Date Awarded

2000

Document Type

Dissertation

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Virginia Institute of Marine Science

Advisor

John Edward Olney

Committee Member

G. David Johnson

Abstract

The marine fish family Ephippidae comprises eight genera and 15 species of extant fishes. Spadefishes or batfishes inhabit nearshore tropical to temperate waters. They are almost circumglobal in distribution, with the highest diversity in the Indo-west Pacific and the lowest diversity in the east Pacific and west Atlantic. Fifty-nine potentially informative morphological characters, 10 outgroup taxa, and eight ingroup taxa (i.e., genera) were used to explore sister group hypotheses to the Ephippidae, as well as generate a phylogeny of the Ephippidae. Seven constraint tree analyses were utilized to examine various sister group hypotheses based on previous morphological and molecular analyses by other researchers. These analyses resulted in maximally parsimonious trees ranging from 184 to 197 steps. as in previous analyses, both the suborder Acanthuroidei and the family Ephippidae were found to be monophyletic. Similar to the results from previous molecular and total evidence analyses, the exact placement of Scatophagidae within the Acanthuroidei could not be determined with this data set. However, in contrast to those results, Drepaneidae was found not to be the sister taxon to Scatophagidae. A single most-parsimonious tree of 187 steps (CI = 0.412) was chosen as the best hypothesis of relationships utilizing all taxa. However, few additional steps are needed to produce very different topologies. The phylogeny of the Ephippidae was invariant for all constraint tree analyses. Homoplask evolution is prevalent within the family (CI = 0.687; Bremer Total Support Index = 0.22). The phylogenetic hypothesis depicts two distinct clades: (Chastodipterus (Ephippus (Tripterodon ( Platax, Zabidius)))) + (Proteracanthus (Parapsettus, Rhinoprenes)). One new synapomorphy is proposed for the Ephippidae: posterior processes of the pelvic-fin girdle elongate, pointed, separate from one another, and parallel to the long axis of the body. Another new synapomorphy, the possession of an elongate fourth pharyngobranchial that completely overlays the dorsal surface of the upper toothplate of the fourth branchial arch, is homoplastically shared with Zanclidae. Ancestral area analysis determined that the ancestor to the Ephippidae most likely had an east Indian/west Pacific distribution. Omnivory is plesiomorphic within the Ephippidae and confirmed to be plesiomorphic for the Acanthuroidei.

DOI

https://dx.doi.org/doi:10.25773/v5-pm7s-3q12

Rights

© The Author

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