The genus Synodontis Cuvier, 1816 ZBK is the most species rich and widespread genus of mochokid catfishes. As currently recognized the genus contains approximately 120 valid species distributed throughout most of the freshwaters of sub-Saharan Africa and the Nile River system. Larger Synodontis ZBK species are important food fishes in many parts of Africa and are commonly known as “squeakers” because they readily produce sounds by stridulating their pectoral spines when handled or disturbed. Furthermore many Synodontis ZBK species are prized ornamental fishes because they have striking pigmentation patterns or display unusual behaviors like an upside down swimming posture.
Poll (1971) last revised the entire genus and noted seven species reported from Gabon based on specimens he examined or previous published accounts and faunal lists: S. angelicus Schilthuis 1891 ZBK , S. albolineatus Pellegrin 1924 ZBK , S. guttatus Guenther 1865 ZBK , S. haugi Pellegrin 1906 ZBK , S. obesus Boulenger 1898 ZBK , S. polyodon Vaillant 1895 ZBK and S. tessmanni Pappenheim 1911 ZBK . Four of these species have well documented type localities within Gabon ( S. albolineatus ZBK , S. haugi ZBK , S. polyodon ZBK and S. tessmanni ZBK ) and appear to be endemics of the Ogôoué or Ntem Rivers and their tributaries.
In contrast, the presences of S. angelicus ZBK , S. guttatus ZBK , and S. obesus ZBK in Gabon are uncertain or possibly erroneous. First, the claim for S. angelicus ZBK is based on the junior synonym S. tholloni Boulenger 1901 ZBK known from a single specimen (MNHN 1890-0030) collected at an unspecified locality possibly within the Ogôoué basin of Gabon. Otherwise, S. angelicus ZBK is known exclusively from the Congo basin. Second, Poll (1971) did not find any specimens of S. guttatus ZBK from Gabon, questioned published records from Gabon by Sauvage (1880, 1884) and concluded that the species is only found in the lower Niger basin. Finally, Boulenger (1898) described S. obesus ZBK based on three syntypes, one from the Opobo River, Nigeria (BMNH 18126.96.36.199) and two from an unspecified locality in Gabon (BMNH 18188.8.131.52-6). Poll (1971) subsequently designated the Nigerian syntype as the lectotype for S. obesus ZBK . Given this type fixation and the uncertain locality data for the paralectotypes, the presence of S. obesus ZBK in Gabon remains ambiguous.
Since Poll’s revision, the first author and others have made many more collections of Gabonese fishes. Review of this material for an upcoming edited book on the freshwater fishes of West Central Africa (Lower Guinea) has revealed the presence of at least eight Synodontis ZBK species in Gabon. These include the previously known endemics ( S. albolineatus ZBK , S. haugi ZBK , S. polyodon ZBK , and S. tessmanni ZBK ), plus four additional species. One of these, S. batesii Boulenger 1907 ZBK , originally described from the Congo basin of Cameroon, is now known from both the Ogôoué and Ntem basins of Gabon. The other newly recorded species are currently under study by several researchers. One of these new species that has unique bony ornamentation and sexual dimorphism is described here.
- John P. Friel, Thomas R. Vigliotta (2006): Synodontis acanthoperca, a new species from the Ogooue River system, Gabon with comments on spiny ornamentation and sexual dimorphism in mochokid catfishes (Siluriformes: Mochokidae). Zootaxa 1125, 45-56: 45-46, URL:http://www.zoobank.org/urn:lsid:zoobank.org:pub:5EFC4D07-EB68-42A8-BE7D-3E99DA13AF1B
Molecular Biology and Genetics
Statistics of barcoding coverage
Specimen Records: 401
Specimens with Sequences: 381
Specimens with Barcodes: 374
Species With Barcodes: 29
Public Records: 163
Public Species: 20
Public BINs: 51
Synodontis is the largest genus of upside-down catfishes. It is the biggest genus within the 10 genera and 190 different species in the Mochokidae family. Synodontis has over 131 different species within the genera. Synodontis are also known as squeakers, due to their ability to make stridulatory sounds through their pectoral fin spines when handled or disturbed. Synodontis make a sound that sounds like squeaking by rubbing their spines together. They do this when they have been frightened or when they become angry. "Synodontis" may also squeak when they are taken out of the water. These catfish are small- to medium-sized fish with many species exhibiting attractive spotted markings. Some species are also known for naturally swimming belly-up, earning the name upside-down catfish. Some of these species are Synodontis contractus and Synodontis nigriventris. While some of these species are known to swim upside down, another species, Synodontis multipunctatus, is a brood parasitic cuckoo catfish.
