Massylaea vermiculata (O. F. Mueller , 1774)

Bouaziz-Yahiatene, Houria, Pfarrer, Beat, Medjdoub-Bensaad, Ferroudja & Eike Neubert,, 2017, Revision of Massylaea Moellendorff, 1898 (Stylommatophora, Helicidae), ZooKeys 694, pp. 109-133 : 119-121

Massylaea vermiculata (O. F. Mueller, 1774) Figs 13-16

Helix vermiculata O. F. Müller, 1774; Vermium terrestrium et fluviatilium 2: 21 [In Italia sabulosis juxta torrentes].

Helix bonduelliana Bourguignat, 1863; Mollusques nouveaux, litigieux ou peu connus, fasc. 1: 9, plate 3 figs 1-4 [Province d’Oran].

Helix vermiculata var. albida Bourguignat, 1863; Malacologie de l’Algérie I: 112, plate 8 fig. 10 [La Calle].

Helix vermiculata var. aspersa Bourguignat, 1863; Malacologie de l’Algérie I: 112 [Cherchell].

Helix vermiculata var. expallescens Bourguignat, 1863; Malacologie de l’Algérie I: 112 [Environs d’Alger, Blidah].

Helix vermiculata var. minuta Bourguignat, 1863; Malacologie de l’Algérie I: 112 [Ile de Galite].

Helix vermiculata var. trizonata Bourguignat, 1863; Malacologie de l’Algérie I: 112 [Philippeville].

Helix fleurati Bourguignat, 1868; Histoire Malacologique de la Régence de Tunis: 12, plate 1 fig. 1-3 [Env. de Tunis (Champs au sud et au sudest de Tunis, entre un vieux puits espagnol et les collines de Sidi ben Hassen et de la forteresse Bordj el Raïs. Ruines d’Oudena. Ruines d’Utique et de Carthage. non loin de la chapelle Saint-Louis]

Helix fleurati var. obesa Bourguignat, 1868; Histoire Malacologique de la Régence de Tunis: 13 [no locality information given].

Helix fleurati var. subcarinata Bourguignat, 1868; Histoire Malacologique de la Régence de Tunis: 13, plate 1 fig. 4 [no locality information given].

Helix (Macularia) vermiculata var. conoidea Issel, 1880; Annali del Mus. Civ. di St. Nat. di Genova, Vol. XV: 263 [Sahel, fra Susa e Bir el Buita e fra Susa ed El Gem].

Helix (Macularia) vermiculata var. depressa Issel, 1880; Annali del Mus. Civ. di St. Nat. di Genova, Vol. XV: 263 [Cartagine].

Helix (Macularia) vermiculata var. minuta Issel, 1880; Annali del Mus. Civ. di St. Nat. di Genova, Vol. XV: 264 [Is. Galita, Galitone, Aguglia, Gallina (Violante, 1877). Cartagine (Bellucci, 1875)].

Helix toukriana Bourguignat in Péchaud 1883; Excursions malagologiques dans le nord de l’Afrique de La Calle a Alger, d’Alger a Tanger: 37 [hauts plateaux du Sersou, entre Aïn-Toukria et le Nahr-Ouassel, dans la direction de Sebaïn-Aïoun].

Helix aecouria Letourneux et Bourguignat, 1887; Prodrome de la malacologie terrestre et fluviatile de la Tunisie: 7 [Environs d’Houmt-Souk dans l’ile de Djerba].

Helix vermiculata var. saharica Kobelt, 1887; Iconographie, (2) 3(1): 9, Taf. 6, fig. 343-345 [Biskra].

Type specimens.

bonduelliana : 1 syntype MHNG-MOLL 118415; aecouria : 3 syntypes MHNG-MOLL 118413; fleurati : syntypes MHNG-MOLL 118440/7 (Env. de Tunis); toukriana : syntype MHNG-MOLL 118487; saharica : not researched.

Diagnosis.

Medium sized shell, teleoconch with a malleate surface sculpture, and aperture with a slightly raised columellar ridge.

