Published online by Cambridge University Press: 31 May 2012
Five new species of Megapenthes are described: apacheorum from Arizona and New Mexico; texanus from Texas, New Mexico, and Arizona; fuscus from Arizona; antennatus from Arizona and Durango (Mexico); and elongatus from Arizona and New Mexico. Four species are redescribed: longicornis Schaeffer, variolatus Van Dyke, megalops Van Dyke, and obtusus Van Dyke. The male genitalia of these species are illustrated, and a key to the 29 nearctic species is included. The position of aterrimus Motschulsky is discussed, Dolopiosomus Motschulsky is considered as a nomen oblitum under Megapenthes, and caprella californicus Brown is synonymized under caprella LeConte.