Ying Xun | PubMed Health

PubMed2026

Complete mitochondrial genomes of eight cyclophyllidean tapeworms: genome pattern and phylogenetic analysis.

Cyclophyllidean tapeworms are widespread parasites of significant medical and veterinary importance. However, mitochondrial (mt) genomic resources for cyclophyllideans from China, particularly those recovered from wildlife hosts, remain comparatively limited. In this study, we sequenced and characterized the complete mt genomes of eight cyclophyllidean isolates collected from diverse wild and domestic hosts in China, including two Hymenolepis sp. isolates and two Raillietina sp. isolates from China, and four additional isolates of previously sequenced Taenia species. The circular mt genomes ranged from 13,387 to 14,021 bp in length, encoding 36 typical genes with variable non-coding regions. Comparative analysis revealed highly conserved gene composition and mostly conserved mt architecture, with localized rearrangement patterns detected among the cyclophyllidean lineages examined. In particular, all sampled Taeniidae exhibited a consistent trnL1-trnS2 arrangement, whereas the examined non-Taeniidae families showed the trnS2-trnL1 arrangement, confirming and extending, across additional wildlife-associated isolates, a previously proposed family-associated gene-order marker within Cyclophyllidea. Phylogenetic analyses based on concatenated amino acid sequences of the 12 protein-coding genes placed the eight isolates within their expected families, in topologies broadly consistent with previous mitogenomic studies. These data provide additional Chinese mitogenomic references, especially for underrepresented wildlife-associated isolates, and support family-associated gene-order patterns in Cyclophyllidea.

Animals↗

PubMed2026

The first complete mitochondrial genome of Strigea falconis (Digenea: Strigeidae) reveals six tandemly repeated trnE-containing units and provides mt evidence for the non-monophyly of the family Strigeidae.

BACKGROUND: Phylogenetic relationships among members in the order Diplostomida remain contentious, with mitochondrial (mt) and nuclear genomic data often yielding conflicting topologies. A major limitation is the availability of only a few mt genomes from the type genus Strigea, hindering a robust test of the monophyly of the family Strigeidae and the order Diplostomida. RESULTS: The mt genome of S. falconis was completely sequenced for the first time, which was a circular molecule of 16,872 bp in length, encoding the typical set of 36 mt genes and six duplicate tRNA-Glu genes. Notably, there were seven identical and consecutive tandem repeat units each consist of a 169 bp non-coding region followed by a trnE gene in the newly assembled genome. Phylogenomic analyses based on concatenated predicted amino acid sequences of 12 proteins robustly placed S. falconis in the same clade as Apharyngostrigea pipientis. Crucially, the family Strigeidae was not recovered as monophyletic. Instead, two species within Strigeidae, Cardiocephaloides medioconiger and Cotylurus marcogliesei, clustered with representatives of Diplostomidae, providing mt evidence for the paraphyly of Strigeidae under the current sampling. CONCLUSIONS: The newly sequenced mt genome of S. falconis reveals a previously unreported six-copy tandem repeat of trnE-containing units among currently available diplostomoid mt genomes. Phylogenetic analyses based on mt protein-coding genes provide additional mt evidence that the family Strigeidae was not recovered as monophyletic under the present taxon sampling. However, because mt genomes represent a single maternally inherited linkage group, broader taxon sampling, independent nuclear phylogenomic data, and explicit sensitivity analyses will be required to confirm these relationships and guide any formal systematic revision.

Animals↗