Tometes trilobatus

No Photo

Valenciennes 1850

 

Systematics and phylogenetic analyses of these fish and their comparison with old specimens kept in collections resulted in the identification and description of Tometes lebaili and T. makue. Differentiation between each other and the type-species of the genus (T. trilobatus) is manifest notably by the position of the mouth and the number of teeth.

 

These species are attached strictly to environments where podostemaceans grow : the adults feed exclusively on leaves whereas the young shelter deeper among the plant masses, eating invertebrates which develop there. These fish, which can weigh over 5 kg and measure over 50 cm long, count among the 15 or so most imposing species les plus described in South America for 50 years.

 

Michel Jégu, Geraldo Mendes Dos Santos, Philippe Keith, and Pierre-Yves Le Bail

Summary. - Tometes trilobatus is a species different of Myleus setiger. Tometes is a kind close to Mylesinus, Ossubtus and sub-genus Myleus (Myleus) with which it shares several single characters at Serrasalminae. The bones of the jaws are laminar and the series of teeth of the prémaxillaire are narrowly coupled the ones with the others. The mésethmoïde is broad, not very thick and the side wings are very reduced. The olfactive window is broad. In front of the pelvic fins, the serrae, very few and reduced to spines, do not draw an abdominal hull. Mylesinus, Ossubtus and Tometes have geared teeth incisiformes bi- and tricuspides. Tometes differs from these two kinds by the teeth of the jaws which are thicker and shorter. The two last teeth of the prémaxillaire of Tometes are different from the first, short and with sigmoid crown. At Mylesinus and Ossubtus, all the teeth of the labial series of the prémaxillaire are high, plane with a rectilinear crown.

Abstract. - Supplementary description and rehabilitation of Tometes trilobatus Valenciennes, 1850, type-species of Tometes Valencian (Characidae: Serrasalminae).

Tometes trilobatus, type-species of Tometes, was placed in synonymy with Myleus setiger since its description in 1850. Tometes was thus considered by authors have synonym of Myleus. Recently, we could show that Myleus setiger, type-species of Myleus, was different from Tometes trilobatus. The examination of the specimens collected in French Guiana and in the State of Amapa in Brazil, associated with has standard studies of the of Tometes enables custom to show that different Tometes is from Myleus and shares several characters with Mylesinus and Ossubtus. After has shorts historical background of various works referring to Tometes trilobatus, we give A detailed re-description of the morpho-anatomical and meristical characteristics of the species, and we rehabilitate the Tometes genus.


Different Tometes trilobatus is from Myleus setiger and T. unilobatus is synonym of T. trilobatus. Tometes has genus closed to Mylesinus, Ossubtus and Myleus (Myleus) sub-genus with which it shares several single characters in the Serrasalminae. The bones of the jaws are laminar and the series of teeth of the premaxillary are placed side by side. The mesethmoïde is broad, not very thick and the supraethmoïdal wings are very reduced. Olfactive The foramen is broad. The prepelvic serrae are few and reduced to spines, and C not Draw abdominal year keel. Mylesinus, Ossubtus and Tometes cuts geared bi- and tricuspid incisiform teeth. Tometes differs from this two genus by thicker and lower teeth. Labial The posteriormost premaxillary teeth of Tometes different are of the anterior ones, shorts and with has sigmoid crown. Labial All the premaxillary teeth of Mylesinus and Ossubtus are planes with has right crown.


Tometes trilobatus seems to be associated with the Podostemaceae, the rupestral seedlings characteristic of the rapids of the studied area. Internal By taking the of some specimens for the parasitic studies of the, we observed Podostemaceae in abundance in the stomachs. Tometes, Mylesinus and Ossubtus present has diet closely related to Podostemaceae, associated with has parasitic hyperinfestation, while Myleus (Myleus), Myleus (Myloplus), Myleus (Paramyloplus) and Myleus (Prosomyleus) present A diet less specialized and composed of exogenic sheets, fruits gold seeds and invertebrates.


The typology of the localities of collection of T. trilobatus confirms that it has rheophilic species. In the three basins considered (Oyapock, Flexal and Araguari), the captures always took place in the high races and more particularly in the zones of rapids.

