Leptoplana mediterranea ( Bock, 1913 ) Bock, 1913

Gammoudi, Mehrez, Egger, Bernhard, Tekaya, Saïda & Noreña, Carolina, 2012, The genus Leptoplana (Leptoplanidae, Polycladida) in the Mediterranean basin. Redescription of the species Leptoplana mediterranea (Bock, 1913) comb. nov., Zootaxa 3178, pp. 45-56 : 47-49

publication ID	https://doi.org/ 10.5281/zenodo.214240
DOI	https://doi.org/10.5281/zenodo.6170837
persistent identifier	https://treatment.plazi.org/id/03B787A9-FFE3-FFB0-028F-E25EFC6ACB4D
treatment provided by	Plazi
scientific name	Leptoplana mediterranea ( Bock, 1913 )
status	comb. nov.

Treatment

Leptoplana mediterranea ( Bock, 1913) comb. nov.

Material examined: A total of 74 specimens were collected. Ten of them were sagittally sectioned, the rest of the specimens served for study of reproduction and embryonic development.

Material deposited (Voucher): One specimen as serial sections (18 slides). Collected on the 4th August, 2009 and deposited in the Museo Nacional de Ciencias Naturales, Madrid. MNCN 4.01/57.

Type locality: Lake of Tunis (36° 49' 06.61" N; 10° 17' 23.37" E). Specimens were collected from under rocks in the Lake of Tunis, Tunisia, a natural lagoon between the city of Tunis and the Gulf of Tunis.

Etymology: Name given by Bock (1913) to the forma “ mediterranea ” of Leptoplana tremellaris and for the geographical area of distribution.

External features: Leptoplana mediterranea showed two distinct colour morphotypes, found in the same locality ( Figs. 1 View FIGURE 1 A–B).

The first morphotype (40 specimens), with a translucent dorsal surface, with a white marginal rim. The digestive branches apparent, which ramify from the main intestine towards the periphery. The digestive branches appear to anastomose only in the pharyngeal region ( Fig. 1 View FIGURE 1 A).

The second morphotype (34 specimens) with beige dorsal surface and with brown speckles. Pigmentation occurs and is more concentrated in the pharyngeal median region. Digestive ramifications were not apparent ( Fig. 1 View FIGURE 1 B).

Both morphotypes with an elongate oval body form. The largest specimen was 33 mm long and 20 mm wide, while.the smallest one was 25 mm long and 16 mm wide. The body is rounded anteriorly and tapering posteriorly. The maximal width is situated at the level of the anterior third of the flattened body. Tentacles are absent. The cerebral organ is situated near or under the eyes. The eyes are arranged in two groups on either side of the median line. The cerebral eyes are smaller and arranged deeper, the tentacular eyes are arranged posteriorly to the cerebral eyes and lying more superficially ( Fig. 1 View FIGURE 1 A–C).

The surface is covered with a ciliated cellular epidermis; the basal membrane is two times thicker dorsally than ventrally. The rod-like rhabdites are located between epidermal cells, and are more numerous dorsally than ventrally. The body wall musculature is more developed ventrally than dorsally. The mouth is situated ventrally behind the middle of the body and opens in the posterior third of the pharyngeal pocket. The plicate ruffled pharynx is located in the first two thirds of the body and has up to 15 pairs of heavy folds. The opening of the intestine into the pharynx is directly above the mouth.

Reproductive system: In live animals, the sperm ducts extend anteriorly on both sides of the pharynx and then turn posteriorly (M-shaped) ( Fig. 1 View FIGURE 1 D) and join in a common expanded sperm duct which curves dorsally to enter the seminal vesicle. The latter is identified easily in vivo: dorsally, as a whitish mass just behind the pharynx and ventrally as a white oval vesicle seen clearly by transparency. The uteri extend from behind the seminal vesicle up to behind the brain, where they converge ( Fig. 3 View FIGURE 3 F).

Two genital pores are evident in the ventral face, between them and closer to the female pore is the genital pit. The genital pit is a depression of the ventral wall of epidermal nature, also known as genital sucker (Rawlinson et al 2008), but not comparable with the true sucker of the Cotylea due to a lack of characteristic muscle-layers and the position between the genital openings instead of posterior to them ( Figs. 1 View FIGURE 1 E–F; 3F).

Internally, the male apparatus is situated inside a muscular bulb.

The vasa deferentia arise in the ventral parenchyma and open together into a common vas deferens which communicates with a well developed (about 400 µm thick and 600 µm long) oval shaped seminal vesicle ( Figs. 1 View FIGURE 1 D–F; 2A). In some specimens, the seminal vesicle occupies more than two thirds of the whole thickness and it is usually filled with spermatozoa.

The interpolated prostatic vesicle is divided into three sections: proximal, median and distal. The proximal section is an elongated diverticulum which extends along the ventral side of the seminal vesicle to the entrance of the common vas deferens ( Figs. 1 View FIGURE 1 E-F). Besides the contact zone, both vesicles are separated only by an epithelial common wall, whose ventral side is of a cubic nature ( Figs 1 View FIGURE 1 F; 2E). There is no musculature between the prostatic and the seminal vesicle. The median section of the prostatic vesicle is orientated dorsally and opens into the dorso-distal region of the seminal vesicle via a narrow opening. The lumen of the distal section of the prostatic vesicle forms a small chamber which opens to the proximal part of the ejaculatory duct, the unarmed penis cirrus. The latter leads to the male atrium that shows a dorso-posteriorly oriented diverticulum. This diverticulum is of various sizes and can reach half of the animal's thickness in some specimens. The male genital pore is wider than the female one.

The oocytes are formed within the ovaries that are mainly distributed dorsally. The eggs in the ovaries show shell granules in the cytoplasm while the eggs in the uterus show a thick layer of granules in the periphery.

The paired uterine ducts unite in a short and narrow common one ( Fig. 3 View FIGURE 3 F) which opens ventrally into the vagina interna ( Figs. 1 View FIGURE 1 E–F; 2B). The vagina interna extends posteriorly and sometimes can develop a rudimentary Lang’s vesicle. Extending anteriorly, the vagina media is forming a reverse “question mark” ( Figs. 1 View FIGURE 1 E–F; 2B). The vagina media is accompanied by a well developed mass of shell glands. The backward curve of the vagina media to the vagina interna (the reverse “question mark”) is common in polyclads. Just before this backward turn, the vagina media shows a spiral folded epithelium ( Fig. 2 View FIGURE 2 B). The vagina externa ( Fig. 2 View FIGURE 2 C) leads then to the female genital pore located in the midventral line. The female pore is about 2 mm behind the male pore. In some specimens, eosinophilous secretions were observed in the lumen of both vagina externa and vagina media. Other specimens showed a huge mass of spermatozoa in the vagina externa ( Fig. 3 View FIGURE 3 D).