Synodontis is a freshwater catfish that is most commonly found throughout Africa, occurring mostly in Central and West Africa. Synodontis is the most widely distributed mochokidae genus, occurring throughout most of the freshwaters of sub-Saharan Africa and the Nile River system. They can live in freshwaters which can be creeks, ponds, streams, lakes, and rivers. Their distribution is similar to that of cichlid fishes, however, unlike cichlids the majority of their diversity occurs in rivers not lakes.
Synodontis catfish form a small endemic radiation in Lake Tanganyika, which includes the non-endemic species S. victoriae. This radiation is thought to have evolved relatively recently (~5.5. Million years ago), having diversified within full lacustrine conditions. This is also the case for other endemic Lake Tanganyika lineages such as mastacembelid eels and platythelphusid crabs for example. Lake Tanganyikan Synodontis have also been shown to be Müllerian mimics, and that at least one species (Synodontis multipunctatus) is a brood parasite.
The earliest fossils of Synodontis in East African are from the Early Miocene. Many Synodontis fossils are the spines because they are very sturdy and so they are preserved better. The fossils of spines that are found are used to determine the family or genera of the fish but it cannot determine the species. Synodontis species that have survived and are still living can be identified by the shape of their whisker like organs on their heads called barbels, which relate to touch. The can also be identified by the color of their skin, the skull bones, and the number and length of the teeth.
Synodontis species are omnivorous generalists, feeding on a wide spectrum of different foods and are largely unspecialized. Insects, crustaceans, mollusks, annelids, seeds, and algae have been found in the stomachs of different species of Synodontis. They are bottom-feeders and may be detritivores, some species may also be able to adapt to filter feeding. This allows them to cope with seasonal and habitat changes and gives them a better ability to colonize different habitats. The different Synodontis species have somewhat different growth rates but most of them are fairly similar. In regards to the Synodontis genus for the different sexes, females are generally larger than the males. There is a great increase in growth the first year in both male and female and then the growth slows down as they become older. The form and structure of these fish are very different compared to other fish. The size and shape of the mouth are distinct because of its ventral mouth and these fish usually are triangular or cylindrical when looking at it from the side. Not much is known about the reproduction in these fish. It has been determined that July to October is when they spawn and that they swim in pairs during this spawning time. Species of Synodontis have been noted to reproduce with the flooding period of the rainy season.
Relationship to humans
Many Synodontis species are prized ornamental fish in the fishkeeping hobby. While some of the Synodontis species are prized because of their color or behavior, other species are wanted for food. Some of the bigger species in the genus are important food sources for the people in Africa.
There are currently 131 recognized species in this genus: Synodontis accounts for about one-quarter of African catfish species. This genus has more members than any other African teleost genus other than Barbus and Haplochromis.
Newer species are listed with references.
- Synodontis acanthomias Boulenger, 1899
- Synodontis acanthoperca Friel & Vigliotta, 2006
- Synodontis afrofischeri Hilgendorf, 1888 (Fischer's Victoria squeaker)
- Synodontis alberti Schilthuis, 1891 (Bigeye squeaker)
- Synodontis albolineatus Pellegrin, 1924
- Synodontis angelicus Schilthuis, 1891 (Angel squeaker)
- Synodontis annectens Boulenger, 1911
- Synodontis ansorgii Boulenger, 1911
- Synodontis arnoulti Román, 1966
- Synodontis aterrimus Poll & Roberts, 1968
- Synodontis bastiani Daget, 1948
- Synodontis batensoda Rüppell, 1832 (Upsidedown catfish)
- Synodontis batesii Boulenger, 1907
- Synodontis brichardi Poll, 1959
- Synodontis budgetti Boulenger, 1911
- Synodontis camelopardalis Poll, 1971
- Synodontis carineae Vreven & Ibala Zamba, 2011
- Synodontis caudalis Boulenger, 1899
- Synodontis caudovittatus Boulenger, 1901
- Synodontis centralis Poll, 1971
- Synodontis clarias (Linnaeus, 1758) (Mandi)
- Synodontis comoensis Daget & Lévêque, 1981
- Synodontis congicus Poll, 1971
- Synodontis contractus Vinciguerra, 1928 (Bugeye squeaker)
- Synodontis courteti Pellegrin, 1906
- Synodontis cuangoanus Poll, 1971
- Synodontis decorus Boulenger, 1899 (Clown squeaker)
- Synodontis dekimpei Paugy, 1987
