Paranaella, a new microcotyline monotypie genus, is erected to accommodate Paranaella luquei sp. n., parasite of gill filaments from Hypostomus sp., Hypostomus regani (Ihering) and Rhinelepis aspera Spix et Agassiz (Loricariidae) from the Paraná River, Brazil. The new genus is most closely related to Microcolyle Van Beneden et Hesse, 1863, Diploslamenides Unnithan, 1971 and Solostamenides Unnithan, 1971. From Microcolyle it differs mainly by having the genital atrium formed by a muscular ring with a concentric row of numerous elongate and straight spines; from Diplostamenides it can be distinguished by the unarmed and not differentiated cirrus and from Solostamenides it differs by the single vaginal pore and absence of larval hooks.
Polylabris lingaoensis sp. n. is described from the gills of the bald glassy, Ambassis gymnocephalus (Chandidae), from the Gulf of Tonkin (South China Sea), near Lingao, Hainan Province, China. The new species is characterized by a midventral vaginal pore, comparatively few (5-7) testes, and 2 parallel rows each comprised of 30-43 microcotylid clamps in the haptor. Polylabris lingaoensis is the only member of the genus known to parasitize a chandid host. Polylabris cf. mamaevi is described from the gills of the mottled spinefoot, Siganus fuscescens (Siganidae), from the South China Sea, which represents new host and locality records for the helminth. The gill parasites from S. fuscescens are tentatively assigned to P. mamaevi pending new collections and restudy of microcotylid species from siganid fishes.