African Zoology

New data on the clupeoids of lakes Mai-Ndombe and Tumba, western Democratic Republic of the Congo, using an integrated approach combining morphology and barcoding

Bo Delling — 2024-06-18

Morphological and molecular comparisons of clupeoid fishes in lakes Tumba and Mai-Ndombe in the Congo Basin revealed that a large- sized form of a common species in Lake Mai-Ndombe had not been distinguished from the small-sized endemic Mai-Ndombe dwarf sprat Nannothrissa stewarti Poll & Roberts, 1976 in ecological studies. The large-sized form differs from the Mai-Ndombe dwarf sprat in several morphological characters and resembles the smalltoothed pellonula Pellonula leonensis Boulenger, 1916, but in barcoding analysis appears more closely related to the bluntnosed sawtooth pellonuline Potamothrissa obtusirostris (Boulenger, 1909). This large- sized form is probably a species new to science but will remain undescribed for now, and is here referred to as Pellonulinae sp. BIG. A slender clupeoid, also from Lake Mai-Ndombe, has recently been referred to as the Lake Tumba dwarf sprat Nannothrissa parva (Regan, 1917), which would be the first record of this species from that lake. Specimens of a slender clupeoid collected from Lake Mai-Ndombe for this study were identified as the losera fangtooth pellonuline Odaxothrissa losera Boulenger, 1899. This is the first confirmed occurrence of this species in Lake Mai-Ndombe, whereas the presence of N. parva could not be confirmed. The phylogenetic analysis strongly supports the genus Nannothrissa as currently delimited, here barcoded for the first time, but also confirms the previously reported mismatch between morphological classification and molecular data in this group. We further note that the Mai-Ndombe dwarf sprat attains a larger size than the maximum size noted in the original description in 1976, and it is suggested that an intense beach- seine fishery that utilises mosquito nets might have led to a population decline followed by decreased intraspecific competition, enhancing individual growth. For the same reason, Pellonulinae sp. BIG might have been less common previously and so remained undetected until now.

Species diversity and distribution-pattern determinants of African rivulines (Cyprinodontiformes: Nothobranchiidae) in rainforest streams of southern Cameroon

F.D. Messu Mandeng — 2024-06-18

Understanding the community structure and ecology of fish populations in rainforest streams is a prerequisite for any actions towards their exploitation, management or conservation. We examined the community structure and species diversity of nothobranchiids (African rivulines) in rainforest streams of Cameroon’s southern plateau and part of the coastal plain, using data on 19 environmental variables for ecological indices and multivariate analyses. In total, 1 019 individual cyprinodontiforms assigned to 14 species (largely species of Aphyosemion) were collected, for a global sampling effort of 78.6%. The presence of nothobranchiids in the study area was associated with several local environmental factors common to all sampling sites, mainly canopy cover above the watercourse and physicochemical characteristics of the stream habitat. Distribution of the species was strongly spatially structured, driven by the site’s elevation and the water temperature, and influenced primarily by the riparian vegetation, substrate type, water conductivity and flow velocity. However, fish species richness did not differ significantly between the five sectors sampled and by elevation. The nothobranchiid communities were highly diverse (Shannon’s H′ = 2.28 ± 0.05; Pielou’s J = 0.87) and the species evenly distributed. Seven species were exclusive to a single sector, others were prevalent in multiple sectors, and no species was common to all sectors. Affinities between species were relatively few, though there were exceptions, and most species tended to exclude each other. These findings highlight nothobranchiids as local fish assemblages having high biotic integrity and responsiveness to environmental degradation. In tropical Africa, these fishes often occupy fragile habitats influenced by anthropogenic activities. A better understanding of the unifying role of habitat in ecology will assist management efforts to promote biodiversity conservation.

