Skeletal ontogeny of the Plainfin Midshipman, Porichthys notatus (Percomorphacea: Batrachoidiformes
Virginia Institute of Marine Science
Journal of Anatomy
Batrachoidiformes are benthic fishes that utilize the undersides of rocks as spawn- ing nests. Their larvae are attached to the nest and nourished by a large yolk sac. The evolutionary shift from feeding, free-swimming larvae to sedentary larvae that are reliant on their yolk sac for nutrition can lead to changes in skeletal develop- ment. Batrachoidiformes also have many morphological specializations, such as five pectoral-fin radials (versus four in other acanthomorphs) that are of uncertain homol- ogy, the determination of which may have phylogenetic implications. A larval series of Porichthys notatus was collected and its skeletal ontogeny is described. In P. notatus the ossification of the pharyngeal toothplates occurs relatively later than in perco- morphs with free-swimming larvae. The posterior basibranchial copula cartilage (= fourth basibranchial) in Porichthys notatus has a unique development among fishes: it initially develops as a paired element at 6.8–7.1 mm NL before fusing posteriorly and forming single median cartilage at 7.4 mm SL. Cartilages of hypobranchial four are transitory, being observed in two specimens of 6.8 and 7.3 mm NL before fusing with ceratobranchial four. The previously identified dorsalmost pectoral radial is a bone formed by a hypertrophied propterygium that ossifies later in development. The earli- est stages of P. notatus have three dorsal spines, but during late larval development, the growth of the third dorsal spine is interrupted. The development of P. notatus is compared and discussed in context to that of other acanthomorph.
development, early-life history, larva, variation
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Vaz, Diego F. B. and Hilton, Eric J., Skeletal ontogeny of the Plainfin Midshipman, Porichthys notatus (Percomorphacea: Batrachoidiformes (2022). Journal of Anatomy.