HIGHER TAXON

Mesonatuta is a genus of the subfamily Cichlasomatinae, tribe Heroini, most closely related to Pterophyllym.

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AUTHOR

Sven O Kullander

HOSTED BY

Mesonauta Günther

Synonymy

Mesonauta Günther, 1862. Catal. Fish. Br. Mus. 4, p. 300 (type species by indication (monotypy) Heros insignis Heckel). - Masculine.

Mesonauta festivus (Heckel), fresh from Laguna Negra, Paraguay. Photo © S.O. Kullander
Mesonauta festivus (Heckel), fresh from Laguna Negra, Paraguay. Photo: S.O. Kullander.

Diagnosis

Cichlasomine cichlids with extremely long, thick first pelvic fin ray, shared only with Pterophyllum.

Included species

Mesonauta acora (Castelnau, 1855)
Chromys?? acora Castelnau, 1855. Anim. nouv. rares. Poissons, p. 17, pl. 9, fig. 1 (lacs de l'Araguay).
Mesonauta egregius Kullander & Silfvergrip, 1991
Mesonauta egregius Kullander & Silfvergrip, 1991. Revue suisse Zool. 98, p. 429, Fig. 21 (Colombia, Departamento Vichada, Rio Vichada drainage, laguna no. 1 on Finca Boca de Guarrojo at the mouth of the Rio Guarrojo).
Mesonauta festivus (Heckel, 1840)
Heros festivus Heckel, 1840. Annln wien. Mus. Natges. 2, p. 376 (Fluss Guapore und dessen nahe gelegenen Moräste).
Mesonauta guyanae (Schindler, 1998)
Mesonauta guyanae Schindler, 1840. Z. Fischk. 5, p. 5 (Rockstone, Essequibo River, Guyana).
Mesonauta insignis (Heckel, 1840)
Heros insignis Heckel, 1840. Annln wien. Mus. Natges. 2, p. 379 (Waldlache bei Marabitanas am Rio-negro).
Mesonauta mirificus Kullander & Silfvergrip, 1991
Mesonauta mirificus Kullander & Silfvergrip, 1991. Revue suisse Zool. 98, p. 430, Fig. 22 (Peru, Departamento Loreto, Rio Napo, Cayapoza, small laguna on left bank island).

Kullander & Silfvergrip (1991) consider that there are at least two more, undescribed species in the genus.

Key to species

1. Microbranchiospines on all four gill arches.....................2
Microbranchiospines on three posterior gill arches only.........3

2. Preoperculum scaled (2-4 scales); bar 5 divided..........M. acora
Preoperculum naked, or a single scale; bar 5 integer..M. festivus

3. Bar 6 split, upper part joining bar 7, lower part joining bar 5.. ....M. insignis
Bars 6 and 7 parallel, bar 6 split vertically...................4

4. Anal fin spines 6-7...................................M. egregius
Anal fin spines 8-9..................................M. mirificus

Etymology

The name Mesonauta was not explained by Günther (1862). It is probably composed of the Greek words mesos, middle or average, and nautes, sailor, alternatively the second word is the Latin nauta, sailor. The gender is masculine. The meaning of the composite is not obvious, but likely the name in some respect refers to the position of the dorsal fin origin posterior to the pelvic fin origin which was Günther's principal diagnostic character.

Geographical distribution

Mesonauta species have been collected in the Orinoco, the middle and Upper Paraguay basin, most of the Brazilian and Peruvian Amazon basin (below lowermost falls except in the Xingu, the Jamari and perhaps the Araguaia), the Bolivian Amazon, Guyana and Amapá.

Geographical distribution of Mesonauta species (from Kullander & Silfvergrip, 1991)
MAP: Geographical distribution of Mesonauta species (from Kullander & Silfvergrip, 1991).

References

KULLANDER, S.O. & A.M.C. SILFVERGRIP. 1991.Review of the South American cichlid genus Mesonauta Günther with descriptions of two new species. Revue suisse Zool. 98: 407-448.

Note added October 1998

Mesonauta guyanae was described by Schindler (1998) from Guyana; comments on this taxon will be added at earliest convenience.