Armatoplana celta, Noreña, Carolina, Rodríguez, Jorge, Pérez, Jacinto & Almon, Bruno, 2015

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 : 163

Armatoplana celta sp. n.

Figure 3

Material examined. Two specimens from Puerto deportivo de Ribeira, Ría de Arousa, Galicia, Spain (09/01/ 2013). 42º33.776'N; 08º59.339'W. Specimens were found among mussels growing on rocks and docks.

Holotype. One sagittally sectioned specimen, stained with Azan and deposited in the Invertebrate Collections of the MNCN; Cat. No. MNCN 4.01/481 to 4.01/497 (17 slides).

Type locality. Puerto deportivo de Ribeira. Depth: 2 metres. (42º33.776'N, 08º59.339'W).

Etymology. The specific name refers to the ancient inhabitants of Galicia, the Celts.

Description. Body shape elongated with wavy lateral margins and rounded anterior and posterior ends, of fleshy appearance; 19 mm long and 6 mm wide, live. Pigmentation light brown with dark patches more abundant in the central regions, body margin translucent, beige ( Fig. 3 A, B). Ventral surface pale, translucent whitish brown. Without tentacles. Tentacular eyes grouped into two circular patches each with 10–12 eyes. Cerebral eyes, 26–28 in total, in two elongated series extending over the brain ( Fig. 3 C, D). Well-developed ruffled pharynx is arranged in the central region of the body, with deep folds ( Fig. 3 E). Oral pore at the middle of the pharynx. Male and female genital pores clearly separate.

Reproductive system ( Fig. 3 E–I): Male copulatory apparatus with spermiducal bulbs, a true prostatic vesicle and an armed penis. The male apparatus is located anterior to the male pore and directed backwards. The vasa deferentia open frontally into the proximal ends of the spermiducal bulbs, which are covered with a well-developed muscular layer. Instead of a true seminal vesicle, spermiducal bulbs are present. The prostatic vesicle is spherical, interpolated and with a smooth, wavy epithelium. The spermiducal bulbs join by the ejaculatory duct, which crosses the prostatic vesicle before opening distally in a long, narrow slightly curved stylet. Prostatic vesicle and penis papilla are enclosed in a muscular bulb.

The female system comprises the ovaries, the uteri or oviducts, the vagina interna and externa and a welldeveloped Lang’s vesicle. The oviducts run anteriorly and open separately between the vagina externa and vagina interna. At the entrance of the oviducts, the vagina turns posteriorly and forms the vagina interna, which narrows before leading into a long, well-developed Lang’s vesicle. The vagina externa, or vagina bulbosa, which is lined with a highly glandular muscular epithelium and is directed ventro-posteriorly, expands greatly before narrowing at the ventral genital pore.

Biology. Armatoplana celta n. sp. was found among mussels growing on rocks and docks.

Discussion. Due to the presence of tentacular and cerebral eyes series, separate gonopores, spermiducal bulbs instead of a seminal vesicle, a male copulatory organ with a long penis stylet, Lang’s vesicle and a vagina bulbosa groups the described species within the genus Armatoplana . Faubel, 1983

The most remarkable characters present by A. celta with respect to the 14 known species of Armatoplana ( Table 2 ) are the presence of spermiducal bulbs and the long, curved stylet. These characters are only shared with A. lactea Laidlaw, 1903 , A. panamensis ( Plehn, 1896) and Armatoplana leptalea Marcus, 1947 , respectively. However, A. celta can be distinguished from both species due to the absence of spermiducal bulbs in A. panamensis and A. leptalea that shows a true seminal vesicle, and the small, curved stylet in A. lactea .

Distribution ( Fig. 1 , grey dots): The genus Armatoplana currently comprises 15 included A. celta species, most known from Central or South America. Four species are known from the shores of Africa while A. reishi ( Hyman, 1959) and A. taurica ( Jacubowa, 1909) are known from California and the Black Sea, respectively ( Table 2 ). Armatoplana celta is the first record of the genus for the European Atlantic shores and the Iberian Peninsula.

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 3. Armatoplana celta n. sp. A, living specimen; B, dorsal view of a fixed specimen C – D, dorsal view of the tentacular and cerebral eyes; E, sagittal reconstruction of a whole specimen; F, histological section of the reproductive system (anterior to the right); G, histological section of the tentacular eyes; H, histological section of the male copulatory organ; I, sagittal reconstruction of the reproductive system. Abbreviations: b, brain; cg, cement glands; ed, ejaculatory duct; fp, female pore; i, intestine; mly, muscle layers; mp, male pore; Lv, Lang’s vesicle; op, oral pore; ovd, oviducts; ph, pharynx; pv, prostatic vesicle; spdb, spermiducal bulb; st, stylet; ve, vagina externa; vi, vagina interna.