Synodontis irsacae

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Synodontis irsacae
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Siluriformes
Family: Mochokidae
Genus: Synodontis
Species:
S. irsacae
Binomial name
Synodontis irsacae
Matthes, 1959

Synodontis irsacae is a species of upside-down catfish endemic to Zambia, the Democratic Republic of the Congo, and Tanzania, where it is only known from Lake Tanganyika. [1] [2] It was first described by Belgian ichthyologist Hubert Matthes in 1959, from specimens collected from Lake Tanganyika at Kalundu, in what is now the Democratic Republic of the Congo. [1] The species name " irsacae" is derived from the abbreviation "I.R.S.A.C.", or Institut pour la Recherche Scientifique en Afrique Centrale. For many years, specimens of the species were considered to be juvenile members of S. dhonti , but in 2006, J.J. Wright and L.M. Page identified unique characteristics of this species that established that they were a unique species. [1]

Contents

Description

Like all members of the genus Synodontis, S. irsacae has a strong, bony head capsule that extends back as far as the first spine of the dorsal fin. [3] The head is about 3⁄10 of the standard length of the fish. [1] The head contains a distinct narrow, bony, external protrusion called a humeral process. [4] The shape and size of the humeral process help to identify the species. In S. irsacae, the humeral process is long, narrow, and rough, with a poorly defined ridge on the bottom edge. [1] The top edge is concave and the end is a rounded point. [1] It is almost 1⁄2 of the length of the head. [1] The diameter of the eye is about 1⁄7 of the length of the head. [1]

The fish has three pairs of barbels. The maxillary barbels are located on the upper jaw, and two pairs of mandibular barbels are on the lower jaw. The maxillary barbel has a distinct membrane attached near the base and is straight without any branches. [1] It extends as far or just past the base of the pectoral fin, about three-quarters of the length of the head. [1] The outer pair of mandibular barbels extends just short of the front of the pectoral girdle, about 1⁄2 of the length of the head, [1] and contains two to seven short branches, with secondary branches sometimes present. [1] The inner pair of mandibular barbels is about half as long as the outer pair, about 2⁄10 of the length of the head, [1] with four to five pairs of branches, with secondary branches present. [1]

The skin of S. irsacae has a large number of tiny vertical skin folds. The exact purpose of the skin folds is not known, but is a characteristic of the species of Syndontis that are endemic to Lake Tanganyika. [1] External papilla are present on the head, but not the body. [1]

The front edges of the dorsal fins and the pectoral fins of Syntontis species are hardened into stiff spines. [4] In S. irsacae, the spine of the dorsal fin is short, about 4⁄5 as long as the head, [1] slightly curved, rough on the front and serrated on the back, and ends with short, dark filament. [1] The remaining portion of the dorsal fin is made up of seven branching rays. [1] The spine of the pectoral fin is slightly curved, about as long as the dorsal fin spine, rough on the front and with large serrations on the back. [1] The pectoral spine ends in a short, dark filament. [1] The rest of the pectoral fins are made up of eight to nine branching rays. [1] The adipose fin does not contain any rays, is long and well developed, and has a convex shape. [1] The pelvic fin contains one unbranched and six branched rays. [1] The front edge of the pelvic fin is vertically aligned halfway between the back edge of the dorsal fin and the origin of the adipose fin. [1] The anal fin contains three to five unbranched and seven to nine branched rays; it is vertically aligned with the first third of the adipose fin. [1] The tail, or caudal fin, is forked, with rounded lobes, and contains eight rays on the upper lobe, nine rays on the lower lobe. [1]

The mouth of the fish faces downward and has wide lips that contain papilla. [1] All members of Syndontis have a structure called a premaxillary toothpad, which is located on the very front of the upper jaw of the mouth. This structure contains several rows of short, chisel-shaped teeth. In some species, this toothpad is made up of a large patch with several rows in a large cluster. In other species of Syndontis, this toothpad is clearly divided into two separate groups, separated by a thin band of skin that divides the toothpad. [1] This character is used as a method of differentiating between two different but similar species of Syndontis. [1] In S. irsacae, the toothpad is interrupted, or separated into two distinct groups. [1] On the lower jaw, or mandible, the teeth of Syndontis are attached to flexible, stalk-like structures and described as "s-shaped" or "hooked". [4] [3] The number of teeth on the mandible is used to differentiate between species; in S. irsacae, there are 15 to 29 teeth on the mandible, arranged in a single row. [1]

