On a remarkable sexual dimorphic trait in the Characiformes related to the olfactory organ and description of a new miniature species of Tyttobrycon Géry (Characiformes: Characidae)

Among the order Characiformes, secondary sexual dimorphism is commonly associated to the occurrence of bony hooks on fins, shape and length of the dorsal and anal fins, and sexual dichromatism. The analysis of a new miniature Characidae species of the genus Tyttobrycon, described herein, yielded to...

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Bibliographic Details
Published in:PloS one 2019-12, Vol.14 (12), p.e0226130-e0226130
Main Authors: Abrahão, Vitor Pimenta, Pastana, Murilo, Marinho, Manoela
Format: Article
Language:English
Subjects:
Animal Fins - anatomy & histology
Animals
Apertures
Biology and Life Sciences
Blotch
Brain
Brain - anatomy & histology
Brain - growth & development
Brazil
Characidae
Characiformes
Characiformes - anatomy & histology
Coloration
Computer and Information Sciences
Congeners
Eye - anatomy & histology
Female
Females
Fins
Hooks
Jaw - anatomy & histology
Lamella
Lamellae
Male
Males
Medicine and Health Sciences
Morphology
New species
Olfactory Bulb - anatomy & histology
Olfactory Bulb - growth & development
Olfactory lamellae
People and places
Phenotype
Sex Characteristics
Sexual dimorphism
Teeth
Tyttobrycon
Vertebra
Vertebrae
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Summary:Among the order Characiformes, secondary sexual dimorphism is commonly associated to the occurrence of bony hooks on fins, shape and length of the dorsal and anal fins, and sexual dichromatism. The analysis of a new miniature Characidae species of the genus Tyttobrycon, described herein, yielded to the discovery of a sexually dimorphic trait related to nostril aperture and number of olfactory lamellae. In this type of dimorphism, mature males present larger nostril aperture and higher number of olfactory lamella than females. A dimorphic olfactory organ is for the first time recorded and described for a member of the Characiformes. Gross morphology and development of brain and peripheral olfactory organ of Tyttobrycon sp. n. are described and compared to other species of Characidae. It is hypothesized that such dimorphic trait is related to male-male detection during cohort competition in small characids. The new species of Tyttobrycon is diagnosed from its congeners by the number of branched anal-fin rays (19-21) and the absence of a caudal-peduncle blotch. It occurs in a small tributary of Rio Madeira basin, near to the limit between Brazil and Bolivia, Acre State, Brazil.
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0226130