A new species of freshwater mussel in the genus Popenaias Frierson, 1927, from the Gulf coastal rivers of central Mexico (Bivalvia: Unionida: Unionidae) with comments on the genus Author Inoue, Kentaro Natural Resources Institute, Texas A & M University, College Station, Texas, USA & Daniel P. Haerther Center for Conservation and Research, John G. Shedd Aquarium, Chicago, IL, USA kinoue @ sheddquarium. org, https: // orcid. org / 0000 - 0001 - 6087 - 3290 Author Cummings, Kevin S. Illinois Natural History Survey, Prairie Research Institute, University of Illinois, Champaign, Illinois, USA, kscummin @ illinois. edu, Environmental Science Center, Laredo Community College, Laredo, Texas, USA, tmiller @ laredo. edu, Author Tiemann, Jeremy S. Illinois Natural History Survey, Prairie Research Institute, University of Illinois, Champaign, Illinois, USA, kscummin @ illinois. edu, Environmental Science Center, Laredo Community College, Laredo, Texas, USA, tmiller @ laredo. edu, & jtiemann @ illinois. edu, https: // orcid. org / 0000 - 0001 - 7635 - 1403 Author Miller, Thomas D. Author Johnson, Nathan A. Wetland and Aquatic Research Center, U. S. Geological Survey, Gainesville, Florida, USA Author Smith, Chase H. Biology Department, Baylor University, Waco, Texas, USA. Author Randklev, Charles R. Natural Resources Institute, Texas A & M University, College Station, Texas, USA & crandklev @ ag. tamu. edu, https: // orcid. org / 0000 - 0002 - 6755 - 1507 text Zootaxa 2020 2020-07-20 4816 4 457 490 journal article 10.11646/zootaxa.4816.4.3 1175-5326 3954602 7683A3B0-5833-49B6-A7CE-675D116DBC67 Popenaias popeii ( Lea, 1857 ) ( Figs. 8C , 9C ) Common name: Texas Hornshell. Original combination: Unio popeii Lea, 1857 . Description of six new species of fresh water and land shells of Texas and Tamaulipas , from the collection of the Smithsonian Institution. Proceedings of the Academy of Natural Sciences of Philadelphia 9:101–102. Not figured. Figured in Lea (1860:372 , pl. 66, fig. 197). Verbatim type locality: “ Devils River and Río Salado , Texas .” Type locality: Río Salado ( Gulf of Mexico—Rio Grande ), 6 air km SSE of Anáhuac , Nuevo León , Mexico , [ 27.19444 , -100.10917 ] . Type specimens: Lectotype : USNM 85895 , designated and the type locality fixed by Johnson (1974:115 , as the “figured holotype ”; 1999:21, 62, pl. 6, fig. 1, as P. popei and incorrectly as USNM 85859 ) . Paralectotypes : from the type locality, USNM 85895 b (2).