- Synodontis depauwi Boulenger, 1899
- Synodontis dhonti Boulenger, 1917
- Synodontis dorsomaculatus Poll, 1971
- Synodontis eupterus Boulenger, 1901 (Featherfin squeaker)
- Synodontis filamentosus Boulenger, 1901
- Synodontis flavitaeniatus Boulenger, 1919 (Orangestriped squeaker)
- Synodontis frontosus Vaillant, 1895
- Synodontis fuelleborni Hilgendorf & Pappenheim, 1903 (Fuelleborn's squeaker)
- Synodontis geledensis Günther, 1896 (Geledi squeaker)
- Synodontis gobroni Daget, 1954
- Synodontis grandiops Wright & Page, 2006
- Synodontis granulosus Boulenger, 1900
- Synodontis greshoffi Schilthuis, 1891
- Synodontis guttatus Günther, 1865
- Synodontis haugi Pellegrin, 1906
- Synodontis ilebrevis Wright & Page, 2006
- Synodontis irsacae Matthes, 1959
- Synodontis iturii Steindachner, 1911
- Synodontis katangae Poll, 1971
- Synodontis khartoumensis Abu Gideiri, 1967
- Synodontis koensis Pellegrin, 1933
- Synodontis kogonensis Musschoot & Lalèyè, 2008
- Synodontis laessoei Norman, 1923
- Synodontis leopardinus Pellegrin, 1914 (Leopard squeaker)
- Synodontis leopardus Pfeffer, 1896
- Synodontis levequei Paugy, 1987
- Synodontis longirostris Boulenger, 1902
- Synodontis longispinis Pellegrin, 1930
- Synodontis lucipinnis Wright & Page, 2006
- Synodontis lufirae Poll, 1971
- Synodontis macrophthalmus Poll, 1971
- Synodontis macrops Greenwood, 1963
- Synodontis macropunctatus Wright & Page, 2008
- Synodontis macrostigma Boulenger, 1911 (Largespot squeaker)
- Synodontis macrostoma Skelton & White, 1990 (Largemouth squeaker)
- Synodontis manni De Vos, 2001 (Feather-barbelled squeaker)
- Synodontis marmoratus Lönnberg, 1895
- Synodontis matthesi Poll, 1971
- Synodontis melanopterus Boulenger, 1903
- Synodontis melanostictus Boulenger, 1906
- Synodontis membranacea (Geoffroy Saint-Hilaire, 1809)
- Synodontis multimaculatus Boulenger, 1902
- Synodontis multipunctatus Boulenger, 1898 (Cuckoo catfish)
- Synodontis nebulosus Peters, 1852 (Cloudy squeaker)
- Synodontis ngouniensis De Weirdt, Vreven & Fermon, 2008
- Synodontis nigrita Valenciennes, 1840
- Synodontis nigriventris David, 1936 (Blotched upsidedown catfish)
- Synodontis nigromaculatus Boulenger, 1905 (Blackspotted squeaker)
- Synodontis njassae Keilhack, 1908 (Malawi squeaker)
- Synodontis notatus Vaillant, 1893 (Onespot squeaker)
- Synodontis nummifer Boulenger, 1899
- Synodontis obesus Boulenger, 1898
- Synodontis ocellifer Boulenger, 1900
- Synodontis omias Günther, 1864
- Synodontis orientalis Seegers, 2008
- Synodontis ornatipinnis Boulenger, 1899
- Synodontis ornatissimus Gosse, 1982
- Synodontis ouemeensis Musschoot & Lalèyè, 2008
- Synodontis pardalis Boulenger, 1908
- Synodontis petricola Matthes, 1959 (Cuckoo Catfish)
- Synodontis pleurops Boulenger, 1897 (Congo squeaker)
- Synodontis polli Gosse, 1982
- Synodontis polyodon Vaillant, 1895
- Synodontis polystigma Boulenger, 1915
- Synodontis pulcher Poll, 1971
- Synodontis punctifer Daget, 1965
- Synodontis punctulatus Günther, 1889
- Synodontis punu Vreven & Milondo, 2009
- Synodontis rebeli Holly, 1926
- Synodontis resupinatus Boulenger, 1904
- Synodontis ricardoae Seegers, 1996 (Ricardo's squeaker)
- Synodontis robbianus Smith, 1875
- Synodontis robertsi Poll, 1974
- Synodontis ruandae Matthes, 1959
- Synodontis rufigiensis Bailey, 1968
- Synodontis rukwaensis Hilgendorf & Pappenheim, 1903 (Lake Rukwa squeaker)
- Synodontis schall (Bloch & Schneider, 1801) (Wahrindi)
- Synodontis schoutedeni David, 1936
- Synodontis serpentis Whitehead, 1962 (Tana squeaker)
- Synodontis serratus Rüppell, 1829
- Synodontis smiti Boulenger, 1902
- Synodontis soloni Boulenger, 1899
- Synodontis sorex Günther, 1864
- Synodontis steindachneri Boulenger, 1913
- Synodontis tanganyicae Borodin, 1936
- Synodontis tessmanni Pappenheim, 1911
- Synodontis thamalakanensis Fowler, 1935
- Synodontis thysi Poll, 1971
- Synodontis tourei Daget, 1962
- Synodontis unicolor Boulenger, 1915
- Synodontis vaillanti Boulenger, 1897
- Synodontis vanderwaali Skelton & White, 1990
- Synodontis velifer Norman, 1935
- Synodontis vermiculatus Daget, 1954
- Synodontis victoriae Boulenger, 1906 (Lake Victoria squeaker)
- Synodontis violaceus Pellegrin, 1919
- Synodontis voltae Román, 1975
- Synodontis waterloti Daget, 1962
- Synodontis woleuensis Friel & Sullivan, 2008
- Synodontis woosnami Boulenger, 1911 (Upper Zambezi squeaker)
- Synodontis xiphias Günther, 1864
- Synodontis zambezensis Peters, 1852 (Plain squeaker)
- Synodontis zanzibaricus Peters, 1868 (Eastcoast squeaker)
- Stephan Koblmüller, Christian Sturmbauer, Erik Verheyen, Axel Meyer & Walter Salzburger (2006). "Mitochondrial phylogeny and phylogeography of East African squeaker catfishes (Siluriformes: Synodontis)". BMC Evolutionary Biology 6: 49. doi:10.1186/1471-2148-6-49. PMC 1543664. PMID 16784525.
