Claroteidae

Parauchenoglanis longiceps, from Boulenger (1916).

Belongs within: Siluriformes.

Cichlids are not the only radiation
Published 30 September 2015
The Congo River catfish Chrysichthys brevibarbis, copyright John P. Sullivan.

With their long barbels around the mouth and lack of scales, the catfish of the Siluriformes are one of most instantly recognisable groups of fishes. They are also one of the more diverse, with close to 3000 species and including a third of the world’s freshwater fishes (Diogo & Peng 2010). Within the catfish, the Claroteidae are a distinctly African group of thirteen genera divided between two subfamilies, the Claroteinae and Auchenoglanididae. They are characterised by a moderately elongate body with a distinct adipose fin, and strong spines in the dorsal and pectoral fins (Geerinckx et al. 2003). Distinctive features of the Claroteinae include the presence of a toothplate on the palate. The Auchenoglanidinae have a rounded caudal fin and the anterior nostrils moved to the anteroventral side of the upper lip (Geerinckx et al. 2004). For a long time, the claroteids were included in the catfish family Bagridae before being raised to the level of their own family in 1991. A molecular phylogenetic analysis of the Siluriformes by Sullivan et al. (2006) placed the claroteids within a clade of African catfish that they somewhat whimsically labelled as ‘Big Africa’. The Bagridae, meanwhile, were placed within ‘Big Asia’ (though one true bagrid genus, Bagrus, does occur in Africa). Sullivan et al. (2006) questioned claroteid monophyly, finding Auchenoglanidinae to be sister to a clade grouping the Claroteinae with the family Schilbidae, but other morphological studies have found claroteids as a monophyletic unit (Diogo & Peng 2010).

Lake Tanganyika catfish Lophiobagrus brevispinis, from tanganyikacichlide.nl.

The Claroteinae are notable for having undergone something of an adaptive radiation in one of African Great Lakes, Tanganyika. Though not as dramatic as the famous radiation of cichlids in the same lake, the Tanganyikan claroteines comprise over a dozen species divided between four genera (Bailey & Stewart 1984; Hardman 2008). Seven of these are placed in the genus Chrysichthys which has a wide distribution around Africa; the other three genera are unique to the lake. Molecular phylogeny indicates that the majority of Tanganyikan claroteines represent a single colonisation of the lake; only Chrysichthys brachynema has colonised Lake Tanganyika independently (Peart et al 2014). This indicates that the genus Chrysichthys as currently defined is non-monophyletic (something that had previously been suggested on morphological grounds) but any consequent reclassification is yet to occur. The species of Chrysichthys are mostly larger than the endemic Tanganyikan genera, ranging from 19 to 77 cm within Tanganyika (species elsewhere in Africa may reach up to 1.5 m). Of the endemic genera, the monotypic Bathybagrus tetranema is about 15 cm in length but the other two genera Phyllonemus and Lophiobagrus are even smaller, less than 10 cm in length. Bathybagrus and Lophiobagrus also both have reduced subcutaneous eyes. In Bathybagrus, this possibly reflects their occurrence at greater depths than other Tanganyika fish, occurring down to 80 m (nowhere near the depths reached by Lake Baikal sculpins but still impressive enough in the low-oxygen depths of a tropical lake). Lophiobagrus species are specialised to live in the gaps between rocky rubble on the lake bottom. The species of this genus have also been observed secreting a toxic mucus that can be fatal to other fish; this mucus is believed to be secreted from enlarged glands behind the pectoral fins.

Subcutaneous eyes are also found in two claroteines outside Tanganyika: the species Amarginops platus and Rheoglanis dendrophorus, both found in the Upper Congo (Hardman 2008). These two species are specialised for life in river rapids.

