Blood-red jewel cichlid Hemichromis lifalili, copyright Hectonichus.

Belongs within: Cichlidae.
Contains: Ectodini, Haplochromini, Tropheini, Neolamprologus, Tilapia, Oreochromis, Chromidotilapiini, Astatotilapia, Sarotherodon.

Steatocranus gibbiceps, the rapid river bumphead
Published 8 August 2021

The cichlid fishes of the Great Lakes of Africa are rightly renowned as one of the world’s most spectacular species radiations. Hundreds of species, occupying a wide range of ecological niches, have evolved in what is, geologically speaking, a short period of time. However, cichlids in Africa are not a phenomenon of the Great Lakes alone and many interesting species may be found in other parts of the continent, some of them belonging to local radiations of their own. Consider, for instance, the Congo River rapids endemic Steatocranus gibbiceps.

Male Steatocranus gibbiceps, copyright Polypterus.

The Congo is one of the largest African rivers with a drainage basin covering one-eighth of the continent (Schwarzer et al. 2011). Downstream of Kinshasa, the river gets funneled into an intermittently deep, narrow channel for a distance of some 300 km before broadening as it approaches the sea. The result is the world’s longest stretch of river rapids. Many fish species are found only in this unique region of fast-flowing waters, among them multiple species of the cichlid genus Steatocranus including S. gibbiceps. The genus as a whole is restricted to the Congo basin; a single species previously recognised from the Volta River has since been transferred to its own genus (Weiss et al. 2019). The names Steatocranus and gibbiceps both basically mean the same thing: ‘fat head’, in reference to a fleshy swelling atop the fish’s noggin. The exact size of this swelling varies between individuals, being most prominent in large males. Vernacular names given to Steatocranus species generally reflect this feature, such as bumphead cichlid or buffalo-head cichlid. Half a dozen species have been named within Steatocranus with several more being recognised but not yet formally described, most of them belonging to the radiation within the rapids. Schwarzer et al. (2012) found evidence for extensive historical cross-breeding between species and suggested that hybridisation may have been a significant factor in the genus’ diversification.

Steatocranus gibbiceps is the largest species in this genus of moderately-sized fishes, growing up to about nine centimetres in length (Roberts & Stewart 1976). Its fast-current habitat is reflected in its slender body form. It is olive brown in coloration with the scales being light in colour at the centre and darker around the margins. Steatocranus gibbiceps is most clearly distinguished from other described species in its genus by its teeth: the front teeth of both the upper and lower jaws are conspicuously large and truncate. It also has a shorter gut than its congeners. This species appears to be specialised in feeding on freshwater snails which it scoops up and swallows whole, though it will take a broader range of food in captivity. Other species of Steatocranus mostly feed on algae.

Steatocranus species are not buoyant and tend to sit at the bottom of the water (Chase Klinesteker describes their behaviour as ‘hopping around the bottom like a goby’). They escape the current by spending time in the hollows and crevices among rocks. Breeding happens within such hollows with dedicated pairs forming and females affixing their eggs to the rocks. Like many other cichlids, Steatocranus gibbiceps are dedicated parents after the eggs hatch. Tending of the fry is mostly the responsibility of the female while the male patrols the territory on the watch for danger. In this way, the baby bumpheads are given the best possible start at life.

