The Kingdom of Lesotho in southern Africa is entirely bordered by South Africa, with which it shares many geological and vegetation types, but the vast extent of alpine vegetation and high altitudes suggests that differences in insect diversity should be expected. Globally, the Diptera are one of the most diverse orders of insects, though biodiversity estimates for the order are lacking for many regions. Here, we present a summary of the limited historical Diptera collections from Lesotho, summarise our collecting expeditions in 2021, 2022 and 2023, and provide photographs and descriptions of the collecting sites. This paper is the first of a series of papers in a Topical Collection of the Diptera of Lesotho in African Invertebrates. We hope to stimulate more research on Afrotropical Diptera and to improve their conservation in Lesotho in particular.

Alpine entomology, biodiversity surveys, conservation, Insecta, southern Africa, species checklists, true flies

The Kingdom of Lesotho is a small (30 355 km²), landlocked country surrounded by the Republic of South Africa. While Lesotho shares most vegetation and habitat types with South Africa, the exception being Western Lesotho Basalt Shrubland (Gd9) (Mucina and Rutherford 2006; SANBI 2006), the country has an average altitude ~900 m higher than South Africa, suggesting that differences in the fauna and flora may exist. As can be expected due to its smaller size, Lesotho has only 13 different vegetation types, all within the grassland biome, while South Africa has 466 vegetation types across nine biomes (Mucina and Rutherford 2006; SANBI 2006). Despite the smaller size, Lesotho’s higher altitude means that alpine vegetation types are much more extensive (e.g., Drakensberg Afroalpine Heathland) and the country offers habitats for alpine adapted species that are less extensive in South Africa (Fig. 1). The eastern border of Lesotho is formed by the Drakensberg escarpment, which rapidly drops in altitude into the South African provinces of KwaZulu-Natal and, in the south west, the Eastern Cape. While small patches of alpine vegetation occur on the South African side of the border, these rapidly transition to mid-altitude vegetation. In the south, high altitude grasslands extend from Lesotho into the Eastern Cape, and in the west and north, highveld grassland and shrubland vegetation types occur on both sides of the border, in Lesotho and the Free State province (Mucina and Rutherford 2006; SANBI 2006).

Figure 1. 

Map of major collecting sites in Lesotho with vegetation types. White indicates historical collecting sites and red indicates sites from recent expeditions (2021, 2022 and 2023). Vegetation data taken from SANBI (SANBI 2006). Arrows 1–5 indicate vegetation types with extents too small to be clearly visible on the map, as indicated on the legend.

Figures 2–5. 

Collecting sites during recent expeditions 2 Afriski Mountain Lodge area, looking southwest down the valley. Large areas of grazed but otherwise undisturbed landscape and disturbed piles of building rubble are visible 3 valley landscape around the tributary of the Malibamatšo River, looking southwest from the A1 road. While some grazing is evident, the landscape is otherwise undisturbed 4 view from Moteng Pass on the A1, looking southeast from near the top of the pass. The habitat is drier than surrounding sites 5 gulley in Khukhune village next to the A1. The area is disturbed, with evidence of grazing and multiple alien plant species (Acacia mearnsii, Eucalyptus sp. and Pyracantha koidzumii are visible in the photograph).

Figures 6–9. 

Collecting sites during recent expeditions 6 Motebong Lodge, looking east. Areas close to the lake are disturbed by fluctuating water levels and increased grazing pressure. Many non-native ornamentals were planted around the lodge 7 Maletsunyane Falls area, sampling area consisted of natural vegetation and is cordoned off with palisade fencing from the surrounding farmlands, protecting it somewhat from overgrazing 8 roadside Pyracantha koidzumii bushes on the A5 between Roma and St Michaels village, looking south. The bushes attract flies, disrupting indigenous pollination networks 9 Blue Mountain Pass, roadside rest stop on A3, moderately grazed, toilet paper and human faeces scattered near the road, less disturbance away from the road.

Figures 10–13. 

Collecting sites during recent expeditions 10 God Help Me Pass, Molimo Ntuse Lodge area on A3, indigenous and exotic trees, with grass elements 11 hillside and fields near Koro-Koro village, looking south. Flat lowland areas extensively cultivated and grazed, resulting in erosion as seen in the bottom left of the photograph. Steeper-sloped areas receive less grazing pressure, with small shrubs and other plants surviving 12 fallow and recently ploughed fields at Matsaba Nkesi, looking west from the A5 road. The dark area in the centre of the image is a seep that has been cultivated. The seep and surrounding areas included many Ranunculus sp. flowers, while the steeper sides have alien vegetation including Pyracantha koidzumii and Rosa rubiginosa 13 malaise trap on the grounds of Roma Trading Post Lodge. The site contained many exotic ornamental plants.

