Trigonoporus cephalophtalmus Lang, 1884

Marquina, Daniel, Osca, David, Rodríguez, Jorge, Fernández-Despiau, Estrella & Noreña, Carolina, 2014, State of knowledge of the Acotylea (Polycladida, Platyhelminthes) from the Mediterranean coasts of Spain: new records and new species, Zootaxa 3780 (1), pp. 108-134 : 117

Trigonoporus cephalophtalmus Lang, 1884

Figs. 1 (3), 6, 7

Material examined. Three mature specimens, collected in the Columbretes and Hormigas Islands and Alborán Island from rocky substrate found at 14.3, 23.5 and 36 metres deep, respectively for each location; Fig. 1 (3).

Description. Fixed specimen is approximately 2 cm long by 5 mm wide. Very elongated body. Colour whitishyellow, partially lost during conservation, with numerous and small brown spots ( Fig. 6 A). Region between the brain and the anterior margin strewn with numerous small eyes spreading out in a fan-like manner ( Fig. 6 B). Marginal eyes arranged along the frontal margin of the body. Tentacles and tentacular eyes lacking. Brain located about 2 mm from the anterior margin ( Figs. 6 C, 7C). Ruffled pharynx situated in the middle third of the body with the oral pore opening in the centre of it. Ovaries dorsal. Separated gonopores ( Fig. 6 C).

Male copulatory complex directed backwards, near the pharyngeal cavity ( Fig. 6 D). Vasa deferentia occupy the middle third of the body due to being dilated, and open laterally into a tubular seminal vesicle thickened in the junctions region ( Figs. 6 D, 7D).The ejaculatory duct runs ventrally from the seminal vesicle to the proximal end of the prostatic vesicle. The prostatic vesicle has a strong muscular envelope and is lined with a smooth and folded glandular epithelium ( Fig. 7 B). The penis papilla, small and unarmed, is conical-shaped, with a strong muscular envelope, housed in a wide, ciliated atrium.

The epidermis around the female pore appears corrugated, forming an adhesive pad ( Figs. 6 D, 7A). The female system consists of an external and internal vagina. The short narrow external vagina runs from the gonopore upwardsto the internal vagina. The internal vagina ascends from the proximal region of the external vagina, curves downwards and backwards and, after receiving the oviducts, continues to the ductus vaginalis. Oviducts lead separately into the middle of the internal vagina. Proximal tract of the internal vagina runs forwards, receiving secretions from the well developed cement glands. Lang’s vesicle lacking. The ductus vaginalis opens to the exterior behind the female pore.

Distribution. Trigonoporus cephalophtalmus has only been found once in the Gulf of Naples, Italy ( Lang 1884). This is the first record for this species both outside of the Gulf of Naples and for the Iberian Peninsula.

Figures

FIGURE 1. Distribution map of examined specimens. General views of A the eastern coast of the Iberian Peninsula, B Mar Menor (Murcia). Numbers: Notoplanella inarmata (1), Notoplanella estelae sp. nov. (2), Trigonoporus cephalophtalmus (3), Leptoplana mediterranea (4), Planocera graffi (5), Imogine mediterranea (6), Imogine stellae sp. nov. (7), Stylochus neapolitanus (8), Stylochus pilidium (9).

FIGURE 6. Trigonoporus cephalophtalmus (Lang, 1884). A Habitus; B, C eyes; D sagittal reconstruction of the whole animal (anterior to the left); E sagittal reconstruction of the male and female genital systems (anterior to the left). Abbreviations: b, brain; cg, cement glands; dv, ductus vaginalis; e, eyes; ed, ejaculatory duct; ev, external vagina; fp, female pore; i, intestine; m, mouth; mp, male pore; o, ovary; ov, oviduct; ph, pharynx; pp, penis papilla; pv, prostatic vesicle; sv, seminal vesicle; vd, vas deferens. Scale bars: A 1 cm, B 2 mm, C 5 mm, D 5 mm, E 500 µm.

FIGURE 7. Histological sections of Trigonoporus cephalophtalmus (Lang, 1884). A eyes; B vas deferens and seminal vesicle; C prostatic vesicle and penis papilla; D female reproductive system. Anterior to the left in all figures. Abbreviations: b, brain; cg, cement glands, d, ductus vaginalis; e, eyes; ed, ejaculatory duct; ev, external vagina; fp, female pore; mp, male pore; pp, penis papilla; pv; prostatic vesicle; sv, seminal vesicle; vd, vas deferens. Scale bars: A 1 mm, B, C, D 500 µm.