Developmental Osteology of Two Species of Economically Important Sciaenids, Sciaenops ocellatus and Cynoscion nebulosus (Teleostei: Sciaenidae)

The red drum (Sciaenops ocellatus) and spotted seatrout (Cynoscion nebulosus) are two ecomomically important sciaenids currently cultured for stock enhancement in Texas. 237 specimens of S. ocellatus, ranging in size from 2.5-26.3mm SL, and 214 specimens of C. nebulosus, ranging in size from 2.6-27.7 mm SL, were investigated and utilized to create ossification sequences depicting development of the entire skeleton for both species.

Development of the skeleton, excluding the basisphenoids and sclerotic bones, was complete in S. ocellatus and C. nebulosus at 14.4 mm SL and 13.5 mm SL, respectively. The basisphenoid did not appear until later in development (21.9 mm SL in S. ocellatus and 19.5 mm SL in C. nebulsosus), while the sclerotic bones were not present in the material examined. No major differences were identified between the ossification sequences compiled for each species. Cynoscion nebulosus exhibited variation in the presence/absence of two elements, supraneural 1 and the coronomeckelian. Development of the skeleton in S. ocellatus and C. nebulosus was compared with Agyrosomus meagre and Micropogonias furnieri, two other species of sciaenid for which information on skeletal development is available. No major differences were identified in the development of the axial skeleton between A. meagre, S. ocellatus or C. nebulosus. Several notable differences were identified in the development of the neurcranium between M. furnieri and that of S. ocellatus and C. nebulosus, suggesting that variation may exist in the development of the neurocranium across Sciaenidae. Lastly, the ossification sequence compiled here for S. ocellatus was compared to that of Danio rerio, the only other species of teleost for which an ossification sequence is available for development of the entire skeleton, and Chanos chanos, for which an ossification sequence is available for the cranial skeleton. Several differences were identified between all three species, suggesting variation of skeletal development exists across Teleostei. The information provided herein will benefit the culture of S. ocellatus and C. nebulosus by providing information on normal skeletal development and a standard reference sequence of skeletal development for both species that will facilitate identification of skeletal malformations should they become an issue in the future.