Pleioplana bosphorensis, Bulnes & Kalkan & Karhan, 2009

Bulnes, Verónica Natalia, Kalkan, Evrim & Karhan, Selahattin Ünsal, 2009, Two new Pleioplana species (Platyhelminthes, Polycladida, Acotylea) from Turkey, Journal of Natural History (J. Nat. Hist.) 43 (37 - 38), pp. 2273-2281 : 2274-2277

Pleioplana bosphorensis sp. nov.

( Figures 1 , 2 )

Type material

Holotype 9.0 µm sagittally sectioned specimen, mounted on eight slides. Altinkum , Bosphorus Strait, Turkey, 41°11′21.22′′ N, 29°04′57.10′′ E, from hard-bottom mussel bed of M. galloprovincialis , collected by E. Kalkan, 6 March 2005. BMNH 2007.9 .26.2

Additional material examined

Two specimens from Altinkum, Bosphorus Strait, collected from hard-bottom mussel bed of M. galloprovincialis by E. Kalkan, 6 March 2005. Nine specimens from Gelibolu, Dardanelles Strait, collected from hard-bottom mussel bed of M. galloprovincialis by S.Ü. Karhan, 4 June 2005.

Etymology

The specific epithet alludes to the type locality, the Bosphorus Strait in Turkey .

Description

Fixed specimens about 8 mm in length and 4 mm in width. Body oval, of fleshy consistency, with few smooth marginal undulations along body ( Figure 1A ). Body surface with yellowish ground colour, speckled with tiny black or brownish-black spots uniformly distributed. Tentacles absent. Tentacular eyes present, cerebral eye spots in two scattered clusters. Ruffled pharynx long, almost one-third of body length, centrally arranged at mid-body and mouth opening posterior in the pharyngeal cavity.

Ventral body wall 70 µm high ( Figure 1B ). Epidermis completely ciliated, cellular, with intraepithelial nuclei and dermal rhabdites. The cilia are covered with a dense film of slimy secretion. Ventral body wall consists of a basement membrane, underlain by a thin circular muscle layer, followed by a well-developed longitudinal muscle layer, and a loose circular layer. Transverse muscle fibres well differentiated. Granular pigmentation in scattered patches.

Dorsal body wall 73 µm high ( Figure 1C ). The cellular ciliated epidermis is higher than the ventral one. Dermal rhabdites densely packed. Beneath the well-differentiated basement membrane, a frail layer of circular muscle fibres is present, followed subsequently by a longitudinal and a circular muscle layer. Pigment granules evenly distributed between the muscular fibres.

Ovaries situated dorsally ( Figure 1D ), testes ventral. The vasa deferentia expand to spermiducal bulbs.

The male reproductive system consists of a true seminal vesicle, an interpolated prostatic vesicle and a stylet ( Figure 1E ). The vasa deferentia enter separately the anteroventral side of the oval-shaped seminal vesicle, which has a distinct muscular wall. Prostatic vesicle rounded with a strong muscular wall; its inner lining is folded to form a few tubular chambers ( Figure 2 A,B ). The ejaculatory duct projects distally into the prostatic vesicle and is lined with a simple, cuboidal and ciliated epithelium. The four tubular chambers are not immediately attached to the ejaculatory duct and open into the distal lumen of the prostatic vesicle. The lining of the prostatic vesicle is a ciliated simple columnar epithelium of glandular nature. Beneath the epithelium some radial muscular fibres are mixed with the glandular cells.

The prostatic duct projects into the ciliated male atrium. With the exception of its proximal part, the prostatic duct is internally and externally sclerotized, forming a cylindrical–pyramidal, two-layered stylet ( Figure 2C ).

The stylet is large, strong, conical, straight and measures 198 µm in length. Proximally it is broader (100 µm in diameter), distally pointed (15 µm in diameter).

The oviducts join medially before entering the vagina from the ventral side. From this point and backwards, a muscularized ciliated female canal curves posteriad and leads to a small Lang’s vesicle. The latter is provided with short and densely packed cilia. From the oviducal opening the female canal follows an abrupt ventrally directed turn and opens into a bulbous vagina. The inner lining of the vagina is deeply wrinkled ( Figure 2D ), consisting of columnar cells; these cells are of glandular nature and have scattered long cilia. The glandular epithelium of the vagina is bounded by longitudinal and circular muscle fibres and is also surrounded by numerous cement glands. The vagina opens via a short, ciliated female atrium to the exterior via a ventral female pore.

Figures

Figure 1. Pleioplana bosphorensis sp. nov. (A) Photographs of the holotype in dorsal (top) and ventral (below) view; (B) sagittal reconstruction of ventral body wall, (C) sagittal reconstruction of dorsal body wall; (D) sagittal view of entire animal; (E) sagittal reconstruction of the copulatory organs. Scale bars: (A) 4 mm; (B) 40 µm; (C) 35 µm; (D) 2 mm; (E) 300 µm.

Figure 2. Pleioplana bosphorensis sp. nov. (A) Photomicrograph of transverse view of prostatic vesicle; (B) transverse view of prostatic vesicle; (C) stylet; (D) sagittal reconstruction of the wall of the vagina. Scale bars: (A, B and D) 100 µm; (C) 80 µm.