The Repository @ St. Cloud State

Open Access Knowledge and Scholarship

Date of Award


Culminating Project Type


Degree Name

Biological Sciences - Ecology and Natural Resources: M.S.




College of Science and Engineering

First Advisor

Matthew Davis

Second Advisor

Matthew Julius

Third Advisor

Matthew Tornow

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Keywords and Subject Headings

Deepsea, Bioluminescence, Phylogenomics, Morphology, Systematics, Taxonomic


Stomiiformes (dragonfishes and their allies) are a diverse radiation of ray-finned fishes found in pelagic deep-sea habitats. With 305 species, the family Stomiidae (dragonfishes) are the most species-rich lineage of stomiiform fishes. They are diagnosed from other stomiiforms, in part, by the possession of a bioluminescent chin barbel, and they are also recognized by their elongate bodies with ventral light organs and enlarged teeth. Previous evolutionary studies examining the relationships among stomiiform fishes have been based on morphological characters or molecular sequence data, and the results of these studies have recovered conflicting hypotheses of relationships. In this study, I investigate the relationships among the dragonfishes and present a novel hypothesis of evolutionary relationships for the family that is based on genome-scale data that includes both ultraconserved elements (UCEs) and additional proteincoding gene fragments. Our new family-level hypothesis includes 25 of the 27 currently recognized stomiid genera and all previously recognized stomiid subfamilies. Our resulting phylogenies were incongruent with the prevailing classification of stomiids based on morphological data, and it rendered several of the currently recognized subfamilies as para- or polyphyletic. The subfamilies Chauliodontinae, Stomiinae, Idiacanthinae, and Malacosteinae were resolved as monophyletic while Astronesthinae was inferred as paraphyletic and Melanostominae were inferred as polyphyletic. Herein, we present a revised classification of the Stomiidae that reflects our recovered relationships and is based exclusively on monophyletic lineages. Our revised classification integrates previously published morphological data to aid in the diagnoses of new, resurrected, and modified stomiid subfamilies. In addition to the revision of stomiid taxa, we investigate the evolution of bioluminescent barbel structures across dragonfishes. These barbels are found on the base of the urohyal bone with high variation of anatomical features along the stem and tip, containing luminous tissues. This structure is hypothesized to be used for prey attraction and communication. Anatomical structures of the barbels can range from simple and elongate stems to the possession of complex structures. These structures include bulbs and bulblets, filaments, and branching networks, as well as flattened and leaf-like structures. The revised Stomiidae phylogeny is used to infer the character evolution of anatomical variation in this light producing appendage. Our results indicate multiple evolutions of barbel modifications on the stem, tip, and sexual dimorphism.


I want to thank the following people and institutions for providing specimens and tissue loans used in this study; K. Hartel and A. Williston (Museum of Comparative Zoology, Cambridge, MA), C. McMahan, K. Swagel, and S. Mochel (The Field Museum, Chicago, IL), and J. Williams and G.D. Johnson (Smithsonian Institution, Washington, DC). Funding for this work was provided by the National Science Foundation (DEB 1258141, 1543654), Proposal Enhancement Grant and Early Career Grants from St. Cloud State University (SCSU), SCSU Student Research Funds, facilities, and equipment at SCSU including the ISELF Integrated Research Space, the American Society of Ichthyologists and Herpetologists Edward C. Raney Award, American Museum of Natural History Lerner-Gray Grant for Marine Research, The Field Museum, and the University of Kansas. I would also like to thank Dr. Sarah Gibson and Dr. Jennifer Lamb as well as my committee members, Dr. Matthew Julius and Dr. Matthew Tornow, for all their comments and suggestions. To my parents, John and Debbie DeArmon and siblings, Steven and Cynthia DeArmon and Chris and Becky Utter for their continued support. A great thank you to my deep-sea lab mates Zachary May, Alex Maile, and Maya for keeping me sane as well as driving me insane. And finally, my advisor Dr. Matthew Davis for his guidance and encouragement throughout my Master’s.

2020 Distinguished Thesis Award Winner

Available for download on Tuesday, April 25, 2023