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. 2026 Jan 23;1267:179–195. doi: 10.3897/zookeys.1267.177123

Complete mitochondrial genome of Echinorhynchus gadi (Acanthocephala, Echinorhynchida) and its phylogenetic implications

FeiMing Chen 1,2, JinWei Gao 1,2, Yu Huang 2, Hao Wu 1, Min Xie 1, ZhenZhen Xiong 1, JiaYu Wu 1, Jia Cai 2, Rong Xu 3, Xiao Jin 2,✉, Rui Song 1,2,✉, DongSheng Ou 1
PMCID: PMC12859643  PMID: 41625081

Abstract

The Echinorhynchidae has a long research history, but its mitochondrial genome evolution remains poorly understood, hindering phylogenetic resolution. In this study, we report the first complete mitochondrial genome of the genus Echinorhynchus, obtained from its type species, Echinorhynchus gadi. The circular mitogenome was 17,696 bp in length and contained 39 genes: 12 protein-coding genes (lacking atp8), two ribosomal RNA genes, and 25 transfer RNA genes, including two extra copies of trnW and one extra copy of trnV. Five non-coding regions were identified; the major non-coding region contained tandem repeats and pseudogene fragments, consistent with a tandem duplication and random loss mechanism. Phylogenetic analysis based on the concatenated amino acid sequences of the 12 protein-coding genes placed E. gadi and E. truttae in a well-supported monophyletic clade representing the genus Echinorhynchus. This clade was sister to Aspersentis megarhynchus, supporting a close relationship between Echinorhynchidae and Heteracanthocephalidae. Because the published E. truttae mitogenome is incomplete, this study fills a critical genomic gap and provides a valuable molecular resource for future taxonomic, systematic, and evolutionary studies of Acanthocephala.

Key words: Acanthocephala , Echinorhynchus gadi , mitochondrial genome, phylogenetic analysis, tRNA duplication

Introduction

Acanthocephalans are obligate endoparasites characterized by a retractable and hook-bearing proboscis used to anchor to the intestinal wall of vertebrate hosts (Perrot-Minnot et al. 2023). This attachment can cause hemorrhage, necrosis, and inflammation, and in severe cases may even lead to intestinal perforation (Dezfuli et al. 2011). Their life cycles typically involve arthropods as intermediate hosts and vertebrates as definitive hosts, making them important in medical, veterinary, and ecological studies, as well as models for physiology and evolutionary biology (Perrot-Minnot et al. 2023; Xie et al. 2025a).

The genus Echinorhynchus Zoega in Müller, 1776 is a key taxon within the order Echinorhynchida, comprising at least 52 described species (Amin 2013; Wayland et al. 2015). However, its morphological homogeneity poses problems for taxonomists because relatively few anatomical characters for discriminating species (Wayland et al. 2015). Therefore, integrating morphological and molecular data is essential for reliable species delimitation. Mitochondrial DNA (mtDNA) is a useful tool due to its low recombination rate, maternal inheritance, and moderate evolutionary rate (Gao et al. 2022). Despite this, available molecular data for Echinorhynchus species remain limited. Only an incomplete mitochondrial genome for Echinorhynchus truttae Schrank, 1788 is available, lacking two protein-coding genes (PCGs) and five transfer RNAs (tRNAs), which limits its phylogenetic utility (Weber et al. 2013; Song et al. 2019; Xie et al. 2025b). Because phylogenetic analyses of acanthocephalans typically rely on all 12 PCGs, sparse and incomplete data hinder robust inference (Gao et al. 2023). Moreover, the mitochondrial genome of the type species, Echinorhynchus gadi Zoega in Müller, 1776, has not yet been sequenced, hindering phylogenetic reconstruction and taxonomic clarity within the genus. Previous studies suggest that E. gadi may actually represent a complex of morphologically cryptic species, complicating accurate species identification within the genus (Väinölä et al. 1994; Wayland et al. 2005; Wayland et al. 2015).

