Melloplana japonica ( Kato, 1937 )

Rodríguez, Jorge, Grande, Cristina, Bulnes, NataliaVeronica, Almon, Bruno, Perez, Jacinto & Noreña, Carolina, 2017, Systematic revision of the family Pleioplanidae Faubel, 1983 (Polycladida, Acotylea): new genus and combinations, European Journal of Taxonomy 264, pp. 1-30 : 25-26

Melloplana japonica ( Kato, 1937) .

Fig. 6D

Notoplana japonica Kato, 1937: 215–216 , figs 5–6, pl. XIV, figs 6–7.

Melloplana japonica – Faubel 1983: 117.

Type locality

JAPAN: Kanayama (Yuzaki, Yunosaki).

Description

Body shape elongated. Cryptic colour. Opaque dorsal appearance. Longitudinal median line not outstanding. Without mottled background. Smooth dorsal surface. Nuchal tentacles absent. Tentacular knobs present. Marginal eyes absent. Tentacles absent; instead tentacular eyes present in rounded and compact clusters. Dorsal and ventral frontal eyes absent. Cerebral eyes in two groups. Pharynx located in second or last body third, strongly ruffled and ventrally oriented. Oral pore position in second body third and in posterior region of pharynx. Intestine with numerous branches without anastomosis. Intestinal vesicles absent. Gonopores clearly separated.

MALE REPRODUCTIVE SYSTEM. Single male pore. Male apparatus not enclosed within muscular bulb, oriented backwards and located in second body third. Ejaculatory duct unarmed, without stylet. Prostatic

vesicle interpolated. Connection between ejaculatory duct and prostatic vesicle with projection. Internal glandular lining of prostatic vesicle with tubular chambers. Extravesicular prostatic secretion. Prostatic glands located at proximal end of prostatic vesicle. Seminal vesicle simple or spindle-like. Spermiducal bulbs absent.

FEMALE REPRODUCTIVE SYSTEM. Vagina elongated, tube-like, looping towards male complex. Enlarged Lang’s vesicle. Paired uterus. Uterine vesicles absent. Tube-like cement chamber. Endolecithal eggs.

Biology

Specimens were collected from the undersurface of stones deeply embedded in the sand at low tide during spring and summer.

Distribution

Japan.

Phylogenetic analysis

The obtained tree had a length of 55 steps and had the following values: Consistency index (CI) = 0.6000; Homoplasy index (HI) = 0.4000; CI excluding uninformative characters = 0.5417; HI excluding uninformative characters = 0.4583; Retention index (RI) = 0.5510 and Rescaled consistency index (RC) = 0.3306.

The recovered topologies from both trees (MP and NJ) support the genus Persica as the sister taxon of all other family members ( Fig. 7 ). In addition, the genera Melloplana , Pleioplana and Laqueusplana gen. nov. group together in a well-supported clade (BP=100), with Izmira as the sister group of this clade. Furthermore, based on the NJ tree, Pleioplana atomata and the two species belonging to Laqueusplana gen. nov. show greater similarity to the Melloplana species than to the other Pleioplana species.

Figures

Fig. 6. Schematic representations comparing the copulatory apparatus. A. Laqueusplana bocki gen. et sp. nov. B. L. megala (Marcus, 1952) comb. nov. C. Melloplana ferruginea (Schmarda, 1859). D. M. japonica (Kato, 1937).

Fig. 7. Maximum parsimony and NJtrees obtainedfrom analyses of Pleioplanidaebased on morphological data. The MP tree is shown on the left with bootstrap values indicated at the nodes. The NJ tree is shown on the right.