Amapacanthus amazonicus n. g., n. sp (Acanthocephala : Diplosentidae : Allorhadinorhynchinae) from Arius passany and Anableps microleps (Pisces) at Maraca Island off northern Brazil

Amapacanthus amazonicus n. g., n. sp. is described from the intestine of Ar ius passany (Valenciennes) and Anableps microleps Muller. The most importan t diagnostic features are: a small globular proboscis armed with 6 diagonal rows of 3 stout hooks; middle hooks conspicuously stouter and larger than anterior ones; terminal hooks as long as middle hooks but straighter and mo re slender; a double-walled proboscis receptacle; a trunk bearing spines an teriorly; and two tubular cement glands in the males. Amapacanthus n. g. is differentiated from Allorhadinorhynchus, Golvanorhynchus and Slendrorhynch us, the other genera of the Allorhadinorhynchinae, by the presence of a glo bular proboscis armed with a small number (18) of hooks. A key to the speci es of the Allorhadinorhynchinae is presented.