Aplysia atromarginata

(Original description in German) The specimen, which underwent a thorough examination, was notably contracted, measuring 16 mm in length with both a height and width of nine mm. Its rhinophores were three mm high, and its tentacles were almost the same size. The foot-flaps extended 11 mm (in a straight line) with a height of four mm. The mantle was ten mm long and eight mm wide, with the shell opening measuring 5.5 mm long and 4.5 mm wide. The mantle siphon was four mm long, and the gill six mm. The penis protruded freely, reaching a length of four mm. The foot sole was four mm wide. The animal's overall color was yellowish. The foot-flaps displayed a narrow black margin along their entire length, and a similar line bordered the mantle opening, creating a stark contrast with the chalk-white shell. The right mantle edge, which extended over the gill cavity, was a dark blue-gray for a width of 1.5 mm, and the foot edge was black. The shell was strongly hardened and chalk-white both externally and internally. It featured a relatively thick, yellow cuticle that easily detached in one piece. The shell itself measured 9 mm in length, 7.5 mm in width, and 3 mm in height. The nuclear part was significantly curved forward and downward. …