Monogenoidea from the monocotylid subfamilies Monocotylinae and Dendromonocotylinae have been studied and the diagnoses of the two subfamilies emended.
The diagnosis of Monocotyle is emended and includes M. myliobatis Taschenberg, 1878; M. diademalis Hargis, 1955; M. ijimae Goto, 1894; M. pricei Pearse, 1949; M. kuhlii sp. n.; M. granulatae sp. n. and M. tritestis sp. n. The diagnosis of Heterocotyle is emended and includes H.pastinacae Scott, 1904; H. americana Hargis, 1955; H. minima (MacCallum, 1916) Price, 1938; H. pseudominima Hargis, 1955; H. robusta (Johnston & Tiegs, 1922) Price, 1938 and H. granulatae sp. n. Dasybatotrema and Spinuris have their diagnoses emended and the type and only species of each restudied. The diagnosis of Horricauda is emended and includes H. rhynchobatidis Tripathi, 1959 and H. rhinobatidis sp. n. The type species of Neoheterocotyle is restudied. The new genera Anoplocotyloides, Decacotyle, Papillicotyle, and Troglocephalus are proposed to contain the species A. papillatus (Doran, 1953) comb, n.; D. lymmae sp. n.; P. floridana (Pratt, 1910) comb, n.; P. octona sp. n. and T. rhinobatidis sp. n.
The diagnosis of bendromonocotyle is emended and includes D. octodiscus Hargis, 1955 and D. kuhlii sp. n. The new genus Clemacotyle is proposed for C. australis sp. n.
Corrections are made where necessary to earlier descriptions of some of the species and all new species are described and figured. Keys to species in the subfamilies are included.