Degree

Doctor of Philosophy (PhD)

Department

Biology

Document Type

Dissertation

Abstract

The catfishes (order Siluriformes) represent over five percent of world’s vertebrate diversity. The story of vertebrate evolution remains incomplete without a thorough evaluation of catfishes, and the ichthyological community is yet to reach consensus on some of the deeper evolutionary patterns within this fascinating group. Our complete macro-evolutionary understanding of catfishes is inhibited by a paucity of information on the taxonomies, phylogenetics, ecologies, and life histories of many understudied groups of catfishes. One such group is the Neotropical whale catfishes of the family Cetopsidae. This dissertation provides an integrated approach to studying the family Cetopsidae. I use genomics to determine the relationships amongst the genera within the family and find that the genus Paracetopsis is nested within Cetopsis. I apply time calibrations to my phylogenomic tree and use the geological history of South America and conclude that cladogenesis of the cetopsine genera occur during the formation and dissolution of the Pebas Mega-Wetland system, and then speciation within genera occur during the formation of the modern Amazon River. Furthermore, I conclude that the trans-Andean clade of Cetopsis speciated after the uplift of the northern Andes. I investigate a report of an tuberous electroreceptor organ in Cetopsis candiru by employing a comparative study of cutaneous organs across the genera of Cetopsidae. I describe the skin and sensory organs of the epidermis, and document the presence of ampullary and tuberous electroreceptors in all cetopsid genera. I present a broad survey of the osteology within the Cetopsinae, using micro-computed tomography scanning to overcome difficulties presented by traditional comparative methods. In the course of this survey, I discover and describe a new species of Cetopsis from the Río Marañón drainage of Peru, diagnosed by reduction of the vomer, loss of associated teeth, and a fully encapsulated swimbladder. The integration of multiple types of data and analytical techniques elucidates the complexity of evolution within the Cetopsidae. This will provide future researchers with a foundation of information to carry out research on this family to continue studying the greater evolution of all catfishes.

Date

2-6-2026

DOI

https://proquest.com/docview/3347817181

First Committee Chair

James Albert

First Committee Member

Matthew Kolmann

Second Committee Member

Michael Markham

Third Committee Member

Mirna Marinić

Fourth Committee Member

Suzanne Fredericq

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