Three new species of African suckermouth catfishes, genus Chiloglanis (Siluriformes: Mochokidae), from the lower Malagarasi and Luiche rivers of western Tanzania

Friel, John P., Vigliotta, Thomas R. (2011): Three new species of African suckermouth catfishes, genus Chiloglanis (Siluriformes: Mochokidae), from the lower Malagarasi and Luiche rivers of western Tanzania. Zootaxa 3063: 1-21, DOI: 10.5281/zenodo.20219

Exceptional levels of species discovery ameliorate inferences of the biogeography and diversification of an Afrotropical catfish family.

Endeavours in species discovery, particularly the characterisation of cryptic species, have been greatly aided by the application of DNA molecular sequence data to phylogenetic reconstruction and inference of evolutionary and biogeographic processes. However, the extent of cryptic and undescribed diversity remains unclear in tropical freshwaters, where biodiversity is declining at alarming rates. To investigate how data on previously undiscovered biodiversity impacts inferences of biogeography and diversification dynamics, we generated a densely sampled species-level family tree of Afrotropical Mochokidae catfishes (220 valid species) that was ca. 70 % complete. This was achieved through extensive continental sampling specifically targeting the genus Chiloglanis a specialist of the relatively unexplored fast-flowing lotic habitat. Applying multiple species-delimitation methods, we report exceptional levels of species discovery for a vertebrate genus, conservatively delimiting a staggering ca. 50 putative new Chiloglanis species, resulting in a near 80 % increase in species richness for the genus. Biogeographic reconstructions of the family identified the Congo Basin as a critical region in the generation of mochokid diversity, and further revealed complex scenarios for the build-up of continental assemblages of the two most species rich mochokid genera, Synodontis and Chiloglanis. While Syndontis showed most divergence events within freshwater ecoregions consistent with largely in situ diversification, Chiloglanis showed much less aggregation of freshwater ecoregions, suggesting dispersal as a key diversification process in this older group. Despite the significant increase in mochokid diversity identified here, diversification rates were best supported by a constant rate model consistent with patterns in many other tropical continental radiations. While our findings highlight fast-flowing lotic freshwaters as potential hotspots for undescribed and cryptic species diversity, a third of all freshwater fishes are currently threatened with extinction, signifying an urgent need to increase exploration of tropical freshwaters to better characterise and conserve its biodiversity

Exceptional levels of species discovery ameliorate inferences of the biogeography and diversification of an Afrotropical catfish family

Endeavours in species discovery, particularly the characterisation of cryptic species, have been greatly aided by the application of DNA molecular sequence data to phylogenetic reconstruction and inference of evolutionary and biogeographic processes. However, the extent of cryptic and undescribed diversity remains unclear in tropical freshwaters, where biodiversity is declining at alarming rates. To investigate how data on previously undiscovered biodiversity impacts inferences of biogeography and diversification dynamics, we generated a densely sampled species-level family tree of Afrotropical Mochokidae catfishes (220 valid species) that was ca. 70% complete. This was achieved through extensive continental sampling specifically targeting the genus Chiloglanis a specialist of the relatively unexplored fast-flowing lotic habitat. Applying multiple species-delimitation methods, we report exceptional levels of species discovery for a vertebrate genus, conservatively delimiting a staggering ca. 50 putative new Chiloglanis species, resulting in a near 80% increase in species richness for the genus. Biogeographic reconstructions of the family identified the Congo Basin as a critical region in the generation of mochokid diversity, and further revealed complex scenarios for the build-up of continental assemblages of the two most species rich mochokid genera, Synodontis and Chiloglanis. While Syndontis showed most divergence events within freshwater ecoregions consistent with largely in situ diversification, Chiloglanis showed much less aggregation of freshwater ecoregions, suggesting dispersal as a key diversification process in this older group. Despite the significant increase in mochokid diversity identified here, diversification rates were best supported by a constant rate model consistent with patterns in many other tropical continental radiations. While our findings highlight fast-flowing lotic freshwaters as potential hotspots for undescribed and cryptic species diversity, a third of all freshwater fishes are currently threatened with extinction, signifying an urgent need to increase exploration of tropical freshwaters to better characterise and conserve its biodiversity

An annotated checklist of the fishes of Gabon

International audienceUsing all data sources available, we collected 2,189 nominal scientific names that have been applied to the fishes from Gabon. Data from the literature and online database indicate that 1,062 valid species of fishes live in Gabonese waters, with 288 of these strictly restricted to freshwaters, 592 strictly restricted to marine environments and 182 species euryhaline species. Among the latter one finds 121 species inhabit in both marine and brackish environments, 16 that occur in both freshwater and brackish environments and 45 found in all salinities. These 1,062 species represent 60 orders and 224 families. An additional 202 species, mostly marine, may be present in Gabon although they have not been yet recorded. Endemic species represent 7% (75) of the 1,062 valid described species for Gabon, within just one of these from marine waters and 74 freshwaters species (mostly killifish within the genus Aphyosemion – 33 species). Regarding the IUIUCN status, 135 present (+19 possible) species (12.7%) are considered as endangered (from near threatened to critically endangered), and 135 (+24 possible) (12.7%) species are not evaluated or data deficient. The remaining species are least concern. Continued descriptions of new species from the waters of Gabon demonstrate that the present total most likely underestimates the species level diversity of the fish fauna.En utilisant toutes les sources disponibles des données, nous avons répertorié 2 189 noms scientifiques de poissons du Gabon. Les données de la littérature et des bases de données montrent que 1 062 espèces de poissons sont actuellement connues des eaux du Gabon, avec 288 strictement en eaux douces et 592 strictement marines, 182 espèces sont euryhalines avec 121 connues des eaux marines et saumâtres, 16 des eaux douces et saumâtres et, pour finir, 45 sont trouvées dans tous les milieux, quel que soit la salinité. Ces 1 062 espèces représentent 60 ordres et 224 familles auxquelles il est possible de rajouter 202 espèces, principalement marines, qui sont peut-être présentes au Gabon mais n’y ont pas encore été observées. Les espèces endémiques représentent 7% (75) du nombre des 1 062 espèces décrites et valides du Gabon : une seule espèce marine et 74 espèces des eaux douces (principalement des “killis” du genre Aphyosemion – 33 espèces). À propos du statut de l’IUCN, 135 des espèces présentes (+19 possibles) (12,7%) sont considérées comme en voie de disparition (de quasi-menacées à en danger critique), et 135 (+24 possibles) (12,7%) ne sont pas évaluées ou bien avec des données insuffisantes. Les autres sont de préoccupation mineure. Des descriptions continuelles de nouvelles espèces provenant des eaux du Gabon démontrent que la diversité de la faune des poissons du Gabon est fortement sous-estimée