Three new species of Macrostomum (Platyhelminthes, Macrostomorpha) from China and Australia, with notes on taxonomy and phylogenetics

In this paper, three species of the macrostomid free-living flatworm genus Macrostomum are described. Two species, Macrostomumlittorale Wang & Shi, sp. nov. and M.shekouense Wang & Shi, sp. nov., were collected from coastal water at Shenzhen, Guangdong Province, China. One species, M.brandi Wang & Shi, sp. nov., was collected from Perth, Western Australia and Queenscliff, Victoria, Australia. Macrostomumlittoralesp. nov. differs from congeneric species within the genus in the length of the stylet, diameter of stylet opening, and the bend of the stylet. Macrostomumshekouensesp. nov. and M.brandisp. nov. differ from similar species within the genus in the stylet morphology, position of the female antrum and developing eggs, or presence or absence of the false seminal vesicle. Phylogenetic analysis based on cytochrome c oxidase subunit I (COI) gene shows that M.littoralesp. nov. and M.hystrix are sister clades on two well-separated branch, M.shekouensesp. nov. and M.brandisp. nov. are sister clades on two well-separated branches. Accordingly, both morphological and molecular evidence support M.littoralesp. nov., M.shekouensesp. nov., and M.brandisp. nov. as three new species.