Morphology of the teleost pharyngeal jaw apparatus in the Neotropical annual killifish genus Cynolebias (Cyprinodontiformes: Aplocheiloidei: Rivulidae)

Costa W.J.E.M.

Date de parution: juin 2009
Volume: 33
Number: 2
Pagination: 145-150
Editeur: Société Française d’Ichtyologie
doi: https://doi.org/10.26028/cybium/2009-332-004
Résumé

The osteological and myological structure of the pharyngeal jaw apparatus (PJA) of a species assemblage of the Brazilian annual killifish genus Cynolebias, known as the Cynolebias-clade α, is first described. The Cynolebias-clade α comprises all species of the genus except C. griseus, and includes species in which males produce sounds during courtship behaviour. The PJA of the Cynolebias-clade α is characterized by a series of morphological traits unique among aplocheiloid cyprinodontiforms: 1) anterior portion of the fifth ceratobranchial narrow and long, 2) robust teeth on the second pharyngobranchial and fifth ceratobranchial, 3) a pronounced process on the ventral surface of the fifth ceratobranchial, 4) fifth ceratobranchials medially in contact, 5) infrabranchial ossification, 6) fourth epibranchial L-shaped and with a process for insertion of the levator posterior muscle, and 7) third and fourth levator externi and protractor pectoralis widened to make levator posterior not visible laterally. All these features are present in all species of the Cynolebias-clade α and absent in all other cynolebiatines, thus should be considered as morphological innovations simultaneously arising at the base of that clade. Some of these derived traits are morphologically convergent to similar traits found in other teleost fishes able to produce sounds through the PJA.

Mots-clés: Cynolebias - Killifishes - Myology - Osteology - Pharyngeal jaws - Rivulidae - Teeth
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