Susceptibility of dwarf chameleons to climate and land use change: a vulnerability framework for conservation planning

Tyron K. Clark — 2024-06-18

Climate and land use changes are eroding biodiversity globally, and reptiles are highlighted as being particularly susceptible. In South Africa, global changes threaten the persistence of an assemblage of dwarf chameleons (Bradypodion) located in a biodiversity hotspot. We used ecological niche modelling to assess the combined effect of climate change and habitat transformation on these species and assessed their susceptibility in a vulnerability framework under optimistic and pessimistic change scenarios. Although our models showed a gain in suitable climatic space for all coastal species in some scenarios, considerable losses were predicted for most species under the most pessimistic change scenarios. Bradypodion ngomeense, for example is predicted to incur a complete loss of climatic suitability by 2050. The vulnerability framework predicts inland species to be more adversely affected by climate change than coastal species. However, no species show resilience to the combined effects of climate change and habitat transformation. Our models predicted a loss of climatically suitable habitat for most species in protected areas. These findings highlight the importance of a protected area network design to remain a step ahead of these anticipated changes.

Geographic distribution of the scorpion fauna in the central Moroccan region of Souss-Massa with potential implications for public health

Fouad Salhi — 2024-06-18

Despite the medical importance of North African scorpions, many aspects of their ecology which may be important to understand envenoming patterns throughout their range, remain understudied. The region of Souss-Massa in central Morocco exhibits a high incidence of scorpion envenomings, with 29 437 cases reported between 2005 and 2010, resulting in 32 deaths. In the present study, we provide an updated inventory of scorpions occurring throughout the Souss-Massa region, with additional information about their distribution and notes on preferred habitats for each species observed. Sampling was carried out at 39 stations over a three-year period: June and August 2020, April and June 2022, and July and August 2023. Twelve species belonging to two families were recovered over the course of the study. The families Buthidae and Scorpionidae were represented by eleven and a single species respectively. Overall, this represents 71% of all species reported to occur in the Souss-Massa region. Apart from Androctonus mauritanicus, A. bourdoni, A. sergenti and Hottentotta gentili which are present in and around human dwellings, all other species were found in uninhabited areas. Apart from Scorpio mogadorensis, all the species of scorpions we recovered can cause severe envenomation with potentially fatal outcomes. Field- based ecological investigations should be encouraged to gain a more accurate and comprehensive understanding of scorpion distribution patterns and habitat preference. In turn, this will inform the health-science community of the etiological factors responsible for scorpion envenoming.

Molecular characterisation and phylogeny of two nematode parasites recovered from the amphibian host Schlerophrys regularis sampled in Lagos metropolis, Nigeria

Okeagu Martin Okechukwu — 2024-06-18

Research on amphibian parasites has been on the increase because of the noticeable decline of amphibians. Studies on these parasites have been limited to their prevalence and infection patterns, and there is still a dearth of knowledge on the phenotypic variations. To characterise and investigate the genetic variability and relatedness of amphibian nematode parasites, two nematode parasites– suspected Cosmocerca sp. and suspected Rhabdias sp.–of the toad Schlerophrys regularis were investigated. One hundred and sixty- eight S. regularis were collected from three study areas: Ikorodu, Ojota and Badagry. Intestines were dissected to obtain the enteric parasites, and lungs were washed in saline solution. Parasites were labelled according to the location of collection (Badagry 5A-5I, Ikorodu 5J–5O, Ojota 5P and 5S) and were then preserved for further identification. Eighteen parasites were identified morphologically using standard keys and by amplification of the 18S small subunit (SSU) ribosomal DNA sequence. Phylogenetic analysis was done using the Neighbour-Joining method. From the sequence homology and phylogenetic analysis, the suspected Cosmocerca sp. shared the closest genetic relatedness with Aplectana chamaeleonis isolate AC3 with 100% similarities while the suspected Rhabdias sp. shared the closest genetic relatedness with Rhabditoides regina isolate DF5012 with 100% similarities. Based on location, four Aplectana chamaeleonis (5E, 5F, 5G, 5H) and five Rhabditoides regina (5A, 5B, 5C, 5D, 5I) were from Badagry, four Aplectana chamaeleonis (5J, 5M, 5N, 5O) and two Rhabditoides regina (5K, 5L) from Ikorodu, one Aplectana chamaeleonis (5S) and two Rhabditoides regina (5P, 5Q) from Ojota. We report that Rhabditoides regina, a parasite known to be associated with insects, was recovered in the lungs of toads. Further investigations to resolve the complexities of superfamily Cosmocercoidea are recommended. Relatedness was not influenced by collection location as parasites were not unique to a specific environment.