Polychromatism and Polymorphism in Breviraja spinosa (Elasmobranchii, Rajiformes), with Description of Three New Species

• Published in: Copeia 1985-12, Vol.1985 (4), p.1035-1052
• Main Authors: McEachran, John D., Matheson, Richard E.
• Format: Article
• Language: English
• Subjects: Agnatha. Pisces; Animal morphology; Biological and medical sciences; Cloaca; Fundamental and applied biological sciences. Psychology; Holotypes; Jaw; Paratypes; Pectorals; Plant spines; Spiracles; Teeth; Vertebrae; Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution
• ISSN: 0045-8511; 1938-5110
• DOI: 10.2307/1445259

Preliminary examination revealed that the highly variable species, Breviraja spinosa, consists of four distinct color morphs. Principal components analyses based on morphometric characters, univariate analyses of meristic characters and morphology of neurocrania, scapulocoracoids and claspers distinguished among all of the color morphs and, thus, supported the hypothesis that each represents a distinct species and that these are distinct from the only other congener, B. colesi. B. spinosa occurs from North Carolina to the Florida Keys and is distinguished by its plain-colored dorsal surface, sooty-gray blotches in the central region of the ventral disc, shape of the rostral appendix and structure of the scapulocoracoid. B. claramaculata occurs from North Carolina to the Florida Keys and is distinguished by its symmetrically arranged white spots on the dorsal surface, light-colored ventral surface, number of tooth rows in the upper jaw, number of predorsal tail vertebrae and rostral structure. B. schroederi occurs from Honduras to Panama and is distinguished by its plain-colored dorsal surface, light-colored ventral surface, number of predorsal tail vertebrae and structure of the clasper. B. nigriventralis occurs from Panama to French Guiana and is distinguished by its plain-colored dorsal surface, largely black-colored ventral surface, structure of the lower jaw, development of the caudal fin and shape of the scapulocoracoid. Based on the distribution of shared derived character states, Raja garmani and R. yucatanensis constitute the sister group of Breviraja; B. claramaculata is the sister group of the other Breviraja species; B. spinosa, B. schroederi and B. nigriventralis and B. colesi form an unresolved trichotomy, in which B. spinosa and/or B. schroederi represent the sister group of a clade composed of B. nigriventralis and B. colesi.