Drusia ( Escutiella ) alexantoni n . sp . ( Gastropoda , Pulmonata , Parmacellidae ) , a new terrestrial slug from the Atlantic coast of Morocco

Drusia (Escutiella) alexantoni n. sp. (Gastropoda, Pulmonata, Parmacellidae), a new terrestrial slug from the Atlantic coast of Morocco.— We describe a new parmacellid, Drusia (Escutiella) alexantoni n. sp. from the Moroccan Atlantic coast. The species most closely related to the new taxon are D. (E.) deshayesii and D. (D.) valenciennii. The new parmacellid differs from D. (E) deshayesii mainly by the presence of external spots and bands on both the back and the shield, a reproductive system with uneven atrial appendices of the horn–shaped organ, and a different reticulated pattern of the inner epiphallus. It differs from D. (D.) valenciennii mainly for the appearance of the shell and the pattern and disposition of the bumps inside the penis, the presence of an elbow–shape in this organ, and the reticulated appearance of the inner wall of the epiphallus. An updated dichotomous key of the family �armacellidae is provided.

In January 2011, we carried out a malacological prospection along the Moroccan Atlantic coast, co� llecting numerous specimens of a parmacelle which we propose as a new species to be included in the subgenus D. (Escutiella).

Results
After a detailed morpho-anatomical study of the collected specimens we observed that they corres� ponded to a parmacelle closely related to the species Drusia (Drusia) valenciennii and Drusia (Escutiella) deshayesii, particularly to the latter, but we believe it is a new species, and we propose naming it Drusia (Escutiella) alexantoni n. sp.

Type material
Formed by 29 specimens.The holotype is deposited at the Museu Valencià d'Història Natural (Valencia, Spain) with the code MVHN-100111�H01a.There are 13 paratypes (in ethanol 70%) with the code MVHN-100111�H01b and four paratypes (in ethanol 96%) with the code MVHN-100111�H01c, all at the same institution.In addition, three paratypes (in etha� nol 70%) were deposited at the Museu de Ciències Naturals de Barcelona (Zoologia, MZB) with the code MZB 2012-0728; three paratypes (in ethanol 70%) at the Nationaal Natuurhistorisch Museum-Naturalis of Leiden (The Netherlands) with the code RMNH.Diagnosis �armacelle of great size.Young specimens present an olive brown dorsum with black lines and spots, es� pecially on the shield, while adult specimens are light orange-brown and with lighter lines and spots.Toward the back of the shield, multiple lines or black bands of different thicknesses converge on the protoconch showing individual pattern variation (character less patent in adults).This protoconch is bright greenish, covered in adults and protruding slightly on the body surface of young individuals.Inside the reproductive atrium there is a thick ligula that extends inside the largest of the horn-shaped accessorial appendices.It has a penis with a lateral bulge, giving it an el� bow-like shape and it has two thick internal bumps.The interior of the epiphallus has a characteristic reticulated form with thick longitudinal folds that can spread out.Between these folds there are other less patent transverse folds that are almost perpendicular.
External appearance (figs.1-11): slug of the family �armacellidae with external features characteristic of this family: large, rough skin, and large, granular shield with the pneumostome in its right posterior portion.Light orange dorsal keel on the caudal part of the animal.Orange dark keel clearly visible in the posterior part of the body, especially in well-deve� loped adult specimens.Very acuminated tail.Foot is of aulacopod type and the sole is light in colour.Caudal gland absent.Adult individuals reach 15 cm in length.Young individuals present a dorsal olive brown background with black lines and spots, especially on the shield; dorsal black bands or lines converge   toward the shield end, having individual pattern variation.The greenish, bright protoconch is slightly protruded in young individuals and even in sub-adult specimens (figs.6-7).In well-developed adults, the overall tone of the body is light orange brown, with more visible bands and spots found only on the edge of the shield, while the rest of the dorsum shows a uniform appearance.In general, adult coloration is lighter than in younger animals.(figs. 6-7, 12-18): the shell is located under the mantle in the posterior part of the shield.It consists of a protoconch, from where a spiral begins, attached to a flat lamina, the limacella (or spatula).The protoconch is greenish, shiny, smooth, and relatively wide.The spiral is clearly visible.The limacella is white, slightly curved and paddle-shaped; it is slightly narrow in comparison and not strictly flat, being more cupped than in other species of the family.The protoconch protrudes slightly from the posterior end of the mantle in young and subadult specimens; it is well-developed and presents a well-marked oval-circular opening (figs.15-16).In the outer flange an arrowhead-shaped, anchoring tooth is appreciable (figs.[15][16].Although at a glance the protoconch looks smooth and glistening, high mag� nification reveals a characteristic form, consisting of longitudinal and transverse lines forming an irregular grid in some areas (figs.17-18).The size of the shell from two of the adult paratypes varies from 12.0 to 14.0 mm in width and from 21.5 to 24.0 mm in length.

