Steatocranus gibbiceps, the Speedy River Bumphead

The cichlid fishes of the Nice Lakes of Africa are rightly famend as one of many world’s most spectacular species radiations. Tons of of species, occupying a variety of ecological niches, have developed in what’s, geologically talking, a brief time frame. Nevertheless, cichlids in Africa will not be a phenomenon of the Nice Lakes alone and plenty of fascinating species could also be present in different elements of the continent, a few of them belonging to native radiations of their very own. Take into account, for example, the Congo River rapids endemic Steatocranus gibbiceps.

Male Steatocranus gibbiceps, copyright Polypterus.

The Congo is likely one of the largest African rivers with a drainage basin protecting one-eighth of the continent (Schwarzer et al. 2011). Downstream of Kinshasa, the river will get funneled into an intermittently deep, slim channel for a distance of some 300 km earlier than broadening because it approaches the ocean. The result’s the world’s longest stretch of river rapids. Many fish species are discovered solely on this distinctive area of fast-flowing waters, amongst them a number of species of the cichlid genus Steatocranus together with S. gibbiceps. The genus as a complete is restricted to the Congo basin; a single species beforehand recognised from the Volta River has since been transferred to its personal genus (Weiss et al. 2019). The names Steatocranus and gibbiceps each principally imply the identical factor: ‘fats head’, in reference to a fleshy swelling atop the fish’s noggin. The precise measurement of this swelling varies between people, being most outstanding in giant males. Vernacular names given to Steatocranus species typically mirror this characteristic, corresponding to bumphead cichlid or buffalo-head cichlid. Half a dozen species have been named inside Steatocranus with a number of extra being recognised however not but formally described, most of them belonging to the radiation inside the rapids. Schwarzer et al. (2012) discovered proof for in depth historic cross-breeding between species and advised that hybridisation might have been a big issue within the genus’ diversification.

Steatocranus gibbiceps is the biggest species on this genus of moderately-sized fishes, rising as much as about 9 centimetres in size (Roberts & Stewart 1976). Its fast-current habitat is mirrored in its slender physique kind. It’s olive brown in coloration with the scales being gentle in color on the centre and darker across the margins. Steatocranus gibbiceps is most clearly distinguished from different described species in its genus by its tooth: the entrance tooth of each the higher and decrease jaws are conspicuously giant and truncate. It additionally has a shorter intestine than its congeners. This species seems to be specialised in feeding on freshwater snails which it scoops up and swallows complete, although it can take a broader vary of meals in captivity. Different species of Steatocranus principally feed on algae.

Steatocranus species will not be buoyant and have a tendency to sit down on the backside of the water (Chase Klinesteker describes their behaviour as ‘hopping across the backside like a goby’). They escape the present by spending time within the hollows and crevices amongst rocks. Breeding occurs inside such hollows with devoted pairs forming and females affixing their eggs to the rocks. Like many different cichlids, Steatocranus gibbiceps are devoted dad and mom after the eggs hatch. Tending of the fry is usually the accountability of the feminine whereas the male patrols the territory on the look ahead to hazard. On this method, the child bumpheads are given the absolute best begin at life.

REFERENCES

Roberts, T. R., & D. J. Stewart. 1976. An ecological and systematic survey of fishes within the rapids of the decrease Zaïre or Congo River. Bulletin of the Museum of Comparative Zoology 147 (6): 239–317.

Schwarzer, J., B. Misof, S. N. Ifuta & U. Ok. Schliewen. 2011. Time and origin of cichlid colonization of the decrease Congo rapids. PLoS One 6 (7): e22380.

Schwarzer, J., B. Misof & U. Ok. Schliewen. 2012. Speciation inside genomic networks: a case research based mostly on Steatocranus cichlids of the decrease Congo rapids. Journal of Evolutionary Biology 25: 138–148.

Weiss, J. D., F. D. B. Schedel, A. I. Zamba, E. J. W. M. N. Vreven & U. Ok. Schliewen. 2019. Paragobiocichla, a brand new genus identify for Gobiochromis irvinei Trewavas, 1943 (Teleostei, Cichlidae). Spixiana 42 (1): 133–139.