Cranial morphology and osteology of the sexually dimorphic electric fish, Compsaraia samueli Albert Crampton (Apteronotidae, Gymnotiformes), with comparisons to C. compsa (Mago-Leccia)
| Autor: | Rachel Keeffe, Mário José Fonseca Thomé de Souza, Eric J. Hilton, Cristina Cox Fernandes |
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| Rok vydání: | 2019 |
| Předmět: |
0106 biological sciences
Male 010607 zoology Zoology 010603 evolutionary biology 01 natural sciences Osteology Seasonal breeder medicine Animals Ecology Evolution Behavior and Systematics Morphometrics Sex Characteristics biology Skull Gymnotiformes Occiput biology.organism_classification Sexual dimorphism medicine.anatomical_structure Animal Science and Zoology Female Allometry Snout Electric Fish |
| Zdroj: | Zootaxa. 4555(1) |
| ISSN: | 1175-5334 |
| Popis: | Sexual dimorphism of the snout has evolved independently in at least four separate clades of the gymnotiform family Apteronotidae. This phenomenon may help identify sex, except in the absence of mature individuals, and has led to confused taxonomy for several species. We examined a large collection of Compsaraia samueli collected during the breeding season from a remote stream in the Rio Negro drainage. This collection contains a wide range of sizes of both sexes, but most individuals were easily identified as mature. To quantify the sexual dimorphism of these specimens, 15 measurements were taken from the head and the body. In addition, some specimens were cleared-and-stained to study cranial osteology. We found that long-snouted males of C. samueli span a wide range of body sizes. As the snout length increases the distance between the eye and the occiput does not increase at the same rate, suggesting that it is only the anterior portion of the head that has an increased allometry. Skeletal anatomy differs between the sexes in that the lower jaw is more triangular in females and more linear in males. The coronomeckelian is small and round in females in contrast to being longer and pointed in males. There is strong interlacing of the dentary and anguloarticular bones in males, whereas this contact is not as extensive in females. We also discuss the implications of sexual dimorphism for identification of this species relative to its congener (C. compsa), and for the evolution of sexual dimorphism in the family. |
| Databáze: | OpenAIRE |
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