Plehnia cascaisensis sp. nov. Histological sections are postero-anteriorly oriented: A. Dorsal view of a living specimen (holotype, MNHNC MB16-000107); B. Dorsal view of a living specimen (additional material, MB16-000108); C. Detail of the eyes (additional material); D. Histological section of the tentacle (holotype); E. Histological section of the male copulatory organs (holotype); F. Histological section of the male and female organs (holotype). Abbreviations: cg, cemental glands; el, epithelial lining; ev, external vagina; fp, female pore; iv, internal vagina; ma, male atrium; mp, male pore; mw, muscular wall; ov, oviduct; ph, pharynx; pp, penis papilla; pv, prostatic vesicle; t, tentacle; vg, vesicular glands.