Biodiversity of Non-Marine Ostracoda (Crustacea) of Botswana: An Annotated Checklist with Notes on Distribution

Abstract

Botswana constitutes a major gap in our knowledge of the distribution of Ostracoda in the region of Southern Africa, restraining thorough biogeographic interpretations. We combine records from previously published surveys along with our own field collections to provide a collation of living and fossil (Late Pleistocene to Holocene) Ostracoda recorded in Botswana. Our survey yielded 17 species, of which nine species have not been recorded before in the country. Including the present update, 54 species (45 living and nine fossil or subfossil) belonging to 22 genera of five families (with 76% species belonging to the family Cyprididae) are currently reported from Botswana. Yet, 23 taxa are left in open nomenclature, indicating the urgent need for sound systematic studies on harmonizing taxonomy of Southern African ostracods, especially of those inhabiting small temporary waterbodies, considered as threatened with extinction before being properly described or discovered. This updated checklist provides detailed information about the distribution and habitat of each recorded species. Species richness, distribution patterns, and diversity of ostracod species regionally and in different freshwater ecoregions are also discussed. We found low alpha (site) diversity (mean 3.3 species per site) and a significant difference in species composition and beta diversity of the Okavango ecoregion versus the Kalahari and Zambezian Lowveld ecoregions.

1. Introduction

Inland waters are home to remarkably high taxonomic diversity, but are also among the world’s most endangered ecosystems in the world. Due to various forms of human activity (such as overexploitation, pollution, flow modification, and habitat degradation) and climate change, one-third of inland aquatic species are threatened with extinction and about 70% of wetlands have been lost since 1900 [1,2,3]. One of the most threatened types of inland aquatic ecosystems are temporary waterbodies, the number of which is disappearing at an alarming rate [4,5,6,7]. To assess the consequences of the anthropogenic stress and climate-change effects on aquatic biological diversity, as well as to evaluate the ecological status of inland wetlands and effectively manage them, it is essential to have comprehensive taxonomic and distributional inventories of aquatic organisms. The acquisition of such databases is considered one of the key topics for current research on freshwater biodiversity in most endangered regions [8].

Inland water ecosystems across much of the region of Southern Africa (hereafter defined as the region south of (and including) the catchments of the Cunene and Zambezi rivers) are under increasing pressure and suffer from both recent human activity and natural climate variation [9], while biodiversity data on their invertebrates are often lacking [10]. Here, we combine records from previously published surveys along with our own field collections to provide a collation of living and fossil (Late Pleistocene to Holocene) Ostracoda inhabiting the wetlands of Botswana.

Botswana is a land-locked country with a prevailing warm, semi-arid climate where droughts are common and rainfall is unpredictable. Mean annual rainfall (restricted mainly to October-April) varies from over 650 mm in the north-east to less than 250 mm in the south-west of the country, and high evapotranspiration rates increase the aridity of the environment. These natural arid conditions and frequent drought periods make Botswana highly susceptible to desertification, further exacerbated by unsustainable grazing practices and soil erosion, which imperil already-stressed water resources and contribute to water-quality problems [11,12,13]. The wetlands of Botswana consist mainly of a variety of seasonally rain-fed waterbodies, such as temporary freshwater or salt pans, temporary rivers, and man-made reservoirs. The only perennial wetlands include the systems of the Okavango river and the Chobe-Linyati-Kwando rivers, both in the north of the country [12]. Botswana includes parts of seven freshwater ecoregions recognized by Abell et al. [14]; from the north to south these are: Upper Zambezi Floodplains, Okavango, Kalahari, Zambezian Lowveld, Southern Kalahari, Southern Temperate Highveld, and Middle Zambezi-Luangwa, of which only a very small part intrudes Botswana in the north-east. The xeric ecoregions of Kalahari and Southern Kalahari cover most of the country. All the above-mentioned types of wetlands, unevenly distributed throughout the freshwater ecoregions in Botswana, constitute habitats suitable for ostracods.

Ostracods are a class of bivalve microcrustaceans that occur in almost all aquatic habitats and have great potential as a model group in both fundamental and applied research, such as advanced ecotoxicological studies, monitoring anthropogenic disturbances, and predicting environmental impacts [15]. Despite a long history of Southern African non-marine ostracod studies [16], checklists of Southern African non-marine ostracods [16,17] include only a few records from Botswana (listed mostly as from Kalahari) collected during the Schultze expedition to Namaland and Kalahari in 1903–1905 [18], the Vernay–Lang Kalahari Expedition in 1930 [19], and the Eccles Makarikari Expedition in 1957 [16]. Since these compilations, there have been no faunistically comprehensive works within the area of Botswana published, except some single-site (or small area) records e.g., [20,21,22].

To attempt to remedy this situation, and to encourage other authors to contribute towards an acquisition of a comprehensive distributional and taxonomic database on the Ostracoda of Botswana, we provide an updated checklist of the living and fossil (Late Pleistocene to Holocene) distribution of non-marine ostracods in this Southern African country, based on both the records published to date and on our own unpublished collection. The checklist does not, however, constitute a revision of previous studies, but rather a collation that may be used for further detailed taxonomic work upon re-examination of the published material. We also investigated patterns in taxonomic diversity at regional and local scales (gamma and alpha diversity), as well as regional differences in the taxonomic composition between some freshwater ecoregions and sites (beta diversity).

2. Materials and Methods

Although several papers mention ostracods from the wetlands of Botswana, mostly those containing records identified down to species level were used in the checklist. Citations of species names originally left in open nomenclature (sp., cf., sp. n., new sp. ?), however, are also included as these most probably represent new species awaiting formal description. Bibliographic searching was undertaken in several ways. First, much use was made of previously published checklists of living ostracods from inland waters of Southern Africa ([16,17]) and the manual or electronic checking of citation lists in published articles was undertaken by the authors. For finding relevant papers, we also used electronic-searching facilities and indices, i.e., the databases of Web of Sciences (All Databases) and Scopus, employing the following simple keyword combination: “Botswana” AND “ostracod*”. We believe that the literature used is complete, though some abstracts, theses, or other papers not generally available may have been missed.

The checklist deals with the occurrence of each species as originally determined from published data; however, these records are placed within the context of presently acceptable taxonomic conventions, and species are listed in a taxonomically-based order following [23]. Species with first records for Botswana are preceded by an asterisk (*).

Each species entry in the checklist includes Botswana records in chronological order (both historical and own) with the following data: the reference with the originally published species name, verbatim locality name with the original site/sample codes, geographical coordinates (in the DMS system, i.e., degrees minutes seconds), altitude (taken from the source reference or estimated on the original description of the locality using Google Earth), and freshwater ecoregion (FEOW) within which the locality is situated (according to the regionalization of the Freshwater Ecoregions Of the World in [14]). These data are followed by the habitat type, collection date, and details on the age, number, sex, and ontogenetic stage of the collected specimens, if available. Other sections under each species headings (excluding species left in open nomenclature) include global distribution after [23] (with the codes of the regions as follows: AT = Afrotropical, AU = Australasian, NA = Nearctic, NT = Neotropical, OL = Oriental, PA = Palaearctic, PAC = Pacific Oceanic Islands) and distribution in Southern Africa, largely after [17,24] (with country codes as follows: BW = Botswana, LS = Lesotho, NAM = Namibia, ZA = South Africa, ZW = Zimbabwe). Finally, notes with taxonomic remarks or comments on the distribution (if relevant) close the species entry.

Our collection of living ostracods was made from 11 sites in Botswana between 11 and 20 September 2012. Samples were collected with a hand-net (mesh size of 120 µm) sweeping the bottom surface at the depth of <50 cm and then fixed in 96% ethanol. In the laboratory, ostracods were sorted, identified, and counted using a stereoscopic microscope. The soft parts of ostracods were mounted in glycerine while valves were stored on the micropalaeontological slides following [25]. Specimens were identified down to the species level using specialized literature (e.g., [17,26,27,28,29,30]). The specimens are housed in the Ostracod Collection of the Department of Evolutionary Genetics and Biosystematics of the University of Gdansk, and the type specimens of Sarscypridopsis harundineti are deposited in the Collection of the Royal Belgian Institute of Natural Science, Brussels (RBINS INV.159064–159067).

The map of the sampling sites was made with ArcGIS Pro 2.8.3. Esri Inc. (Figure 1).

