Enchiridium magec Noreña 2017, n. sp.
Creators: name: Noreña, Carolina
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Platyhelminthes
Rhabditophora
Polycladida
Prosthiostomidae
Enchiridium
Enchiridium magec

description: Enchiridium magec n. sp.
(Figs. 3 and 11 D)
Material examined. 19 specimens fixed for morphological and molecular studies, two of which were histological sectioned, and designed as the holotype and a paratype respectively.
Holotype. One specimen from north of El Balito (16/06/2015), Tenerife, Canary Islands (Fig. 1, T7; Table 1 and 2) by Leopoldo Moro and Daniel Cuadrado. 87 slides of sagittal serial sectioned specimen and stained with AZAN; Catalogue number: MNCN 4.01 / 1218-1305.
Type locality. El Balito, Tenerife, Canary Archipelago, rocky substrates, at depths of 4–20 metres.
Paratype. One specimen in La Maceta (19/06/2015) in northern El Hierro, Canary Islands (Fig. 1, H3; Table 1 and 2) by Leopoldo Moro and Daniel Cuadrado. 80 slides of sagittal serial sectioned specimen and stained with AZAN; Catalogue number: MNCN 4.01 / 1306-1386.
Etymology. The specific name refers to Magec; according to the native Guanche culture, the name given to the god of the sun.
Occurrence in the Canary Islands. The individuals were captured from rocky substrates, alone or in groups of 4– 5 specimens, at depths of 4–20 metres. Some small differences can be observed between the pigmentation of captured exemplars. By some adults the brown spots in the dorsal region appear as a broad brown band, and another ones the leaf shaped parches at the posterior end can be very reduced and almost disappear.
Description. Body shape elongated. Body length range: 1–3.5 cm. Smooth dorsal surface. Background colour whitish to cream with brown caramel spots, arranged more densely in the central region. Pigment patches, leaf shaped, at the posterior end. This feature, together with the numerous uterine vesicles, gives the animal a characteristic dorsal band that clearly contrasts with the colour of the rest of the body (Fig. 3 A and B). Ventral sucker is located close to the female pore. Anterior margin smooth and rounded. With marginal eyes in the first third of the body and two long clusters of cerebral eyes (Fig. 3 C). Tubular pharynx located in the anterior third of the body, forwards orientated. Oral pore in the first third of the body and posterior to the cerebral ganglion.
Reproductive system: single male copulatory organ, anterior to the female system (Fig. 3 E and F) and ventrally orientated. The sinuous and bulky spermiducal bulbs enter laterally into the seminal vesicle. The seminal vesicle is oval with very thick muscular walls and opens into the narrow ejaculatory duct. The ejaculatory duct is curved and runs at the base of the prostatic vesicles. The spherical vesicles are surrounded by a muscular wall and bound with a common muscle sheath that includes the ejaculatory duct or is pierced by it. The short prostatic ducts join the ejaculatory duct at the base of the penis papilla. The three ducts run together until the end of the penis papilla within the stylet (Fig. 3 D). The stylet is delicate, thin and flexible conus.
The female system is characterized by conspicuous uterine vesicles, distributed along the longitudinal axis of the body. The female atrium is small and opens into a small external vagina, which enlarges into a cement pouch that receives the numerous cement glands. The proximal end of the vagina (the internal vagina) expands in the uterine vesicle.
Discussion. Enchiridium magec belongs to the genus Enchiridium due to the presence of two muscular prostatic vesicles surrounded by a common muscle and a free muscular seminal vesicle. Enchiridium comprises seven species: E. delicatum (Palombi, 1939); E. evelinae Marcus, 1949; E. gabriellae (Marcus, 1949); E. japonicum Kato, 1943; E. periommatum Bock, 1913; E. punctatum Hyman, 1953 and E. russoi (Palombi, 1939). Most are known from the western Atlantic and Pacific coasts, with exception of E. delicatum and E. russoi, which are known from the Indian Ocean (Palombi 1939).
The main anatomical feature of Enchiridium is the complex of prostatic vesicles. Both vesicles are covered with circular muscles and share a common cover of muscle fibres. This muscular cover is either pierced or not pierced by the ejaculatory duct. This difference will serve, in part, to distinguish the species within this genus. For instance, E. delicatum, E. russoi, E. gabriellae and E. punctatum show a “free” ejaculatory duct excluded from the muscular prostatic complex, and by E. japonicum, E. evelinae, E. periommatum and E. magec, the ejaculatory duct crosses the prostatic complex. In E. evelinae and E. periommatum, in the middle or near the vesicles, and in E. japonicum and E. magec n. sp. by the base. Differences in the arrangement of the marginal eyes and in pigmentation distinguish these four species. Marginal eyes are found around the entire body margin in E. periommatum, E. evelinae and E. japonicum but only in the anterior margin in E. magec. Pigmentation is pale and without pigment spots in E. periommatum and with yellow and brown pigment spots in E. evelinae. In E. japonicum, pigmentation is yellowish with brownish dots that are denser in the midline of the body.
A similar dorsal colour pattern was observed in E. russoi and recently described morphotype of E. evelinae (Bahia et al. 2014) from northern Brazil. Nevertheless E. russoi and E. evelinae can easy differentiated through the disposition of prostatic vesicles and ejaculatory duct.
description: Published as part of Noreña, Carolina, 2017, The Polycladida (Platyhelminthes) of the Canary Islands. New genus, species and records in Zootaxa 4312 (1), DOI: 10.11646/zootaxa.4312.1.2, http://zenodo.org/record/852062