Redescription and phylogenetic assessment of Helicometra antarcticae Holloway & Bier, 1968 (Trematoda, Opecoelidae), with evidence of non-monophyletic status of the genus Helicometra Odhner, 1902 Author Sokolov, Sergey G. Centre of Parasitology, A. N. Severtsov Institute of Ecology and Evolution, Moscow, Leninskiy Av. 33, 119071 (Russia) sokolovsg @ mail. ru sokolovsg@mail.ru Author Shchenkov, Sergei V. Department of Invertebrate Zoology, St. Petersburg State University, St. Petersburg, Universitetskaya nab., 7 / 9, 199034 (Russia) svshchenkov @ yandex. ru svshchenkov@yandex.ru Author Khasanov, Fuat K. Centre of Parasitology, A. N. Severtsov Institute of Ecology and Evolution, Moscow, Leninskiy Av. 33, 119071 (Russia) fuatka @ mail. ru fuatka@mail.ru Author Kornyychuk, Yuliya M. A. O. Kovalevsky Institute of Biology of the Southern Seas, Sevastopol, Nakhimov Ave., 2, 299011 (Russia) miju 2811 @ mail. ru Author Gordeev, Ilya I. Department of Pacific Salmon, Russian Federal Research Institute of Fisheries and Oceanography, Moscow, Okruzhnoy Proyezd 19, 105187 (Russia) and Department of Invertebrate Zoology, Lomonosov Moscow State University, Moscow, Leninskiye Gory 1 / 12, 119234 (Russia) gordeev _ ilya @ bk. ru (corresponding author) ilya@bk.ru text Zoosystema 2022 2022-09-06 44 15 423 433 journal article 141491 10.5252/zoosystema2022v44a15 8181cd68-5f9f-4e60-aa6c-4ec5e1e1a720 1638-9387 7076017 urn:lsid:zoobank.org:pub:8A516E81-F1BA-4C79-AF57-0672548CC3FA Helicometra fasciata ( Rudolphi, 1819 ) Odhner, 1902 sensu lato ( Fig. 3 ) Distoma fasciatum Rudolphi, 1819: 373 . Distoma pulchellum Rudolphi, 1819: 367 . Distoma sinuatum Rudolphi, 1819: 374 . Distomum gobii Stossich, 1883: 116 . Distomum labri Stossich, 1886: 30 . Allocreadium fasciatum – Odhner 1901: 485 . Allocreadium sinuatum – Odhner 1901: 490 . Allocreadium labri – Odhner 1901: 493 . Loborchis mutabilis Stossich, 1902: 579 . FIG. 3.. — Helicometra fasciata ( Rudolphi, 1819 ) Odhner, 1902 sensu lato from intestine of black scorpionfish, Scorpaena porcus Linnaeus, 1758 , Black Sea; whole mount, ventral view. Scale bar: 0.5 mm. Loborchis fasciatum – Stossich 1902: 582 . Loborchis gobii – Stossich 1902: 582 . Loborchis labri – Stossich 1902: 582 . Helicometra fasciata – Odhner 1902: 162 . — Palombi 1929: 262 . — Naĭdenova & Dolgikh 1969: 10 . — Bray 1979: 401 ; 1987: 1069 . — Hassanine 2007: 20 . — Blend & Dronen 2015: 245 . Helicometra pulchella – Odhner 1902: 161 . — Nicoll 1910: 336 . — Sekerak & Arai 1974: 710 . Helicometra sinuata – Odhner 1902: 162 . Helicometra flava Stossich, 1903: 373 . Helicometra mutabilis – Stossich 1903: 375 . Helicometra gobii – Stossich 1904: 12 . Helicometra hypodytis Yamaguti, 1934: 301 . Helicometra markewitschi Pogorel’tseva, 1954 : 133. Helicometra dochmosorchis Manter & Pritchard, 1960: 653 . Helicometra marmoratae Nagaty & Abdel Aal, 1962: 310 . Helicometra upapalu Yamaguti, 1970: 83 . Helicometra scorpaenae Wang, 1982: 188 . Helicometra neoscorpanae Wang, Wang & Zhang, 1992: 72 . TYPE LOCALITY. — Tyrrhenian Sea. TYPE MATERIAL. — We could find no information about deposition of K. A. Rudolphi’s original H. fasciata material. MATERIAL EXAMINED. — Black Sea • 6 adult whole-mounted, 1 sequenced specimens; Severnaya Bay , Crimean Peninsula ; intestine of the black scorpionfish, Scorpaena porcus ; 44°37’32”N , 33°32’7”E ; 27.VII.2000 ; ISSS RAS 1369.Tr.39.v2-15; GenBank: OK644194 (28SrRNA gene) . DESCRIPTION General morphology and digestive system Body