In this study, we sequenced and annotated the complete mitochondrial genome of E. gadi, providing the first complete mitochondrial genome for both the genus Echinorhynchus and the family Echinorhynchidae. We conducted detailed phylogenetic analyses to assess the evolutionary status of E. gadi within Acanthocephala. This dataset provides a foundation for species identification and future taxonomic, systematic, and evolutionary studies of Acanthocephala.

Materials and methods

Sample collection

Specimens of E. gadi were collected in May 2022 from the intestinal tracts of Gadus chalcogrammus, purchased at a seafood market in Dalian City, Liaoning Province, China (39°03'N, 121°52'E). Parasites were preserved in 70% ethanol for morphological examination and in 100% ethanol for molecular analyses. All specimens were stored at 4 °C. A voucher specimen (DLegadi2205) was deposited at the Hunan Fisheries Research Institute and Aquatic Products Seed Stock Station.

DNA extraction, mitogenome sequencing, assembly, and annotation

Genomic DNA was extracted using the TIANamp Micro DNA Kit (Tiangen Biotech, Beijing, China). Primers were designed based on conserved regions of related acanthocephalan mitogenomes (Suppl. material 1). PCR amplicons were purified and Sanger-sequenced (Sangon Biotech, Shanghai) using a primer-walking strategy. Nanopore sequencing (QitanTech QPursue-6k, Aoke Biotechnology, Wuhan, China) was used to resolve repetitive regions.

Genome assembly was performed using DNASTAR v7.1 (Burland 2000), and initial annotation of PCGs, tRNAs, and ribosomal RNAs (rRNAs) was conducted with MitoZ v3.4.2 (Meng et al. 2019) and ARWEN v1.2 (Laslett and Canbäck 2008). PCG annotations were refined using NCBI ORFfinder, and gene boundaries were verified by comparison with homologous sequences. Some tRNA genes not recognized by MitoZ were identified by aligning them with published acanthocephalan tRNA sequences and were manually corrected. A circular mitogenome map was generated using Proksee (Grant et al. 2023). Codon usage and relative synonymous codon usage (RSCU) were analyzed using PhyloSuite v1.2.3 (Zhang et al. 2020).

Phylogenetic analyses

To assess the phylogenetic status of E. gadi, we sequenced its complete mitochondrial genome and compared it with available acanthocephalan mitogenomes. The analysis included all available mitochondrial genomes of acanthocephalans as of 18 July 2025, including 43 taxa from across the phylum. We used concatenated amino acid sequences of 12 PCGs for phylogenetic inference, selecting Rotaria rotatoria and Philodina citrina as outgroups (Table 1). Sequences were extracted using PhyloSuite, aligned with MAFFT v7.471 (Katoh and Standley 2013), and trimmed with trimAl v1.2 (Capella-Gutiérrez et al. 2009). The optimal partitioning scheme and substitution models (Suppl. material 2) were selected using ModelFinder (Kalyaanamoorthy et al. 2017) based on the Bayesian Information Criterion. Maximum-likelihood phylogenetic analyses were performed in IQ-TREE (Nguyen et al. 2015) with 5,000 ultrafast bootstrap replicates. Bayesian inference was performed for 1 × 106 MCMC generations under MrBayes v3.2 (Ronquist et al. 2012). Resulting trees were visualized using iTOL (Zhou et al. 2023).

Table 1.

Detailed information on representatives of Acanthocephala included in the present phylogeny.

