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Helminthol."],"published-print":{"date-parts":[[2026]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>\n                    The genus\n                    <jats:italic>Contracaecum<\/jats:italic>\n                    is an important group of anisakid nematodes containing species of veterinary, medical, and economic importance. However, current genetic sequences and the mitogenomic database for\n                    <jats:italic>Contracaecum<\/jats:italic>\n                    spp. are limited. In the present study, the nuclear 18S, 28S, and ITS regions and the mitochondrial\n                    <jats:italic>cox1<\/jats:italic>\n                    ,\n                    <jats:italic>cox2<\/jats:italic>\n                    , and 12S data for\n                    <jats:italic>C. ovale<\/jats:italic>\n                    (Linstow 1907) were sequenced based on the newly collected specimens from\n                    <jats:italic>Tachybaptus ruficollis<\/jats:italic>\n                    (Podicipediformes: Podicipedidae) in China. These sequences exhibited 100% similarity in the 18S and 28S regions and 99.8% similarity in the ITS-1 region (the presence of only a single locus of nucleotide polymorphism), compared with samples of\n                    <jats:italic>Contracaecum ovale<\/jats:italic>\n                    from\n                    <jats:italic>Podiceps cristatus australis<\/jats:italic>\n                    in New Zealand. Molecular analysis of two different individuals of\n                    <jats:italic>C. ovale<\/jats:italic>\n                    , collected from\n                    <jats:italic>T. ruficollis<\/jats:italic>\n                    in China, showed no genetic divergence with respect to the 18S, 28S, ITS,\n                    <jats:italic>cox<\/jats:italic>\n                    1, and 12S regions, but a low level of divergence in the\n                    <jats:italic>cox<\/jats:italic>\n                    2 sequences (0.73%). The complete mitogenome of\n                    <jats:italic>C. ovale<\/jats:italic>\n                    , presented for the first time, is 13,769 bp in length and includes 12 protein-coding genes, 22 tRNA genes, 2 ribosomal RNAs, and 2 non-coding regions. The mitogenome of\n                    <jats:italic>C. ovale<\/jats:italic>\n                    represents the smallest known anisakid mitogenome, and its overall A + T content (71.5%) is the highest level of A + T content of any anisakid. The mitogenomic phylogeny of those\n                    <jats:italic>Contracaecum<\/jats:italic>\n                    spp. whose mitochondrial protein-coding genes (PCGs) have been studied suggests that\n                    <jats:italic>C. rudolphii<\/jats:italic>\n                    and\n                    <jats:italic>C. ogmorhini<\/jats:italic>\n                    are more closely related to each other than either is to\n                    <jats:italic>C. ovale.<\/jats:italic>\n                    The genetic and mitogenomic data presented herein will be helpful for future studies on the population genetics and phylogenetics of\n                    <jats:italic>Contracaecum<\/jats:italic>\n                    spp.\n                  <\/jats:p>","DOI":"10.1017\/s0022149x2610203x","type":"journal-article","created":{"date-parts":[[2026,9,18]],"date-time":"2026-09-18T07:59:13Z","timestamp":1789718353000},"source":"Crossref","is-referenced-by-count":0,"title":["Molecular characterisation and complete mitochondrial genome of\n                    <i>Contracaecum ovale<\/i>\n                    (Linstow, 1907) (Ascaridida: Ascaridoidea) from the little grebe\n                    <i>Tachybaptus ruficollis<\/i>\n                    (Pallas) (Podicipediformes: Podicipedidae)"],"prefix":"10.1017","volume":"100","author":[{"given":"L.-W.","family":"Li","sequence":"first","affiliation":[{"id":[{"id":"https:\/\/ror.org\/004rbbw49","id-type":"ROR","asserted-by":"publisher"}],"name":"Hebei Normal University"},{"name":"Cangzhou Technical College"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Z.-J.","family":"Hou","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/02yxnh564","id-type":"ROR","asserted-by":"publisher"}],"name":"Northeast Forestry University"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Y.-Y.","family":"Xie","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/004rbbw49","id-type":"ROR","asserted-by":"publisher"}],"name":"Hebei Normal University"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2338-1099","authenticated-orcid":false,"given":"L.","family":"Li","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/004rbbw49","id-type":"ROR","asserted-by":"publisher"}],"name":"Hebei Normal University"},{"name":"Biochemistry and Molecular Biology"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"56","published-online":{"date-parts":[[2026,9,18]]},"reference":[{"key":"S0022149X2610203X_r26","first-page":"617","volume-title":"Osnovy 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