Variation of the synarcual in the California Ray, Raja inornata (Elasmobranchii: Rajidae)

Abstract

Seven juvenile specimens of Raja inornata were CT scanned and digitally modeled to examine the variation of synarcual morphology with changing size. The synarcual is a highly variable skeletal element across batoids with great potential for use in phylogenetic studies. Results show that as R. inornata increases in body size, the synarcual becomes more elongate and laterally compressed. Projections of the synarcual become more pronounced with increasing size as well. The synarcual of R. inornata is narrower than that of R. erinacea. There appears to be a correlation between median crest width and synarcual spine size.Also, in the context of higher-level batoid phylogenetics, the morphologically ventral position of the u-shaped lateral stay is considered primitive.