Meeting Abstract
The family Bramidae represents 20 species across 7 genera that inhabit oceanic waters. Despite a global distribution, they are seldom collected and therefore understudied. Of the bramids, the fanfishes (Pteraclis and Pterycombus) are especially rare and exhibit a striking anatomical exaggeration consisting of anteriorly elongated dorsal and anal fins. Changes in fin morphology are a driving force in the functional diversification of ray-finned fishes. Such diversification may be facilitated by compensatory changes to the underlying musculoskeletal system that support novel fin morphologies but impose a trade-off on other functional systems such as prey acquisition. Using µCT scans, staining methods, and morphometrics we compare the anatomy and ontogeny of Pterycombus petersii (Hilgendorf, 1878) to other bramid fishes to gain insights into the form, function, and evolution of their musculoskeletal architecture. In particular, we describe anatomical modifications that accommodate the exaggerated dorsal fins of the fanfishes, including a modified neurocranium with a greatly reduced supraoccipital crest (SOC). The SOC normally provides surface area for the anterior epaxial musculature, and is important for cranial elevation during feeding, especially suction-feeding. In fanfish, the dorsal aspect of the skull has been modified to serve as the attachment site for dorsal fin muscles. This modification is required to operate an elongated dorsal fin and may come at the expense of prey-capture capabilities, representing another example of an evolutionary trade off in those systems with exaggerated, naturally selected traits.
