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

摘要

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