Six species of freshwater mussel are of conservation concern throughout their range in East Texas, (Texas pigtoe (Fusconaia askewi), triangle pigtoe (Fusconaia lananensis), southern hickorynut (Obovaria jacksoniana), sandbank pocketbook (Lampsilis satura), Louisiana pigtoe (Pleurobema riddellii), and Texas heelsplitter (Potamilus amphichaenus)). These species warranted listing in Texas due, in part, to their restricted distributions and low abundances. These mussels, like most unionids, exhibit an unusual life cycle, unique to Unionidae, in which their larvae, called glochidia, are obligate ectoparasites on fish. Knowledge of host fish species is severally lacking for many mussels, as many hosts are unknown or have not been verified. Such natural history data is critical to the conservation of unionids. The purpose of this study was to evaluate if host fish identified in the laboratory act as hosts in natural populations. In addition, new species will be assessed as possible hosts by sampling naturally parasitized fish in the wild. Morphological identification of glochidia to the species level is very difficult due to the small size of glochidia (50-500 µm), therefore a species molecular identification dataset utilizing the sequence of the ND1 gene was developed prior to sampling naturally parasitized fish. A molecular identification dataset designed from sequences of 37 mussel species found in East Texas was successfully designed and utilized to identify encysted glochidia on wild-caught fish. A total of 151 glochidia were successfully identified from eight mussel species. New potential fish hosts were identified for two state-threatened species, Fusconaia askewi (Texas pigtoe) and Pleurobema riddellii (Louisiana pigtoe). Glochidia abundance and diversity was found to differ over the sampling season within the Sabine River. Ecological niche modeling in Maxent supported the results found in fish host use of naturally encysted glochidia. These findings are critical for understanding the complex relationships between mussels and their fish hosts, which is necessary for conservation planning.

Date of publication

Spring 5-23-2014

Document Type




Persistent identifier


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