OutdoorNebraska

68 Pondhorn, Uniomerus tetralasmus Description: The shell of the Pondhorn is moderately elongate to trapezoidal and up to 120mm long. The shell is not very thick but solid. The anterior end is rounded while the posterior has a bluntly pointed end that often has a downward droop in adults. The exterior is smooth and glossy with a low rounded posterior ridge. The posterior slope will have a pair of grooves radiating from the beak to the posterior edge of the shell. Juveniles are light tan and may have faint green rays on the posterior ridge. Adults are a dark brown. There are thin lateral and pseudocardinal teeth in both valves. The beaks stand above the dorsal edge and the sculpture consists of several distinctive concentric circular ridges that radiate from a single point. Similar species: Juveniles of the Pondhorn resemble the Creeper and the Cylindrial papershell but the presence of lateral and psuedocardinal teeth separates them. The shell shape of large Pondhorns resembles that of the Spike, Elliptio dilatata. The Spike usually has purple nacre and their beak sculpture is three or four coarse angular ridges. Conservation status: G5, N5, S5. This species is fairly common in southeastern Nebraska, especially in the flood control reservoirs. Hosts: Golden shiner Habitats used: Ponds, small creeks, and the headwaters of larger streams in mud or sand. (Cummings and Mayer 1992). Quiet, slow-moving, shallow waters of sloughs, ponds, ditches, and meandering streams. Can survive extended periods of desiccation by burying itself deep into the substrate (Parmalee and Bogan 1998). Small creeks, small rivers, embayments of lakes. Seems to prefer prairie areas (Watters et.al. 2009). Distribution: Found in the central Mississippi River basin. From central Louisiana to northern Indiana and Ohio to Colorado. Collection notes: The Pondhorn is found throughout southeastern Nebraska in the Big Blue, Salt Creek, and Nemaha River basins as well as Shell Creek in the Lower Platte basin. It is also found in the Republican River basin and, rarely, the Elkhorn. There are numerous archeological records from the Republican River basin. Comments: This species does well in small muddy creeks as well as the flood-control reservoirs in southeast Nebraska. Hosts are probably fishes commonly stocked in our flood-control reservoirs. While golden shiners are present, they aren't common enough to explain the health of the populations. The Pondhorn is unique in that it has the ability to bury itself deep into the substrate when water levels drop and can remain buried for over a year, waiting for the water to return.

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