elongate-oval, length 1.464 -2.383 (1840), maximum width 620-726 (675) in posterior half of body. Tegument unarmed. Pre-oral lobe absent. Oral sucker spherical or subspherical, 140-189 (167) / 144-184 (167), mouth opening subterminal. Ventral sucker globular or subglobular, 215-285 (237) / 199-250 (224). Oral sucker to ventral sucker width ratio 1: 1.21-1.55 (1.35). Forebody 30.5-36.4 (33.9) % of body length. Prepharynx short, distinct. Pharynx well-developed, 47-83 (67) / 43-88 (59). Intestinal bifurcation in second or posterior third of forebody. Caeca blind distance from caecal ends to posterior end of body reaching 95-171 (137). Male reproductive system Two testes, variously lobed, contiguous, median, tandem, post-equatorial; anterior testis 172-282 (206) / 283-470 (401), posterior testis 188-394 (268) / 359-447 (381). Posttesticular region 13.3-18.2 (14.9) % of body length. Cirrussac well-developed, 319-551 (433) / 65-93 (78), overlapping 2.4-28.7 (22.4)% of ventral sucker. Internal seminal vesicle long, tubular, folded. Pars prostatica tubular, surrounded by numerous prostatic gland-cells. Ejaculatory duct distinct, cirrus not visible. Genital atrium indistinct. Genital pore median, at midlevel of oesophagus. Female reproductive system Ovary variously lobed, median or slightly dextro-sumedian, anterior or slightly antero-dextral to and slightly overlapping anterior testis, 89-136 (118) / 290-393 (340). Canalicular seminal receptacle saccular, antero-dextral to ovary. Laurer’s canal and oötype together with Mehlis’ gland not visible. Uterus preovarian, coiled, intercaecal. Metraterm not visible. Eggs operculate, with long unipolar filament; length without filament 63.0-87.3 (75.1), width 26.1-40.2 (34.2). Vitellarium follicular; follicles in two lateral fields, extending from level anterior quarter or middle of oesophagus to near posterior end of body; fields overlapping caeca dorsally in forebody and uterus area and ventrally in post-testicular region, usually encroaching caeca along rest of their length ventrally and dorsally, not confluent in post-testicular region, usually confluent on dorsal side of forebody; anterior border of ventral follicles some distance posterior to that of dorsal follicles. FIG. 4. — Phylogenetic relationships of helicometrine species based on dataset of 28S rRNA gene sequences. The bootstrap (≥ 50) and posterior probability (≥ 0.90) values are given near the nodes for ML and BI analyses, respectively. Newly obtained sequences are underlined. Excretory system Excretory pore terminal. Excretory vesicle clavate, extending to ovary, posterior end surrounded by numerous glands and small subterminal muscular sphincter. PHYLOGENETIC DATA BI and ML analyses supported the sister position of H. antarcticae to Helicometra sp. described in this study ( Fig. 4 ). The divergence between these species was low (p-distance = 0.7%). The H. antarcticae + Helicometra sp. clade had a sister relationship with the well-supported clade containing Helicometrina nimia Linton, 1910 and other Helicometra spp. Helicometrina nimia was sister taxon to the well-supported terminal Helicometra epinepheli Yamaguti, 1934 + ( H. fasciata sensu lato + Helicometra manteri Andres, Ray, Pulis, Curran & Overstreet, 2014 ) subclade, though this sister relationship was poorly supported in both analyses. Helicometra equilata (Manter, 1933) Siddiqi & Cable, 1960 occupied a basal position to H. nimia and members of the terminal subclade mentioned above.