To evaluate if the sampling effort was sufficient to represent the biodiversity of the ostracod assemblages in the studied area, we performed species accumulation curves of the observed and expected species number by the Chao 2 index based on 28 sites with the living incidence records (including both historical and own material). The mean and standard deviation of species richness estimates were calculated from 9999 permutations with sites added in random order. To test for similarity in beta diversity among freshwater ecoregions (with the number of sites/samples >2), the test for homogeneity of multivariate dispersions (PERMDISP) was used with 9999 permutations and sites added in random order on the basis of a taxonomically dissimilarity measure Gamma+, which is a natural extension of the Bray–Curtis dissimilarity on presence/absence data. A five-level classification (species, genus, subfamily, family, and superfamily) was used according to [23]. We also tested for significance of species composition among freshwater ecoregions using a one-way ANOSIM followed by pair-wise tests. To visualize the pattern exhibited by the ecoregions on the basis of their ostracod fauna, a non-metric Multi-Dimensional Scaling (mMDS) ordination was constructed from bootstrap averages using the above Gamma+ resemblance matrix. All procedures were run on PRIMER 7 software [38] with the PERMANOVA+ add-on package [39].

3. Results

3.1. Checklist of Non-Marine Living and Fossil (Late Pleistocene to Holocene) Ostracoda of Botswana

Class: Ostracoda Latreille, 1802

Subclass: Podocopa Sars, 1866

Order: Podocopida Sars, 1866

Suborder: Cypidocopina Baird, 1845

Superfamily: Cypridoidea Baird, 1845

Family: Cyprididae Baird, 1845

Subfamily: Cypricercinae McKenzie, 1971

Tribe: Cypricercini McKenzie, 1971

Genus: Cypricercus Sars, 1895

 

*Cypricercus cf. cuneatus Sars, 1895

Present paper: Kolobeng river near the village of Manyana, site no SA-113/coord. 24°46′08″ S, 25°35′22″ E, 1133 m a.s.l./FEOW: 576 Zambezian Lowveld/Habitat: river/Coll. date: 20 September 2012/2 ♀♀, 9 juv.

 

Cypricercus inermis (Brady, 1904)

Jocqué et al. [20]: Kgale Siding near Gabarone/coord. 24°40′30″ S, 25°50′20″ E, 1040 m a.s.l./FEOW: 576 Zambezian Lowveld/Habitat: nine temporary granite rock pools/Coll. dates: entire inundation cycle of the rainy season of 2002–2003/number of specimens unspecified.

Distribution: AT (BW, ZA)

 

Genus: Strandesia Stuhlmann, 1888

 

Strandesia cf. prava Klie, 1935

• Szwarc et al. [22]: Thamalakane river near the city of Maun, site no SA-97/coord. 19°55′52″ S, 23°30′38″ E, 940 m a.s.l./FEOW: 569 Okavango/Habitat: river side channel/Coll. date: 13 September 2012/2 ♀♀, 9 juv;
• Present paper: Botanic Garden in the city of Gabarone, site no SA-112/coord. 24°39′56″ S, 25°56′40″ E, 987 m a.s.l./FEOW: 576 Zambezian Lowveld/Habitat: artificial rock-pool/Coll. date: 19 September 2012/2 ♀♀.

 

Strandesia n. sp. (gr. sudanica) Sywula, 1970

Jocqué et al. [20]: Kgale Siding near Gabarone/coord. 24°40′30″ S, 25°50′20″ E, 1040 m a.s.l./FEOW: 576 Zambezian Lowveld/Habitat: nine temporary granite rock pools/Coll. dates: entire inundation cycle of the rainy season of 2002–2003/number of specimens unspecified.

 

Strandesia sp.

Riedel et al. [36]: sediment core 1.5 km east of Kubu Island at the south-western edge of Sua Pan in Makgadikgadi Basin/coord. 20°53′30″ S, 25°50′30″ E, 900–903 m a.s.l./FEOW: 570 Kalahari/Habitat: palaeo-mega-lake system (sediment core to 3.0 m depth)/Coll. dates: September 2007, April 2008, July 2010/fossil valves in a sedimentary sequence dated from ca. 37 ka to 2 ka cal. BP (calibrated years before the present).

 

Subfamily: Cypridinae Baird, 1845

Genus: Pseudocypris Daday, 1910

 

Pseudocypris circularis Sars, 1924

• Barnard [19]: 1 mile north of Tsotsoroga Pan, localities nos 1204a and 1214/approx. coord. 18°43′00″ S, 24°21′00″ E, 940 m a.s.l./FEOW: 569 Okavango/Habitat: not indicated/Coll. dates: 19–20 June 1930/number of specimens unspecified;
• Barnard [19]: N’kate (= Nekati) Pan, locality no 1505/approx. coord. 20°05′00″ S, 26°01′00″ E, 920 m a.s.l./FEOW: 570 Kalahari/Habitat: shallow pan in limestone formation/Coll. date: 7 August 1930;
• McKenzie [16]: Makarikari expedition, no further details given/FEOW: 570 Kalahari/Habitat: not indicated/Coll. date: 2.10.1958/number of specimens unspecified, det. D.H. Eccles;
• Martens [24]: collected by the Vernay-Lang Kalahari expedition 1930, no further details given (probably same localities as in [19])/ca. 100 ♂♂ and ♀♀.

Distribution: AT (BW, NAM, ZW)

 

Pseudocypris gibbera Sars, 1924

• Barnard [19]: N’kate (=Nekati) Pan, locality no 1510a/approx. coord. 20°05′00″ S, 26°01′00″ E, 920 m a.s.l./FEOW: 570 Kalahari, Habitat: a pan/Coll. date: 8 August 1930/two empty valves;
• Martens [24]: collected by the Vernay-Lang Kalahari expedition 1930, no further details given (probably same localities as in [19])/few specimens.

Distribution: AT (BW, NAM)

 

Subfamily: Cypridopsinae Kaufmann, 1900

Tribe: Cypridopsini Kaufmann, 1900

Genus: Cypridopsis Brady, 1867

 

*Cypridopsis vidua (O.F. Müller, 1776)

• Present paper: Kang Nkisi Guest House in the village of Kang, site no SA-95/coord. 23°04′50″ S, 22°45′55″ E, 1142 m a.s.l./FEOW: 570 Kalahari/Habitat: artificial pool/Coll. date: 12 September 2012/7 ♀♀, 5 juv;
• Present paper: Botanic Garden in the city of Gabarone, site no SA-112/coord. 24°39′56″ S, 25°56′40″ E, 987 m a.s.l./FEOW: 576 Zambezian Lowveld/Habitat: artificial rock-pool/Coll. date: 19 September 2012/11 ♀♀, 28 juv;
• Present paper: Kolobeng river near the village of Manyana, site no SA-113/coord. 24°46′08″ S, 25°35′22″ E, 1133 m a.s.l./FEOW: 576 Zambezian Lowveld/Habitat: river/Coll. date: 20 September 2012/3 ♀♀, 2 juv;
• Present paper: Ramatlabama river near the village of Ramatlabama, site no SA-117/coord. 25°38′29″ S, 25°34′27″ E, 1276 m a.s.l./FEOW: 571 Southern Kalahari/Habitat: river/Coll. date: 20 September 2012/2 ♀♀.

Distribution: AT (ZA), AU, NA, NT, OL, PA, PAC

 

Tribe: Plesiocypridopsini Jacobs & Martens, 2022

Genus: Plesiocypridopsis Rome, 1965

 

Plesiocypridopsis newtoni (Brady & Robertson, 1870)

• McCulloch et al. [21] as Plesiocypridopsis aldabrae: North Basin of Makgadikgadi Pan/approx. coord. 20°24′00″ S, 26°12′00″ E, 890 m a.s.l./FEOW: 570 Kalahari/Habitat: ephemeral saline lake (water conductivity 320-24400 µS/cm, pH: 8.6–10.1)/Coll. dates: beginning of the 1999–2000 flood/low abundance;
• Szwarc et al. [22]: floodplains south of Okavango Delta near the city of Maun, site no SA-103/coord: 19°52′12″ S, 23°20′23″ E, 940 m a.s.l./FEOW: 569 Okavango/Habitat: grassy shore of temporary pond/Coll. date: 15 September 2012/3 ♀♀, 2 ♂♂;
• Present paper: Tati river near the town of Francistown, site no SA-108/coord. 21°10′48″ S, 27°30′44″ E, 982 m a.s.l./FEOW: 576 Zambezian Lowveld/Habitat: pools in riverbed/Coll. date: 18 September 2012/3 juv;
• Present paper: Botanic Garden in the city of Gabarone, site no SA-112/coord. 24°39′56″ S, 25°56′40″ E, 987 m a.s.l./FEOW: 576 Zambezian Lowveld/Habitat: artificial rock-pool/Coll. date: 19 September 2012/61 ♀♀ and ♂♂, 283 juv.

Distribution: AT (BW, ZA), OL, PA

 

Genus: Sarscypridopsis McKenzie, 1977

 

Sarscypridopsis cf. elizabethae (Sars, 1924)

Szwarc et al. [22]: Thamalakane river near the city of Maun, site no SA-97/coord. 19°55′52″ S, 23°30′38″ E, 940 m a.s.l./FEOW: 569 Okavango/Habitat: river side channel/Coll. date: 13 September 2012/19 ♀♀, 1 ♂, 2 juv.