Shell
Reproductive system (figs.[19][20][21][22][23][24]: hermaphrodite gland partly covered by digestive organs is bilobed and formed by irregular acini.In young specimens it is lighter and in adults it is darker in colour, greyish, with the same colour as the hepatopancreas.Herma� phrodite duct long and winding.Very large, triangular, whitish and irregular albumen gland, larger than in D. (E.) desayesii and D. (D).valenciennii.Ovispermiduct relatively short, shorter than the albumen gland; distally it separates into feminine and masculine ducts.The masculine duct consists of vas deferens, epiphallus and penis, and together is longer than the ovisper� miduct.The vas deferens is flared at its distal part, turning into the epiphallus, which presents a series of very thick longitudinal folds that can spread out along with other transverse, perpendicular, some of them oblique, less patent folds which give it a reticular appearance interiorly (fig.24).This reticular appearance is similar to that of D. (E.) deshayesii, although this species has both the transverse and longitudinal folds similarly well-marked.The retractor muscle is inserted in the distal part of the epiphallus and it enlarges markedly turning into the penis.The penis has a lateral protrusion close to the retractor muscle, giving it an elbow-like shape.Interiorly, the penis is completely covered with tight papillae.Inside the penis, in its proximal part, there is a bump next to the area of insertion of the muscle retractor (figs.21,23).Another larger bump is present in a distal position inside the elbow area.No complete spermatophores have been recovered (figs.[25][26].Inside the bursa copulatrix of four adult paratypes occurred several spermatophores (up to four in one of them), partially digested but quite complete.The spermatophores have the characteristics of the parmacelle morphology, and they are formed by a spiral from which a long filament emerges ending in a star-shaped fixing disk.We did not find entire anchoring disks whose morphology is a character of possible taxonomic value among the partially digested spermatophores, but some of them fairly complete (fig.26).The female duct begins with a short and cylindrical free oviduct which ends in a widened structure which also converges at the duct of the bursa copulatrix.This widened structure is smooth and ovoid, with a hemispherical bulge in front of the end of the short bursa duct; the bursa is rather large and has very thin walls, although its size and shape vary greatly depending on the presence and degree of digestion of the spermatophores (fig.19).The widened area increases its width becoming more glandular in aspect, having a bean-shape; it is the so-called peri� vaginal gland.The vagina is surrounded by this gland and ends in the atrium, which is rather short and has two conspicuous appendices attached, unequal in size and shape (figs. 19, 22).They are the atrial appendices; together they constitute the corniform organ, which has an irregular croissant shape.In the interior of the atrium, as is typical in the genus Drusia, there is a highly developed fleshy ligula that expands through the larger corniform organ appendix (Martínez-Ortí & Borredà, 2012)

μm
New key for the determination of the family �armacellidae �.Fischer, 1856.
1 Vagina surrounded by a perivaginal gland not thickened and provided with a long finger-shape caecum Candaharia (Central Asia) Vagina with a swollen perivaginal gland, well-developed and bean-shaped.No caecum.2 2 �enital atrium without appendices.Bursa copulatrix without thickening Cryptella (Canary Islands) �enital atrium with two appendices, or at least one.Duct of the bursa with a thickening where the spermatophores are attached 3 3 Atrial appendices of similar size.Elongated and well-developed distal part of the atrium from the insertion of appendices to the genital pore.Without intraatrial stimulators, only fleshy folds, with small ridges on its wall Parmacella (Libya, Egypt) 4 Atrial appendices of different size.Short distal part of the atrium.One or more intraatrial large and fleshy stimulator folds Drusia 5 4 Ornamented protoconch with small parallel spiral grooves.
Very long epiphallus with two bends P. festae Smooth protoconch.Epiphallus shorter and with a single curvature P. olivieri 5 Adults presenting dorsum with a shield that has dark stains and/or bands.Smooth penis without extrusion.Interior of the epiphallus not reticulated.�rotoconch amber coloured and limacella in form of broad paddle D. (Drusia) s. str.6 Adults with dorsum and shield of uniform reddish-brown colour, or only with small lines at the end of the shield.Epiphallus internally reticulated.�enis with side extrusion, sometimes elbow-shaped.�reenish protoconch and a little wide limacella in the form of elongated paddle.37), in crops of argan (Argania spinosa (L.) Skeels).One of the authors (Martínez-Ortí) collected all the specimens living in colonies underneath the stones and small walls between these crops along with the �apillionaceae plant Ononix natrix L. which is possibly part of their diet.It has also been cited in lacustrine riparian environments (Martínez, 2009).

Discussion
This new species undoubtedly belongs to the genus Drusia and we decided to include it in the subgenus D.
(Escutiella) due to the appearance of its shell and other features.Besides, it is very similar to D. (E.) deshayesii due to the following reproductive characters: i) penis with a lateral protrusion, ii) inside the penis there are two thick and solid bumps and iii) reticulated epiphallus inside with thick longitudinal folds.It differs from D. (E.) deshayesii by i) a reproductive system with uneven atrial appendices of the hornshaped organ, ii) lateral protrusion that gives it an elbow-like shape that is not present in D. (E.) deshayesii, iii) the arrangement and number of bumps inside the penis, only two of them in D. (E.) alexantoni n. sp and up to four in D. (D.) desayeshii, iv) the reticulated appearance of the inner wall of the epiphallus is diffe� rent, with the longitudinal folds being much larger in D. (E.) alexantoni n. sp. and v) the very large albumen gland of the new species.
These reproductive characters are taxonomically more relevant than the external appearance which in juveniles, with spots and bands, could be confused with the subgenus D. (Drusia) s. str.and with the species Drusia (D.) valenciennii.Equally, the two appendices of the corniform organ are very unequal in the new species, which makes it more like D. (D.) valenciennii.However, due to the set of characters mentioned and described above, it seems much more related to D. (E.) deshayesii and we have in� cluded it in the subgenus D. (Escutiella).The radula maximum dimensions of D. (E.) alexantoni n. sp. are 4.65 x 3.00 mm, being slightly smaller than in D. deshayesii (6.75 x 3.95 mm) and D. (D.) valenciennii (7.00 x 4.00 mm).In addition, the radular formula of D.