small endotherms. Although there is a growing literature on the effect of high temperatures on birds, comparable data are scarcer for bats. Those data that do exist suggest that roost microsite may predict tolerance of high air temperatures. To examine this possibility further, we quantified the upper limits to heat tolerance and evaporative cooling capacity in three southern African bat species inhabiting the same hot environment but using different roost types (crevice, foliage or cave). We used flow-through respirometry and compared heat tolerance limits (highest air temperature (Ta) tolerated before the onset of severe hyperthermia), body temperature (Tb), evaporative water loss, metabolic rate, and maximum cooling capacity (i.e., evaporative heat loss/metabolic heat production). Heat tolerance limits for the two bats roosting in more exposed sites, Taphozous mauritianus (foliage-roosting) and Eptesicus hottentotus (crevice-roosting), were Ta=~44°C and those individuals defended maximum Tb between 41°C and 43°C. The heat tolerance limit for the bat roosting in a more buffered site, Rousettus aegyptiacus (cave-roosting), was Ta=~38°C with a corresponding Tb of ~38°C. These interspecific differences, together with a similar trend for higher evaporative cooling efficiency in species occupying warmer roost microsites, add further support to the notion that ecological factors like roost choice may have profound influences on physiological traits related to thermoregulation.

Biomass partitioning in an endemic southern African salt marsh species Salicornia tegetaria (Chenopodiaceae)

The below ground biomass of salt marsh species accounts for more than half of the total plant biomass in salt marsh systems, yet no biomass data exist for salt marsh species in South Africa. The aims of the current study were to compare the biomass allocation of Salicornia tegetaria in six estuaries and relate findings to their environmental conditions. The current study measured the physico-chemical variables of the sediment (moisture content, organic matter content, electrical conductivity, pH) and pore water (temperature, salinity, pH, depth) at Olifants, Berg, Langebaan, Heuningnes, Nahoon and Kwelerha estuaries. Above and below ground biomass and stem height measurements were also collected. The below ground biomass (1.51 ± 0.24 kg m−2) and root/shoot ratio (1.36 ± 0.17) was the lowest at Heuningnes Estuary with no significant difference at the remaining estuaries, suggesting that factors, such as geomorphology and sedimentological processes, could have a stronger effect on the biomass allocation in this species. Important drivers of biomass allocation were sediment pH, redox potential and pore water depth. The current study provides baseline information for S. tegetaria, an endemic salt marsh species, for which there is a paucity of data. This species plays a major role in the ecology of the lower intertidal zone, which will be vulnerable to sea-level rise.

A taxonomic revision of Schoenus cuspidatus and allies (Cyperaceae, tribe Schoeneae)—Part 2

This is the second half of a two-part taxonomic revision on the morphologically complex Schoenus cuspidatus and allies group. This revision is a continuation of recent taxonomic work that has transferred 24 southern African species from Tetraria and Epischoenus into Schoenus, revised the taxonomy of the Schoenus compar—Schoenus pictus and allies group, as well as part of the S. cuspidatus group. Most recently, we presented descriptions of three new species and a new combination among the Southern African Schoenus species. Here, we revise the delimitations and distributions of five species (Schoenus compactus, Schoenus crassus, S. cuspidatus, Schoenus galpinii and Schoenus riparius) based on data from a review of specimens from twelve herbaria and recent field collections. We also describe three new species to science: Schoenus australis, Schoenus brunnescens and Schoenus graciliculmis—the first two of which are endemic to the Western Cape Province of South Africa, while S. graciliculmis is endemic to the Eastern Cape Province. We present a taxonomic key, an updated nomenclature and provide revised descriptions and distribution maps for these nine Schoenus species. Finally, we discuss unresolved taxonomic issues within this group, especially within the broadly circumscribed S. cuspidatus, and outline circumscriptions and specimens that require further study. Species within this group are perennial, caespitose graminoids with terete, leafless culms, and although most of these species have broad elliptic nutlets, there are differences in growth and spikelet forms that differentiate species.