 

Tometes lebaili

Michel Jégu, P. Keith, E. Belmont-Jégu (2002)

 

Tometes makue

NO PHOTO

Jégu, Santos & Belmont-Jégu 2002

 

Summary. - Tometes makue is a new species of Tometes of the Guianese shield. This species differs from T. trilobatus and T. lebaili by a smaller number of serrae prépelviennes and a greater number of teeth to the dental one. At T. makue and T. trilobatus, the mouth is horizontal, whereas it is oblique and round upwards at T. lebaili. T. makue is also an endemic species rhéophile basins of Orénoque, in Venezuela, and of Rio Negro, in Brazil.

Abstract. - Tometes makue (Characidae: Serrasalminae), has new species from Guiana shield, described from the Rio Negro Basin (Brazil) and Orinoco Basin (Venezuela).

Tometes makue has new species of Tometes Valenciennes, 1850 from Guiana shield. Previously identified have has Mylesinus species by Kner (1860), Sepulveda (1984) and Jégu and Al (1989), T. makue present the hand characteristics of T. trilobatus Valenciennes, 1850, standard species of Tometes, and T. lebaili Jégu and Al, 2002. T. makue differs from Mylesinus by stronger and shorter tri and bicuspid teeth, two last sigmoid premaxillary teeth, has shorter side premaxillary lingual process and the two median teeth bracked together. T. makue differs from T. trilobatus and T. lebaili by has smaller number of prepelvic serrae, which are often absent in the larger specimens (0-9 in adults vs. 11-24 in T. trilobatus and 19-26 in T. lebaili). T. makue differs from T. trilobatus by has greater number of dentary teeth one the labial series (6-11 vs. 5-6 in T. trilobatus). T. makue and T. trilobatus present horizontal year and final mouth, whereas it is oblique and upturned in T. lebaili. Youthful of T. makue present 6 to 10 vertical black stripes one the sides and has humeral black spot between 40 and 85 mm SL. Larger specimens are uniformly grey. Content observations one stomach indicate that T. makue feed mainly one Podostemaceae. T. makue, which edge reach 379 mm SL, is year endemic rheophilic species from Orinoco basin, in Venezuela, and Rio Negro basin, in Brazil. T. makue, T. trilobatus, T. lebaili and Mylesinus paraschomburgkii form has group of broad phytophagous serrasalmins endemic of the Podostemaceae meadows of Guiana shield, from Caroni to rivet in Venezuela to Maroni to rivet in French Guiana.

 

The herbivorous serrasalminids, dependent on the Podostemaceae beds growing in the Guianan plateau rapids, have the special feature of belonging at once to the natural and to the cultural heritage of the Amerindians. The discovery of T. lebaili and T. makue shows that the distribution area of the large herbivorous serrasalminids is not limited to the wide deep rivers of the Amazonian plain but extend to the rapids of the Guianan plateau. Investigations are continuing in order to improve knowledge about these fish and their habitat.

 

REFERENCES

  • JÉGU M., G.M. dos SANTOS, P. KEITH & P.-Y. LE BAIL, 2002. Description complémentaire et réhabilitation de Tometes trilobatus Valenciennes, 1850, espèce-type de Tometes Valenciennes (Teleostei: Characidae: Serrasalminae). Cybium, 26(2): 99-122.

  • JÉGU M., G.M. dos SANTOS & E. BELMONT-JÉGU, soumis décembre 2001. Tometes mahkue (Teleostei: Characidae: Serrasalmiane), une nouvelle espèce de bouclier guyanais décrite des bassins du rio Negro (Brésil) et de l'Orénoque (Vénézuéla ). Cybium, 26(3).

  • JEGU M., KEITH P., BELMONT-JEGU E., 2002.- Une nouvelle espèce de Tometes (Teleostei : Characidae : Serrasalminae) du bouclier guyanais, Tometes lebaili n. sp. Bull. Fr. Pêche Piscic., 364: 23-48.

  • H. Pagezy, M. Jégu - Valeur patrimoniale de Serrasalminae herbivores du Haut Maroni (Guyane française) : approches biologique et socioculturelle en pays Wayana, Bull. Fr. Pêche Piscic., 364 : 49 - 69, 2002.

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UPDATED: 07/10/2009