Order Family Species Accession Size AT% References
Bdelloidea Philodinidae Rotaria rotatoria GQ304898 15,319 73.2 (Min and Park 2009)
Philodina citrina FR856884 14,003 77.7 (Weber et al. 2013)
Moniliformida Moniliformidae Moniliformis tupaia OK415026 14,066 66.2 (Dai et al. 2022)
Moniliformis sp. OP413683 14,150 63.7 unpublished
Oligacanthorhynchida Oligacanthorhynchidae Macracanthorhynchus hirudinaceus FR856886 14,282 65.2 (Weber et al. 2013)
Oncicola luehei JN710452 14,281 60.2 (Gazi et al. 2012)
Gyracanthocephala Quadrigyridae Acanthogyrus cheni KX108947 13,695 65.3 (Song et al. 2016)
Acanthogyrus bilaspurensis MT476589 13,360 59.3 (Muhammad et al. 2023)
Pallisentis celatus JQ943583 13,855 61.5 (Pan and Nie 2013)
Neoechinorhynchida Neoechinorhynchidae Neoechinorhynchus violentum KC415004 13,393 59.4 (Pan and Jiang 2018)
Tenuisentidae Paratenuisentis ambiguus FR856885 13,574 66.9 (Weber et al. 2013)
Polyacanthorhynchida Polyacanthorhynchidae Polyacanthorhynchus caballeroi KT592358 13,956 56.3 (Gazi et al. 2016)
Echinorhynchida Echinorhynchidae Echinorhynchus truttae FR856883 13,659 63.1 (Weber et al. 2013)
Echinorhynchus gadi PV976760 17,696 61.6 Present study
Heteracanthocephalidae Aspersentis megarhynchus PP965112 14,661 64.6 (Xie et al. 2024)
Arhythmacanthidae Heterosentis pseudobagri OP278658 13,742 62.5 (Gao et al. 2023)
Heterosentis holospinus PQ675784 16,560 61.5 (Chen et al. 2025)
Cavisomidae Cavisoma magnum MN562586 13,594 63.0 (Muhammad et al. 2020a)
Pomphorhynchidae Pomphorhynchus bulbocolli JQ824371 13,915 59.9 unpublished
Pomphorhynchus laevis JQ809446 13,889 57.1 unpublished
Pomphorhynchus rocci JQ824373 13,845 60.7 unpublished
Pomphorhynchus tereticollis JQ809451 13,965 56.9 unpublished
Pomphorhynchus zhoushanensis MN602447 14,546 56.0 unpublished
Longicollum pagrosomi OR215045 14,632 55.8 (Ren et al. 2025)
Pseudoacanthocephalidae Pseudoacanthocephalus sp. OQ588705 14,883 61.5 unpublished
Pseudoacanthocephalus nguyenthileae PP476192 13,701 56.3 (Zhao et al. 2024)
Pseudoacanthocephalus bufonis MZ958236 14,056 58.4 (Zhao et al. 2023)
Leptorhynchoididae Brentisentis yangtzensis MK651258 13,864 68.3 (Song et al. 2019)
Leptorhynchoides thecatus AY562383 13,888 71.4 (Steinauer et al. 2005)
Micracanthorhynchinidae Micracanthorhynchina dakusuiensis OP131911 16,309 56.8 (Gao et al. 2022)
Polymorphida Centrorhynchidae Centrorhynchus clitorideus MT113355 15,884 55.5 (Muhammad et al. 2020c)
Centrorhynchus milvus MK922344 14,314 54.5 (Muhammad et al. 2019b)
Centrorhynchus aluconis KT592357 15,144 55.6 (Gazi et al. 2016)
Sphaerirostris lanceoides MT476588 13,478 58.0 (Muhammad et al. 2020b)
Sphaerirostris picae MK471355 15,170 58.1 (Muhammad et al. 2019a)
Polymorphida Polymorphidae Southwellina hispida KJ869251 14,742 63.9 (Gazi et al. 2015)
Bolbosoma nipponicum OR468096 14,296 60.9 (Li et al. 2024)
Bolbosoma balaenae MZ357084 14,301 62.6 (García-Gallego et al. 2023)
Bolbosoma capitatum MZ357085 14,319 63.9 (García-Gallego et al. 2023)
Bolbosoma vasculosum MZ357087 14,313 63.9 (García-Gallego et al. 2023)
Bolbosoma turbinella MZ357086 14,199 60.4 unpublished
Corynosoma bullosum PQ516697 14,879 63.8 (Xie et al. 2025a)
Corynosoma evae PQ516696 13,947 61.6 (Xie et al. 2025a)
Corynosoma villosum OR468095 14,241 60.9 (Li et al. 2024)
Polymorphus minutus MN646175 14,149 64.4 (Sarwar et al. 2021)
Plagiorhynchidae Plagiorhynchus transversus KT447549 15,477 61.1 (Gazi et al. 2016)
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Results

Species identification

The specimens were identified as E. gadi based on morphological characteristics (Fig. 1), consistent with previous descriptions (Wayland et al. 2015; Amin et al. 2021). A BLASTn search of the mitochondrial cox1 sequence showed >99% similarity to published E. gadi sequences, providing strong molecular support for this identification. In addition, a maximum-likelihood (ML) phylogenetic tree based on cox1 sequences (Fig. 2) clearly placed our specimens within the E. gadi clade, corroborating the morphological identification.