Some of the species of Synodontis have an opening or series of openings called the axillary pore. It is located on the sides of the body below the humeral process and before the pectoral fin spine. The exact function of the port is not known to scientists, although its presence has been observed in seven other catfish genera. Fish in the genus Acrochordonichthys are known to secrete a mucus with toxic properties from their axillary pore, but there is no scientific consensus as to the exact purpose of the secretion or the pore. [1] S. irsacae does not have an axillary pore. [1]

The back of the fish is gray-brown to copper-brown. [1] The underside is slightly lighter. [1] Juveniles have scattered, irregularly-shaped spots on the body that become smaller with age. [1] Most of the species of Synodontis of Lake Tanganyika have a recognizable pattern consisting of dark triangles at the bases of all of the rayed fins, present in S. irsacae when young, and the back edges of the fins are white in color. [1] The caudal fin is black with white on the very end. [1] The barbels are white. [1]

The maximum standard length of known specimens is 15.7 centimetres (6.2 in) with a total length of 19 centimetres (7.5 in). [1] [2] Generally, females in the genus Synodontis tend to be slightly larger than males of the same age. [5]

Habitat and behavior

In the wild, the species is endemic to Lake Tanganyika, which has an observed temperature range of 22 to 26 °C (72 to 79 °F), an approximate pH of 8.5 – 9, and a dH range of 4-15. [6] [2] The fish lives in the littoral zone and the benthic zones over shell, sand, and mud bottoms, to a maximum depth of 40 metres (130 ft). [1] The reproductive habits of most of the species of Synodontis are not known, beyond some instances of obtaining egg counts from gravid females. [1] Spawning likely occurs during the flooding season between July and October, and pairs swim in unison during spawning. [7] As a whole, species of Synodontis are omnivores, consuming insect larvae, algae, gastropods, bivalves, sponges, crustaceans, and the eggs of other fishes. [1] The growth rate is rapid in the first year, then slows down as the fish age. [5]

Related Research Articles

Synodontis dhonti is a species of upside-down catfish endemic to the Democratic Republic of the Congo where it is only known from Lake Tanganyika. It was first described by Belgian-British zoologist George Albert Boulenger in 1917, based upon a single specimen collected from Lake Tanganyika at Kilewa Bay, in what is now the Democratic Republic of the Congo. The species is named after M.G. Dhont-De Bie, who accompanied the collector, Dr. L. Stappers, on his expedition. At one point, identified specimens Synodontis irsacae was believed to be juvenile individuals of S. dhonti and the two were considered to be the same species, but further research has identified differences between the two species and they are once again recognized as distinct from each other.

<i>Synodontis granulosus</i> Species of fish

Synodontis granulosus is a species of upside-down catfish endemic to the Democratic Republic of the Congo, Burundi, Zambia, and Tanzania, where it is only known from Lake Tanganyika. It was first described by Belgian-British zoologist George Albert Boulenger in 1900, from specimens collected at multiple points along the shore of Lake Tanganyika. The species name comes from the Latin word "granulum", meaning of grain, and refers to the granular papillae present on the skin of the fish's body.

<i>Synodontis nigrita</i> Species of fish

Synodontis nigrita, known as the false upside down catfish, is a species of upside-down catfish that occurs widely in northern Africa. It was first described by French zoologist Achille Valenciennes in 1840. The type specimen is in the Muséum National d' Histoire Naturelle de Paris.

Synodontis polli, known as Poll's synodontis, is a species of upside-down catfish endemic to the Democratic Republic of the Congo, Burundi, Zambia, and Tanzania, where it is only known from Lake Tanganyika. It was first described by Belgian ichthyologist Jean-Pierre Gosse in 1982, from specimens collected at multiple points along the shore of Lake Tanganyika.