The complete mitogenome of the fairy shrimp Streptocephalus cafer (Lovén, 1847) (Crustacea: Branchiopoda: Anostraca) from an ephemeral pond in Botswana, southern Africa

Fairy shrimps (Anostraca) constitute an important component of seasonally aquatic habitats, but few complete mitochondrial genomes have been published for this group. Here, we report the mitogenome of a common southern African species, Streptocephalus cafer, from Botswana (accession number: MN720104). Low-coverage shotgun sequencing recovered two contigs 15653 bp and 1347 bp in length that are separated by a repetitive region of unknown length within the non-coding control region. The mitogenome’s GC content is 31.80%. Phylogenetic analysis using protein-coding genes confirms the sister taxon relationship of S. cafer with the only other congener whose mitogenome has been reconstructed to date, the Asian S. sirindhornae.

Stem and leaf structure of Searsia erosa (Thunb.) Moffett (Anacardiaceae) with systematic, ecological and ethnobotanical implications

The anatomy of stems and leaves of the southern African evergreen shrub Searsia erosa (Anacardiaceae) was studied. This species shows the suite of typical traits of Anacardiaceae, such as the presence of secretory canals in the cortex, secondary phloem, wood rays and vascular bundle of leaf midrib, pericyclic fibres in nearly continuous bands, compound sieve plates on oblique walls, simple perforation plates, alternate intervessel pitting, and septate libriform fibres. Like other Searsia species, S. erosa has abundant sclereids in non-conducting secondary phloem, multicellular peltate glandular trichomes on leaf epidermis, short vessel elements and minute intervessel pits; two latter characters are thought to be diagnostic for this genus. Unlike Asian species of Searsia, S. erosa lacks marginal axial parenchyma as well as prismatic crystals in axial parenchyma and in libriform fibres, but it shows the helical thickenings on vessel walls. The presence of the last trait in a southern African species agrees with association of helical thickenings with the regions that experience water stress. The tangential expansion of secondary phloem in S. erosa and probably in other Searsia species is mainly performed by considerable increase in volume of its cells by their sclerification. Such a way of bark growth in girth is out of scope of bark anatomists. Searsia erosa is distinctive from other congeneric species in its hypostomatous leaves with abundant glandular trichomes on adaxial side. This condition demonstrates a labor division between the adaxial side with glandular trichomes that may contribute to leaf protection, and the stomata-bearing abaxial side providing the gas exchange. Unlike most members of Anacardiaceae, the secretory canals of S. erosa produce the oleoresin containing terpenoids (essential oils) and lipids, but lack polysaccharides. The abundance of glandular trichomes and secretory canals producing terpenoids is a presumable reason of the use of S. erosa in traditional medicine by the Basotho people.

The genetic consequences of habitat specificity for fig trees in southern African fragmented forests

Theory predicts that fragmentation will lead to reduced gene flow between populations, with loss of genetic diversity and increased population differentiation. However, these predictions may not always hold true, especially for long-lived woody plants and some fig trees (Ficus species) may not be affected by fragmentation because their fig wasps can transfer pollen for distances of over 100 km. Here we contrast the extent of genetic isolation caused by fragmentation among three southern African Ficus species with different habitat dependencies and distributional ranges. Two of the species are restricted to forest environments, which have been fragmented since at least the Pleistocene, and provide an indication of the long-term genetic effects of forest fragmentation. The third species is less forest-dependent, with a more general habitat association and more continuous populations. We found significant population differentiation in all three species. Populations of F. bizanae, a forest specialist with a highly restricted distribution, displayed the most genetic structure, followed by the second forest specialist, F. craterostoma. Populations of the habitat-generalist F. sur were the least genetically structured. Forest specialist Ficus species are clearly not immune to habitat fragmentation, despite extensive pollen flow, and other southern African forest trees are likely to have experienced similar or greater effects of habitat fragmentation. The strong genetic structure of F. bizanae suggests a limited seed dispersal range and local dispersal by the fig wasp pollinator, a possible adaptation to the limited range of its host fig tree.

Wild antelope skeletal muscle antioxidant enzyme activities do not correlate with muscle fibre type or oxidative metabolism