 

Sarscypridopsis glabrata (Sars, 1924)

Riedel et al. [36]: sediment core 1.5 km east of Kubu Island at the south-western edge of Sua Pan in Makgadikgadi Basin/coord. 20°53′30″ S, 25°50′30″ E, 900–903 m a.s.l./FEOW: 570 Kalahari/Habitat: palaeo-mega-lake system (sediment core to 3.0 m depth)/Coll. dates: September 2007, April 2008, July 2010/fossil valves in a sedimentary sequence dated from ca. 37 ka to 2 ka cal. BP.

Distribution: AT (BW, NAM, ZA)

 

Sarscypridopsis cf. gregaria Sars, 1895

• Jocqué et al. [20] as Sarscypridopsis cf. gregaria: Kgale Siding near Gabarone/coord. 24°40′30″ S, 25°50′20″ E, 1040 m a.s.l./FEOW: 576 Zambezian Lowveld/Habitat: nine temporary granite rock pools/Coll. dates: entire inundation cycle of the rainy season of 2002–2003/number of specimens unspecified;
• Jocqué et al. [20,37] as Sarscypridopsis cf. gregaria: near Thamaga/coord. 24°41′50″ S, 25°31′00″ E in [20] and 24°40′30″ S, 25°31′00″ E in [37], 1105 m a.s.l./FEOW: 576 Zambezian Lowveld/Habitat: nine temporary granite rock pools/Coll. dates: entire inundation cycle of the rainy season of 2002–2003/number of specimens unspecified.

 

Sarscypridopsis harundineti Szwarc et al., 2021

• Szwarc et al. [22]: Lake Ngami, site no SA-96/coord: 20°28′57″S, 22°42′08″E, 930 m a.s.l./FEOW: 569 Okavango/Habitat: endorheic lake/Coll. date: 12 September 2012/1 juv;
• Szwarc et al. [22]: Thamalakane river near the city of Maun, site no SA-97/coord. 19°55′52″ S, 23°30′38″ E, 940 m a.s.l./FEOW: 569 Okavango/Habitat: river side channel/Coll. date: 13 September 2012/11 ♀♀, 1 juv;
• Szwarc et al. [22]: floodplains south of Okavango Delta near the city of Maun, site no SA-98/coord: 19°52′15″ S, 23°21′06″ E, 940 m a.s.l/FEOW: 569 Okavango/Habitat: temporary channel/Coll. date: 14 September 2012/6 ♀♀;
• Szwarc et al. [22]: floodplains south of Okavango Delta near the city of Maun, site no SA-99/coord: 19°52′15″ S, 23°20′45″ E, 940 m a.s.l/FEOW: 569 Okavango/Habitat: temporary channel/Coll. date: 14 September 2012/16 ♀♀, 1 juv;
• Szwarc et al. [22]: floodplains south of Okavango Delta near the city of Maun, site no SA-100/coord: 19°52′04″ S, 23°20′38″ E, 940 m a.s.l/FEOW: 569 Okavango/Habitat: flooded swamp and grassland/Coll. date: 14 September 2012/11 ♀♀;
• Szwarc et al. [22]: floodplains south of Okavango Delta near the city of Maun, site no SA-101/coord: 19°51′39″ S, 23°19′41″ E, 940 m a.s.l/FEOW: 569 Okavango/Habitat: isolated pool in flooded grassland/Coll. date: 15 September 2012/6 ♀♀;
• Szwarc et al. [22]: floodplains south of Okavango Delta near the city of Maun, site no SA-102/coord: 19°52′06″ S, 23°20′41″ E, 940 m a.s.l/FEOW: 569 Okavango/Habitat: floodplain channel/Coll. date: 15 September 2012/1 ♀;
• Szwarc et al. [22]: North-West District, floodplains south of Okavango Delta near the city of Maun, site no SA-103/coord: 19°52′12″ S, 23°20′23″ E, 940 m a.s.l./FEOW: 569 Okavango/Habitat: grassy shore of temporary pond/Coll. date: 15 September 2012/28 ♀♀.

Distribution: AT (BW)

 

*Sarscypridopsis cf. reniformis (Sars, 1924)

Present paper: Ramatlabama river near the village of Ramatlabama, site no SA-117/coord. 25°38′29″ S, 25°34′27″ E, 1276 m a.s.l./FEOW: 571 Southern Kalahari/Habitat: river/Coll. date: 20 September 2012/76 ♀♀, 121 juv.

 

Sarscypridopsis sp.

Jocqué et al. [20]: near Thamaga/coord. 24°41′50″ S, 25°31′00″ E, 1105 m a.s.l./FEOW: 576 Zambezian Lowveld/Habitat: nine temporary granite rock pools/Coll. dates: entire inundation cycle of the rainy season of 2002–2003/number of specimens unspecified.

 

Tribe: Potamocypridini Ghetti & McKenzie, 1981

Genus: Potamocypris Brady, 1870

 

Potamocypris deflexa (Sars, 1924)

Szwarc et al. [22]: floodplains south of Okavango Delta near the city of Maun, site no SA-99/coord: 19°52′15″ S, 23°20′45″ E, 940 m a.s.l/FEOW: 569 Okavango/Habitat: temporary channel/Coll. date: 14 September 2012/2 ♀♀.

Distribution: AT (BW, ZA)

 

Potamocypris mastigophora (Methuen, 1910)

• Barnard [19] as Cyprilla producta Sars: Kaotwe Pan, locality no 374/approx. coord. 22°33′00″ S, 23°15′00″ E, 1011 m a.s.l./FEOW: 570 Kalahari/Habitat: a pan/Coll. date: 10 April 1930/very numerous;
• Olszewski et al. [34]: Makgadikgadi depression/coord: 20°08′02″ S, 25°33′41″ E, 934 m a.s.l./FEOW: 570 Kalahari/Habitat: raised from a sample of dry sediment from temporary shallow salt lake/Coll. date: 19 September 2012/number of specimens unspecified;
• Szwarc et al. [22]: Thamalakane river near the city of Maun, site no SA-97/coord. 19°55′52″ S, 23°30′38″ E, 940 m a.s.l./FEOW: 569 Okavango/Habitat: river side channel/Coll. date: 13 September 2012/697 ♀♀ and ♂♂, 135 juv;
• Szwarc et al. [22]: floodplains south of Okavango Delta near the city of Maun, site no SA-99/coord: 19°52′15″ S, 23°20′45″ E, 940 m a.s.l/FEOW: 569 Okavango/Habitat: temporary channel/Coll. date: 14 September 2012/1 ♀;
• Present paper: Mahalapye river near the town of Mahalapye, site no SA-110/coord. 23°06′09″ S, 26°50′21″ E, 1006 m a.s.l./FEOW: 576 Zambezian Lowveld/Habitat: small river dam/Coll. date: 18 September 2012/8 ♀♀, 11 juv;
• Present paper: Botanic Garden in the city of Gabarone, site no SA-112/coord. 24°39′56″ S, 25°56′40″ E, 987 m a.s.l./FEOW: 576 Zambezian Lowveld/Habitat: artificial rock-pool/Coll. date: 19 September 2012/595 ♀♀ and ♂♂, 679 juv;
• Present paper: Bathoen near the town of Kanye, site no SA-114/coord. 24°56′54″ S, 25°20′39″ E, 1255 m a.s.l./FEOW: 575 Southern Temperate Highveld/Habitat: river flood pool/Coll. date: 20 September 2012/1 ♀.

Distribution: AT (BW), PA

 

Potamocypris variegata (Brady & Norman, 1889)

Riedel et al. [36]: sediment core 1.5 km east of Kubu Island at the south-western edge of Sua Pan in Makgadikgadi Basin/coord. 20°53′30″ S, 25°50′30″ E, 900–903 m a.s.l./FEOW: 570 Kalahari/Habitat: palaeo-mega-lake system (sediment core to 3.0 m depth)/Coll. dates: September 2007, April 2008, July 2010/fossil valves in a sedimentary sequence dated from ca. 37 ka to 2 ka cal. BP.

Distribution: AT (BW), NA, PA

 

Potamocypris sp.

Jocqué et al. [20] and Jocqué et al. [37] as Potamocypris spec: near Thamaga/coord. 24°41′50″ S, 25°31′00″ E, 1105 m a.s.l./FEOW: 576 Zambezian Lowveld/Habitat: nine temporary granite rock pools/Coll. dates: entire inundation cycle of the rainy season of 2002–2003/number of specimens unspecified.

Potamocypris new sp. ?

