Freshwater mussels (Unionidae): Central and West Texas Final Report

The goal of this study was two-fold: (1) assess the taxonomic identity and phylogenetic
placement of Quadrula aurea (Golden Orb) [Federal Candidate], Quadrula houstonensis
(Smooth Pimpleback) [Federal Candidate], and Quadrula petrina (Texas Pimpleback) [Federal
Candidate] through mitochondrial and nuclear DNA sequencing; and (2) provided additional
information on the distribution and abundance for mussel species petitioned for listing under
ESA through field surveys in portions of several major rivers in Central and West Texas. The
final report is organized by 4 research tasks as per contract (see Appendix A) and submitted
proposals. Below is an outline of goal-oriented tasks for this project:

Task 1 – Conduct comprehensive surveys of portions of the Brazos, Colorado, and Guadalupe
River basins
Task 2 – Conduct comprehensive surveys of portions of the Rio Grande Basin
Task 3 – Develop conservation status assessment maps for 9 state-threatened mussel species in Texas
Task 4 – Delineate species boundaries, test for cryptic species, and assess phylogenetic
relationships for threatened Texas mussel species in the genus Quadrula
Note the following 2 tasks were either not funded in the current contract or was a modification of
the contract and added as a project deliverable:
Task 5 – Delineate species boundaries, test for cryptic species, and assess phylogenetic
relationships for east Texas mussel species in the genus Fusconaia (Not Funded)
Task 6 – Evaluate the conservation status of Texas hornshell and other mussels in the Pecos and Devils Rivers (Contract amendment, results combined with Task 2).

Detailed descriptions of the research tasks and findings are found within each chapter of the
report. Here, we outline and summarize project deliverables and major findings for each task.