Stylochus neapolitanus Lang, 1884

Pérez-García, Patricia, Gouveia, Filipa, Calado, Gonçalo, Noreña, Carolina & Cervera, Juan Lucas, 2024, Acotylea (Platyhelminthes, Polycladida) from the southern and western Iberian Peninsula, with the description of five new species, Zoosystematics and Evolution 100 (4), pp. 1487-1513 : 1487-1513

Stylochus neapolitanus Lang, 1884

Fig. 2

Planaria neapolitana Delle Chiaje, 1841 –1844.

Material examined.

• MNCN 4.01/3281 to 3334, Station 11 , 23 February 2015, 28 mm long, sagittaly sectioned into 54 slides. All of the measurements from the description refer to this specimen .

The specimen from Station 3 was damaged during transport to the laboratory. However, it could be photographed in situ. This information has been added to the material as a comment.

Description.

Stylochus neapolitanus from Cadiz agrees with the original description of the species by Lang 1884.

Body shape elongated, with pointed anterior and rounded posterior end, 28 mm long alive. Dorsal surface with dark brown background colour with scattered whitish and greenish spots (Fig. 2 A ), larger at the margins and smaller in the body centre. An orange band surrounds the margins. Ventral whitish (Fig. 2 B ). Nuchal tentacles conical, white, and with remarkable orange spots on the tips. Tentacular eyes at the base and on the tentacles. Cerebral eyes between tentacles. Marginal eyes present only in the anterior margin. Pharynx ruffled, with well-developed lateral branches (Fig. 2 B ). Oral pore at the centre of the pharynx. Male and female pores separated (0.2 mm) and located near the posterior end.

Reproductive system.

Male copulatory apparatus with a true seminal vesicle, an oval prostatic vesicle, and a small penis papilla. Elongated seminal vesicle 0.7 mm in length. Free prostatic vesicle surrounded by extravesicular glands. Short penis papilla housed in a small atrium. Sperm and prostatic ducts join medially. Female apparatus consists of a folded external vagina and a smooth internal vagina (Fig. 2 D, E ). Well-developed cement gland surrounds the external vagina. Internal vagina extends backwards, receiving the oviducts at the end. Lang’s vesicle absent.

Biology.

This species was found among samples of the alga Dictyota dichotoma ( Phaeophyceae, Ochrophyta) collected from rocky substrates in intertidal areas. Previously, it was also collected in substrate covered by the green algae Caulerpa prolifera (Forsskal) J. V. Lamouroux 1809 (Chlorophyta, Caulerpaceae ) ( Marquina et al. 2014 a) or on the bottom surface of barges and lamellibranch empty shells ( Noreña et al. 2015).

Distribution.

Stylochus neapolitanus was recorded in Sicily, Naples ( Lang 1884), Cape Verde ( Laidlaw 1906), Senegal ( Palombi 1939), Catalonia ( Novell 2001, Murcia ( Marquina et al. 2014 a), Galicia ( Noreña et al. 2015), and Sidi Ifni ( Cuadrado et al. 2021). This is the first report of S. neapolitanus in Andalusia.

Figures

Figure 2. Stylochus neapolitanus (MNCN 4.01 / 3281 to 3334). Histological sections are postero-anteriorly oriented: A. Dorsal view of a living specimen; B. Ventral view; C. Histological section of the male copulatory organs; D. Histological section of the female apparatus; E. Sagittal reconstruction of the reproductive system. Abbreviations: cg, cemental glands; eg, extravesicular glands; ev, external vagina; fp, female pore; i, intestine; iv, internal vagina; ma, male atrium; mp, male pore; pp, penis papilla; pv, prostatic vesicle; sv, seminal vesicle; vd, vas deferens.