a The comparison of nucleotide skewness of the full genomes for the mitogenome of Parabreviscolex niepini and other cestodes b, c Principal component (PC) analysis of the codon usage and amino acid usage in the PCGs of P. niepini and other cestodes. The first PC (PC1) and the second PC (PC2) of the codon usage and amino acid usage accounted for 96.7% and 98.08% of the variability, respectively. d G+T content of complete genomes and their individual elements. The six caryophyllideans are represented by triangles in a-c. Abbreviations: AH: Atractolytocestus huronensis; BO: Breviscolex orientalis; Ksp2: Khawia sp. 2; KSK: Khawia sinensis; Ksp1: Khawia sp. 1; PN: Parabreviscolex niepini.