Wild antelope are some of the fastest land animals in the world, presenting with high oxidative and glycolytic skeletal muscle metabolism. However, no study has investigated their muscle antioxidant capacity, and may assist in understanding their physical ability and certain pathophysiological manifestations, such as capture myopathy. Therefore, the primary aim of this study was to determine the antioxidant activities superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GR), as well as five key regulatory enzymes that serve as markers of glycolysis (phosphofructokinase (PFK) and lactate dehydrogenase (LDH)), the tricarboxylic acid cycle (citrate synthase (CS)), β-oxidation (3-hydroxyacetyl CoA dehydrogenase (3HAD)) and the phosphagen pathway (creatine kinase (CK)), in the Vastus lateralis muscle of six southern African wild antelope species (mountain reedbuck, springbok, blesbok, fallow deer, black wildebeest and kudu). Four different muscle groups from laboratory rats served as reference values for the enzyme activities. SOD, CS and LDH activities were the highest in the wild antelope, whereas CK appeared highest in rat fast twitch muscles. Between the wild antelope species, differences exist for SOD, CAT, PFK, CK and LDH, but not for CS, 3HAD and GR. CAT and GR correlated positively only with type I fibres. No correlations could be found between muscle fibre type and the oxidative enzymes, CS and 3HAD, from the wild animals, concurring with previous studies on porcine and rats. However, wild antelope and rat muscle CK and SOD strongly correlated, hinting towards an antioxidant role for CK.

Antimicrobial activity and toxicity profile of selected southern African medicinal plants against neglected gut pathogens

Anaerobes outnumber aerobic bacteria in the human gut. The most commonly isolated microorganisms in intra-abdominal infections include Escherichia coli, Peptostreptococcus micros as well as Bacteroides and Clostridium species. Several studies have been undertaken on southern African medicinal plant species and their antimicrobial efficacy against pathogens such as E. coli that cause stomach ailments. However, pathogens such as Helicobacter pylori, Fusobacterium varium as well as others have been neglected in medicinal plant antimicrobial research. The aim of this study was to evaluate the antimicrobial activity of selected medicinal plants documented for stomach ailments against neglected gut pathogens. A total of 102 aqueous and organic extracts were prepared from 40 different plant species. These plant samples were screened for antimicrobial efficacy against eight anaerobes and two microaerophilic strains using the micro-dilution antimicrobial assay. Plant extracts that displayed noteworthy antimicrobial activity against Clostridium perfringens were further evaluated for antibiofilm activity using the crystal violet staining assay. The toxicity profiles of plants that displayed noteworthy antimicrobial activity were evaluated using the brine shrimp lethality assay which revealed that most of the tested plant samples were non-toxic in nature, and the aqueous extracts proved to be safer. The organic extract of Lippia javanica leaf showed the best antimicrobial activity with a minimum inhibitory concentration of 0.5 μg/mL against C. perfringens. The organic extract of Salvia africana-caerulea displayed the best antibiofilm activity overall, at cell attachment (4 h) biofilm developmental stage with inhibition percentages of 82.8%.
 Significance:
 
 L. javanica and Gunnera perpensa demonstrated the highest antimicrobial activity with minimum inhibitory concentrations of 0.5 μg/mL and 2.0 μg/mL against C. perfringens, respectively.
 Salvia africana-caerulea was the most effective plant species demonstrating biofilm attachment.
 Lowest toxic effects were observed for the organic extracts of Aloe marlothii, A. tenuior, Bridelia cathartica, G. perpensa leaf and the aqueous extracts of G. perpensa (leaf and rhizome).
 This study demonstrates, for the first time, both antimicrobial and antibiofilm activities for most of these plant species against neglected anaerobes.
 Noteworthy antimicrobial activities in many cases validate traditional use and safety.

A new forest dwelling button spider from South Africa (Araneae, Theridiidae, Latrodectus).

The medically important spider genus Latrodectus Walckenaer 1805, commonly referred to as "button spiders" in South Africa, is represented by six species in the country. Using morphology and the COI barcoding gene we describe a new forest dwelling species,Latrodectus umbukwane n. sp. Wright, Wright, Lyle and Engelbrecht. Females have red markings on both the ventral and posterior dorsal surfaces of the abdomen, parallel spermathecae and three loops of the copulatory ducts. Males have an embolus with four loops and diagnostic white markings on the ventral surface of the abdomen that darken with age. Egg sacs are smooth, large, and bright purple when freshly laid, turning shiny grey with time. Latrodectus umbukwane n. sp.is known only from sand forest vegetation types in northern Zululand, KwaZulu-Natal, South Africa. A predicted geographic distribution for this species is provided based on cartographic mapping of known habitat and altitudinal preference, from which area of occupancy (AOO; 698 km2) and extent of occurrence (EOO; 4963 km2) were calculated to assess potential IUCN Red List status. Due to the uncertainty of the distribution of this species, a Red List status of Data Deficient (DD) is recommended. An updated key to the southern African species of Latrodectus is provided.

