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

Abstract

In this paper, three species of the macrostomid free-living flatworm genus Macrostomum are described. Two species, Macrostomum littorale 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. Macrostomum littoralesp. nov. differs from congeneric species within the genus in the length of the stylet, diameter of stylet opening, and the bend of the stylet. Macrostomum shekouensesp. 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.

Genome assemblies of the simultaneously hermaphroditic flatworms Macrostomum cliftonense and Macrostomum hystrix

“…It is also noteworthy that the larger total number of genes that MITOS2 identified in M. hystrix is primarily due to a large number of gene annotations being split into 2 or more parts in the same way as for COI. Together, these findings point to potentially many more structural mutations in the mitochondrial genome of M. hystrix , and potentially other closely related Macrostomum species ( Shi et al . 2022 ).…”