Figure 1.

Figure 1.

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Morphology of Echinorhynchus gadi (A) and sketch (B).

Figure 2.

Figure 2.

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ML phylogeny of Echinorhynchus gadi inferred from mitochondrial cytochrome c oxidase subunit I (cox1) sequences. Pomphorhynchus laevis was used as the outgroup.

Mitochondrial genome organization and composition

The complete mitochondrial genome of E. gadi was 17,696 bp in length and contained 39 genes—12 PCGs (lacking atp8), 2 rRNAs, and 25 tRNAs. This gene content included two extra copies of trnW and one extra copy of trnV. All genes were encoded on the heavy strand and shared the same transcriptional orientation. The genome contained five non-coding regions (NCRs) (Table 2). Nucleotide composition was A = 21.8%, T = 39.8%, C = 10.7%, and G = 27.7% (A+T = 61.6%; G+C = 38.4%). The AT-skew and GC-skew were −0.292 and 0.445, respectively. A graphical circular map of the mitogenome is shown in Fig. 3, presenting gene order and orientation.

Table 2.

Annotations and gene organization of Echinorhynchus gadi.

Gene Start End Size (bp) Intergenic nucleotides Codon start Codon stop Anti-codon Strand
cox1 1 1539 1539 GTG TAA H
trnG 1539 1591 53 −1 TCC H
trnQ 1582 1633 52 −10 TTG H
trnY 1634 1686 53 GTA H
rrnL 1687 2608 922 H
trnL1 2609 2662 54 TAG H
nad6 2663 3098 436 GTG T H
trnD 3099 3151 53 GTC H
atp6 3274 3858 585 122 GTG TAA H
nad3 3872 4205 334 13 ATT T H
trnW 4206 4266 61 TCA H
trnW–2 4867 4927 61 600 CCA H
trnV 6707 6766 60 1779 TAC H
trnW–3 6836 6896 61 69 TCA H
trnV–2 8353 8412 60 1456 TAC H
trnK 8407 8467 61 −6 CTT H
trnE 8462 8515 54 −6 TTC H
trnT 8517 8571 55 1 TGT H
trnS2 8572 8624 53 TGA H
nad4L 8625 8900 276 ATG TAG H
nad4 8918 10186 1269 17 ATG TAG H
trnH 10187 10237 51 GTG H
nad5 10241 11899 1659 3 ATG TAG H
trnL2 11899 11951 53 −1 TAA H
trnP 11960 12012 53 8 TGG H
cytb 12013 13131 1119 ATG TAG H
nad1 13135 14031 897 3 TTG TAA H
trnI 14385 14438 54 353 GAT H
trnM 14442 14498 57 3 CAT H
rrnS 14499 15078 580 H
trnF 15079 15131 53 GAA H
cox2 15132 15780 649 ATG T H
trnC 15781 15832 52 GCA H
cox3 15855 16571 717 22 ATG TAA H
trnA 16570 16622 53 −2 TGC H
trnR 16622 16677 56 −1 ACG H
trnN 16669 16723 55 −9 GTT
trnS1 16722 16776 55 −2 ACT
nad2 16777 17694 918 GTG TAA
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Figure 3.

Figure 3.

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Gene map of the mitochondrial genome of Echinorhynchus gadi. The outermost ring depicts GC content and the innermost ring shows GC skew.

