Psenes sio Haedrich, 1970. Sio Driftfish or Twospine Driftfish. To 28 cm (11 in) TL (Robertson and Allen 2008). Southern Baja California (Ahlstrom et al. 1976) to Chile (Robertson and Allen 2015), including Gulf of California (Galván-Magaña et al. 1996), and Islas Galápagos (Grove and Lavenberg 1997). Depth: surface to 500 m (1,640 ft) (Robertson and Allen 2002).