FN Archimer Export Format PT J TI “Something old, something new, something borrowed, and the oioxeny is true”: Description of Plectanocotyle jeanloujustinei n. sp. (Polyopisthocotylea, Plectanocotylidae) from the MNHN Helminthology collection with novel molecular and morphological data for Plectanocotyle gurnardi sensu stricto from Sweden BT AF Cappelletti, Alice Bouguerche, Chahinez AS 1:1,2,3;2:4; FF 1:PDG-RBE-HMMN-LRHBL;2:; C1 Department of Life and Environmental Sciences, Università degli Studi di Cagliari, Cagliari, Italy IFREMER, Channel and North Sea Fisheries Research Unit, 150 Quai Gambetta, BP 699, F-62 321, Boulogne-sur-Mer, France ANSES, Laboratory for Food Safety, 62200, Boulogne-sur-Mer, France Department of Zoology, Swedish Museum of Natural History, Box 50007, SE-104 05, Stockholm, Sweden C2 UNIV CAGLIARI, ITALY IFREMER, FRANCE ANSES, FRANCE SWEDISH MUSEUM NAT HIST, SWEDEN SI BOULOGNE SE PDG-RBE-HMMN-LRHBL IF 1.8 TC 0 UR https://archimer.ifremer.fr/doc/00877/98914/108650.pdf LA English DT Article CR INTERNATIONAL BOTTOM TRAWL SURVEY (IBTS) DE ;Polyopisthocotylea;Plectanocotyle;Gurnard;Triglidae;Mitochondrial DNA;Morphology;Coast of Sweden;Mediterranean;Museum;Collection AB Natural history museums worldwide house billions of apposite specimens, offering the potential for cost-free parasitological datasets. Herein, we provide novel morphological and molecular data (28S and cox1) for the polyopisthocotylean Plectanocotyle gurnardi sensu stricto from the type-host Eutrigla gurnardus from Sweden based on newly collected specimens from the Northeast Atlantic, and specimen from T. Odhner's collections at the Swedish Museum of Natural History. The newly generated 28S sequences of P. gurnardi from E. gurnardus from the Northeast Atlantic were identical to those from the Western Mediterranean, and nested in a single clade, suggesting the presence of a single species. A 28S sequences of P. gurnardi sensu stricto from Sweden and those from the U.K. (type locality for P. caudata) were identical; we confirm that P. caudata and P. gurnardi are conspecific and formally synonymize them. A single 28S sequence of Plectanocotyle sp. from Chelidonichthys lastoviza off France differed from P. gurnardi from the Northeast Atlantic by 3–4 % and from P. gurnardi from France by 3%. Plectanocotyle sp. ex C. lastoviza off France is clearly not P. gurnardi, suggesting an oioxenic specificity of P. gurnardi to E gurnardus. Careful re-examination of Plectanocotyle cf. gurnardi from C. lastoviza from the Western Mediterranean from the Helminthology collection of Muséum national d'Histoire naturelle revealed that it differs from all congeners by morphometry (size of clamps, of terminal lappet and its hamuli and uncinuli, and size of atrial spines). The cox1 divergences between Plectanocotyle cf. gurnardi and P. major, P. lastovizae, and P. gurnardi sensu stricto were 10–11 %, 10–11 % and 8 % respectively, falling within the interspecific variations range. Plectanocotyle from the Mediterranean is described as a new species, P. jeanloujustinei n. sp. We apprise nomenclature problems in Plectanocotyle and consider P. elliptica a species inquirenda. PY 2024 PD APR SO International Journal for Parasitology: Parasites and Wildlife SN 2213-2244 PU Elsevier BV VL 23 DI 10.1016/j.ijppaw.2024.100914 ID 98914 ER EF