“…The phylogenetic tree, based on the 18S rRNA gene, reveals unstable internal relationships and numerous weakly supported nodes within the order Spathidiida, consistent with previous reports (Chi, Wang, et al., 2021; Huang et al., 2018; Jang et al., 2017, 2022; Jiang et al., 2021; Pomahač et al., 2023; Rajter et al., 2019; Rajter & Vďačný, 2016, 2017; Vďačný et al., 2011, 2014; Yıldız, 2018). Interestingly, although Actinobolina and Papillorhabdos differ in all key features such as general appearance (ellipsoidal with numerous tentacles vs. cylindrical), extrusomes (stored in the tentacles vs. anchored to the cortex), circumoral kinety (present vs. absent), composition of somatic kineties (kinetosome clusters vs. monokinetids), and dorsal brush rows (1 vs. 4), they have an unexpectedly and fully supported phylogenetic relationship in the 18S rRNA gene tree.…”