<i>Synodontis petricola</i> Species of fish

Synodontis petricola, known as the cuckoo catfish, or the pygmy leopard catfish, is a species of upside-down catfish endemic to Burundi, Zambia, the Democratic Republic of the Congo, and Tanzania where it is only known from Lake Tanganyika. It was first described by Belgian ichthyologist Hubert Matthes in 1959. The species name "petricola" is derived from a combination of the Latin petra, meaning stone or rock, and the Latin cola, meaning inhabitant. This refers to the rocky environment where this species is found.

<i>Synodontis budgetti</i> Species of fish

Synodontis budgetti, known as Budgett's synodontis, is a species of upside-down catfish native to Benin, Cameroon, Central African Republic, Côte d'Ivoire, Mali, Niger, and Nigeria where it occurs in Lake Nokoue and the Niger. It was first described by Belgian-British zoologist George Albert Boulenger in 1911, from specimens collected in Lokoja, Nigeria. The species name budgetti comes from name of the collector of the original specimen, J.S. Budgett.

<i>Synodontis caudalis</i> Species of fish

Synodontis caudalis, known as the filament tailed synodontis, or the whiptail synodontis, is a species of upside-down catfish native to the Democratic Republic of the Congo. It was first described by Belgian-British zoologist George Albert Boulenger in 1899, from specimens collected in what is now the Democratic Republic of the Congo. The species name caudalis comes from the Latin word cauda, meaning tail, and refers to the elongated filaments in the caudal fin of the species.

<i>Synodontis caudovittatus</i> Species of fish

Synodontis caudovittatus, known as the white-finned synodontis, is a species of upside-down catfish that is native to the Nile basin of Ethiopia, South Sudan, and Sudan. It was first described by British-Belgian zoologist George Albert Boulenger in 1901, from specimens collected in the White Nile, at the mouth of Lake No in South Sudan. The species name caudovittatus comes from the Latin word cauda, meaning "tail", and the Latin word vitta, meaning "stripe" and refers to the coloration of the tailfin.

<i>Synodontis filamentosus</i> Species of fish

Synodontis filamentosus, known as the longfin synodontis, is a species of upside-down catfish that is native to the basins of the Nile, Volta and Niger Rivers as well as the Chad Basin. It was first described by British-Belgian zoologist George Albert Boulenger in 1901, from specimens obtained near the mouth of Lake No, on the White Nile in Sudan. The species name filamentosus comes from the elongated rays of the dorsal and caudal fins.

<i>Synodontis frontosus</i> Species of fish

Synodontis frontosus, known as the Sudan squeaker, is a species of upside-down catfish that is widely distributed throughout northern and central Africa. It has been reported in Chad, Democratic Republic of the Congo, Ethiopia, Kenya, Somalia, Sudan, and Uganda. It was first described by French zoologist Léon Vaillant in 1895, from specimens collected in the White Nile in Sudan. The species name frontosus is Latin, and means "broad head".

<i>Synodontis grandiops</i> Species of fish

Synodontis grandiops is a species of upside-down catfish endemic to the Democratic Republic of the Congo, Burundi, and Tanzania, where it is only known from Lake Tanganyika. It was first described by Jeremy John Wright and Lawrence M. Page in 2006, from specimens collected at multiple points along the shore of Lake Tanganyika. The species name is a Latinized combination of the Latin "grandi", meaning large or big, and the Greek "ops", meaning eye, a reference to the relatively large eyes of this fish.

<i>Synodontis guttatus</i> Species of fish

Synodontis guttatus is a species of upside-down catfish that is native to the Niger River basin of Nigeria. It was first described by German ichthyologist Albert Günther in 1865, from the Niger River. The species name guttatus is the Latin word for "spotted", referring to the spots appearing on the fins and body of the fish.

Synodontis ilebrevis is a species of upside-down catfish endemic to Zambia, where it is only known from Lake Tanganyika. It was first described by Jeremy John Wright and Lawrence M. Page in 2006, from specimens collected from Lake Tanganyika at Cape Chaitika, Zambia. The species name comes from the Latin word "ile", meaning intestine, and the Latin word "bevis", meaning short, and refers to the relatively short gut of this species.

<i>Synodontis nigromaculatus</i> Species of fish

Synodontis nigromaculatus, known as the spotted squeaker, the blackspotted squeaker, or the speckled squeaker, is a species of upside-down catfish that is found widely in southern Africa. It has been identified in Angola, Botswana, the Democratic Republic of the Congo, Mozambique, Namibia, South Africa, Zambia, and Zimbabwe. It was first described by British-Belgian zoologist George Albert Boulenger in 1905, from specimens collected in Lake Bangweulu in Zambia.