Genetic variation among different springbok (Antidorcas marsupialis) colour variants

The linebreeding of southern African antelope species, involving selection for specific coat colour phenotypes, is a wide-spread practice in the South African game farming industry. Concerns have been voiced with regards to the genetic status of these line-bred colour variants, due to the high risk of inbreeding. The springbok (Antidorcas marsupialis) is one of the most well-known examples of such linebreeding. Numerous colour variants have been observed, with the most notable the black, copper and white colour phenotypes. To our knowledge, no research has been performed on the genetic basis of these springbok colour variants. In this study, we aimed to 1) assess the level of genetic variation within and among the common, black, copper and white colour variants of springbok, and 2) investigate the possible genetic mechanisms involved in the coat colour of these variants. Portions of the mtDNA control region (CR) and two immune-linked Toll-like receptor (TLR4 and TLR7) genes were sequenced for the genetic diversity estimates. A 50 K Bovine SNP chip was also screened to assess the level of genetic diversity of a subset of samples. The complete melanocortin 1 receptor (MC1R) gene was targeted for the second aim. Comparable levels of diversity were identified across specimens. Pairwise genetic diversity analysis of the SNP data identified the white springbok as a unique group within springbok, with Bayesian clustering analysis supporting this observation. A possible reason for this clustering pattern was linked to the historical occurrence of white springbok in nature. The level of genetic diversity observed for each colour variant was associated with 1) the large historical and extant population sizes of springbok providing a deep genetic pool and/or 2) the management practices of the managers/farmers that are aimed at preventing or minimizing inbreeding and loss of genetic diversity. The MC1R assessment identified a nonsynonymous SNP (c. G902A) unique to white springbok (homozygous AA). A 24 bp deletion was observed in black, copper and king springbok colour variants. This deletion was complete for ∼21 % of black springbok. The heterozygous variant was observed in ∼88 % of copper springbok and ∼5 % of black springbok. This would suggest that additional genetic factors are involved in coat colour determination (due to the incomplete association of the 24 bp deletion). Further research is therefore needed to identify the other possible genetic factors involved.

<p><strong>A taxonomic revision of the southern African species of <em>Pelargonium</em> section <em>Peristera </em>(Geraniaceae)</strong></p>

The genus Pelargonium (Geraniaceae) includes ca. 281 species, organised into 16 sections and four subgenera. Since the last revision of the genus by Knuth in 1912, recent revisions have been completed for all of the currently recognised sections of the genus with the exception of three, sections Ciconium, Otidia and Peristera. Pelargonium sect. Peristera is lectotypified, and a taxonomic revision of the southern African species of this section is presented, recognising 11 species, of which one, P. sessiliflorum, is described as new. An identification key is provided along with nomenclature, descriptions, distribution maps, habitat information, and conservation notes for the 11 recognised species, synonymising nine names.

A beautiful new species of Hyalonthophagus Palestrini & Giacone, 1988 (Coleoptera: Scarabaeidae: Scarabaeinae), from the Northern Cape Province, South Africa

Hyalonthophagus Palestrini Giacone, 1988, from Afrotropical savanna, is raised to generic status having been originally described as a subgenus within the genus Onthophagus Latreille, 1802. Hyalonthophagus pulcher Deschodt Davis, new species is described from the Northern Cape, South Africa. Maps are provided to show (1) the locally-restricted distribution pattern of the new species isolated from adjoining savanna in warm, dry Karoo climate to the south of the Orange River, and, (2) the disjunct distribution pattern in relation to those of three other southern African species centred in savanna to the northeast beyond areas with unsuitable climatic or ecological conditions. An assessment of the conservation status for Hyalonthophagus pulcher Deschodt Davis, new species is also provided.

New southern African species and a revalidation in the dung beetle genus Gyronotus van Lansberge, 1874 (Scarabaeidae: Scarabaeinae) with an updated key.

Three new species are described in the genus Gyronotus van Lansberge, 1874 (Scarabaeidae: Scarabaeinae), from upland grasslands of South Africa. They are Gyronotus dracomontanus Deschodt Davis, new species, Gyronotus ovalis Deschodt Davis, new species and Gyronotus kearneyorum Deschodt Davis, new species. The South African coastal forest species, Gyronotus marginatus Péringuey, 1888, status revised, is removed from synonymy with Gyronotus pumilus (Boheman, 1857) and revalidated at species level. An updated key to all South African and eSwatini species is provided.

