Osteology of the prickleback genus Xiphister (Cottiformes: Zoarcoidei: Stichaeidae)

The two members of the genus Xiphister, Xiphister atropurpureus and Xiphister mucosus, are inter- and subtidal marine fishes from the west coast of North America, ranging from southern Alaska to southern California. Although both species were described over 150 years ago and portions of their anatomy have been described in several studies, a detailed description of their anatomy and morphology is lacking. In this article, we describe and illustrate the skeletal anatomy of the genus, clarifying aspects of the skull roof and neurocranium, jaws, suspensorium, opercular series, vertebral column, dorsal and anal fins, trunk lateral-line canals and pectoral girdle. We describe for the first time the elements of the hyoid and gill arches and scales. The genus is one of several within Stichaeidae with multiple, complexly branching trunk lateral lines, a feature that is found in only fifteen families of teleostean fishes. The development of the lateral-line canals and scales in Xiphister is discussed. Data reported herein will establish a foundation for the further anatomical and systematic studies of Stichaeidae and Zoarcoidei generally.