PCGs and codon usage

The 12 PCGs had a total length of 10,395 bp (excluding termination codons) and encoded 3,465 amino acids. Gene lengths ranged from 276 bp (nad4L) to 1,659 bp (nad5). Four PCGs started with GTG (cox1, nad6, atp6, nad2), six started with ATG (nad4L, nad4, nad5, cytb, cox2, cox3), one started with ATT (nad3), and one used the less common start codon TTG (nad1). Five PCGs terminated with TAA (cox1, atp6, nad1, cox3, nad2), four terminated with TAG (nad4L, nad4, nad5, cytb), and three had an incomplete stop codon T (nad6, nad3, cox2) (Table 2). Analysis of amino acid frequencies revealed that Val (valine) was the most prevalent amino acid, whereas Glu (glutamic acid) was the least prevalent. Accordingly, the most frequently used codons were UUU (Phe), followed by UUA (Leu) and GUU (Val), whereas the rarest codons were CCC (Pro) and CGC (Arg). Codon usage patterns are summarized in Fig. 4 and Table 3.

Figure 4.

Figure 4.

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Relative synonymous codon usage (RSCU) of Echinorhynchus gadi. The codon families (in alphabetical order) are labelled on the x-axis. Values at the top of each bar represent amino acid usage as a percentage.

Table 3.

Genetic code and codon usage for 12 PCGs in the mitochondrial genome of Echinorhynchus gadi.

Codon Count RSCU Codon Count RSCU Codon Count RSCU Codon Count RSCU
UUU(F) 252 1.83 UCU(S) 81 1.71 UAU(Y) 100 1.41 UGU(C) 53 1.63
UUC(F) 23 0.17 UCC(S) 7 0.15 UAC(Y) 42 0.59 UGC(C) 12 0.37
UUA(L) 228 2.4 UCA(S) 32 0.67 UAA(*) 5 1.11 UGA(W) 43 0.75
UUG(L) 169 1.78 UCG(S) 12 0.25 UAG(*) 4 0.89 UGG(W) 71 1.25
CUU(L) 63 0.66 CCU(P) 39 2.33 CAU(H) 38 1.62 CGU(R) 20 1.74
CUC(L) 9 0.09 CCC(P) 3 0.18 CAC(H) 9 0.38 CGC(R) 3 0.26
CUA(L) 59 0.62 CCA(P) 17 1.01 CAA(Q) 15 0.83 CGA(R) 10 0.87
CUG(L) 43 0.45 CCG(P) 8 0.48 CAG(Q) 21 1.17 CGG(R) 13 1.13
AUU(I) 130 1.79 ACU(T) 43 1.74 AAU(N) 36 1.41 AGU(S) 83 1.75
AUC(I) 15 0.21 ACC(T) 8 0.32 AAC(N) 15 0.59 AGC(S) 38 0.8
AUA(M) 91 1.06 ACA(T) 36 1.45 AAA(K) 31 1.07 AGA(S) 49 1.03
AUG(M) 80 0.94 ACG(T) 12 0.48 AAG(K) 27 0.93 AGG(S) 78 1.64
GUU(V) 219 1.75 GCU(A) 97 2.17 GAU(D) 49 1.75 GGU(G) 178 1.9
GUC(V) 31 0.25 GCC(A) 23 0.51 GAC(D) 7 0.25 GGC(G) 45 0.48
GUA(V) 113 0.9 GCA(A) 31 0.69 GAA(E) 24 0.61 GGA(G) 27 0.29
GUG(V) 138 1.1 GCG(A) 28 0.63 GAG(E) 55 1.39 GGG(G) 124 1.33
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tRNA genes and rRNA genes

The E. gadi mitogenome contained 25 tRNA genes, ranging from 51 bp (trnH) to 61 bp (trnW) in length and totaling 1,383 bp (Table 2). This set included the standard 22 tRNAs plus three extra tRNA copies—two extra trnW and one extra trnV. The two trnV copies were identical, whereas the three trnW copies showed nucleotide substitutions and carried distinct anticodons: one copy had CCA and two copies had TCA (both encoding trnW). These differences suggested that trnW may be undergoing functional divergence or pseudogenization.

rrnL (922 bp) was located between trnY and trnL1, and rrnS (580 bp) was located between trnM and trnF. Their A+T contents were 65.6% and 63.1%, respectively, consistent with the overall AT-rich composition of the genome.

