P1.111 Wednesday, Jan. 4 Morphological variation in the pharyngeal jaw apparatus of Cypriniformes RADE, CM*; HERNANDEZ, LP; George Washington University; George Washington University firstname.lastname@example.org
Cypriniformes is a morphologically diverse order of teleosts characterized by a novel pharyngeal jaw apparatus (PJA). While perciform pharyngeal jaws of various fish groups, including cichlids, haemulids, and labrids have been studied, morphological diversity within cypriniform pharyngeal jaws has been largely neglected. This is an especially glaring omission given that the cypriniform PJA consists of a significantly hypertrophied ceratobranchial 5 and loss of the upper pharyngeal jaws, a character seen only at the base of this group. Here we provide a detailed description of the musculoskeletal differences characterizing the cypriniform PJA. Using both cleared and stained specimens and fixed specimens we examine inter- and intra-familial morphological variation. Cypriniform families examined exhibit either patterns of conserved morphology or significant variation at the familial level. Within Balitoridae and Gyrinocheilidae, interspecific variation is minimal. Alternatively while Cyprinidae and Cobitidae show common features at the subfamilial level, there is significant variation in PJA across these families. While significant hypertrophy of the pharyngeal jaws characterizes most cypriniform fishes, gyrinocheilids tend to have smaller and more slender pharyngeal jaws; this is in strong contrast to the thicker and broader pharyngeal jaws of several of the examined cyprinids. Overall, this comparative study identifies various morphological features, including some that are potentially correlated with tropic niches; for instance, gyrinocheilids, which predominantly feed on algae, have slender pharyngeal jaws with a great number of small comb-like pharyngeal teeth. Results here will be important to elucidating the importance of the PJA in relation to cypriniform fishes’ trophic diversity and ecological success.