- John P. Friel & Thomas R. Vigliotta (March 2, 2009). "Mochokidae Jordan 1923: African squeaker and suckermouth catfishes". Tree of Life Web Project. Retrieved December 4, 2012.
- Friel, John P.; Vigliotta, Thomas R. (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)" (PDF). Zootaxa 1125: 45–56.
- Lalèyè, Philippe; Chikou, Antoine; Gnohossou, Pierre; Vandewalle, Pierre, Philippart, Jean Claude; Teugels, Guy (2006). "Studies on the biology of two species of catfish Synodontis schall and Synodontis nigrita (Ostariophysi : Mochokidae) from the Ouémé River, Bénin" (PDF). Belgian Journal of Zoology 136 (2): 193–201.
- Julia J. Day & Mark Wilkinson (2006). "On the origin of the Synodontis catfish species flock from Lake Tanganyika" (PDF). Biology Letters 2 (4): 548–552. doi:10.1098/rsbl.2006.0532. PMC 1833983. PMID 17148285.
- J. J. Day, R. Bills & J. P. Friel (2009). "Lacustrine radiations in African Synodontis catfish". Journal of Evolutionary Biology 22 (4): 805–817. doi:10.1111/j.1420-9101.2009.01691.x.
- Brown KJ, Rüber L, Bills R, Day JJ (2010). "Mastacembelid eels support Lake Tanganyika as an evolutionary hotspot of diversification". BMC Evolutionary Biology 10: 188. doi:10.1186/1471-2148-10-188. PMC 2903574. PMID 20565906.
- Marijnissen SA, Michel E, Daniels SR, Erpenbeck D, Menken SB, Schram FR (August 2006). "Molecular evidence for recent divergence of Lake Tanganyika endemic crabs (Decapoda: Platythelphusidae)". Molecular Phylogenetics and Evolution 40 (2): 628–34. doi:10.1016/j.ympev.2006.03.025. PMID 16647274.
- Wright JJ (February 2011). "Conservative coevolution of Müllerian mimicry in a group of rift lake catfish". Evolution; International Journal of Organic Evolution 65 (2): 395–407. doi:10.1111/j.1558-5646.2010.01149.x. PMID 20964683.
- Sato T (1986). "A brood parasitic catfish of mouthbrooding cichlid fishes in Lake Tanganyika". Nature 323 (6083): 58–9. doi:10.1038/323058a0. PMID 3748180.
- Pinton A, Fara E, Otero O (January 2006). "Spine anatomy reveals the diversity of catfish through time: a case study of Synodontis (Siluriformes)". Die Naturwissenschaften 93 (1): 22–6. doi:10.1007/s00114-005-0051-4. PMID 16261332.
- H. M. Bishai & Y. B. Abu Gideiri (1965). "Studies on the biology of genus Synodontis at Khartoum". Hydrobiologia 26 (1–2): 85–97. doi:10.1007/BF00142257.
- Froese, Rainer, and Daniel Pauly, eds. (2014). Species of Synodontis in FishBase. June 2014 version.
- Jeremy J. Wright & Lawrence M. Page (2006). "Taxonomic revision of Lake Tanganyikan Synodontis (Siluriformes: Mochokidae)" (PDF). Bulletin of the Florida Museum of Natural History 46 (4): 99–154.
- Jeremy J. Wright & Lawrence M. Page (2008). "A new species of Synodontis (Siluriformes: Mochokidae) from tributaries of the Kasai River in northern Angola". Copeia 2008 (2): 294–300. doi:10.1643/CI-07-040.
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