Non-coding regions (NCRs)

Five NCRs were identified in the E. gadi mitogenome, totalling approximately 4,310 bp (≈24% of the genome) and ranging from 122 to 1,779 bp. A large tandem repeat array located between nad3 and trnK comprised three units (661 bp, 1,969 bp, and 1,596 bp), each with sharply defined boundaries and high sequence similarity to the others. This array contained the duplicated trnW and trnV genes, together with a truncated trnK pseudogene. This pattern was consistent with an origin via tandem duplication followed by random loss.

Phylogenetic analysis

Based on the concatenated amino acid sequences of the 12 PCGs, phylogenetic analyses supported the division of Acanthocephala into three major monophyletic clades, consistent with previous studies (Fig. 5). Clade I comprised four species of Archiacanthocephala. Clade II comprised five species of Eoacanthocephala and Polyacanthorhynchus caballeroi. Clade III, the largest of the three clades, corresponded to Palaeacanthocephala (33 species).

Figure 5.

Figure 5.

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Phylogenetic analyses inferred from the ML based on concatenating amino acid sequences of 12 mitochondrial PCGs. Rotaria rotatoria and Philodina citrina are the outgroup. Echinorhynchus gadi is highlighted in red.

Within Clade III, the analysis indicated that Echinorhynchida was polyphyletic. The Leptorhynchoididae formed an independent lineage, separated from other families of Echinorhynchida. This suggested that Leptorhynchoididae represented a distinct evolutionary lineage within the order. Furthermore, Echinorhynchidae and Heteracanthocephalidae diverged early within the main Echinorhynchida clade, supporting the hypothesis that they evolved from a common ancestor at an early stage.

Focusing on the genus Echinorhynchus, E. gadi and E. truttae formed a well-supported monophyletic clade. This confirmed the validity of their traditional taxonomic status within the Echinorhynchus and Echinorhynchidae. This clade was sister to Aspersentis megarhynchus (Heteracanthocephalidae), indicating a close relationship between Echinorhynchidae and Heteracanthocephalidae.

The BI analysis produced a tree topology that was congruent with the ML tree, providing additional confidence in our results (Suppl. material 3). The consistency between the ML and BI tree topologies lent additional robustness to our phylogenetic conclusions.

Discussion

The mitochondrial genome of E. gadi was exceptionally large for an acanthocephalan, primarily due to expanded NCRs, notably the large tandem repeat array described above (Xie et al. 2024, 2025b). These findings support the hypothesis that mitogenome size evolution in acanthocephalans is driven mainly by the accumulation of repetitive elements rather than increased coding capacity. The presence of duplicated tRNA genes within the tandem repeat array was notable. Although tandem repeats in NCRs are common in acanthocephalans, arrays that include tRNA genes have been reported only in Leptorhynchoides thecatus (Pan and Nie 2013; Gao et al. 2022; Chen et al. 2025). Our results provide empirical support for the “tandem duplication followed by random loss” model of mitochondrial genome evolution. This process can generate repeat arrays and sporadic gene duplications, and it has been invoked to explain gene rearrangements in animal mitogenomes. The duplicated tRNAs may contribute to functional diversification via novel anticodons, potentially enhancing translational efficiency or representing a step toward neofunctionalization (Romanova et al. 2020). Excluding the duplicated tRNAs in E. gadi, we found that the gene order was identical to those reported for Bolbosoma, Neoechinorhynchus, Pseudoacanthocephalus, and Moniliformis spp., indicating strong conservation of gene arrangement (Fig. 6) (Pan and Jiang 2018; Dai et al. 2022; Zhao et al. 2023, 2024; Li et al. 2024).

Figure 6.

Figure 6.

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Comparison of linearized mitochondrial genome arrangement of Echinorhynchus gadi and other Acanthocephalan species.

Phylogenetic analyses supported a close relationship between Echinorhynchidae and Heteracanthocephalidae, consistent with previous studies (Xie et al. 2024). Echinorhynchus gadi grouped with E. truttae, highlighting their close relationship, which aligns with their traditional taxonomy. Because only two Echinorhynchus species were included, we did not test the monophyly of the genus. Phylogenetic analyses indicated that including the incomplete E. truttae mitogenome did not alter the overall topology. Nevertheless, denser sampling across Echinorhynchus and additional complete mitogenomes will be necessary to test genus-level monophyly and to clarify interspecific relationships.

