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Euchilichthys royauxi, Suckermouth
Mr. Thomas Vigliotta - Cornell University
Euchilichthys royauxi
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Cornell University Museum of Vertebrates (CU 91380)

Image processing: Dr. Jessie Maisano
Publication Date: 05 Feb 2007

Specimens: front half | head only

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Euchilichthys royauxiEuchilichthys royauxi is a member of a family of African catfishes, the Mochokidae (Teleostei: Siluriformes). The family is better known for members of the genus Synodontis, which includes the well known upside-down catfishes. Euchilichthys and the two closely related genera, Atopochilus and Chiloglanis, are known as sucker-mouthed mochokids or suckermouths for their large ventrally directed oral discs. These sucker-mouthed genera have also been referred to as Chiloglanines, based loosely on a subfamily of the Mochokidae, the Chiloglanidinae (Riehl & Baensch, 1990).

Euchilichthys is a small genus with only 5 valid species from a total of 6 nominal forms. The closely allied genus Atopochilus has 7 valid species and a number of other nominal forms that were subsequently moved to Euchilichthys. The respective identity of these two genera is based largely on body form and tooth shape, but is questionable at best. Nonetheless, it seems likely that together they form a monophyletic group. The genus Chiloglanis, composed of what are typically smaller sucker-mouthed forms, is fairly diverse with about 50 species. The monophyly of this genus with respect to other mochokids is still untested; it is conceivable that it would be a paraphyletic group without including Euchilichthys and Atopochilus. It seems pretty clear, however, that Chiloglanines, as a group, are monophyletic.

Euchilichthys species can reach at least 55cm in total length and probably rival the largest Synodontis (at about 80cm). Species of Atopochilus (left) also reach large sizes, but it is unclear just how large (at least 25cm TL). Atopochilus savorgnaniChiloglanis asymetricaudalisChiloglanis (right) species are much smaller, on the order of 10cm total length at their largest. The most notable feature of Chiloglanines is a ventrally directed oral disc. Further, Chilolglanines are characterized by depressed heads and skin covered in tubercles, especially near the head. Like some other mochokids, Chiloglanines are known to exhibit obvious sexual dimorphism. The most prevalent of these is dimorphism of the caudal fin, as seen in many Chiloglanis species such as the one pictured here. In males of various Chiloglanis species, the lobes of the caudal fin are elongated or differently shaped as compared to females (Roberts, 1989; Seegers, 1996). In Atopochilus savorgnani the anal fin of males is larger than that of females (personal observation).

Euchilichthys (and Atopochilus) are largely restricted to the Congo Basin, but spill over into neighboring rivers of western Africa. Chiloglanis has a broader distribution, similar to that seen in Synodontis (i.e., covering most of sub-Saharan Africa). All of the Chiloglanine genera inhabit rivers of central Africa and some Chiloglanis have invaded the rift lakes of eastern Africa. Not surprisingly, Chiloglanines are largely benthic, keeping to the bottom most of the time. Larger Euchilichthys and Atopochilus may be relatively solitary, but some smaller species (especially certain Chiloglanis species) are known to occur in great numbers when present. As far as known, there are no fossils attributable to the Chiloglanine genera.

The ecology of Euchilichthys and the other Chiloglanines is not well studied; the only information with regards to the ecology of these species pertains to diet. As with other mochokids, it is expected that most Chiloglanines are omnivorous. However, the levels of plant versus animal material in the diet vary widely (personal observation, Vigliotta). The diet of many Chiloglanis species seems typical of Synodontis; the gut usually contains a fair amount of sand, plant matter and detritus interspersed with larval insects, worms and other small invertebrates. In the larger Chiloglanines the gut is quite often filled by dark, fine grit, presumably silt or sand mixed with algae; it is much less common to find larger invertebrates in the guts of these species. In this respect Euchilichthys and Atopochilus are very likely the most herbivorous/detritivorous of the mochokids. At least twelve species of Chiloglanis and one species of Atopochilus have been listed as threatened on the IUCN red list.

Euchilichthys royauxiThe relationship of Euchilichthys to other mochokids is still unclear, though it seems likely that Chiloglanines, as a whole, represent a monophyletic group. Furthermore, as stated above, it seems likely that Euchilichthys and Atopochilus form a monophyletic group. All or most Chiloglanines are characterized by the following features, which can be seen in the images above and in this labeled image (left): sucker-like mouth incorporating trifurcate barbels into lower lip; mesethmoid entirely without anterolateral cornua; posterolateral corner of neurocranium greatly modified; 5 infraorbitals; enlarged premaxillary tooth plates; shortened palatine; posterior end of palatine without cartilage; ball-shaped condyle where hyomandibula meets the underside of the neurocranium; posterohyal flared distally; relatively straight mesocoracoid arch; absence of pectoral locking foramen; absence/reduction of serrae on the posterior edge of the pectoral spine; reduced number of dorsal rays; plate-shaped first anal fin pterygiophores; strut-like parapophysis of the 6th centrum; absence/reduced number of mandibular canal pores; and partially or greatly reduced gas bladder.

About the Species

This specimen was collected from the Oubangui River shoreline at the uncompleted bridge at Mobaye, Basse-Kotto, Central African Republic by Bills, Friel and Reid on 27 February 2006. It was made available to the University of Texas High-Resolution X-ray CT Facility for scanning by Dr. John Friel and Mr. Thomas Vigliotta of the Cornell University Museum of Vertebrates. Funding for scanning was provided by the All Catfish Species Inventory project (NSF DEB-0315963), and funding for scanning and image processing was provided by a National Science Foundation Digital Libraries Initiative grant to Dr. Timothy Rowe of The University of Texas at Austin.