Figures 14–17. 

Collecting sites during recent expeditions 14 Semonkong roadside, brief sampling from shrubs and grasses on verge 15 Semonkong Lodge, mixed indigenous and exotic vegetation with some garden elements 16 seep and grassland at St Michaels village. Some Ranunculus sp. visible in foreground. Alien Acacia mearnsii visible in the background. Note the proximity of the latrine (top right) to the watercourse 17 stream next to the A14. Some grazing and disturbance due to road building.

Figures 18–21. 

Collecting sites during recent expeditions 18 puddle and flowers in Khatleli village on the A1. Environment is heavily degraded, with agriculture and domestic disturbances evident 19 Sehlabathebe National Park, grassland vegetation near the new lodge and camping area 20 Sehlabathebe National Park, Malaise trap over small stream near new lodge area 21 Sehlabathebe National Park, semi-wetland area near old lodge, sampling from grass and shrubs.

Figures 22–25. 

Collecting sites during recent expeditions 22 fallow field near Letšeng la Letsie (Letsie’s Lake). Diverse annual flowers growing in a highly modified habitat 23 Letšeng la Letsie view looking northwest. The site is the largest water source in the area, providing a suitable environment for livestock and therefore heavily influenced by grazing 24 hill above Mphaki, looking westwards. The site is on the edge of town and has some domestic buildings and other disturbances 25 Mphaki Farmers Training Centre garden. Vegetation is mostly exotic: alien (Cirsium sp. visible), ruderal or agricultural (Juglans sp. and Prunus sp. visible).

Figures 26–29. 

Collecting sites during recent expeditions 26 steep roadside cutting with exposed rocks and flowering Scenecio sp. Alien species are evident, including Salix sp. growing in riparian zone and Rosa rubiginosa on the steeper slopes 27 seep with Ranunculus sp. flowers. Grazing and other agriculture evident in the image 28 large high-altitude wetland with Ranunculus sp. flowers. Evidence of agriculture is visible in the background 29 Sani Pass area, overgrazing and other human disturbance visible.

Figures 30, 31. 

Evidence of land degradation during recent expeditions 30 high grazing density at Letšeng la Letsie. Cattle, sheep, goats, horses and donkeys were observed 31 deep erosion gullies at Koro-Koro. Poor agricultural practices are the primary cause, for example ploughing of fields in the riparian zone (see fields in the background and in figs 11, 12). Scale bar: 1 m (31).

Geologically, the country is similarly limited. The geology is solely comprised of Karoo Supergroup strata, predominantly Drakensberg formation basalts with some exposed sedimentary rocks of the Elliot formation in the river valleys and western lowlands. In the western lowlands, some exposed Tarkastad formation sedimentary rocks and Karoo Dolerite also occur. These four geological types are significantly fewer than the 119 lithographies found in South Africa. This pattern is also reflected in the geomorpholgy, with only the Lesotho Highlands and Eastern Escarpment Hinterland geomorphic provinces represented in the country, compared to 43 geomorphic provinces in South Africa (Partridge et al. 2010).

While there has been widespread collecting of insects, and Diptera in particular, in South Africa, collecting in Lesotho has been less common (Kirk-Spriggs 2017). The combination of regionally rare habitats and comparative under-sampling creates an opportunity for research in Lesotho. With this in mind, three field trips were undertaken: 3 to 14 December 2021, 21 November to 1 December 2022 and 21 to 30 January 2023 by the authors of this introductory article to enhance the Diptera collections from Lesotho.

To increase collection effort without identifying the material within the collections is short-sighted, and so this special collection of articles on the Diptera of Lesotho was conceived. This will turn these specimens into published knowledge of the Diptera of Lesotho and promote conservation in the country. We have chosen to initiate this as a collection of articles rather than a special issue, to allow family accounts to be published as they are completed and thus make the knowledge available more rapidly.

Specimens from Lesotho are in various South African and international collections, but large samples are less common. Expeditions to Lesotho were undertaken by the Lund Zoological Institute (Hanström 1955), Brian and Pamela Stuckenberg, KwaZulu-Natal Museum (NMSA, South Africa), A. Lionel Bevis, Durban Natural Science Museum (DMSA, South Africa), and Charles Jacot-Guillarmod, Albany Museum (AMGS, South Africa) (Kirk-Spriggs 2017).