Systematics of the dung beetle tribe Sisyphini Mulsant (Scarabaeidae: Scarabaeinae) inferred from a molecular phylogeny and biogeography of southern African species

AbstractThe tribe Sisyphini Mulsant was recently redefined following the transfer of the endemic southern African genus Epirinus Dejean from the polyphyletic tribe Deltochilini Lacordaire. A molecular phylogeny of the southern African members of Sisyphini supports Epirinus as sister to Sisyphus Latreille and recovered three major clades in Sisyphus classified here as subgenera Sisyphus (Neosisyphus Müller) stat. rev., Sisyphus (Parasisyphus Barbero, Palestrini & Zunino) stat.n. and Sisyphus (Sisyphus) stat.n. A molecular clock analysis suggests that Sisyphus and Epirinus diverged from their last common ancestor during the Lower to Middle Oligocene (c. 29.37 Ma). Biogeographical analysis indicated that southern African Sisyphus species are centred in the east and northeast in Highveld grassland and warmer savannah regions. By contrast, Epirinus species are largely restricted to the southwest and southeast in the cooler winter and bimodal rainfall regions plus arid highland Karoo and Highveld grasslands. Based on morphological and biogeographical differences between Epirinus and Sisyphus, we propose that the monogeneric Epirinus be placed in its own tribe, Epirinini van Lansberge stat. rev.

Seasonal and habitat effects on the nutritional properties of savanna vegetation: Potential implications for early hominin dietary ecology

The African savannas that many early hominins occupied likely experienced stark seasonality and contained mosaic habitats (i.e., combinations of woodlands, wetlands, grasslands, etc.). Most would agree that the bulk of dietary calories obtained by taxa such as Australopithecus and Paranthropus came from the consumption of vegetation growing across these landscapes. It is also likely that many early hominins were selective feeders that consumed particular plants/plant parts (e.g., leaves, fruit, storage organs) depending on the habitat and season within which they were foraging. Thus, improving our understanding of how the nutritional properties of potential hominin plant foods growing in modern African savanna ecosystems respond to season and vary by habitat will improve our ability to model early hominin dietary behavior. Here, we present nutritional analyses (crude protein and acid detergent fiber) of plants growing in eastern and southern African savanna habitats across both wet and dry seasons. We find that many assumptions about savanna vegetation are warranted. For instance, plants growing in our woodland habitats have higher average protein/fiber ratios than those growing in our wetland and grassland transects. However, we find that the effects of season and habitat are complex, an example being the unexpectedly higher protein levels we observe in the grasses and sedges growing in our Amboseli wetlands during the dry season. Also, we find significant differences between the vegetation growing in our eastern and southern African field sites, particularly among plants using the C4 photosynthetic pathway. This may have implications for the differences we see between the stable carbon isotope compositions and dental microwear patterns of eastern and southern African Paranthropus species, despite their shared, highly derived craniodental anatomy.

Synergistic activity of extracts of three South African alien invasive weeds combined with conventional antibiotics against selected opportunistic pathogens

Plants are known to play a major role in the treatment of microbial infections, as they contain important bioactive components that may act in synergism with conventional antibiotics, which are presently under threat of microbial resistance. Synergistic activity between dichloromethane, acetone, 70% ethanol, 50% methanol and hot water extracts of three southern African alien invasive plant species, namely Chromolaena odorata, Gomphrena celosioides and Tithonia rotundifolia and gentamicin, streptomycin, rifampicin and amphotericin B was studied using the checkerboard method. Antioxidant activity of the extracts was determined using the quantitative 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) decolourisation methods. The anti-inflammatory activity was determined with the 15-lipoxygenase enzyme assay. Synergistic to additive effects were observed among all tested extracts in combination with the conventional antibiotics against most of the tested strains. This was evident when the extracts were combined with gentamicin or amphotericin B against Klebsiella pneumoniae, Enterococcus faecalis, Salmonella Typhimurium, Cryptococcus neoformans and Candida albicans. The extracts of C. odorata had the best antioxidant activity in the ABTS assay with the 70% ethanol extract showing a minimum inhibitory concentration (IC50) of 1.960 μg/mL, better than that of vitamin C (IC50 = 2.027 μg/mL). The dichloromethane extract of T. rotundifolia displayed promising radical scavenging activity in the DPPH assay with an IC50 of 16.231 μg/mL. Most of the extracts of C. odorata (except the acetone extract) had anti-inflammatory activity better than that of the positive control quercetin (IC50 = 24.601 μg/mL). Results from this study indicate that extracts of these weedy plant species contain bioactive compounds that may act in synergy with conventional antibiotics in the fight against resistant microbial strains. Additionally they may reduce oxidative stress and inflammation.

