Fig. 1

Phylogeny of the family Styelidae and diversity of budding modes. a Simplified phylogenetic tree of Styelidae family (modify from Alié et al. 2018), showing the distribution of solitary species (shown in black) and colonial species (in red). The yellow star indicates the branches in which vascular budding evolved. b–d Schematic representation of peribranchial budding in Botryllus schlosseri (b), Polyandrocarpa misakiensis (c), and Stolonica socialis (d), from peribranchial evagination to double vesicle stage. e Schematic representation of the budding process in Polyandrocarpa zorritensis from the formation of vascular stolon to double vesicle stage. (tu tunic, ep epidermis, he haemocytes, pe peribranchial epithelium)