Three species of Dendromonocotyle Hargis, 1955 (Monogenea: Monocotylidae) collected from Japanese rays.

Eighteen species of Dendromonocotyle Hargis, 1955 (Monogenea: Monocotylidae) have so far been described from elasmobranchs worldwide. In this paper, two new species are described; Dendromonocotyle tsutsumii n. sp. from the skin of the Japanese eagle ray, Myliobatis tobijei Bleeker from Tokyo Bay and the pitted stingray, Dasyatis matsubarai Miyosi, from Ooarai, Ibaraki Prefecture, Japan, and Dendromonocotyle fukushimaensis n. sp. from the skin of the cow stingray, Dasyatis ushiei (Jordan & Hubbs) reared at an aquarium in Fukushima Prefecture, Japan. Dendromonocotyle tsutsumii is distinguished from the congeners by the presence of a sclerotised duct connecting the vagina with the seminal receptacle, and De. fukushimaensis by the large body size and the presence of a donut-shaped structure encircling the male copulatory organ near its distal end. Additionally, the reproductive system of Dendromonocotyle akajeii Ho & Perkins, 1980 is redescribed, based on specimens from the skin of the whip stingray, Hemitrygon akajei (Müller & Henle) (syn. Dasyatis akajei) caught in Hamana Lake, Shizuoka Prefecture, Japan. A key to the 20 species of Dendromonocotyle including the present new species is provided.