Drinking water treatment using indigenous wood filters combined with granular activated carbon

Abstract A gravity-driven wood filtration system, incorporating granular activated carbon (GAC) as an appropriate point of-use technology for the rural poor, has been designed, tested and optimized. Four systems were assessed in respect of metal, bacteria and particle removal when exposed to polluted river water with and without GAC. These were evaluated using fresh, wet preserved and dry preserved Southern African indigenous wood species. Initially, all filter systems with the following indigenous wood species Combretum erythrophyllum in System 1, Tarchonanthus camphoratus in System 2, Leonotis leonurus in System 3 and Salix mucronata in System 4 did not incorporate GAC. The systems recorded 83.3, 85.4, 94.3 and 57.3% Escherichia coli removals, respectively, for fresh filters. Incorporation of GAC in Systems 1 and 4 showed high potential for significant E. coli removals (>99.9%) . Particulate removals were: 97% TSS (total suspended solids) and 96% turbidity removals by System 1; and 100% TSS and 100% turbidity removals by System 4. Metal removals by the combined systems were noteworthy and in the following order: Fe > Pb > Ni > Al > Zn > Cu > As > Cr > Cd > Mn (with average removals for the first five >90% and the last five >50%). Each combined system consistently met turbidity guidelines (≤5 NTU) and produced water with pleasant aesthetic aspects.

Three new species and a new combination among Southern African Schoenus (Cyperaceae, tribe Schoeneae)

Schoenus is a morphologically complex, predominately austral genus. The taxonomy of the southern African clade of Schoenus has received recent attention with the transfer of 24 southern African species into Schoenus from Tetraria and Epischoenus in 2017. A taxonomic revision in early 2018 both revised the taxonomy of the Schoenus compar—Schoenus pictus and allies group, as well as described three new species endemic to the Cape Floristic Region of South Africa. In addition, seven new species were described in early 2019 as part of a revision of the Schoenus cuspidatus group. Here, we build on this recent taxonomic work by providing descriptions for three new species (Schoenus bracteosus, Schoenus comparoides and Schoenus triticoides). We also provide a new name at species rank for a taxon previously named as a variety of Tetraria sylvatica. We present detailed species descriptions, distribution maps and an updated identification key.

Geographic-based metabolomic variation and toxicity analysis of Sutherlandia frutescens L. R.Br. – An emerging medicinal crop in South Africa

Sutherlandia frutescens (syn. Lessertia frutescens), an indigenous southern African species, is important for the local and global phytomedicine's industry. As farming of medicinal plants in South Africa is not extensive, wild populations are also used as a source of material to bulk available cultivated yields prior to industrial processing. This may cause inconsistency in the quality of medicinal products derived from this species, inducing discrepancies in the plant’s therapeutic profile. The current study aimed to elucidate the phytochemical variations among S. frutescens plants growing in different geographical localities, especially in areas which have not been studied before. One set of extracts were generated using a 50% acetonitrile and formic acid solution (0.1%) (v/v). By using a targeted metabolomics approach, two major phytochemical groups, sutherlandins and sutherlandiosides were used to display metabolite-based clusters after LC–MS/MS analysis. Plants from different geographical locations grouped into separate chemical lineages. Another set of ethanol and aqueous extracts of pooled leaf materials were screened for their toxicity effect on the hatching rate of zebrafish embryos and mortality of larvae at different concentrations, ranging from 5 to 300 μg ml−1. We also calculated the LC50 values using a zebrafish microplate bioassay and this value was 297.57 μg ml−1 for the water extract. The aqueous extracts were relatively less toxic compared to ethanol extracts (LC50 value of 40.54 μg ml−1). Both the hatching rate and mortality were negatively affected by increasing extract dosages. The highest concentrations, between 200 to 300 μg ml−1, caused acute lethal effects for both extract types. This study adds additional evidence of the cytotoxicity reported by others in this species and will further aid in the domestication of S. frutescens.