McCulloch et al. [21]: North Basin of Makgadikgadi Pan/approx. coord. 20°24′00″ S, 26°12′00″ E, 905 m a.s.l./FEOW: 570 Kalahari/Habitat: ephemeral saline lake (water conductivity 320-24400 µS/cm, pH: 8.6–10.1)/Coll. dates: beginning of the 1999–2000 flood/low abundance.

Tribe: Zonocypridini Higuti & Martens, 2012

Genus: Zonocypris G.W. Müller, 1898

 

Zonocypris costata (Vávra, 1897)

Szwarc et al. [22]: floodplains south of Okavango Delta near the city of Maun, site no SA-99/coord: 19°52′15″ S, 23°20′45″ E, 940 m a.s.l/FEOW: 569 Okavango/Habitat: temporary channel/Coll. date: 14 September 2012/1 ♀.

Distribution: AT (BW, ZA), PA

 

Zonocypris tuberosa G.W. Müller, 1908

Szwarc et al. [22]: floodplains south of Okavango Delta near the city of Maun, site no SA-100/coord: 19°52′04″ S, 23°20′38″ E, 940 m a.s.l/FEOW: 569 Okavango/Habitat: flooded swamp and grassland/Coll. date: 14 September 2012/1 ♀.

Distribution: AT (BW, ZA)

 

Subfamily: Cyprinotinae Bronstein, 1947

Genus: Hemicypris Sars, 1903

 

Hemicypris inversa (Daday, 1913)

1.

Daday [18] as Cyprinotus inversus: Ku-Gudië between Phitshane and Kooa, South Kalahari, site no 5/approx. coord. 25°40′00″ S, 25°06′00″ E, 1100–1200 m a.s.l./FEOW: 571 Southern Kalahari/Habitat: unspecified/Coll. date: January 1905/numerous females and males;

Note: Original locality name Ku-Gudië could not be found. Approximate coordinates are estimated based on the description of the Kalahari Expedition by Schultze [40], where a detailed collection date can also be found as 25 January 1907.

2.

Smith [41]: specimens from unspecified locality in Botswana originated most probably from the Schultze Kalahari Expedition/duplicate record of [18];

3.

Szwarc et al. [22]: Lake Ngami, site no SA-96/coord: 20°28′57″ S, 22°42′08″ E, 930 m a.s.l./FEOW: 569 Okavango/Habitat: endorheic lake/Coll. date: 12 September 2012/2 ♀♀.

Distribution: AT (BW), PA

 

Hemicypris reticulata (Klie, 1930)

Jocqué et al. [20] as Hemicypris reticulata: not indicated from which of the two studied sites the species was recorded, either Kgale Siding (coord. 24°40′30″ S, 25°50′20″ E) or near Thamaga (coord. 24°41′50″ S, 25°31′00″ E)/FEOW: 576 Zambezian Lowveld/Habitat: temporary granite rock pools/Coll. dates: entire inundation cycle of the rainy season of 2002–2003/number of specimens unspecified.

Distribution: AT (BW, ZA), NT, OL

 

Genus: Heterocypris Claus, 1892

 

Heterocypris giesbrechti (G.W. Muller, 1898)

1.

Savatenalinton & Martens [31] as Heterocypris giesbrechti: Ku-Gudië between Phitshane and Kooa, South Kalahari, site no 5/approx. coord. 25°40′00″ S, 25°06′00″ E, 1100–1200 m a.s.l./FEOW: 571 Southern Kalahari/Habitat: unspecified/Coll. date: January 1905/numerous females and males;

Note: Among individuals identified originally by [18] as Hemicypris inversa, the authors distinguished males belonging to Heterocypris giesbrechti.

2.

Szwarc et al. [22]: Lake Ngami, site no SA-96/coord: 20°28′57″ S, 22°42′08″ E, 930 m a.s.l./FEOW: 569 Okavango/Habitat: endorheic lake/Coll. date: 12 September 2012/1 ♀, 3 ♂♂, 7 juv;

3.

Szwarc et al. [22]: floodplains south of Okavango Delta near the city of Maun, site no SA-98/coord: 19°52′15″ S, 23°21′06″ E, 940 m a.s.l/FEOW: 569 Okavango/Habitat: temporary channel/Coll. date: 14 September 2012/2 ♀♀, 9 juv.

Distribution: AT (BW, ZA), OL

 

Heterocypris incongruens (Ramdohr, 1808)

Jocqué et al. [37] as Heterocypris incongruens: near Thamaga/coord. 24°40′30″ S, 25°31′00″ E, 1105 m a.s.l./FEOW: 576 Zambezian Lowveld/Habitat: granite rock pools, surfacing in a mainly savannah matrix of grasslands and shrubs/Coll. dates: 15 January–2 March 2003/number of specimens unspecified.

Distribution: AT (BW), AU, NA, NT, OL, PA, PAC

 

Heterocypris cf. incongruens (Ramdohr, 1808)

Present paper: Ramatlabama river near the village of Ramatlabama, site no SA-117/coord. 25°38′29″ S, 25°34′27″ E, 1276 m a.s.l./FEOW: 571 Southern Kalahari/Habitat: river/Coll. date: 20 September 2012/8 ♀♀, 72 juv.

Heterocypris oblonga (Sars, 1924)

• Szwarc et al. [22]: Thamalakane river near the city of Maun, site no SA-97/coord. 19°55′52″ S, 23°30′38″ E, 940 m a.s.l./FEOW: 569 Okavango/Habitat: river side channel/Coll. date: 13 September 2012/132 ♀♀ and ♂♂, 90 juv;
• Szwarc et al. [22]: floodplains south of Okavango Delta near the city of Maun, site no SA-99/coord: 19°52′15″ S, 23°20′45″ E, 940 m a.s.l/FEOW: 569 Okavango/Habitat: temporary channel/Coll. date: 14 September 2012/153 ♀♀, 106 juv;
• Szwarc et al. [22]: floodplains south of Okavango Delta near the city of Maun, site no SA-100/coord: 19°52′04″ S, 23°20′38″ E, 940 m a.s.l/FEOW: 569 Okavango/Habitat: flooded swamp and grassland/Coll. date: 14 September 2012/14 ♀♀, 6 juv;
• Szwarc et al. [22]: floodplains south of Okavango Delta near the city of Maun, site no SA-101/coord: 19°51′39″ S, 23°19′41″ E, 940 m a.s.l/FEOW: 569 Okavango/Habitat: isolated pool in flooded grassland/Coll. date: 15 September 2012/25 ♀♀, 17 ♂♂, 1 juv;
• Szwarc et al. [22]: floodplains south of Okavango Delta near the city of Maun, site no SA-102/coord: 19°52′06″ S, 23°20′41″ E, 940 m a.s.l/FEOW: 569 Okavango/Habitat: floodplain channel/Coll. date: 15 September 2012/1 ♀, 2 juv;
• Szwarc et al. [22]: North-West District, floodplains south of Okavango Delta near the city of Maun, site no SA-103/coord: 19°52′12″ S, 23°20′23″ E, 940 m a.s.l./FEOW: 569 Okavango/Habitat: grassy shore of temporal pond/Coll. date: 15 September 2012/16 ♀♀, 2 juv.

Distribution: AT (BW, NAM, ZA)

 

Heterocypris ovularis (Sars, 1924)

• Barnard [19] as Herpetocypris ovularis Sars: 2 miles north of Tsotsoroga, localities nos 1204b/approx. coord. 18°40′00″ S, 24°19′00″ E, 1058 m a.s.l./FEOW: 569 Okavango/Habitat: not specified/Coll. dates: 19 June 1930/mostly empty valves;
• Barnard [19] as Herpetocypris ovularis Sars: Kaotwe Pan, locality no 374a/approx. coord. 22°33′00″ S, 23°15′00″ E, 1011 m a.s.l./FEOW: 570 Kalahari/Habitat: a pan/Coll. date: 10 April 1930/a few specimens.

Distribution: AT (BW, NAM, ZA)

 

Heterocypris sp.

• Jocqué et al. [20]: Kgale Siding near Gabarone/coord. 24°40′30″ S, 25°50′20″ E, 1040 m a.s.l./FEOW: 576 Zambezian Lowveld/Habitat: nine temporary granite rock pools/Coll. dates: entire inundation cycle of the rainy season of 2002–2003/number of specimens unspecified;
• Jocqué et al. [20] and Jocqué et al. [37] as Heterocypris sp. nov.: near Thamaga/coord. 24°41′50″ S, 25°31′00″ E, 1105 m a.s.l./FEOW: 576 Zambezian Lowveld/Habitat: nine temporary granite rock pools/Coll. dates: entire inundation cycle of the rainy season of 2002–2003/number of specimens unspecified.