<i>Synodontis omias</i> Species of fish

Synodontis omias is a species of upside-down catfish native to the Niger River basin of Guinea, Mali, Niger and Nigeria. It was first described by German-born British zoologist, ichthyologist, and herpetologist Albert Günther in 1864, from a specimen collected in Jebba, Nigeria, on the Niger River. There have been very few specimens of this species identified, and it may be the same species as S. budgetti from the Upper Niger.

Synodontis tanganyicae is a species of upside-down catfish endemic to the Democratic Republic of the Congo, Zambia, and Tanzania, where it is only known from Lake Tanganyika. It was first described by Russian-American ichthyologist Nikolai Andreyevich Borodin in 1936, from specimens collected at Kasaga, in what is now the Democratic Republic of the Congo. The species name tanganyicae comes from the habitat of the species, Lake Tanganyika.

<i>Synodontis woosnami</i> Species of fish

Synodontis woosnami, known as the Upper Zambezi squeaker, or bubblebarb squeaker, is a species of upside-down catfish that is native to Angola, Botswana, Namibia, Zambia and Zimbabwe where it is found in the upper Zambezi and Okavango River basins and the Cunene River. It was first described by British-Belgian zoologist George Albert Boulenger in 1911, from a specimen collected in the Okavango River in the Lake Ngami district of Botswana. The species name woosnami is derived from R. B. Woosnam, the collector of the first specimen.

<i>Synodontis xiphias</i> Species of fish

Synodontis xiphias is a species of upside-down catfish that is native to the Niger River basin of Nigeria. It was first described by German ichthyologist Albert Günther in 1864, from specimens obtained in the Niger River. The species name xiphias comes from the Greek word xiphos, meaning sword, which refers to the long snout that was observed on the stuffed type specimen.

Synodontis lucipinnis is a species of upside-down catfish endemic to Zambia, where it is only known from the Musende Rocks area (Mpulungu) of Lake Tanganyika. It was first described by Jeremy John Wright and Lawrence M. Page in 2006. The species name "lucipinnis" is derived from a combination of the Latin luci, meaning bright or clear, and the Latin pinnis, meaning fin. This refers to the light coloration in a patch on the base of the fins of this species.

<i>Synodontis melanostictus</i> Species of fish

Synodontis melanostictus is a species of upside-down catfish endemic to Lake Tanganyika and its tributaries. It has been found in Zambia, the Democratic Republic of the Congo, and Burundi. It was first described by British-Belgian zoologist George Albert Boulenger in 1906, based upon a specimen from the Lofubu River. The species name "melanostictus" is derived from a combination of the Greek melano, meaning black, and the Greek stiktos, meaning punctured or spotted. This refers to the black spotted pattern that occurs on the body of this species.

References

  1. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 Wright, J.J. and L.M. Page (2006). "Taxonomic Revision of Lake Tanganyikan Synodontis (Siluriformes: Mochokidae)". Florida Mus. Nat. Hist. Bull. 46 (4): 99–154. doi:10.58782/flmnh.bnkq3478.
  2. 1 2 3 Froese, Rainer; Pauly, Daniel (eds.) (2016). "Synodontis irsacae" in FishBase. June 2016 version.
  3. 1 2 Cuvier, Georges. (1934). The Animal Kingdom Arranged in Conformity with its Organization, Volume 10. Translated by Griffith, Edward. London: Whittaker and Co. p. 406.
  4. 1 2 3 "Synodontis irsacae Wright & Page, 2006". Planet Catfish. 31 Jan 2013. Retrieved 21 October 2016.
  5. 1 2 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.
  6. ↑ Smith, F. (2001). "A preliminary investigation of some chemical and physical profiles of Lake Tanganyika" (PDF). Retrieved 19 October 2016.
  7. ↑ John P. Friel & Thomas R. Vigliotta (March 2, 2009). "Mochokidae Jordan 1923: African squeaker and suckermouth catfishes". Tree of Life Web Project . Retrieved 19 October 2016.

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