Description.

shell medium sized, with a globular to depressed conical spire, basic colour white to grey, up to five brown spiral bands may be present or completely missing; protoconch large (diameter ca. 4 mm), corneous to white; whorls regularly increasing, the last whorl declining at the aperture; teleoconch suture of moderate depth, surface of teleoconch with a characteristic malleate sculpture (sometimes only present close to the aperture!); spiral bands 2+3 often merging, and bands may fuse to a large brown area on the last whorl before the aperture; aperture usually porcelain white with a thick lip, columellar part of aperture with a raised ridge; peristome slightly thickened, umbilicus completely covered by a large reflection of the columellar part of aperture.

Genital organs (after Giusti et al. 1995; Neubert and Bank 2006; Holyoak and Holyoak 2017): penis clubshaped, bipartite; the bilobed muscular proximal part not visible in outer morphology; epiphallus longer than penis; penial retractor muscle simple, attaching at the boundary of penis and epiphallus; internally, the proximal penial chamber filled by a solid penial papilla, epiphallus opening into the penial chamber via a small pore or on top of a flat papilla.

Dart sac opening laterally into the short vagina; glandulae mucosae with two central stems giving rise to at least three subsequent branches with at least 40 tubules; diverticulum branches off in a central position from the pedunculus surpassing the bursa copulatrix enormously.

Distribution.

This species is widely recorded throughout Tunisia and eastern Algeria.

Remarks.

The synonymy list and illustrations only cover synonyms of M. vermiculata important for the area from east Algeria and Tunisia. Here, this species inhabits Mediterranean shrublands as well as the wooded hinterland. It also tolerates coastal dunes with salty spray, and semiarid steppes. Holyoak and Holyoak (2017) justify the synoynmisation of constantina with vermiculata with the similar morphology of the genital organs and the wide overlap in shell size and banding pattern. However, in many land-snails, closely related species cannot be differentiated by the morphology of their genital organs. More attention should be paied to the construction of the penis (bilobed muscular proximal part visible from outside or not) and the variability of attaching system of the retractor muscle, which is much larger (and also connects to the atrium) in the specimen of constantina than in any vermiculata seen so far. The most important character state that separates the species is the absence of any malleation on the shell surface in constantina . Additionally, the phenotypic plasticity of the shells of vermiculata is markedly contrasted by the congeneric M. constantina , which is extremely stable in respect of the spiral banding pattern.

One species mentioned by Kobelt (1887) as a closely related species to his vermiculata - constantina -complex is Helix bonduelliana Bourguignat, 1863, with the type locality "Province d’Oran” in western Algeria. Kobelt doubts the correctness of this locality, and speculates that it might originate from Tunisia. According to his personal experience in Algeria, M. vermiculata reaches the Isser, but does not expand much to the west of this river. The only exception he found was Cherchell west of Algiers, where the species occurred in large numbers, but restricted to and around the harbour, so it can be considered being introduced there. It is not clear how the situation is today along the central and western Algerian coast, but Kobelt’s lines can be seen as an information on the natural range of this species in northern Africa. In the same year, Bourguignat (1887: 8) records H. bonduelliana from Ghardimaou (Tunisia) (= MHNG-BBT 118417/3). Bourguignat’s collection has another record from "environs de Tunis" under MHNG-MOLL 18416/1. Later, Pallary (1898) mentions his and Debeaux’s unsuccessful attempts to recollect the species in Oran. Summarising it can be said that the type locality of H. bonduelliana is apparently wrong, and the specimens are very probably of Tunisian offspring. This nominal taxon fully falls into the colour variation of M. vermiculata , which can reach from completely white shells as exemplified by H. fleurati (Fig. 15) to the typical morph as seen in H. aecouria (Fig. 14). The shell shape, however, is quite stable in most of these forms, and typical for M. vermiculata . The synonymisation of saharica Kobelt, 1887 needs reconfirmation by study of the type specimens.