Systematics of Pseudocrenilabrinae
| | | |--S. macrocephalus (Boulenger 1899)KC-L22
| | | |--S. robustusS04
| | | `--S. thumbergiAA12
| | |--HaplochrominiS04
| | |--TropheiniAM99
| | |--Boulengerochromis [Boulengerochromini]S04
| | | `--B. microlepis (Boulenger 1899)B06
| | `--+--NeolamprologusS04
| | `--ChalinochromisS04
| | |--C. brichardi Poll 1974B06
| | `--C. popelini Brichard 1989B06
| `--TilapiiniB06
| |--TilapiaS04
| |--OreochromisB06
| |--ChilochromisB06
| |--GobiocichlaB06
| | |--G. ethelwynnaeB06
| | `--G. wonderi Kanazawa 1951B06
| `--SteatocranusB06
| |--S. casuarius Poll 1939B06
| |--S. gibbicepsB06
| |--S. irvinei (Trewavas 1943) [=Gobiochromis irvinei]B06
| `--S. tinanti (Poll 1939)B06
| `--+--ChromidotilapiiniS04
| `--Tylochromis [Tylochromini]S04
| |--T. intermedius (Boulenger 1916)KC-L22
| |--T. jentinkiEA03
| |--T. leonensisS04
| `--T. polylepisS04
`--+--Heterochromis [Heterochromidinae]S04
| `--H. multidens (Pellegrin 1900)B06
| `--SarotherodonS04
|--Anomalochromis thomasi Greenwood 1985B06
|--H. bimaculatus Gill 1862C01
|--H. elongatus (Guichenot 1861)B06
|--H. fasciatus Peters 1858B06
|--H. frempongi Loiselle 1979B06
|--H. letourneuxi Sauvage 1880KC-L22
`--H. lifaliliB06

Pseudocrenilabrinae incertae sedis:
Lamprologus Schilthuis 1891TP86 [LamprologiniB06]
|--*L. congoensis Schilthuis 1891B06
|--L. callipterus Boulenger 1906B06
|--L. lemairii Boulenger 1899B06
|--L. lethops Roberts & Stewart 1976TP86
|--L. ocellatus (Steindachner 1909)B06
`--L. stappersiB50
|--A. calvus (Poll 1978)B06
`--A. compressiceps (Boulenger 1898)B06
|--J. dickfeldi Staeck 1975B06
|--J. marlieri Poll 1956B06
|--J. ornatus Boulenger 1898B06
|--J. regani Poll 1942B06
`--J. transcriptus Matthes 1959B06
|--L. cunningtoni (Boulenger 1906)B06
|--L. elongatus (Boulenger 1898)B06
|--L. kendalli (Poll & Stewart 1977)B06
|--L. nkambae (Staeck 1978)B06
`--L. profundicolaB06
|--T. bifrenatus Myers 1936B06
|--T. brichardi Louisy 1989B06
|--T. dhonti (Boulenger 1919)B06
`--T. vittatusMMS94
Cyphotilapia [Cyphotilapini]B06
|--C. frontosa (Boulenger 1906)B06
`--C. gibberosa Takahashi & Nakaya 2003B06
|--Cyprichromis leptosoma (Boulenger 1898)B06
|--P. brieniMMS94
`--P. nigripinnis (Boulenger 1901)B06
|--Eretmodus cyanostictus Boulenger 1898B06
|--Tanganicodus irsacae Poll 1950B06
|--S. erythrodon Boulenger 1900B06
`--S. marlieri Poll 1950B06
|--Reganochromis calliurus (Boulenger 1901)B06
|--Greenwoodochromis [Greenwoodochromini]B06
| `--G. christyi (Trewavas 1953)B06
|--Benthochromis [Benthochromini]B06
| `--B. tricoti (Poll 1948)KC-L22
|--L. auritus (Boulenger 1901)B06
`--L. permaxillarisB96
| |--P. microlepisC96
| `--P. straeleniMMS94
`--Plecodus straeleni Poll 1948B06
Bathybates [Bathybatini]B06
|--B. fasciatus Boulenger 1901B01
|--B. feroxMMS94
`--B. vittatus Boulenger 1914B06
Trematocara [Trematocarini]B06
|--T. marginatumB01
`--T. unimaculatum Boulenger 1901B01
|--Pterochromis congicusB06
`--Pelmatochromis buettikoferi (Steindachner 1894)B06
Etia nguti Schliewen & Stiassny 2003B06

*Type species of generic name indicated


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

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