01831nas a2200181 4500008004100000245013800041210006900179300000900248490000900257520123900266100001701505700001601522700001401538700001601552700001301568700001601581856005201597 2022 eng d00aThree new species of Macrostomum (Platyhelminthes, Macrostomorpha) from China and Australia, with notes on taxonomy and phylogenetics0 aThree new species of Macrostomum Platyhelminthes Macrostomorpha  a1-280 v10993 a

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 littorale sp. 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 shekouense sp. nov. and M. brandi sp. 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. littorale sp. nov. and M. hystrix are sister clades on two well-separated branch, M. shekouense sp. nov. and M. brandi sp. nov. are sister clades on two well-separated branches. Accordingly, both morphological and molecular evidence support M. littorale sp. nov., M. shekouense sp. nov., and M. brandi sp. nov. as three new species.

1 aShi, Yongshi1 aZeng, Zhiyu1 aWang, Jia1 aZhang, Siyu1 aDeng, Li1 aWang, Antai uhttps://macrostomorpha.myspecies.info/node/525803461nas a2200169 4500008004100000022001400041245011700055210006900172260001600241300000700257490000700264520290600271100002403177700002103201700002003222856004903242 2022 eng d a1741-700700aMating behavior and reproductive morphology predict macroevolution of sex allocation in hermaphroditic flatworms0 aMating behavior and reproductive morphology predict macroevoluti cFeb-07-2022 a350 v203 a

Abstract Background Sex allocation is the distribution of resources to male or female reproduction. In hermaphrodites, this concerns an individual’s resource allocation to, for example, the production of male or female gametes. Macroevolutionary studies across hermaphroditic plants have revealed that the self-pollination rate and the pollination mode are strong predictors of sex allocation. Consequently, we expect similar factors such as the selfing rate and aspects of the reproductive biology, like the mating behaviour and the intensity of postcopulatory sexual selection, to predict sex allocation in hermaphroditic animals. However, comparative work on hermaphroditic animals is limited. Here, we study sex allocation in 120 species of the hermaphroditic free-living flatworm genus Macrostomum. We ask how hypodermic insemination, a convergently evolved mating behaviour where sperm are traumatically injected through the partner’s epidermis, affects the evolution of sex allocation. We also test the commonly-made assumption that investment into male and female reproduction should trade-off. Finally, we ask if morphological indicators of the intensity of postcopulatory sexual selection (female genital complexity, male copulatory organ length, and sperm length) can predict sex allocation. Results We find that the repeated evolution of hypodermic insemination predicts a more female-biased sex allocation (i.e., a relative shift towards female allocation). Moreover, transcriptome-based estimates of heterozygosity reveal reduced heterozygosity in hypodermically mating species, indicating that this mating behavior is linked to increased selfing or biparental inbreeding. Therefore, hypodermic insemination could represent a selfing syndrome. Furthermore, across the genus, allocation to male and female gametes is negatively related, and larger species have a more female-biased sex allocation. Finally, increased female genital complexity, longer sperm, and a longer male copulatory organ predict a more male-biased sex allocation. Conclusions Selfing syndromes have repeatedly originated in plants. Remarkably, this macroevolutionary pattern is replicated in Macrostomum flatworms and linked to repeated shifts in reproductive behavior. We also find a trade-off between male and female reproduction, a fundamental assumption of most theories of sex allocation. Beyond that, no theory predicts a more female-biased allocation in larger species, suggesting avenues for future work. Finally, morphological indicators of more intense postcopulatory sexual selection appear to predict more intense sperm competition.

1 aBrand, Jeremias, N.1 aHarmon, Luke, J.1 aSchärer, Lukas uhttp://dx.doi.org/10.1186/s12915-022-01234-102316nas a2200193 4500008004100000022001400041245012300055210006900178260001600247300001100263490000800274520168200282100002401964700002101988700002102009700002202030700002002052856005002072 2022 eng d a1055-790300aLarge-scale phylogenomics of the genus Macrostomum (Platyhelminthes) reveals cryptic diversity and novel sexual traits0 aLargescale phylogenomics of the genus Macrostomum Platyhelminthe cJan-01-2022 a1072960 v1663 a

Free-living flatworms of the genus Macrostomum are small and transparent animals, representing attractive study organisms for a broad range of topics in evolutionary, developmental, and molecular biology. The genus includes the model organism M. lignano for which extensive molecular resources are available, and recently there is a growing interest in extending work to additional species in the genus. These endeavours are currently hindered because, even though >200 Macrostomum species have been taxonomically described, molecular phylogenetic information and geographic sampling remain limited. We report on a global sampling campaign aimed at increasing taxon sampling and geographic representation of the genus. Specifically, we use extensive transcriptome and single-locus data to generate phylogenomic hypotheses including 145 species. Across different phylogenetic methods and alignments used, we identify several consistent clades, while their exact grouping is less clear, possibly due to a radiation early in Macrostomum evolution. Moreover, we uncover a large undescribed diversity, with 94 of the studied species likely being new to science, and we identify multiple novel morphological traits. Furthermore, we identify cryptic speciation in a taxonomically challenging assemblage of species, suggesting that the use of molecular markers is a prerequisite for future work, and we describe the distribution of putative synapomorphies and suggest taxonomic revisions based on our finding. Our large-scale phylogenomic dataset now provides a robust foundation for comparative analyses of morphological, behavioural and molecular evolution in this genus.

1 aBrand, Jeremias, N.1 aViktorin, Gudrun1 aWiberg, Axel, W.1 aBeisel, Christian1 aSchärer, Lukas uhttp://dx.doi.org/10.1016/j.ympev.2021.107296