Euchilichthys royauxi

Lateral view of the scanned specimen.



About this Specimen

The specimen was scanned by Matthew Colbert on 21 September 2006 along the coronal axis for a total of 840 slices. Each 1024x1024 pixel slice is 0.09599 mm thick, with an interslice spacing of 0.09599 mm and a field of reconstruction of 45 mm.

About the
Scan

Links

Mochocidae page on MongaBay.com

Literature

Bishai, H. M. and Y. B. Abu Gideiri. 1965. Studies on the biology of the genus Synodontis at Khartoum. I. Age and growth. Hydrobiologia 26:85-97.

Chardon, M. 1968. Anatomie comparée de l'appareil de Weber et des structures connexes chez les Siluriformes. Annales de Musée Royale de l'Afrique Centrale (Ser.8), Sciences Zoologiques. 169:1-227.

Diogo, R. 2005. Morphological Evolution, Aptations, Homoplasies, Constraints and Evolutionary Trends : Catfishes as a Case Study on General Phylogeny and Macroevolution. Science Publishers, Enfield, NH, 491 pp.

Ferraris, C. J. Jr. 1988. The Auchenipteridae: Putative monophyly and systematics, with a classification of the neotropical Doradoid catfishes (Ostariophysi: Siluriformes). Unpublished PhD thesis, City University of New York, New York, NY.

Friel, J. P. and T. R. Vigliotta. 2006. Synodontis acanthoperca, a new species from the Ogôoué River system, Gabon with comments on spiny ornamentation and sexual dimorphism in mochokid catfishes (Siluriformes: Mochokidae). Zootaxa 1125:45-56.

Günther, A. 1864. Catalogue of the Fishes in the British Museum. Catalogue of the Physostomi, Containing the Families Siluridae, Characinidae, Haplochitonidae, Sternoptychidae, Scopelidae, Stomiatidae in the Collection of the British Museum. Vol. 5. British Museum (Natural History), London, 455 pp.

Hardman, M. 2005. The phylogenetic relationships among non-diplomystid catfishes as inferred from mitochondrial cytochrome b sequences; the search for the ictalurid sister taxon (Otophysi : Siluriformes). Molecular Phylogenetics and Evolution 37:700-720.

Higuchi, H. 1992. A phylogeny of the South American thorny catfishes (Osteichthyes; Siluriformes, Doradidae). Unpublished PhD thesis, Harvard University, Cambridge, MA.

Lundberg, J. G. 1993. African-South American freshwater fish clades and continental drift: problems with a paradigm. Pp. 156-199. In: Goldblatt, P. (ed.). Biological relationships between Africa and South America. Yale University Press, New Haven, CT.

Mo, T. -. 1991. Anatomy, Relationships and Systematics of the Bagridae (Teleostei:Siluroidei) with a Hypothesis of Siluroid Phylogeny. Koeltz Scientific Books, Koenigstein Germany ; Champaign, IL, 216 pp.

de Pinna, M. C. C. 1993. Higher-level phylogeny of Siluriformes (Teleostei, Ostariophysi), with a new classification of the order. Unpublished PhD thesis, City University of New York, New York, NY.

de Pinna, M. C. C. 1998. Phylogenetic relationships of neotropical Siluriformes (Teleostei: Ostariophysi): historical overview and synthesis of hypotheses. Pp. 279-330. In: L. R. Malabarba, R. E. Reis R. P. Vari, Z. M. Lucena, and C.A.S. Lucena (eds.), Phylogeny and classification of Neotropical fishes. EDIPUCRS, Porto Alegre.

Poll, M. 1971. Révision des Synodontis Africains (Famille Mochocidae). Annales de Musée Royale de l'Afrique Centrale (Ser.8), Sciences Zoologiques 191:1-497.

Riehl, R. and H. A. Baensch. 1990. Mergus Aquarien Atlas, Band 3. Mergus Verlag, Melle, Germany, 1104.

Roberts, T. R. 1989. Systematic revision and description of new species of suckermouth catfishes (Chiloglanis, Mochokidae) from Cameroun. Proceedings of the California Academy of Sciences 46:151-178.

Sanyanga, R. A. 1998. Food composition and selectivity of Synodontis zambezensis (Pisces : Mochokidae) in Lake Kariba, and the ecological implications. Hydrobiologia 361:89-99.

Sato, T. 1986. A brood parasitic catfish of moothbrooding cichlid fishes in Lake Tanganyika. Nature 323:58-59.

Seegers, L. 1996. The fishes of the Lake Rukwa drainage. Annales de Musée Royale de l'Afrique Centrale (Ser.8), Sciences Zoologiques 278:1-407.

Stewart, K. M. 2001. The freshwater fish of Neogene Africa (Miocene-Pleistocene): Systematics and biogeography. Fish and Fisheries (Oxford) 2:177-230.

Sullivan, J. P., Lundberg, J. G., and M. Hardman. A phylogenetic analysis of the major groups of catfishes (Teleostei: Siluriformes) using rag1 and rag2 nuclear gene sequences. Molecular Phylogenetics and Evolution (2006), article in press.

Winemiller, K. O., and L. C. Kelso-Winemiller. 1996. Comparative ecology of catfishes of the Upper Zambezi River floodplain. Journal of Fish Biology 49:1043-1061.

Wisenden, B. D. 1999. Alloparental care in fishes. Reviews in Fish Biology and Fisheries 9:45-70.

Literature
& Links

Front page image.

Euchilichthys royauxi
Additional
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To cite this page: Mr. Thomas Vigliotta, 2007, "Euchilichthys royauxi" (On-line), Digital Morphology. Accessed October 20, 2014 at http://digimorph.org/specimens/Euchilichthys_royauxi/whole/.

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