Understanding patterns and processes in biological diversity is a critical task given current and rapid environmental change. Such knowledge is even more essential when the taxa under consideration are important ecological and evolutionary models. One of these cases is the monogonont rotifer cryptic species complex Brachionus plicatilis, which is by far the most extensively studied group of rotifers, is widely used in aquaculture, and is known to host a large amount of unresolved diversity. Here we collate a dataset of previously available and newly generated sequences of COI and ITS1 for 1273 isolates of the B. plicatilis complex and apply three approaches in DNA taxonomy (i.e. ABGD, PTP, and GMYC) to identify and provide support for the existence of 15 species within the complex. We used these results to explore phylogenetic signal in morphometric and ecological traits, and to understand correlation among the traits using phylogenetic comparative models. Our results support niche conservatism for some traits (e.g. body length) and phylogenetic plasticity for others (e.g. genome size).

In this paper we describe Macrobiotus paulinae, a new species of the hufelandi group from the Kenyan highlands. In addition to the traditional taxonomic description, aided with morphometrics as well as light and scanning microscopy imaging, we also provide nucleotide sequences of three nuclear (18S rRNA, 28S rRNA, ITS-2) and one mitochondrial (COI) DNA fragment of the new species. The sequences allowed not only a more accurate description but also provided an independent verification of the taxonomic status of Ma. paulinae sp. nov. Such integrative approach requires a considerable number of individuals and eggs, which we have partially subsidised by employing an in vitro culture of the new species. Our analyses revealed that Ma. paulinae sp. nov. is most similar to Macrobiotus madegassus Maucci, 1993 and Macrobiotus modestus Pilato & Lisi, 2009, however it differs from these species, as well as from all other known species of the hufelandi group, by the presence of seven paired dorso-lateral patches of cuticular granulation and the presence of chorionic filaments growing out of terminal discs of egg processes. Macrobiotus paulinae sp. nov. is an example of a species with a miniaturised buccal apparatus (i.e. with reduced peribuccal lamellae and oral cavity armature, and stylet supports inserted on the buccal tube more anteriorly than in typical Ma. hufelandi group species), and it therefore resembles two recently described two-macroplacoided Minibiotus species: Mi. acadianus Meyer & Domingue, 2011 and Mi. julianae Meyer, 2012. The re-examination of the type material for these two species confirmed that they are equipped with peribuccal lamellae and therefore we transfer them to the genus Macrobiotus, specifically to the hufelandi group.

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We report a dataset of all known and published occurrence records of animals of the phylum Rotifera, including Bdelloidea, Monogononta, and Seisonacea (with the exclusion of Acanthocephala) for Africa and surrounding islands and archipelagos. The dataset includes 24,704 records of 914 taxa (subspecies: 38; species: 783; genus: 76; family: 17), gathered from 610 published papers. The published literature spans from 1854 to 2022, with the highest number of records in the decades 1990-1999 and 2010-2019. The African countries with the highest number of taxa are Nigeria, Algeria, South Africa, and Democratic Republic of the Congo, whereas no records are yet available for a dozen countries. The number of species known from each country can be explained mostly by sampling efforts, measured as the number of papers published for each country up to now. The dataset is available through the Open Science Framework (OSF) and in the Global Biodiversity Information Facility (GBIF).

The rotifer fauna of Africa has been studied for >100 years, but there has been no recent synthesis. We compiled data from 265 publications that reported information on African rotifers. Our dataset yielded information on the distribution of 765 taxa from ~1850 separate sites; these included both natural and artificial habitats such as lakes, ponds, puddles, oases, artificial systems, rivers and wetlands. A heat map of predicted rotifer biodiversity indicated that the greatest diversity should be present in the sub-Saharan region including a large hotspot in Mali and several smaller ones scattered in that region. Lakes Kariba, Tanganyika and Malawi showed high-predicted diversity, but surprisingly, Lake Victoria had lower diversity than expected. Two regions showed unusually high-predicted diversity: northwestern Algeria extending into Morocco and Egypt. Equatorial Africa is rich in habitats well suited for rotifers, yet their predicted biodiversity seems low. Latitude and elevation were negatively correlated with richness, while permanent water source and littoral zone were positively correlated according to generalized linear modeling results. Partial RDA analyses showed significant correlations among several environmental features and species occurrences. It is clear that more survey work remains to be done to achieve a better understanding of African rotifers.