 

Subfamily: Herpetocypridinae Kaufmann, 1900

Tribe: Isocypridini Rome, 1965

Genus: Amphibolocypris Rome, 1965

 

Amphibolocypris arida Jocqué & Martens, 2010

• Jocqué et al. [20] as Amphibolocypris sp. n. sp.: Kgale Siding near Gabarone/coord. 24°40′30″ S, 25°50′20″ E, 1040 m a.s.l./FEOW: 576 Zambezian Lowveld/Habitat: nine temporary granite rock pools/Coll. dates: entire inundation cycle of the rainy season of 2002–2003/number of specimens unspecified;
• Jocqué et al. [20] as Amphibolocypris sp. n. sp.: near Thamaga/coord. 24°41′50″ S, 25°31′00″ E, 1105 m a.s.l./FEOW: 576 Zambezian Lowveld/Habitat: nine temporary granite rock pools/Coll. dates: entire inundation cycle of the rainy season of 2002–2003/number of specimens unspecified;
• Jocqué et al. [37]: near Thamaga/coord. 24°40′30″ S, 25°31′00″ E, 1105 m a.s.l./FEOW: 576 Zambezian Lowveld/Habitat: granite rock pools in a mainly savannah matrix of grasslands and shrubs/Coll. dates: 15 January–2 March 2003/type material consisted of 3 ♀♀ and 3 ♂♂ (duplicate record of [20]).

Distribution: AT (BW)

 

Genus: Isocypris G.W. Müller, 1908

 

Isocypris cf. priomena G.W. Müller, 1908

• Szwarc et al. [22]: Thamalakane river near the city of Maun, site no SA-97/coord. 19°55′52″ S, 23°30′38″ E, 940 m a.s.l./FEOW: 569 Okavango/Habitat: river side channel/Coll. date: 13 September 2012/2 ♀♀, 1 juv;
• Present paper: Bathoen reservoir near the town of Kanye, site no SA-115/coord. 24°57′06″ S, 25°20′33″ E, 1267 m a.s.l./FEOW: 575 Southern Temperate Highveld/Habitat: reservoir/Coll. date: 20 September 2012/50 ♀♀, 353 juv.

 

Tribe: Stenocypridini Ferguson, 1964

Genus: Chrissia Hartmann, 1957

 

Chrissia fascigera (Sars, 1924)

Barnard [19] as Stenocypris fascigera Sars: 1 mile north-east of Tsotsoroga, locality no 1223/approx. coord. 18°42′00″ S, 24°22′00″ E, 930 m a.s.l./FEOW: 569 Okavango/Habitat: not specified/Coll. date: 22 June 1930/number of specimens unspecified.

Distribution: AT (BW, NAM)

 

*Chrissia cf. pectinata (Sars, 1924)

Present paper: Bathoen near the town of Kanye, site no SA-114/coord. 24°56′54″ S, 25°20′39″ E, 1255 m a.s.l./FEOW: 575 Southern Temperate Highveld/Habitat: river flood pool/Coll. date: 20 September 2012/1 ♀.

 

Chrissia cf. perarmata (Brady, 1904)

Szwarc et al. [22]: Thamalakane river near the city of Maun, site no SA-97/coord. 19°55′52″ S, 23°30′38″ E, 940 m a.s.l./FEOW: 569 Okavango/Habitat: river side channel/Coll. date: 13 September 2012/1 ♀.

 

Genus: Stenocypris Sars, 1889

 

Stenocypris malayica Victor and Fernando, 1981

• Szwarc et al. [22]: Thamalakane river near the city of Maun, site no SA-97/coord. 19°55′52″ S, 23°30′38″ E, 940 m a.s.l./FEOW: 569 Okavango/Habitat: river side channel/Coll. date: 13 September 2012/2 ♀♀, 3 juv;
• Szwarc et al. [22]: floodplains south of Okavango Delta near the city of Maun, site no SA-100/coord: 19°52′04″ S, 23°20′38″ E, 940 m a.s.l/FEOW: 569 Okavango/Habitat: flooded swamp and grassland/Coll. date: 14 September 2012/1 ♀.

Distribution: AT (BW), NT, OL, PA, PAC

 

Subfamily: Megalocypridinae Rome, 1965

Tribe: Megalocypridini Rome, 1965

Genus: Apatelecypris Rome, 1965

 

Apatelecypris schultzei (Daday, 1913)

Barnard [19] as Megalocypris brevis Sars: N’kate (= Nekati) Pan, locality no 1504/approx. coord. 20°05′00″ S, 26°01′00″ E, 920 m a.s.l./FEOW: 570 Kalahari/Habitat: a shallow pan in limestone formation/Coll. date: 7 August 1930/number of specimens unspecified.

Distribution: AT (BW, NAM)

 

Genus: Sclerocypris Sars, 1924

 

Sclerocypris clavularis Sars, 1924

Jocqué et al. [20] as Sclerocypris clavularis: not indicated from which of the two studied sites the species was recorded, either Kgale Siding (coord. 24°40′30″ S, 25°50′20″ E) or near Thamaga (coord. 24°41′50″ S, 25°31′00″ E)/FEOW: 576 Zambezian Lowveld/Habitat: temporary granite rock pools/Coll. dates: entire inundation cycle of the rainy season of 2002–2003/number of specimens unspecified.

Distribution: AT (BW, ZA)

 

Sclerocypris exserta makarikarensis Martens, 1988

• Martens [32] and Seaman et al. [33] as Sclerocypris excerta Sars (typographical error of exserta): Makgadikgadi Pan/approx. coord. 20°42′00″ S, 24°57′00″ E, 905 m a.s.l./FEOW: 570 Kalahari/Habitat: huge, temporary salt pan endorheic system/Coll. date: 4 May 1957, collected by Rhodesian Schools Exploration Society/number of specimens unspecified;
• McCulloch et al. [21]: North Basin of Makgadikgadi Pan/approx. coord. 20°24′00″ S, 26°12′00″ E, 905 m a.s.l./FEOW: 570 Kalahari/Habitat: ephemeral saline lake system (water conductivity 320-24400 µS/cm, pH: 8.6–10.1)/Coll. dates: December 1999–June 2001/number of specimens unspecified;
• McCulloch et al. [21]: Middle Basin of Makgadikgadi Pan/approx. coord. 20°39′00″ S, 26°04′00″ E, 905 m a.s.l./FEOW: 570 Kalahari/Habitat: ephemeral saline lake system (water conductivity 730-91600 µS/cm, pH: 8.6–10.1)/Coll. dates: December 1999–June 2001/number of specimens unspecified.

Distribution: AT (BW)

 

Sclerocypris methueni (Kempf, 2015)

Olszewski et al. [34] as Sclerocypris tuberculata (Sars) (= Sclerocypris sarsi Martens): Makgadikgadi depression/coord: 20°08′02″ S, 25°33′41″ E, 934 m a.s.l./FEOW: 570 Kalahari/Habitat: raised from a sample of dry sediment from temporary shallow salt lake/Coll. date: 19 September 2012/number of specimens unspecified.

Distribution: AT (BW, ZA)

 

Sclerocypris sp.

Szwarc et al. [22]: Thamalakane river near the city of Maun, site no SA-97/coord. 19°55′52″ S, 23°30′38″ E, 940 m a.s.l./FEOW: 569 Okavango/Habitat: river side channel/Coll. date: 13 September 2012/1 ♂.

 

Family: Candonidae Kaufmann, 1900

Subfamily: Candoninae Kaufmann, 1900

Tribe: Candonini Kaufmann, 1900

Genus: Pseudocandona Kaufmann, 1900

 

*Pseudocandona sp.

• Present paper: Shashe river near the village of Shashe, site no SA-109/coord. 21°23′20″ S, 27°27′20″ E, 956 m a.s.l./FEOW: 576 Zambezian Lowveld/Habitat: pools in riverbed/Coll. date: 18 September 2012/97 ♀♀;
• Present paper: Mahalapye river near the town of Mahalapye, site no SA-110/coord. 23°06′09″ S, 26°50′21″ E, 1006 m a.s.l./FEOW: 576 Zambezian Lowveld/Habitat: small river dam/Coll. date: 18 September 2012/1 ♀;
• Present paper: Bathoen near the town of Kanye, site no SA-114/coord. 24°56′54″ S, 25°20′39″ E, 1255 m a.s.l./FEOW: 575 Southern Temperate Highveld/Habitat: river flood pool/Coll. date: 20 September 2012/10 ♀♀.

 

Tribe: Candonopsini Karanovic, 2004

Genus: Candonopsis (Candonopsis) Vávra, 1891

 

*Candonopsis nama Daday, 1913

Present paper: Bathoen near the town of Kanye, site no SA-114/coord. 24°56′54″ S, 25°20′39″ E, 1255 m a.s.l./FEOW: 575 Southern Temperate Highveld/Habitat: river flood pool/Coll. date: 20 September 2012/20 ♀♀, 22 ♂♂, 1 juv.

