MACHIDATREMA N. GEN. (DIGENEA, HEMIURIDAE, BUNOCOTYLINAE) AND PHYLOGENETIC ANALYSIS OF ITS SPECIES

Machidatrema n. gen. is proposed to include Neotheletrum frontilatum ( Manter, 1969) Gibson and Bray, 1979, Neotheletrum akeh Machida, 1989, Genolinea kyphosi Yamaguti, 1970, and Genolinea chilostoma Machida, 19 80. The new genus is characterized by the presence of strong muscles i n the anterior part of the body, the hermaphroditic duct divided into 2 sections, prostatic vesicle, and excretory pore in a midventral posi tion. Phylogenetic analysis of the 4 species, based on 14 characters, produced 1 most parsimonious tree with a consistency index of 0.938. T he tree suggests that Machidatrema frontilatum and Machidatrema akeh a re sister species: Machidatrema kyphosi is the sister species of the f ormer 2, and Machidatrema, chilostoma is the sister species of them al l. The genus appears to have originated in the Pacific Ocean, parasiti zing fishes belonging to Kyphosus; the common ancestor of M. frontilat um and M. akeh appears to have originated by a host-switching event to fishes belonging to Siganus, and M. frontilatum originated by allopat ric speciation involving dispersal to the Indo-Pacific and Australia.