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| Zygantroides serpulidicola Oya, Tsuyuki & Kajihara, 2020 |
We describe a new species of ilyplanid polyclad, Zygantroides serpulidicola sp. nov., from Amakusa, Kumamoto, Japan. This is the third member of Zygantroides Faubel, 1983 and the first record of the genus from the Pacific Ocean. Zygantroides serpulidicola sp. nov. is characterized by i) the mouth opening near the common gonopore, ii) the sperm ducts separately entering a pear-shaped seminal vesicle, iii) an elongated Lang’s-vesicle duct, and iv) the horseshoe-shaped Lang’s vesicle located posterior to the common gonopore. We provide a partial sequence of the mitochondrial cytochrome c oxidase subunit I (COI) gene (712 bp) as a DNA barcode for the species. Our phylogenetic analyses based on concatenated sequences of the 16S, 18S, and 28S ribosomal DNA and COI indicate that Z. serpulidicola sp. nov. is nested in a clade comprised of Discocelidae and Ilyplanidae; the latter does not appear to be monophyletic.
Keywords: Acotylea, Discoceloidea, DNA barcoding, marine flatworm
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| Fig. 1. Photograph of a living individual of Zygantroides serpulidicola sp. nov. on tubes of serpulid annelids. |
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| Fig. 2. Zygantroides serpulidicola sp. nov., photographs taken in life. A, Dorsal view, ICHUM 6023 (holotype); B, dorsal view, ICHUM 6025 (paratype); C, ventral view, ICHUM 6023 (holotype). Abbreviations: ph, pharynx; sp, sperm duct. Scale bars: 5mm (A–C). |
Taxonomy
Genus Zygantroides Faubel, 1983
Redefinition. Ilyplanidae without tentacles and marginal
eyes. Pharynx somewhat oriented posteriorly. Genital tracts
entering separately into common genital atrium; male complex with seminal vesicle and papillate penis. Distal part of
ejaculatory duct lined with glandular ciliated epithelium.
Lang’s vesicle present (see Remarks).
Zygantroides serpulidicola sp. nov.
Etymology. The new specific name serpulidicola is a noun
in apposition and refers to the habit that the flatworms dwell
on tubes of serpulid annelids (Fig. 1).
Yuki Oya, Aoi Tsuyuki and Hiroshi Kajihara. 2020. A New Species of Zygantroides (Platyhelminthes: Polycladida) from Amakusa, Japan. Species Diversity. 25(2); 189–196. DOI: 10.12782/specdiv.25.189
