geminis, Tetrapleurodon Álvarez [J.] 1966:121, Fig. 5 [Anales de la Escuela Nacional de Ciencias Biológicas, México v. 13 (nos 1-4) (for 1964); ref. 20548] Río Celio at Jacona, Michoacán, Mexico. Holotype: whereabouts unknown. Paratypes: (12) UMMZ 186438 (1). •Valid as Lampetra geminis (Álvarez 1966) (often dated 1964) -- (Espinosa Pérez et al. 1993:7 [ref. 22290], Cochran et al. 1996:174 [ref. 22597], Lyons et al. 1996:366 [ref. 25521], Castro-Aguirre et al. 1999:37 [ref. 24550], Nelson et al. 2004:48 [ref. 27807], Scharpf 2005:5 [ref. 28940], Miller 2006:77 [ref. 28615]). •Valid as Tetrapleurodon geminis Álvarez 1966 (often dated 1964) -- (Yamazaki & Goto 2000:8 [ref. 24514], Lang et al. 2009:48 [ref. 31599], Renaud 2011:81 [ref. 31770], Page et al. 2013:48 [ref. 32708], Pereira et al. 2021:[10] 1991 [ref. 40490], Page et al. 2023:36 [ref. 40505]). Current status: Valid as Tetrapleurodon geminis Álvarez 1966. Petromyzontidae. Distribution: North America: Pacific slope of Mexico. Habitat: freshwater.