One of the first major expeditions to include Lesotho was the “Lund University Swedish South African Expedition” of 1950–51 (Brink 1955; Brink and Rudebeck 1955; Hanström 1955; Kirk-Spriggs 2017). Historically, the term “South Africa” has been used to refer to both the Republic of South Africa and (less frequently) the entire Southern African region (e.g., Schultze 1908) and so while the majority of the expedition covered South Africa, collections were also made in Namibia (previously South West Africa) and Lesotho (previously Basutoland) and, to a lesser extent, Eswatini, Zimbabwe and Zambia (previously Swaziland, Southern Rhodesia or Rhodesia, and Northern Rhodesia) (Brink and Rudebeck 1955). The expedition entered Lesotho twice, first collecting at Qacha’s Nek before returning to South Africa and re-entering near Quthing, where they were based for ten days. From there, the expedition travelled by road to Nazareth. The expedition moved by air to Mokhotlong and collections were undertaken in the high mountains on horseback (Brink 1955; Brink and Rudebeck 1955). Twenty-five undescribed Diptera species were collected from Lesotho during this expedition, notably six Asilidae (Hull 1967), four Empididae (Smith 1967) and three Tipulidae (Alexander 1964), all published in the South African Animal Life series.

A.L. Bevis occupied various positions during his tenure at the Durban Museum and Art Gallery and travelled to Lesotho multiple times for collecting (see Clancey 1956; Stuckenberg 1956). These trips were multidisciplinary and not focussed on Diptera collecting, but still resulted in the discovery of undescribed species (e.g., Stuckenberg 1956). About 770 specimens were accumulated during these trips and are housed at the DMSA.

Brian and Pamela Stuckenberg collected at seven sites in Lesotho in 1963 and 1964. These collections generated 884 specimens. Most of the sites were in western Lesotho, though specimens were also collected on God Help Me Pass (Lekhalong La Molimo Nthuse) (on labels as Bushman’s Pass) and Blue Mountain Pass (Lekhalong La Thaba Putsoa). These expeditions yielded undescribed species (e.g. Whittington 1992). Along with other specimens accumulated over time, these specimens form the bulk of the collection of approximately 1 100 specimens housed at the NMSA.

Charles Jacot-Guillarmod was Entomologist and later Director of the AMGS. His parents ran a trading post in Ha-Masupha (called Mamathes at the time, now Mamathe or Masupha are also used) and he collected many specimens while visiting them. The majority of his collections were of Hymenoptera, but approximately 1 500 Diptera specimens from this collection are housed at the AMGS.

Three expeditions were undertaken to Lesotho (Fig. 1) at six sites in 2021, seventeen in 2022 and seven in 2023 (Figs 2–29). The primary focus of activity was in the eastern highland regions, though some lowland sites were also visited. Details of these sites are given in Table 1. We focused our collecting on the eastern highlands for two reasons. Firstly, the highlands in eastern Lesotho are more extensively covered in alpine vegetation elements (Fig. 1). Secondly, western Lesotho is more densely populated and agricultural pressure is more intense than in eastern Lesotho. This is not to say that environmental degradation is absent from eastern Lesotho. The greatest threats to the environment in all regions of Lesotho are overgrazing (Fig. 30) and agriculture in, or very close to, riparian zones (Figs 11, 12), which lead to soil erosion (Figs 12, 31). Significant threats from mining activities are also present. In general, these are much less extensive than agricultural activities, but pollution impacts may be carried further by streams and rivers. Conservation planning and management should be aware of these threats, though effective management advice is beyond the scope of this paper.

Most collecting was done using sweep netting and hand collecting (Figs 16, 24) but where conditions allowed, Malaise traps were also deployed. Depending on the sites, either Gressitt-and-Gressitt (Fig. 13) or Townes-style (Fig. 20) traps were used. In total, 7 144 specimens were collected in these three expeditions.

In all, historic South African collections and the recent expeditions have generated a collection of approximately 10 580 Diptera specimens from Lesotho (Table 2), excluding the material from the Lund Expedition. Despite this, there is little published information on the Diptera of Lesotho. That which is published is mostly in the South African Animal Life series, based on the Lund expedition (e.g., Alexander 1964; Hull 1964, 1967; Smith 1967). Other publications are fragmented and sporadic. The aim of initiating this Topical Collection in African Invertebrates is to bring this information together in one series, creating a resource for a diverse set of users. While we endeavoured to collect a diverse group of specimens, it is inevitable that some groups were sampled more thoroughly than others. This collection should be seen as a starting point for future research in Lesotho. Despite this, it is still of value for conservation practitioners in the region as it is the first attempt at a consolidated Diptera checklist for the country. The details of the collecting sites provided in Table 1 and the site photographs (Figs 2–29) are also intended to pre-empt repetition in future contributions to this Special collection but also allows future collectors to plan their trips with existing material in mind.

We thank the Lesotho Ministry of Tourism, Environment and Culture, Department of Environment for issuing permits to undertake the fieldwork. BSM acknowledges support from the National Museum, Bloemfontein.