Ontogeny, variation, and homology in Salvelinus alpinus caudal skeleton (Teleostei: Salmonidae)

Abstract

The ontogeny of the caudal skeleton in the Arctic charr, Salvelinus alpinus was examined using an extensive series of cleared and stained specimens. We demonstrate the presence of skeletal components never reported previously within the Salmonidae. In contrast to the generalized condition for salmonids, seven hypurals (instead of six), and four uroneurals (instead of three) have been found in some specimens. Variation in the number and condition of epurals is documented. New hypotheses are proposed concerning (1) relationships among centra and their associated elements, (2) phylogenetic distribution of caudal characters within the Salmonidae, and (3) homology of caudal components. Using the published phylogenetic hypotheses, we provide evidence, that a seventh hypural and a fourth uroneural are taxic atavism in salmonids. The development of the salmonid homocercal fin is discussed in the light of a polyural scheme based on evidences of a one-to-one relationship among ural centra and their associated elements.

Skeletal development in the heterocercal caudal fin of spotted gar (lepisosteus oculatus) and other lepisosteiformes

“…6F), similar to a previously described longnose gar specimen (Nybelin, 1977) and drawn, but not mentioned, in two specimens of shortnose gar (Fig. 7 in (Schultze and Arratia, 1986)), and similar to the anterior process often observed in some teleost species such as salmonids (Arratia and Schultze, 1992; Grünbaum and Cloutier, 2010). …”

“…Scale bars ¼ 1 mm. teleost species such as salmonids (Arratia and Schultze, 1992;Gr€ unbaum and Cloutier, 2010).…”

Vestiges, rudiments and fusion events: the zebrafish caudal fin endoskeleton in an evo‐devo perspective

“…In salmonids such as Thymallus , most specimens display a diural (two ural centra) condition. Yet a polyural (more than two ural centra), more primitive, character may be present in some individuals (Arratia and Schultze ; Grünbaum and Cloutier ) and is likely not an abnormality but rather an atavistic condition.…”

Dynamic skeletogenesis in fishes: Insight of exercise training on developmental plasticity

“…1G-I). Generally, 28 caudal elements are present although a seventh hypural (H7) and a fourth uroneural (UN4) were found in some specimens (see Grü nbaum and Cloutier, 2010). UN4 and H7 were not considered in the analyses because of their seldom occurrence.…”