Munseoma maculata, Bulnes & Faubel & Park, 2005

Bulnes, V. N., Faubel, A. & Park, J. - K., 2005, Two new marine species from South Korea with remarks on the family Stylochidae (Acotylea, Polycladida, Plathelminthes), Journal of Natural History (J. Nat. Hist.) 39 (23), pp. 2089-2107 : 2104-2106

Munseoma maculata sp. nov.

( Figure 6 )

Material examined

Holotype: one specimen from intertidal coral rocky ground of Munseom Island , Jeju-do Province, Korea, 126 ° 349080E, 33 ° 139280N; leg. Dr Hyun Soo Rho; one specimen in sagittal serial section, deposited in ZMUH, V 13243 . Paratype: one specimen from intertidal coral rocky ground of Munseom Island , Jeju-do Province, Korea, 126 ° 349080E, 33 ° 139280N; leg. Dr Hyun Soo Rho, 16 October 2001 ; one specimen in sagittal serial section, deposited in ZMUH, V 13244 .

Habitat. Eulittoral benthal, crevice of empty oyster shell attached on coral rocky ground, marine.

Etymology

The specific name refers to the maculated pattern of the body surface.

Description

Outline of preserved specimen with anterior slightly rounded, oval with elongated terminal end. Body 19.5 mm long and 14 mm wide. Opaque, compact, with 1–1.5 mm varying width. In incident light, basic coloration yellowish with specific dark brown pattern, ventral surface white. Cerebral and frontal eyes present; marginal eyes numerous and line the periphery of the body in clusters with an apparently random distribution, never forming a distinct band along the margin; on the dorsal surface eyes scattered more densely in the anterior half than in the posterior. Dorsal eyes are only to see when serial sections examined because of the dark brown pattern of the specimens ( Figure 6A ).

Brain encapsulated, bilobed, and located mid-ventrally below intestinal ramification.

Pharynx ruffled; mouth ventral, in posterior half of pharyngeal cavity, opens to the exterior posteriorly to mid-body. Intestine occupies most of the body, reaching the frontal and distal end, widely ramified.

Body completely ciliated; dorsal epidermis 80.26 mm thick and underlain by a welldeveloped basal membrane. Body muscle wall with outer circular layer, followed interiad by a longitudinal and a diagonal layer. Granular pigmentation inter-muscular, between layer of circular and longitudinal muscle fibres. Ventral body muscle wall thicker than dorsal, mean 173 mm. Epidermis underlain by a well-developed basal membrane followed by circular, longitudinal, circular and longitudinal muscle layers; the outer circular layer is very thin and the innermost longitudinal layer represents a loose texture of muscle fibres ( Figure 6B ).

Reproductive system. Bilateral testes follicles ventral, numerous in front of the pharynx and oogonia of bilateral ovaries between intestinal branches with dorsal orientation, welldeveloped, widely distributed. The male copulatory apparatus consists of spermiducal bulbs, small free prostatic vesicle, and penis papilla. True seminal vesicle absent. Paired vasa deferentia lead posteriad and combine to form a common vas deferens with numerous spermiducal bulbs containing sperm. The prostatic vesicle, an open, sac-shaped indentation of the ejaculatory duct, extends proximad from the entrance of the common vas deferens; its glandular lining is smooth. A prostatic duct is absent. The ejaculatory duct opens at the tip of the penis papilla. Penis papilla housed in small distal ciliated atrium. The female apparatus consists of female atrium, vagina and Lang’s vesicle. From the female gonopore, the vagina arises dorsad, then curves posteriad and passes into Lang’s vesicle. The duct of the vagina posteriad directed, is received by the oviducts from latero-dorsal. The proximal part of the vagina and Lang’s vesicle ciliated; the distal part of the vagina and female atrium entered by cement glands, the lining of which is rich in glands ( Figure 6C ).

Discussion

After Hyman (1953), the Callioplanidae are Stylochoidea with a ruffled pharynx arranged centrally or somewhat anteriorly to the centre of the body. Male copulatory apparatus is directed backwards or perpendicularly; with true ejaculatory duct and free prostatic vesicle. The prostatic vesicle is provided with a smooth glandular lining. Considering the diagnostic characters of the Callioplanidae , the new species Munseoma maculata is a member of this family.

At present, 12 genera are placed within the Callioplanidae . The new genus Munseoma has been erected for the described species in this paper because the combination of characters is unknown for any existing genus of Callioplanidae . The absence of a true seminal vesicle, the nature of the prostatic vesicle, and therefore, the restriction of the prostatic duct to the ejaculatory duct, characterizes the new genus Munseoma . On the basis of the presence of Lang’s vesicle and an unarmed penis papilla, M. maculata resembles most closely the species of the genera Crassiplana Hyman, 1955 and Koinostylochus Faubel, 1983 . The most conspicuous autapomorphies of the genera are as follows: in species of Crassiplana the female copulatory apparatus is directed backwards, in species of Koinostylochus the female copulatory apparatus is directed forwards, and the seminal vesicle is absent in Munseoma maculata . That clearly justifies the establishment of the monotypic genus Munseoma within the Callioplanidae .

Figures

Figure 6. Munseoma maculata gen. et sp. nov. (A) Dorsal view of fixed specimen; (B) sagittal reconstruction of whole organism; (C) sagittal reconstruction of male and female genital system. Scale bars: 8 mm (A); 5 mm (B); 6 mm (C).