Discocelis tigrina ( Blanchard, 1847 ) Lang 1884

Noreña, Carolina, Rodríguez, Jorge, Pérez, Jacinto & Almon, Bruno, 2015, New Acotylea (Polycladida, Platyhelminthes) from the east coast of the North Atlantic Ocean with special mention of the Iberian littoral, Zootaxa 4039 (1), pp. 157-172 : 167-171

Discocelis tigrina ( Blanchard, 1847) Lang 1884

Figure 6

Material examined. All specimens were captured in Galicia, Spain. One specimen from "Os Esqueiros", Ría de Arousa, (10/12/2011). 42º56.083'N; 08º56.083'W. Two specimens from "A Ameixida", Ría de Arousa, (20/03/2014 and 28/01/2015). 42º32.058'N; 08º59.309'W. One specimen from "Beluso", Ría de Pontevedra, (6/12/2014). 42º20.145'N; 08º47.970'W.

Description. Fixed worms 30 mm long and 15 mm wide. Body shape elongated with rounded anterior and posterior ends. Dorsal surface beige with brown spots of several sizes, light wavy margins sometimes smooth ( Fig. 6 A, B). Dorsal surface smooth and whitish ( Fig. 6 C). Without tentacles. Marginal, tentacular and cerebral eyes clusters present. Brain between the tentacular and cerebral eyes. Oral pore ventral, anterior body end; pharynx ruffled with deep pharyngeal folds. Male and female systems open through a common genital pore at the last third of the body. Ovaries dorsal and well developed.

Reproductive system ( Fig. 6 E,F). The male and female copulatory system are arranged near the posterior body margin. They open to a common genital atrium. Male system consists of two voluminous lobes bearing the prostatoid organs. Vasa deferentia, swollen in spermiducal vesicles and open into the ejaculatory duct. The ejaculatory duct runs between the atrial male lobes into the dorsolateral region of the common genital atrium.

The slender vagina externa opens into the common atrium genitale. In the studied exemplars the characteristic kidney-shaped Lang’s vesicle was not developed, therefore the form and structure of the same cannot be described. Shell glands cover the distal region of the vagina. Ovaries dorsal.

Biology. Discocelis tigrina was found in several locations in Galicia, always under partially buried stones on sandy bottoms. Depth range for captured specimens varied between 5 and 20 m. Living worms were approximately 40 mm long and 25 mm wide when moving.

Most specimens were found resting inside a mucous sheath, probably self-secreted. These sheaths were found throughout the year, suggesting that they are not a seasonal phenomenon.

Distribution ( Fig. 1 ). Peninsula de Río de Oro, Western Sahara; and Nouadhibou (formerly Port-Étienne), Mauritania ( Palombi, 1939). Gulf of Naples, Italy ( Lang, 1884). Within the Iberian Peninsula, Discocelis tigrina was record previously for Catalonia ( Novell, 2003) and Asturias, Spain (Marquina et al. 2014a). This is the first record for the North Atlantic shores.

Figures

FIGURE 1. Studied Acotylea species distribution. A, Acotylea distribution in Europe; B, Acotylea distribution in the Iberian Peninsula; C, Acotylea distribution in Galicia, Spain; D, Cryptocelis compacta (green dots); E, Hoploplana elisabelloi n. sp. (orange dots); F, Discocelis tigrina (purple dots); G, Armatoplana celta n. sp. (grey dots); H, Stylochus neapolitanus (blue dots).

FIGURE 6. Discocelis tigrina (Blanchard, 1847) Lang 1884. A – D, living specimens; E, sagittal reconstruction of a whole specimen; F, sagittal reconstruction of the reproductive system (anterior to the right). Abbreviations: ca, common atrium; cgo, common genital opening; i, intestine; Lv, Lang’s vesicle; m, muscle layers; ml, male lobes; ofgs, opening of the female genital system; op, oral pore; ph, pharynx; po, prostatoid organs; spv, spermiducal vesicle; te, tentacular eyes.