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Sexual dimorphism in the electric knifefish, Gymnorhamphichthys rondoni (Rhamphichthyidae: Gymnotiformes)
- Source :
- Acta Amazonica v.49 n.3 2019, Acta Amazonica, Instituto Nacional de Pesquisas da Amazônia (INPA), instacron:INPA, Acta Amazonica, Vol 49, Iss 3, Pp 213-220 (2019), Repositório Institucional do INPA
- Publication Year :
- 2019
- Publisher :
- FapUNIFESP (SciELO), 2019.
-
Abstract
- Sexual dimorfism refers to morphological differences between males and females of a species. It may be a result of different selection pressures acting on either or both sexes and may occur in any sexually-reproducing dioecious species, including fishes. We analyzed 63 females and 63 adult males of Gymnorhamphichthys rondoni (Gymnotiformes) collected by us or deposited in museum collections. Sex was identified through abdominal dissection. We measured length from snout to posterior end of anal-fin, anal-fin length, distance from anus to anal-fin origin, distance from genital papilla to anal-fin origin, body width at beginning of anal-fin, and head length. Morphometric data submitted to a Principal Component Analysis (PCA) grouped males and females according to variables related to body size (along the first component) and to head length and body height along the second and third components. Females were larger than males, whereas males had proportionally larger heads and higher bodies than females. The urogenital papilla of males and females showed differences in shape, size and relative position on the body. The female papilla was elongated horizontally, larger than that of males, and was located on a vertical line below the eye, while the papilla of the males was vertically elongated and located on a vertical line below the operculum. To our knowledge, this is the first recorded case of sexual dimorphism in a species of Rhamphichthyidae, a condition that is now known in all the currently recognized families of Gymnotiformes. © 2019, Instituto Nacional de Pesquisas da Amazonia. All rights reserved.
- Subjects :
- 0106 biological sciences
Science (General)
morphological variation
urogenital papilla
010603 evolutionary biology
01 natural sciences
electric fish
Rhamphichthyidae
Q1-390
Genital papilla
head morphology
Morphometrics
biology
010604 marine biology & hydrobiology
Gymnotiformes
Anatomy
biology.organism_classification
Sexual dimorphism
Major duodenal papilla
visual_art
visual_art.visual_art_medium
General Agricultural and Biological Sciences
Snout
Operculum (gastropod)
sexual differences
Subjects
Details
- ISSN :
- 18094392 and 00445967
- Volume :
- 49
- Database :
- OpenAIRE
- Journal :
- Acta Amazonica
- Accession number :
- edsair.doi.dedup.....e331e5b6f232c59badec1e31ae3bef6d