Anatomy and evolution of the pectoral filaments of threadfins (Polynemidae)

Author(s)

Presti, Paulo ^[1] ; Johnson, G. David ^[2] ; Datovo, Alessio ^[1]

Affiliation

^[1] Univ Sao Paulo, Museu Zool, Ave Nazare 481, BR-04263000 Sao Paulo, SP - Brazil

^[2] Smithsonian Inst, Natl Museum Nat Hist, Washington, DC 20560 - USA

• Document type: Journal article
• Source: SCIENTIFIC REPORTS; v. 10, n. 1 OCT 20 2020.
• Web of Science Citations: 0

Abstract

The most remarkable anatomical specialization of threadfins (Percomorphacea: Polynemidae) is the division of their pectoral fin into an upper, unmodified fin and a lower portion with rays highly modified into specialized filaments. Such filaments are usually elongate, free from interradial membrane, and move independently from the unmodified fin to explore the environment. The evolution of the pectoral filaments involved several morphological modifications herein detailed for the first time. The posterior articular facet of the coracoid greatly expands anteroventrally during development. Similar expansions occur in pectoral radials 3 and 4, with the former usually acquiring indentations with the surrounding bones and losing association with both rays and filaments. Whereas most percomorphs typically have four or five muscles serving the pectoral fin, adult polynemids have up to 11 independent divisions in the intrinsic pectoral musculature. The main adductor and abductor muscles masses of the pectoral system are completely divided into two muscle segments, each independently serving the pectoral-fin rays (dorsally) and the pectoral filaments (ventrally). Based on the innervation pattern and the discovery of terminal buds in the external surface of the filaments, we demonstrate for the first time that the pectoral filaments of threadfins have both tactile and gustatory functions. (AU)

• FAPESP's process: 17/16192-7 - Phylogenetic relations and evolution of the skeletal-muscle system of Polynemidae (Teleostei: Percomorphacea: Perciformes)
• Grantee: Paulo Presti Migliavacca
• Support Opportunities: Scholarships in Brazil - Master
• FAPESP's process: 18/19399-4 - Skeletal development in Polynemidae (Teleostei: Percomorphacea: Perciformes)
• Grantee: Paulo Presti Migliavacca
• Support Opportunities: Scholarships abroad - Research Internship - Master's degree
• FAPESP's process: 16/19075-9 - Diversity and evolution of Gymnotiformes (Teleostei, Ostariophysi)
• Grantee: Naercio Aquino Menezes
• Support Opportunities: Research Projects - Thematic Grants