Within the Mochokidae family, there are currently six species of Chiloglanis recorded in South Africa, where they are largely restricted to the Limpopo, Olifants, Crocodile and Phongolo River systems. The genus is separated from Synodontis by the absence of elongated branched mandibular barbels, and the presence of a disc mouth form.
The habitat preferences of most Chiloglanis are cobbled substrates with fast flowing, clear water of varied depths. The hydraulic units where these species are found consist of run, riffle and cascade biotopes. In these locations this genus can be collected in high abundances where they are observed clinging to the undersides of cobbles, directly on the bedrock or within cracks and crevices.
Habitat of Chiloglanis species
Chiloglanis pretoriae - Shortspine Suckermouth
This species was first described from the Appies and Crocodile (west) Rivers around Pretoria, where it is now extinct as a result of urbanisation and the subsequent water quality deterioration. This Least Concern species is a typical Chiloglanis which occurs over cobbled substrates in flowing water.
The distribution of the species is within a wide range of the Limpopo River drainage, where it occurs in the mainstem and tributaries of the river from its source, including the Olifants and Inkomati River systems. The species is differentiated from other Chiloglanis by the presence of a smooth dorsal spine, short mandibular barbels, closely spaced teeth and the presence of an emarginate caudal fin (Skelton, 2001).
Chiloglanis Paratus - SAWFIN Suckermouth
Chiloglanis paratus is a peculiar species as it is found in standing and flowing waters within the mainstem and tributaries of the greater Limpopo River southwards to the Phongolo River. C. paratus has the widest distribution of the Chiloglanis species found in South Africa and is considered as Least Concern by the IUCN (2022).
C. paratus is known to have a varying habitat preference, from riffles and fast flowing runs, to standing pools with abundant riparian and instream cover. Typically Chiloglanis are found in flowing waters where they feed upon aquatic invertebrates. It is anticipated that during drought periods, when the species is restricted to pools, that the species is able to survive by shifting its dietary targets.
This species is separated by other Chiloglanis by the presence of a serrated dorsal spine.
Chiloglanis anoterus - Pennant-tailed Suckermouth
Chiloglanis anoterus is considered as Least Concern by the IUCN (2022). The species is the most southernly found Chiloglanis, where the distribution occurs from the Inkomati River southwards to the Phongolo and Mfolozi River systems.
The species is easily differentiated from other Chiloglanis by the presence of a pointed caudal fin in the males.
Chiloglanis Swierstrai - Lowveld Suckermouth
This species is restricted to the mainstems and tributaries of the middle and lower reaches of the Limpopo and Olifants River systems. The habitat preference of this species appears to be fast flowing habitats where both sandy substrates and cobbles are common, this was also observed by Gaigher (1973). Given its wide distribution, the species is considered as Least Concern (IUCN, 2022)
This species is readily differentiated from other Chiloglanis by the presence of a smooth dorsal spine, short, widely spaced short mandibular teeth with long maxillary and mandibular barbels (Skelton, 2001).
Chiloglanis emarginatus - Phongolo Suckermouth
Chiloglanis emarginatus has a small distribution range where it is found in the tributaries of the Inkomati and Phongolo Rivers. Given its limited distribution, its high requirement for unmodified watersheds and ongoing development, the species is considered to be Vulnerable (IUCN, 2022). The species is differentiated from other Chiloglanis by the presence of a smooth dorsal spine, long widely spaced mandibular teeth and an emarginate caudal fin.
Chiloglanis bifurcus - InKomati Suckermouth
Chiloglanis bifurcus has the smallest distribution range of the considered species and is considered as Critically Endangered (IUCN, 2022). The species is endemic to the Crocodile and Inkomati River systems where it occurs at altitudes above 900m (Skelton, 2001).
The species is differentiated from other Chiloglanis by the presence of a smooth dorsal spine, long widely spaced mandibular teeth, with a forked caudal fin with large round lobes (Skelton, 2001).
REFERENCES
Skelton P. 2001. A complete guide to the freshwater fishes of southern Africa. Struik Publishers, South Africa.
Gaigher IG. 1973. The Habitat Preferences of Fishes from the Limpopo River System, Transvaal and Mocambique. Koedoe: 16; 103–116. https://doi.org/10.4102/koedoe.v16i1.888.
International Union for the Conservation of Nature (IUCN). 2022. The Red List of Threatened Species.
International Union for the Conservation of Nature (IUCN). 2022. The Red List of Threatened Species. Digital Distribution Maps on The IUCN Red List of Threatened Species™. Version 6.2.