Distribution: AT (NAM)

 

Candonopsis navicula Daday, 1910

Szwarc et al. [22]: Thamalakane river near the city of Maun, site no SA-97/coord. 19°55′52″ S, 23°30′38″ E, 940 m a.s.l./FEOW: 569 Okavango/Habitat: river side channel/Coll. date: 13 September 2012/1 ♀.

Distribution: AT (BW)

Subfamily: Cyclocypridinae Kaufmann, 1900

Genus: Physocypria Vávra, 1897

Physocypria cf. capensis (Sars, 1895)

• Szwarc et al. [22]: Thamalakane river near the city of Maun, site no SA-97/coord. 19°55′52″ S, 23°30′38″ E, 940 m a.s.l./FEOW: 569 Okavango/Habitat: river side channel/Coll. date: 13 September 2012/1 ♀;
• Present paper: Kolobeng river near the village of Manyana, site no SA-113/coord. 24°46′08″ S, 25°35′22″ E, 1133 m a.s.l./FEOW: 576 Zambezian Lowveld/Habitat: river/Coll. date: 20 September 2012/15 ♀♀, 46 juv;
• Present paper: Bathoen near the town of Kanye, site no SA-114/coord. 24°56′54″ S, 25°20′39″ E, 1255 m a.s.l./FEOW: 575 Southern Temperate Highveld/Habitat: river flood pool/Coll. date: 20 September 2012/5 ♀♀, 3 juv.

 

Family: Ilyocyprididae Kaufmann, 1900

Subfamily: Ilyocypridinae Kaufmann, 1900

Genus: Ilyocypris Brady & Norman, 1889

 

*Ilyocypris cf. gibba (Ramdohr, 1808)

• Present paper: Tati river near the town of Francistown, site no SA-108/coord. 21°10′48″ S, 27°30′44″ E, 982 m a.s.l./FEOW: 576 Zambezian Lowveld/Habitat: pools in riverbed/Coll. date: 18 September 2012/2 ♀♀;
• Present paper: Mahalapye river near the town of Mahalapye, site no SA-110/coord. 23°06′09″ S, 26°50′21″ E, 1006 m a.s.l./FEOW: 576 Zambezian Lowveld/Habitat: small river dam/Coll. date: 18 September 2012/8 ♀♀, 2 juv;
• Present paper: Bathoen near the town of Kanye, site no SA-114/coord. 24°56′54″ S, 25°20′39″ E, 1255 m a.s.l./FEOW: 575 Southern Temperate Highveld/Habitat: river flood pool/Coll. date: 20 September 2012/1 ♀, 1 juv.

 

Ilyocypris sp.

• Riedel et al. [35]: an outcrop on Kubu Island at the south-western edge of Sua Pan in Makgadikgadi Basin/coord. 20°53′29″ S, 25°51′14″ E, 901 m a.s.l./FEOW: 570 Kalahari/Habitat: palaeo-mega-lake system (sediments representing relics of the 8.5 ka B.P. last “mega-lake event”)/Coll. dates: September 2007, April 2008, July 2010/fossil valves;
• Riedel et al. [36]: sediment core 1.5 km east of Kubu Island at the south-western edge of Sua Pan in Makgadikgadi Basin/coord. 20°53′30″ S, 25°50′30″ E, 900–903 m a.s.l./FEOW: 570 Kalahari/Habitat: palaeo-mega-lake system (core to 3.0 m depth)/Coll. dates: September 2007, April 2008, July 2010/fossil valves in a sedimentary sequence dated from ca. 37 ka to 2 ka cal. BP.

 

*Ilyocypris sp. n.

Present paper: Mahalapye river near the town of Mahalapye, site no SA-110/coord. 23°06′09″ S, 26°50′21″ E, 1006 m a.s.l./FEOW: 576 Zambezian Lowveld/Habitat: small river dam/Coll. date: 18 September 2012/a few empty valves.

Note: A species resembling representatives of the fossil genus Juxilyocypris Kempf, 2011 known exclusively from Pleistocene to Holocene deposits in Europe ([42,43]).

 

Family: Notodromadidae Kaufmann, 1900

Subfamily: Oncocypridinae De Deckker, 1979

Genus: Oncocypris G.W. Müller, 1898

 

*Oncocypris muelleri (Daday, 1910)

• Present paper: Bathoen reservoir near the town of Kanye, site no SA-115/coord. 24°57′06″ S, 25°20′33″ E, 1267 m a.s.l./FEOW: 575 Southern Temperate Highveld/Habitat: reservoir/Coll. date: 20 September 2012/subfossil empty valves;
• Present paper: Moshenang Dam near the village of Kanye, site no SA-116/coord. 24°54′50″ S, 25°16′15″ E, 1282 m a.s.l./FEOW: 576 Zambezian Lowveld/Habitat: reservoir/Coll. date: 20 September 2012/subfossil empty valves.

Distribution: AT (ZA)

 

Superfamily: Cytheroidea Baird, 1850

Family: Limnocytheridae Sars, 1925

Subfamily: Limnocytherinae Sars, 1925

Tribe: Limnocytherini Klie, 1938

Genus: Limnocythere Brady, 1867

 

Limnocythere inopinata (Baird, 1843)

Riedel et al. [36]: sediment core 1.5 km east of Kubu Island at the south-western edge of Sua Pan in Makgadikgadi Basin/coord. 20°53′30″ S, 25°50′30″ E, 900–903 m a.s.l./FEOW: 570 Kalahari/Habitat: palaeo-mega-lake system (core to 3.0 m depth)/Coll. dates: September 2007, April 2008, July 2010/fossil valves in a sedimentary sequence dated from ca. 37 ka to 2 ka cal. BP.

Distribution: AT (BW, ZA), NA, PA

 

Limnocythere cf. stationis Vavra, 1891

• Szwarc et al. [22]: Thamalakane river near the city of Maun, site no SA-97/coord. 19°55′52″ S, 23°30′38″ E, 940 m a.s.l./FEOW: 569 Okavango/Habitat: river side channel/Coll. date: 13 September 2012/8 ♀♀, 2 juv;
• Szwarc et al. [22]: North-West District, floodplains south of Okavango Delta near the city of Maun, site no SA-103/coord: 19°52′12″ S, 23°20′23″ E, 940 m a.s.l./FEOW: 569 Okavango/Habitat: grassy shore of temporary pond/Coll. date: 15 September 2012/1 ♀;
• Present paper: Shashe river near the village of Shashe, site no SA-109/coord. 21°23′20″ S, 27°27′20″ E, 956 m a.s.l./FEOW: 576 Zambezian Lowveld/Habitat: pools in riverbed/Coll. date: 18 September 2012/10 ♀♀, 1 juv;
• Present paper: Mahalapye river near the town of Mahalapye, site no SA-110/coord. 23°06′09″ S, 26°50′21″ E, 1006 m a.s.l./FEOW: 576 Zambezian Lowveld/Habitat: small river dam/Coll. date: 18 September 2012/3 ♀♀;
• Present paper: Bathoen reservoir near the town of Kanye, site no SA-115/coord. 24°57′06″ S, 25°20′33″ E, 1267 m a.s.l./FEOW: 575 Southern Temperate Highveld/Habitat: reservoir/Coll. date: 20 September 2012/28 ♀♀.

 

Limnocythere thomasi Martens, 1990

• Riedel et al. [35] as Limnocythere thomasi–group: an outcrop on Kubu Island at the south-western edge of Sua Pan in Makgadikgadi Basin/coord. 20°53′309″ S, 25°49′00″ E, 908 m a.s.l./FEOW: 570 Kalahari/Habitat: palaeo-mega-lake system (sediments representing relics of the 8.5 ka B.P. last “mega-lake event”)/Coll. dates: September 2007, April 2008, July 2010/fossil valves;
• Riedel et al. [36]: sediment core 1.5 km east of Kubu Island at the south-western edge of Sua Pan in Makgadikgadi Basin/coord. 20°53′30″ S, 25°50′30″ E, 900–903 m a.s.l./FEOW: 570 Kalahari/Habitat: palaeo-mega-lake system (core to 3.0 m depth)/Coll. dates: September 2007, April 2008, July 2010/fossil valves in a sedimentary sequence dated from ca. 37 ka to 2 ka cal. BP.

