Haplocotyle japonica, Nitta & Nagasawa, 2017

Nitta, Masato & Nagasawa, Kazuya, 2017, Haplocotyle japonica n. gen., n. sp. (Monogenea: Microbothriidae) Parasitic on Rhinobatos hynnicephalus (Elasmobranchii: Rajiformes: Rhinobatidae) in Japanese Waters, Species Diversity 22, pp. 117-125 : 122

Haplocotyle japonica n. sp.

( Fig. 1 )

[New Japanese name: yamato-kagi-nashi-hada-mushi]

Holotype. Adult (NSMT-Pl 6167 collected on 24 June 2013).

Paratypes. Nine adults (NSMT-Pl 6168, 6289 collected on 24 June 2013) and four adults (NSMT-Pl 6290 collected on 6 July 2016).

Description. Body ( Fig. 1A ) elliptical, 2452–3983 (3253; n =14) long (including haptor), 1058–1471 (1301; n =14) wide. Haptor oval to fan-shaped, without sclerotized armature, 203–318 (248; n =13) long, 211–440 (307; n =13) wide. Eyes absent. Mouth opening sub-terminal of body; prepharynx with small buccal cavity connected anterior glands on each side; pharynx bell-shaped, 171–261 (214; n =13) long, 199–292 (248; n =13) wide with anterior aperture surrounded by papillae; esophagus short; bifurcate intestinal caecum with numerous diverticula leading laterally. Pair of excretory bladders located at same level as upper part of genital pouch.

Testis single, rounded, posterior to ovary, 213–407 (306, n =14) long, 316–501 (425, n =14) wide. Vas deferens exiting testis anteriorly, traveling medially on ventral side of body, left of oötype entering genital pouch at left posterior side, forming seminal vesicle, and connecting proximal part of male copulatory tract. Unsclerotized male copulatory organ ( Fig. 1B ) in elliptical genital pouch [219–473 (367, n =14) long, 403–520 (455, n =14) wide], consisting of muscular proximal part of male copulatory tract and distal part of male copulatory tract. Muscular proximal part of male copulatory tract, 282–413 (343, n =14) long, 130–195 (164, n =14) wide, divided into three parts; wall of proximal part of male copulatory tract formed to become thicker as closer to distal part of male copulatory tract. Distal part of male copulatory tract, 137–292 (221, n =14) long, 54–125 (84, n =14) wide, with small caliber at base, curving, widening, and connecting small male genital opening at ventral body surface in common genital pore located posterior of genital pouch. Interior surface of distal part of male copulatory tract covered by small papillae. Seminal vesicle and distal part of male copulatory tract surrounded by male accessory glands.

Ovary ( Fig. 1C ) lobate to round, in mid-body, 125–233 (187, n =14) long, 208–362 (278, n =14) wide. Oviduct arising from anterior part of ovary, connecting left side of ovovitelline duct. Unarmed vaginal pore on ventral surface, between right intestinal caecum and midpoint of oötype. Vaginal tube thin, extends to seminal receptacle ventrally. Seminal receptacle anterior of ovary, curving ventro-dorsally, ducting ovovitelline duct directly. Ovovitelline duct extending anteriorly, to base of oötype. Oötype thick-walled, traveling medially, meandering with top formed tetrahedral shape, and opening posterior to male genital opening in common genital pore. Mehlis’ glands located base of oötype. Vitellarium co-extensive with intestinal caecum. Transverse vitelline duct crossing laterally, at level of anterior portion of seminal receptacle, connecting right side of ovovitelline duct. Egg with long coiled filament ( Fig. 1D ), 105–142 (126, n =13) long, 98–125 (112, n =13) wide without filament, in oötype.

Type host. Rhinobatos hynnicephalus ( Elasmobranchii: Rajiformes: Rhinobatidae ).

Type locality. The central Seto Inland Sea off Ōsakikami-jima Island, Hiroshima Prefecture, Japan.

Other locality. The southern Sea of Japan off Tsuyazaki Port, Fukuoka Prefecture, Japan.

Sites of infection. Ventral skin and gill cavities.

Etymology. The specific name is derived from the locality, Japan.

Japanese name. The new Japanese specific name is based on the new Japanese generic name.

Sequence data. Two sequences of the 28S rDNA (842 bp) gene accorded and were submitted to DDBJ (accession no. LC150819 , LC228581 ). The phylogenetic analysis based on 28S rDNA sequences suggests that the new species shows affinity with Dermophthirius and Dermopristis ( Fig. 2 ).

Figures

Fig. 1. Haplocotyle japonica n. gen., n. sp. from Rhinobatos hynnicephalus. A–C, holotype (NSMT-Pl 6167); D, paratype (NSMT-Pl 6168). A, whole mount (ventral view); B, male copulatory organ; C, reproductive system; D, egg in oötype. Scale bars: A, 200µm; B–D, 100µm. Abbreviations: ag, anterior gland; bc, buccal cavity; cgp, common genital pore; dmc, distal part of male copulatory organ; eb, excretory blad- der; gp, genital pouch; h, haptor; in, intestinal caeca; m, mouth; mag, male accessory gland; mco, male copulatory organ; mg, Mehlis’ gland; mgo, male genital opening; o, oötype; od, oviduct; oo, opening of oötype; ov, ovary; ovd, ovovitelline duct; ph, pharynx; pmc, proximal part of male copulatory organ; sr, seminal receptacle; sv, seminal vesicle; t, testis; tv, transverse vitelline duct; v, vagina; vd, vas deferens; vi, vitellarium; vid, vitelline duct; vp, vaginal pore.

Fig. 2. Maximum likelihood (ML) tree for the Microbothriidae obtained using partial 28S rDNA sequences with Calicotyle japonica Kitamura, Ogawa, Shimizu, Kurashima, Mano, Taniuchi, and Hirose, 2010 (Monocotylidae), Benedenia seriolae (Yamaguti, 1934) and Capsala pricei Hidalgo-Escalente, 1959 (Capsalidae) as outgroups. Bootstrap values shown along the branches are based on 1,000 replicates for the ML and NJ analysis.