Assessing the osteology of Notropis (Cypriniformes: Leuciscidae)

• Author / Creator

  Jessen, Erika K

• The genus Notropis (Cypriniformes: Leuciscidae) represents one of the largest genera of freshwater fishes in North America. The osteology of Notropis and closely associated genera including Cyprinella, Luxilus and Lythrurus, has been the subject of two primary areas of research. First is research examining a specific region of the skeleton including, but not limited to, the cranium, pharyngeal teeth and dental formulae, and the caudal skeleton. Second is research examining and comparing osteological characters to determine the evolutionary relationship within and between Notropis and its allies, sometimes termed ‘notropin fishes’. However, no research has been done to assess the osteological variation of a single Notropis species. Furthermore, no research has assessed and compared notropin osteology in the context of recent molecular phylogenies. Therefore, this thesis had two objectives: (1) describe and analyze the osteology of Notropis hudsonius within and between different populations, and (2) compare the osteology of 11 different Notropis species, which according to recent molecular studies represent four subgenera as well as two species of unclear placement. In the first part of this thesis, I describe the osteology of N. hudsonius and outline key osteological differences within and among 15 populations from Alberta, Northwest Territories, Manitoba and Ontario. Specific focus is placed on the elements of the oral jaws, suspensorium, opercular series, branchial apparatus, hyoid region, circumorbital series, pectoral girdle, pelvic girdle, caudal skeleton and skull. The second part of this thesis builds on my description of N. hudsonius and compares the osteological characteristics of Notropis atherinoides, N. blennius, N. buchanani, N. dorsalis, N. heterodon, N. heterolepis, N. hudsonius, N percobromus, N. stramineus, N. texanus and N. volucellus. According to recent molecular studies, nine of these species are classified in four subgenera while two (N. dorsalis and N. heterolepis) are of unclear placement. My analysis of the osteology of N. hudsonius reveals variation in all examined regions except the pelvic girdle. Regional differentiation between eastern and western populations is especially evident in the degree of fusion of the pectoral girdle, fusion of the parhypural and first hypural of the caudal skeleton, and shape of the urohyal. In comparing the osteology of 11 Notropis species, I found that interspecific differences are not usually restricted to specific subgenera. Some traits, such as those of the palatine and pharyngeal teeth, are reinterpreted as convergent rather than synapomorphic based on recent molecular phylogenies. These findings provide insight into the intraspecific variation of N. hudsonius and help reinterpret osteological traits in notropin evolution, distinguishing between synapomorphies and convergent traits.

• Subjects / Keywords

  • Osteology
  • Notropis
  • Intraspecific variation
  • Interspecific variation
  • Notropis hudsonius

• Graduation date

  Fall 2024

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-pspp-mn77

• License

  This thesis is made available by the University of Alberta Library with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.