Distribution: AT (BW)

 

Limnocythere tudoranceai Martens, 1990

• Martens et al. [44]: no further details given (not listed from Botswana also in the checklist of Martens [17]);
• McCulloch et al. [21]: North Basin of Makgadikgadi Pan/approx. coord. 20°25′00″ S, 26°11′00″ E, 890 m a.s.l./FEOW: 570 Kalahari/Habitat: temporary salt pan/Coll. dates: December 1999–June 2001/number of specimens unspecified;
• McCulloch et al. [21]: Middle Basin of Makgadikgadi Pan/approx. coord. 20°41′00″ S, 26°06′00″ E, 904 m a.s.l./FEOW: 570 Kalahari/Habitat: temporary salt pan/Coll. dates: December 1999–June 2001/number of specimens unspecified;
• McCulloch et al. [21]: South Basin of Makgadikgadi Pan/approx. coord. 21°00′00″ S, 26°12′00″ E, 904 m a.s.l./FEOW: 570 Kalahari/Habitat: temporary salt pan/Coll. dates: December 1999–June 2001/number of specimens unspecified.

Distribution: AT (BW, NAM)

 

Limnocythere sp.

Present paper: Nata river near the village of Nata, site no SA-107/coord. 20°12′55″ S, 26°11′09″ E, 915 m a.s.l./FEOW: 570 Kalahari/Habitat: pools in riverbed/Coll. date: 17 September 2012/empty valves.

 

The inventory of living and (sub)fossil non-marine Ostracoda of Botswana is presented in

Table 1. Checklist of living (L), subfossil (SF = empty valves found in samples of wet surface sediment of existing waterbodies), and fossil (F = valves from Late-Pleistocene-Holocene sediments) non-marine Ostracoda from Botswana. Records of our own, unpublished field collection are denoted by X in the Reference column, and species with first records for Botswana are marked with an asterisk (*). Records included in the previous checklist of Ostracoda of the region of Southern Africa [16] are indicated in the brackets ([16]) after the original references.

No.	Species	References	Fossil/ Living	No.	Species	References	Fossil/Living
1.	Amphibolocypris arida	[20,37]	L	28.	*Oncocypris muelleri	X	SF
2.	Apatelecypris schultzei	[19] ([16])	L	29.	Physocypria cf. capensis	[22], X	L
3.	*Candonopsis nama	X	L	30.	Plesiocypridopsis newtoni	[21,22], X	L
4.	Candonopsis navicula	[22]	L	31.	Potamocypris deflexa	[22]	L
5.	Chrissia fascigera	[19] ([16])	L	32.	Potamocypris mastigophora	[19,22,34], X ([16])	L
6.	*Chrissia cf. pectinata	X	L	33.	Potamocypris variegata	[36]	F
7.	Chrissia cf. perarmata	[22]	L	34.	Potamocypris new sp. ?	[21]	L
8.	*Cypricercus cf. cuneatus	X	L	35.	Potamocypris sp.	[20,37]	L
9.	Cypricercus inermis	[20]	L	36.	*Pseudocandona sp.	X	L
10.	*Cypridopsis vidua	X	L	37.	Pseudocypris circularis	[16,19,24] ([16])	L
11.	Hemicypris inversa	[18,22,41] ([16])	L	38.	Pseudocypris gibbera	[19,24] ([16])	L
12.	Hemicypris reticulata	[20]	L	39.	Sarscypridopsis cf. elizabethae	[22]	L
13.	Heterocypris giesbrechti	[22,31]	L	40.	Sarscypridopsis glabrata	[36]	F
14.	Heterocypris incongruens	[37]	L	41.	Sarscypridopsis cf. gregaria	[20,37]	L
15.	Heterocypris cf. incongruens	X	L	42.	Sarscypridopsis harundineti	[22]	L
16.	Heterocypris oblonga	[22]	L	43.	*Sarscypridopsis cf. reniformis	X	L
17.	Heterocypris ovularis	[19] ([16])	L	44.	Sarscypridopsis sp.	[20]	L
18.	Heterocypris sp.	[20,37]	L	45.	Sclerocypris clavularis	[20]	L
19.	*Ilyocypris cf. gibba	X	L	46.	Sclerocypris exserta makarikarensis	[21,32,33]	L
20.	Ilyocypris sp.	[35,36]	F	47.	Sclerocypris methueni	[34]	L
21.	*Ilyocypris sp. n.	X	SF	48.	Sclerocypris sp.	[22]	L
22.	Isocypris cf. priomena	[22], X	L	49.	Stenocypris malayica	[22]	L
23.	Limnocythere inopinata	[36]	F	50.	Strandesia cf. prava	[22], X	L
24.	Limnocythere cf. stationis	[22], X	L	51.	Strandesia n. sp. (gr. sudanica)	[20]	L
25.	Limnocythere thomasi	[35,36]	F	52.	Strandesia sp.	[36]	F
26.	Limnocythere tudoranceai	[21,44]	L	53.	Zonocypris costata	[22]	L
27.	Limnocythere sp.	X	SF	54.	Zonocypris tuberosa	[22]	L

.

3.2. Biodiversity of Non-Marine Ostracods of Botswana

Although numbers of specimens were recorded in our material, the results presented here have a qualitative character, and species incidence was investigated rather than abundance to be comparable with the published results of other studies. Our survey produced 17 records of ostracod species from 11 new locations, mainly from the east and south-east of Botswana (Figure 1, Table 1). Together with other published records, the present checklist includes, in total, 54 (45 living and nine fossil or subfossil) ostracod species currently reported from Botswana, with 23 taxa left in open nomenclature. Of the total number, nine species were found only as empty valves either in samples of wet surface sediment of the existent waterbodies (four taxa of subfossil material) or in the Late-Pleistocene-Holocene sediments (Table 1). The majority (75.9%) of the species in the checklist belong to the family Cyprididae.

The accumulation plot of the observed species number was unsaturated, not reaching asymptotic levelling-off (Figure 2). The total observed species richness, based on living ostracod records from 28 sites (11 own sites, eight from [22], three from [21], three from [19] supplemented by [24], two from [20,37], and one from [18] revised by [31]) was 65.2% of the species number estimated by the Chao 2 index (mean ± SD = 69.0 ± 13.31).

Compared with the total (gamma) diversity (54 species of the total inventory), alpha diversity expressed by species richness at the individual sampling site was low and ranged from 1 to 12 (median = 3, mean ± SD = 3.3 ± 2.25), with four sites having only one species recorded. The most common species based on the samples from the above-mentioned 28 sites were Sarscypridopsis harundineti (eight sites, 28.6% of the total 28) as well as Heterocypris oblonga and Potamocypris mastigophora (both present at six sites, 21.4%).

Species were mainly distributed across the freshwater ecoregions of Okavango, Zambezian Lowveld, and Kalahari (22, 21, and 18, respectively), where the highest number of sites were sampled. Two other freshwater ecoregions (Southern Kalahari and Southern Temperate Highveld) were represented by only two sampling sites each, and were thus not included in the statistical tests. The ANOSIM showed significant differences among the three mentioned most frequently sampled freshwater ecoregions (Global R = 0.314, p < 0.001). Pairwise tests showed significant differences for Okavango vs. Zambezian Lowveld (R = 0.339, p = 0.001) and Okavango vs. Kalahari (R = 0.488, p < 0.001). The main species principally responsible for this separation included Sarscypridopsis harundineti and Heterocypris oblonga. The pattern exhibited by the ecoregions on the basis of their ostracod fauna is presented by a non-metric, Multi-Dimensional Scaling (mMDS) plot on bootstrap averages (Figure 3).

Similar results were obtained when the homogeneity of multivariate dispersions (PERMDIP) test was used to assess differences in beta diversity among the three most-intensively sampled freshwater ecoregions (Okavango, Zambezian Lowveld, and Kalahari). PERMDISP showed significant differences among these ecoregions (F = 8.869, p (perm) = 0.008), and pairwise tests showed significant differences for Okavango vs. Zambezian Lowveld (t = 4.042, p = 0.002) and Okavango vs. Kalahari (t = 3.592, p = 0.006).

4. Discussion

The present field collection with the collation of previously and recently published surveys brings the total number of living, subfossil, and Late-Pleistocene-Holocene species of non-marine Ostracoda of Botswana to 54 (Table 1) and places this country, together with South Africa (122 species according to Martens [17]) and Namibia (52 species according to Curtis [45] and Curtis et al. [46]), in the group of South African countries having the highest species record. The highest ostracod species richness in South Africa may partly be explained by the largest surface and greatest topographic, climatic, and environmental diversity of this country in the region. A detailed discussion of the distribution and zoogeography of ostracods in Southern Africa would, however, be premature as the state of knowledge of ostracods of this region is very unevenly distributed and vast areas still remain to be investigated. Only limited surveys have been done in Angola, Mozambique, Zambia, and Zimbabwe, which produced only a few records of non-marine ostracods from each of these countries (see [17,47]).

