Leptoplana mediterranea (Bock, 1913)

Gammoudi, Mehrez, Bulnes, Verónica N. & Kurt, Güley, 2022, The polyclad fauna (Platyhelminthes, Rhabditophora) of the Sinop Peninsula (Black Sea, Turkey) with a description of a new species of Cryptocelis Lang, 1884 Abstract, Mediterranean Marine Science (Hong Kong, China) 22 (1), pp. 141-156 : 152-153

Leptoplana mediterranea (Bock, 1913)

( Figs. 6B and 8C )

Material examined. Ten specimens, 23.10.2013, M5, 5 m deep. Three specimens, 02.07.2014, station M5, 5 m deep. Two specimens were sagittally sectioned (7 slides and 6 slides).

Description. Body broadest anteriorly, tapering distally. Preserved specimens between 10-22 mm long and 4-8 mm wide. Tentacles lacking. Genital pit present. Cerebral eyes clusters distributed over the brain region, extending distally up to the area of the tentacular eyes. The tentacular eyes bigger than the cerebral ones ( Fig. 8C ).

Digestive system. Pharynx located in the posterior second third of the body. The deeply ruffled pharynx may develop up to 16 pairs of folds. Mouth opening in the second half of the body in the posterior third of the pharyngeal pocket.

Reproductive system. Testes are disposed in ventral parenchyma between digestive ramifications, whereas ovaries are arranged dorsally. Vasa deferentia extend anteriorly up to the level of the last third of pharynx, then turn posteriorly and join in a common vas deferens before entering a developed oval seminal vesicle ( Fig. 6B ). The interpolated prostatic vesicle slender, elongated, arranged ventrally to the seminal vesicle. The prostatic vesicle extends anteriorly up to the level of the union of the common vas deferens to the seminal vesicle. The anterior section of the prostatic vesicle, or diverticulum (proximal chamber after Marquina et al. 2014, p. 117), is arranged ventrally alongside the seminal vesicle. The ventral margin of the seminal vesicle is divided from the dorsal limit of the prostatic diverticulum by a common layer of cuboidal epithelial cells. The ejaculatory duct link the distal portion of the seminal vesicle to the distal section of the prostatic vesicle, near the connection to the short unarmed cirrus. With a distinct male atrium and male gonopore. Genital sucker present.

The female gonopore is located 2 mm behind male gonopore. The external vagina extends vertically, curves anteriorly, immersed in a dense mass of cement glands. The internal vagina receives ventrally the paired uterine ducts.

Remarks. The observed characters agree with the specimens described from Tunisia ( Gammoudi et al., 2012) and Spain ( Marquina et al., 2014). This is the first record from the oriental basin of the Mediterranean Sea.

Figures

Fig. 6: Sagittal sections of the reproductive system of A, Echinoplana celerrima; B, Leptoplana mediterranea; C, Leptoplana tremellaris. Abbreviations to the figures: cb, cirrus bulb; cg, cement glands; cr, cirrus; ed, ejaculatory duct; mp, male gonopore; ph, pharynx; pv, prostatic vesicle; sv, seminal vesicle; vd, vas deferens. Scale bars: A: 500 µm; B: 200 µm; C: 500 µm.

Fig. 8: Pleioplana okusi. A, sagittal section of the prostatic vesicle; B, sagittal section of the ovary; C-D, sagittal section of the vagina and female atrium. The arrows point the sperm mass. Abbreviations to the figures: ch, tubular chamber of the prostatic vesicle; ed, ejaculatory duct; fg, female gonopore; o, ovary; pi, epidermal pigment; pp, penis papilla; pv, prostatic vesicle. Scale bars: A: 100 µm; B: 50 µm; C: 30 µm; D: 50 µm.