Morphology and Phylogeny of the Studfish Clade, Subgenus Xenisma (Teleostei: Cyprinodontiformes)
Phylogenetic relationships within the studfish clade, subgenus Xenisma, were elucidated using parsimony analysis of 21 morphological transformation series, primarily osteology and external morphology. The analysis supports monophyly of subgenus Xenisma and the studfishes sensu strictu (Fundulus bifax, Fundulus catenatus, and Fundulus stellifer). Fundulus julisia and Fundulus albolineatus are recognized as sister taxa and together are recognized as sister to the F. bifax, F. catenatus, and F. stellifer clade. Contrary to a previous allozyme study of the subgenus, Fundulus rathbuni is recognized as sister to a monophyletic group composed of all other Xenisma species. This relationship is biogeographically consistent with the vicariant pattern previously demonstrated within darters of the subgenus Percina and suckers of the genus Hypentelium. The biogeography of the rest of subgenus Xenisma is complex and the sister-group relationship between F. catenatus and F. bifax is recognized as anomalous when compared to other Mississippi-Mobile basin biogeographic relationships in North American fishes.Abstract
Semidiagrammatic illustrations. (A) Ventral view of coelomic cavity of Fundulus stellifer, KU 20263; (B) dorsal view of anterior neurocranium of Fundulus rathbuni, UMMZ 147615; (C) dorsal view of anterior neurocranium of Fundulus catenatus, KU 11550; (D) ventral view of neurocranium of F. rathbuni, UMMZ 147615; (E) ventral view of neurocranium of F. catenatus, KU 11550; (F) dorsal view of ventral branchial skeleton of F. rathbuni, UMMZ 147615, (G) dorsal view of ventral branchial skeleton of F. catenatus, JFBM 37920; (H) ventral view of dorsal branchial skeleton of F. rathbuni, UMMZ 147615; (I) ventral view of dorsal branchial skeleton of F. catenatus, JFBM 37920. Anterior is up in all drawings. Scale bars = 1 mm. Arrows indicate transformation series number and character states separated by a hyphen (e.g., 2–1 is transformation series 2, character state 1).
Strict consensus of three equally most parsimonious phylogenetic trees rooted on Fundulus zebrinus. Branch lengths based on ACCTRAN optimization above branches, Bremer (1988) decay indices below branches
Contributor Notes
(MJG, MPD) Department of Biology D-8, Regis University, 3333 Regis Boulevard, Denver, Colorado 80221-1099; and (AMS) University of Minnesota, Department of Fisheries, Wildlife and Conservation Biology and Bell Museum of Natural History, 200 Hodson Hall, 1980 Folwell Avenue, St. Paul, Minnesota 55108. (MJG)mghedott@regis.edu Send reprint requests to MJG.