Out of 54 species (including nine fossil or subfossil records) reported so far from Botswana, 23 are unfortunately left in open nomenclature due to the immature taxonomy of Southern African ostracods. These records need thorough taxonomic verification and several of them cannot be considered new species until more morphological (and molecular) evidence is available. At least some of these records, however, are new taxa just awaiting formal descriptions (see e.g., Strandesia n. sp. in [20] or Ilyocypris sp. n. and Pseudocandona sp. in the present paper). This indicates the urgent need for sound systematic studies on harmonizing taxonomy of Southern African ostracods. Nevertheless, of 17 species yielded by our own survey of 11 sites, nine are new records for Botswana (Table 1).

The observed and estimated species richness may suggest that the sampling effort is still not perfectly adequate to represent the number of ostracod species in Botswana. The recorded species amounted to 65% of the estimated species richness (Figure 2). While further sampling may increase the range of some of already reported taxa, the continuing increase in species number recorded from the country over time and non-saturated species accumulation curve clearly indicate that additional range-restricted species are likely to be found, and, thus, support the assertion that the recorded ostracod species richness in Botswana is still considerably underestimated. Most previous sampling sites were situated in the northern part of the country, while our survey extends the ostracod distribution records in the south and east of Botswana (Figure 1). Yet, significant regions of the country still have not been investigated, especially the most arid south-west region with difficult accessibility. No significant efforts have also been made to investigate ostracods in the permanent marshlands and seasonally flooded plains of the vast Okavango Delta system, although ostracods, as a group, have been reported frequently from this area (e.g., [48,49,50]). The general level of taxonomic exploration of hydrobionts in the Okavango freshwater ecoregion is considered reasonable and the delineation of the ecoregion justified [14,51]. Showing significant differences in ostracod species composition (with endemic Sarscypridopsis harundineti [22]) and lower beta diversity of the Okavango ecoregion versus other two ecoregions of Botswana (Kalahari and Zambezian Lowveld), our preliminary results seem to support the distinctiveness of the Okavango ecoregion. The microcrustacean (mainly planktonic cladocerans and copepods) and Odonata faunas of the Okavango Delta have close affinities with their counterparts of the Bangweulu swamps in Zambia [51,52], while other groups of Okavango aquatic invertebrates biogeographically resemble those occurring in the catchments of the Zambezi and Congo Rivers [14]. Additional larger-scale studies of subcontinental range are needed to investigate the biogeographical relationships between various catchments to locate evidence for former connections and geomorphological evolution of the river systems in Southern Africa. There is also a need for ecological studies, e.g., on salinity tolerances or effects of increasing temperature; thus, any taxonomic and faunistic surveys must routinely be accompanied by records of water and sediment properties. In future research, high priority should also be given to yet unexplored areas and habitats, e.g., there remains much to be learned about the ostracod distribution in the groundwater of various aquifers in Botswana.

The taxonomic composition of the ostracod fauna of Botswana shows that representatives of the family Cyprididae make up 76% of the total specific diversity of the country. This is expected in an arid land such as Botswana, where most of waterbodies are temporary, as species of this family can produce drought-resistant eggs, which can survive unfavorable conditions and can be passively dispersed via zoochory or anemochory to other waterbodies [15,17]. The most species-rich subfamily of Cyprididae in the ostracod fauna of Botswana was Cypridopsinae (24% of the total species inventory), two species of which (Sarscypridopsis harundineti and Potamocypris mastigophora) were also the most common at the sites considered in the present checklist (eight and six sites of the total of 28, respectively). The Cypridopsinae is also one of the most common and most taxonomically difficult subfamilies of non-marine ostracods in Southern Africa [17].

Although we encountered some species in the ostracod fauna of Botswana that are widespread geographically, e.g., cosmopolitan (Cypridopsis vidua and Heterocypris incongruens) or nearly cosmopolitan (Ilyocypris gibba and Stenocypris malayica), the majority (23 species, approx. 43%) are restricted to the Afrotropical region or originally recorded and described from that region and subsequently also reported elsewhere in one or two other zoogeographical regions (seven species, 13%). There are relatively few known endemics for Botswana: Amphibolocypris arida from rock pools in the south of the country within the ecoregion of Zambazian Lowveld [20,27], Sarscypridopsis harundineti from floodplains south of Okavango Delta near the city of Maun [22], and Sclerocypris exserta makarikarensis from the Makgadikgadi ephemeral saline lake system within the Kalahari ecoregion [21,32]. Even if a cautiously possible four more species (undescribed new species left in open nomenclature) are added to the list of species endemic to Botswana, the overall level of endemism is still low compared with Namibia, where 18 species of the total of 52 (i.e., ca. 35%) are considered endemics [45,46] or with the Western and Eastern Cape provinces of South Africa with several endemic species [10,17]. Since our present knowledge of the ostracod distribution in Botswana is limited, and we do not know which species are likely to be endangered, potential endemics are certainly worthy of protection.

Local momentary ostracod species richness (alpha diversity) at the individual sampling sites included in the present ostracod checklist of Botswana was rather low and ranged from 1 to 12 (mean = 3.3). In a study on ostracods from 60 permanent and temporary waterbodies in the Eastern Cape province of South Africa, Martens and de Moor [53] reported a similar range and mean value of alpha diversity (1–11; mean ca. 4.7). The study of Martens et al. [44] of ostracods in a shallow, semi-estuarine coastal lake-river-swamp system in the Western Cape province showed alpha diversity varying in a saline gradient between 1 and 6 (with a mean value of 4.4). Considerably lower momentary alpha diversities of other microcrustaceans were found by West and van As [54] in a temporary system of the Nata River in north-eastern Botswana, i.e., 0–1 species of Cladocera and 0–2 species of Copepoda. Obviously, numerous and intrinsically related factors influence biodiversity of temporary inland waters in drier climates, e.g., size, isolation, habitat heterogeneity, longevity and frequency of the inundation period, salinity, pH and ionic composition, oxygen concentration as well as stochastic events, human interventions, and biological interactions [55,56,57]. Moreover, invertebrate communities of a local system of temporary waterbodies during the course of the inundation period undergo ecological succession ensuing hydrological changes, which finally leads to seasonal, annual, and interannual variations in the species composition, so that (coupled with an often-patchy distribution) at any sampling moment the community represents only a portion of the entire species richness of the community [54,58]. Frequent and severe disturbances may also lead to intense selection and species sorting, resulting in a reduction of the total number of species to most tolerant ones [59]. In that case, sampling success varies with the seasonal conditions, and to gather more complete taxa lists either repeated samples of active communities are required (which is often limited in arid regions with erratic rainfall) or instead studying morphologically banks of drought-resistant eggs deposited in the sediment to reconstruct diversity of dormant communities as proposed by Meyer-Milne et al. [58] for branchiopods in dryland wetlands of South Africa. Such an approach has, however, not yet been explored for ostracods and we do not know if egg morphology is species-specific. Alternatively, sediment egg banks may be studied through environmental DNA analysis as was successfully documented for ostracod identification in surface sediment samples collected from Lake Nam Co on the Tibetan Plateau [60].

Threats to biodiversity of aquatic ecosystems are often more severe when compared to terrestrial ecosystems. In the face of global climate change and increasing anthropogenic pressures on temporary wetlands, investigations of spatial and temporal trends in biodiversity loss, especially in drier climates, are becoming increasingly important [2,3,56,61]. Although an arid land, Botswana has diverse wetland habitats which house a variety of aquatic fauna [61], including at least 50 species of Ostracoda, most of which are specialist species adapted to temporary water conditions. Such species produce dormant eggs that are extremely resistant and withstand recurrent dry periods [62], have some risk-spreading strategies (hatching in fractions during a single inundation [63]), and disperse in space via various biotic and abiotic vectors [15]. Characteristics of dormancy and dispersal, partly controlled by the hydrological regime, size, and spatial pattern of waterbodies, which, in term, are affected by human disturbance and climate change, are crucial for the successful long-term persistence of metapopulations and metacommunities of inhabitants of temporary waters [64]. By contributing to the knowledge of the biodiversity and spatial distribution of ostracods in Botswana, we hope to help address some of the knowledge gaps impeding the conservation of temporary waters in this country.

Note

Just when we received reviews of our manuscript, one more paper was published with records of ostracods from Botswana, which we could not take into account despite its relevance. Franchi et al. [65] found fossil valves of seven taxa of the species rank (five left in open nomenclature) from Late-Pleistocene-Holocene sediments of the Makgadikgadi Basin (Kalahari): Candonopsis sp., Ilyocypris sp., Limnocythere spp., Potamocypris sp., Sarscypridopsis ochracea (Sars, 1924), Sarscypridopsis glabrata (Sars, 1924), and Sclerocypris cf. bicornis (Müller, 1900). Sarscypridopsis ochracea and Sclerocypris cf. bicornis are new records for Botswana.