ABSTRACT
The taxonomy and the systematics of the genus Makatinus are discussed by means of the characterization of its morphological pattern and the first molecular (D2-D3 expansion segments of 28S rDNA) analysis of a representative of this taxon, Makatinus crassiformis from Costa Rica. The presence of two or more pairs of male ad-cloacal genital papillae is the most characteristic autapomorphy of the genus, but the status of its species on this concern differ among them. Both morphological and molecular data support a relationship with Aporcelaimellus, which, however, might not be as close as usually assumed. An emended diagnosis of the genus, a key to species identification, and a compendium of their morphometrics are provided. Makatinus siddiqii is regarded as species inquirenda, Makatinus simus is retained under Eudorylaimus, and Makatinus tritici becomes a junior synonym of Aporcelaimellus tritici.