Conclusions

We obtained the first complete mitochondrial genome of the genus Echinorhynchus from its type species, E. gadi. The E. gadi mitogenome was unusually large due to expanded NCRs, whereas core gene content and gene order remained highly conserved aside from tRNA duplications. Phylogenetic analyses supported a sister relationship between Echinorhynchidae and Heteracanthocephalidae. This genomic resource clarified phylogenetic relationships within the order Echinorhynchida and provided a robust molecular framework for future taxonomic, systematic, and evolutionary studies.

Acknowledgements

We thank our labmates, teachers, and the supporting facilities for their assistance during sampling and sequencing. We also appreciate the reviewers and subject editor for their careful review, constructive feedback, and valuable suggestions, which greatly improve the manuscript.

Citation

Chen FM, Gao JW, Huang Y, Wu H, Xie M, Xiong ZZ, Wu JY, Cai J, Xu R, Jin X, Song R, Ou DS (2026) Complete mitochondrial genome of Echinorhynchus gadi (Acanthocephala, Echinorhynchida) and its phylogenetic implications. ZooKeys 1267: 179–195. https://doi.org/10.3897/zookeys.1267.177123

Funding Statement

Research Fund Program of Guangdong Provincial Key Laboratory of Aquatic Animal Disease Control and Healthy Culture Guangdong Province for the transformation of science and technology to promote regional urban-rural development

Contributor Information

Xiao Jin, Email: 1101219314@qq.com.

Rui Song, Email: ryain1983@163.com.

Additional information

Conflict of interest

The authors have declared that no competing interests exist.

Ethical statement

This study was conducted under the protocol of Hunan Fisheries Research Institute and Aquatic Products Seed Stock Station (protocol number 2022HFRI001). All applicable national and international guidelines for the protection and use of animals were followed.

Use of AI

No use of AI was reported.

Funding

This research was funded by the National Natural Science Foundation of China (No. 32173020) and the Research Fund Program of Guangdong Provincial Key Laboratory of Aquatic Animal Disease Control and Healthy Culture (No. PBEA2022ZD03). It was also supported by a special project of Guangdong Province for the transformation of science and technology to promote regional urban-rural development (2025B0202010041).

Author contributions

Conceptualization: FMC, JWG, XJ, RS. Methodology: FMC, MX, HW, ZZX, RS. Investigation: FMC, MX, HW, ZZX, RX. Data curation: YH, JC, JYW. Formal analysis: FMC, YH, JC, JYW. Resources: JWG, RX, DSO. Project administration: DSO, RS. Funding acquisition: RS, JWG, JC. Visualization: JYW, JC. Writing – original draft: FMC, JWG. Writing – review and editing: XJ, RS. Supervision: XJ, RS.

Author ORCIDs

FeiMing Chen https://orcid.org/0009-0000-0743-4096

JinWei Gao https://orcid.org/0000-0003-0551-1339

Yu Huang https://orcid.org/0000-0001-7589-0974

Hao Wu https://orcid.org/0000-0002-3104-4474

Min Xie https://orcid.org/0000-0003-2304-3954

ZhenZhen Xiong https://orcid.org/0009-0004-2149-2603

JiaYu Wu https://orcid.org/0009-0001-5521-1556

Jia Cai https://orcid.org/0000-0002-9501-7336

Xiao Jin https://orcid.org/0000-0002-2521-6591

Rui Song https://orcid.org/0000-0002-3856-4069

Data availability

The complete mitochondrial genome of E. gadi has been deposited in the GenBank under accession number PV976760.

Supplementary materials

Supplementary material 1

Primers and PCR gel plot of Echinorhynchus gadi

This dataset is made available under the Open Database License (http://opendatacommons.org/licenses/odbl/1.0/). The Open Database License (ODbL) is a license agreement intended to allow users to freely share, modify, and use this Dataset while maintaining this same freedom for others, provided that the original source and author(s) are credited.