Systematics of Claroteidae
<==Claroteidae
    |--AuchenoglanidinaeGA03
    |    |--Auchenoglanis Günther 1865SLH06, GA03
    |    |    |--A. biscutatus (Geoffroy Saint-Hilaire 1808)GA03
    |    |    `--A. occidentalis (Valenciennes 1840)GA03
    |    `--+--Anaspidoglanis Teugels et al. 1991SLH06, GA03
    |       |    |--*A. macrostoma (Pellegrin 1909) [=Parauchenoglanis macrostoma]GA03
    |       |    |--A. akiri (Risch 1987) [=Auchenoglanis akiri, Parauchenoglanis akiri]GA03
    |       |    `--A. boutchangai (Thys van den Audenaerde 1965) [=Parauchenoglanis boutchangai]GA03
    |       `--Parauchenoglanis Boulenger 1911SLH06, GA03
    |            |--*P. guttatus (Lönnberg 1895)GA03
    |            |--P. ahli (Holly 1930)GA03
    |            |--P. altipinnis (Boulenger 1911)GA03
    |            |--P. balayi (Sauvage 1879)GA03
    |            |--P. buettikoferi (Popta 1913)GA03
    |            |--P. longiceps (Boulenger 1913)GA03
    |            |--P. ngamensis (Boulenger 1911)GA03
    |            |--P. pantherinus (Pellegrin 1929)GA03
    |            `--P. punctatus (Boulenger 1902)GA03
    `--+--SchilbidaeSLH06
       |    |  i. s.: SiluranodonDP09
       |    |--ParailiaSLH06
       |    `--+--Pareutropius debauwi (Boulenger 1900)SLH06, KC-L22
       |       `--SchilbeSLH06
       |            |--S. intermediusEA03
       |            |--S. mandibularisEA03
       |            `--S. mystusF15
       `--ClaroteinaeSLH06
            |  i. s.: Clarotes laticeps (Rüppel 1829)AT05
            |--+--Lophiobagrus brevispinnisSLH06
            |  `--+--Bathybagrus tetranemaSLH06
            |     `--Phyllonemus typusSLH06
            `--+--Rheoglanis dendrophorusSLH06
               `--ChrysichthysSLH06
                    |--C. acutirostrisF15
                    |--C. ansorgii Boulenger 1910F15
                    |--C. auratusEA03
                    |--C. maurusEA03
                    |--C. nigrodigitatusEA03
                    |--C. sharpii Boulenger 1901B01
                    `--C. walkeriF15

*Type species of generic name indicated

References

[AT05] Agnese, J.-F., & G. G. Teugels. 2005. Insight into the phylogeny of African Clariidae (Teleostei, Siluriformes): implications for their body shape evolution, biogeography, and taxonomy. Molecular Phylogenetics and Evolution 36: 546–553.

Bailey, R. M., & D. J. Stewart. 1984. Bagrid catfishes from Lake Tanganyika, with a key and descriptions of new taxa. Miscellaneous Publication, Museum of Zoology, University of Michigan 168: 1–41.

[B01] Boulenger, G. A. 1901. Descriptions of four new African freshwater fishes. Annals and Magazine of Natural History, series 7, 7: 80–82.

[DP09] Diogo, R., & Z. Peng. 2009. State of the art of siluriform higher-level phylogeny. In: Grande, T., F. Poyato-Ariza & R. Diogo (eds) Gonorynchiformes and Ostariophysan Relationships: A Comprehensive Review pp. 465–515. Springer.

[EA03] Écoutin, J.-M., & J.-J. Albaret. 2003. Relation longueur-poids pour 52 espèces de poissons des estuaires et lagunes de l’Afrique de l’Ouest. Cybium 27 (1): 3–9.

[F15] Fowler, H. W. 1915. Notes on nematognathous fishes. Proceedings of the Academy of Natural Sciences of Philadelphia 67 (2): 203–243.

[GA03] Geerinckx, T., D. Adriaens, G. G. Teugels & W. Verraes. 2003. Taxonomic evaluation and redescription of Anaspidoglanis akiri (Risch, 1987) (Siluriformes: Claroteidae). Cybium 27 (1): 17–25.

Geerinckx, T., D. Adriaens, G. G. Teugels & W. Verraes. 2004. A systematic revision of the African catfish genus Parauchenoglanis (Siluriformes: Claroteidae). Journal of Natural History 38: 775–803.

Hardman, M. 2008. New species of catfish genus Chrysichthys from Lake Tanganyika (Siluriformes: Claroteidae). Copeia 2008 (1): 43–56.

[KC-L22] Kmentová, N., A. J. Cruz-Laufer, A. Pariselle, K. Smeets, T. Artois & M. P. M. Vanhove. 2022. Dactylogyridae 2022: a meta-analysis of phylogenetic studies and generic diagnoses of parasitic flatworms using published genetic and morphological data. International Journal for Parasitology 52: 427–457.

Peart, C. R., R. Bills, M. Wilkinson & J. J. Day. 2014. Nocturnal claroteine catfishes reveal dual colonisation but a single radiation in Lake Tanganyika. Molecular Phylogenetics and Evolution 73: 119–128.

[SLH06] Sullivan, J. P., J. G. Lundberg & M. Hardman. 2006. A phylogenetic analysis of the major groups of catfishes (Teleostei: Siluriformes) using rag1 and rag2 nuclear gene sequences. Molecular Phylogenetics and Evolution 41: 636–662.

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