A phylogeographic assessment redefines the distributions of <i>Truncilla</i> species (Bivalvia: Unionidae) in Texas

ABSTRACT Truncilla macrodon¸ the Texas Fawnsfoot, is currently considered to be restricted Brazos and Colorado river drainages in central Texas, USA. Subfossil specimens resembling T. macrodon from shell middens Trinity drainage have raised questions about its presumptive range. Extant populations occupying are believed donaciformis, but species identity has not been assessed using molecular techniques. In this study, we set out use phylogeographic morphometric approaches resolve distribution of spp. with an emphasis on assessing drainage. Our analyses indicated individuals rather than ratios length, width height supports finding showed differentiation among macrodon, cognata donaciformis. These combined findings suggest range larger previously recognized includes Colorado, drainages. The status San Jacinto basin remains unclear due lack information historical or extant populations, recommend conservationists consider as part mussel fauna since shares embayment Molecular data also population distinct from, more genetically diverse than, populations. This difference suggests River should treated a separate management unit facilitate effective conservation recovery planning. study adds growing body literature highlighting utility freshwater mussels.