FeiMing Chen, JinWei Gao, Yu Huang, Hao Wu, Min Xie, ZhenZhen Xiong, JiaYu Wu, Jia Cai, Rong Xu, Xiao Jin, Rui Song, DongSheng Ou

Data type

docx

Supplementary material 2

Partitioning scheme and corresponding best-fit models for phylogenetic analysis

This dataset is made available under the Open Database License (http://opendatacommons.org/licenses/odbl/1.0/). The Open Database License (ODbL) is a license agreement intended to allow users to freely share, modify, and use this Dataset while maintaining this same freedom for others, provided that the original source and author(s) are credited.

FeiMing Chen, JinWei Gao, Yu Huang, Hao Wu, Min Xie, ZhenZhen Xiong, JiaYu Wu, Jia Cai, Rong Xu, Xiao Jin, Rui Song, DongSheng Ou

Data type

docx

Supplementary material 3

Phylogenetic analyses inferred from the BI based on concatenating amino acid sequences of 12 mitochondrial PCGs

This dataset is made available under the Open Database License (http://opendatacommons.org/licenses/odbl/1.0/). The Open Database License (ODbL) is a license agreement intended to allow users to freely share, modify, and use this Dataset while maintaining this same freedom for others, provided that the original source and author(s) are credited.

FeiMing Chen, JinWei Gao, Yu Huang, Hao Wu, Min Xie, ZhenZhen Xiong, JiaYu Wu, Jia Cai, Rong Xu, Xiao Jin, Rui Song, DongSheng Ou

Data type

png

Explanation note

Rotaria rotatoria and Philodina citrina are the outgroup. Echinorhynchus gadi is highlighted in red.

References

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Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

Supplementary material 1

Primers and PCR gel plot of Echinorhynchus gadi

This dataset is made available under the Open Database License (http://opendatacommons.org/licenses/odbl/1.0/). The Open Database License (ODbL) is a license agreement intended to allow users to freely share, modify, and use this Dataset while maintaining this same freedom for others, provided that the original source and author(s) are credited.

FeiMing Chen, JinWei Gao, Yu Huang, Hao Wu, Min Xie, ZhenZhen Xiong, JiaYu Wu, Jia Cai, Rong Xu, Xiao Jin, Rui Song, DongSheng Ou

Data type

docx

zookeys-1267-179_article-177123__-s001.docx (109.7KB, docx)
Supplementary material 2

Partitioning scheme and corresponding best-fit models for phylogenetic analysis

This dataset is made available under the Open Database License (http://opendatacommons.org/licenses/odbl/1.0/). The Open Database License (ODbL) is a license agreement intended to allow users to freely share, modify, and use this Dataset while maintaining this same freedom for others, provided that the original source and author(s) are credited.

FeiMing Chen, JinWei Gao, Yu Huang, Hao Wu, Min Xie, ZhenZhen Xiong, JiaYu Wu, Jia Cai, Rong Xu, Xiao Jin, Rui Song, DongSheng Ou

Data type

docx

zookeys-1267-179_article-177123__-s002.docx (12.8KB, docx)
Supplementary material 3

Phylogenetic analyses inferred from the BI based on concatenating amino acid sequences of 12 mitochondrial PCGs

This dataset is made available under the Open Database License (http://opendatacommons.org/licenses/odbl/1.0/). The Open Database License (ODbL) is a license agreement intended to allow users to freely share, modify, and use this Dataset while maintaining this same freedom for others, provided that the original source and author(s) are credited.

FeiMing Chen, JinWei Gao, Yu Huang, Hao Wu, Min Xie, ZhenZhen Xiong, JiaYu Wu, Jia Cai, Rong Xu, Xiao Jin, Rui Song, DongSheng Ou

Data type

png

Explanation note

Rotaria rotatoria and Philodina citrina are the outgroup. Echinorhynchus gadi is highlighted in red.

zookeys-1267-179_article-177123__-s003.png (1.5MB, png)

Data Availability Statement

The complete mitochondrial genome of E. gadi has been deposited in the GenBank under accession number PV976760.

Articles from ZooKeys are provided here courtesy of Pensoft Publishers

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