title: Osteology of the crescent gunnel Pholis laeta and the phylogeny of the family Pholidae (Cottiformes, Zoarcoidei).
abstract: This study provides a complete description of the osteology of the crescent gunnel Pholis laeta based on cleared-and-stained specimens and X-rays to help provide sufficient morphological data to generate a robust phylogeny for the family Pholidae. Pholis laeta exhibits high variation in the structure of its caudal skeleton. The length of the preural (pu)2 neural spine is variably reduced (most common) or elongated (i.e. of similar length to that of pu3). Additionally, the neural spine of pu3 is either bifurcated or single. These results document and describe characters useful for phylogenetic inference of the family, including the insertion pattern of anal-fin pterygiophores between haemal spines. Pholidae was recovered as monophyletic (synapomorphies: ribs absent, haemonephropophyses present, gill membranes broadly joined, first neural arch fused to centrum, first anal-fin spine very robust, the dorsal fin comprises only spines and the presence of five branchiostegals), with monophyletic genera Pholis and Apodichthys (Rhodymenichthys is monotypic) and Apodichthys and Rhodymenichthys as sister taxa. The elongation of its pu2 neural spine defines Pholis and synapomorphies for Apodichthys include five infraorbital bones, no pelvic fin, a hypertrophied first anal-fin spine, the presence of two or three empty interhaemal spaces after the anteriormost anal-fin spine and having 35-46 abdominal vertebrae. Apodichthys and Rhodymenichthys are sister taxa based on the continuity of the caudal fin with the dorsal and anal fins and uniform colouration. Future study is needed to more fully resolve the interrelationships of species within Pholidae (especially the genus Pholis) and solidify the position of Pholidae within the Zoarcoidei.
authors.affiliation: College of William and Mary, Williamsburg, VA, 23186, U.S.A.
authors.forename: P W
authors.initials: PW
authors.lastname: Sweetser
authors.affiliation: Virginia Institute of Marine Science, College of William and Mary, Gloucester Point, VA, 23062, U.S.A.
authors.forename: E J
authors.initials: EJ
authors.lastname: Hilton
mesh_terms: D000818:Animals; D001842:Bone and Bones / Q000033:anatomy & histology*; D059166:Osteology; D010473:Perciformes / Q000033:anatomy & histology* / Q000145:classification*; D010802:Phylogeny; D013045:Species Specificity; D013131:Spine / Q000033:anatomy & histology
keywords: Acanthomorpha; Percomorpha; comparative morphology; phylogeny; skeletal anatomy