Phylogenetic analyses
We used all Diestramima samples as well as the samples of adjacent genera Diestrammena and Raphidophora in the phylogenetic tree construction. For each fragment, DNA alignment was conducted by MEGA7 software (Loytynoja & Goldman 2010; Kumar et al . 2016). Saturation level of sequences was verified by Xia’s test (Xia et al ., 2003) in dambe 7 (Xia, 2018). In PhyloSuite (Zhanget al . 2020), the best-fit evolutionary model GTR was derived from ModelFinder (Kalyaanamoorthy et al . 2017), and the Maximum likelihood (ML) analysis was performed in IQ-Tree (Nguyen et al . 2014) with 1000 ultrafast bootstrap replicates. Node support is shown as posterior probabilities and bootstrap value, as directly estimated from the majority rule consensus topology.