Monacha (Monacha) solitudinis (Bourguignat, 1852)

Neubert, Eike & Bariche, Michel, 2013, On the Monacha species of Lebanon (Gastropoda, Hygromiidae), ZooKeys 311, pp. 1-18 : 11-13

Monacha (Monacha) solitudinis (Bourguignat, 1852) Figs 12-14, 17

Helix solitudinis Bourguignat, Testacea novissimae …: 15 [Circa Heliopolim Syriae (Baalbek) habitat]. 1852

Helix solitudinis , - L. Pfeiffer, Monographia heliceorum viventium IV: 280. 1859

Helix solitudinis , - L. Pfeiffer, Monographia heliceorum viventium V: 365. 1868

Helicella (Monacha) solitudinis , - Gude, Journal of Malacology, 9: 128. 1902

Helix (Monacha) solitudinis - Germain, Mollusques terrestres et fluviatiles de Syrie I: 156. 1921

Metafruticicola solitudinis , - Pallary, Mémoires présentés a l’Institut d’Ègypte 39: 8. 1939

Monacha sp., - Boessneck, Zoology in the Middle East, 54: figs 5a, 42, 48. 2011

Type specimens.

Figured syntype NHMG 16032a; second syntype NHMG 16032b; Baalbek 34.0061°N, 36.2122°E.

Specimens examined.

Bcharre, Jabal el Mekmel ca. 7 km SE of Bcharre, loose calcareous vegetation, 34.2138°N, 36.0683°E, 2600 m alt, leg. U. Boessneck et al.; NMBE 508041/1, NMBE 508044/12, AUBM-MOLL, Falougha above Soha water plant, 33.835°N, 35.756°E, 1610 m alt., 17.08.2008; NMBE 508043/3, Falougha next to Soha water plant, 33.835°N, 35.752°E, 1474 m alt., 17.08.2008; NMBE 508042/8, Falougha, 33.8352°N, 35.7561°E, 1591 m alt., 29.10.2011; NMBE 515472/1, ditto (preserved).

Diagnosis.

shell medium sized, with a white spiral band at the periphery of the last whorl, aperture subrectangular, umbilicus open, cylindrical, penial papilla large and stout, flagellum longer than epiphallus.

Re-description.

shell medium sized, spire depressed; protoconch consists of 2 smooth whorls; shell colour light brown to yellowish brown with a white spiral band at the periphery of the last whorl; teleoconch with a malleate sculpture and fine axial riblets; suture deep, simple; teleoconch with up to seven densely coiled whorls; last whorl slightly bending towards the aperture; aperture broadly subrectangular, reinforced by a small white lip; peristomial rim sharply bounded, simple; umbilicus open, cylindrical, a triangular columellar callus is indicated.

Genital organs (Figs 12a, b): The only specimen that could be investigated was quite strongly contracted; it is a species of Monacha sensu str., because the genitalia show an appendicula, but the penial retractor muscle is missing. Penis very short (0.8 mm), penial papilla large, stout with a central perforation completely filling the atrial lumen (preservation artefact?), basis of the papilla with a strong collar (Fig. 12b); epiphallus a thick-walled tube, its lumen filled with several finely crenulated pilasters (1.9 mm); flagellum short (2.1 mm), but surmounting the length of the epiphallus; appendicula (4.9 mm) branching off the atrium, subdivided in a thicker basal part, and a shorter part with a narrower lumen; two glandulae mucosae poorly ramified, inserting in the middle of the vagina; vesicle of bursa copulatrix large, hammer-like, pedunculus quite long (4.7 mm); atrial lumen with two pilasters, one of them large, knob-like, the other narrow and elongate; right ommatophoran retractor passes left to the genital organs.

Measurements. Syntype figured: H = 9.2; D = 14.6; PH = 4.81; PD = 7.92. Fig. 14: H = 7.28; D = 13.31; PH = 4.34; PD = 7.32.

Distribution.

This species has only been recorded from two localities in Lebanon so far. The type locality Baalbek is not too far away and they were probably collected on the way towards Baalbek. Both new localities are in the central chain of Mt. Lebanon at high altitudes. The habitats are characterised by coarse limestone boulders with interspersed subalpine grassland vegetation and is covered by snow during winter. In October 2011, two living animals were found actively crawling over the rocks (ca. 10°C and heavy rainfall), while in August 2008, only dead shells were encountered.

Differential diagnosis.

This species differs from all other species in the Levante area by the shape of its umbilicus, which is cylindrical like a borehole. All other Monacha species with an open umbilicus deeply differ by either having a keeled ( Monacha nummus ) or a smaller and hairy shell ( Monacha crispulata ). Monacha bari and Monacha compingtae are conchologically similar to Metafruticicola solitudinis , but these species have a narrow and almost closed umbilicus (refer to the discussion of Monacha bari ). Information on the genital organs of the two latter species is scarce, only Hausdorf (2000: 84) reported on a subadult specimen of Monacha compingtae from southern Turkey. In this species, the penial papilla is short (large but stout in Metafruticicola solitudinis ), the epiphallus is longer than the flagellum (vice versa in Metafruticicola solitudinis ), and the appendicula is much shorter than in Metafruticicola solitudinis . The specimen figured by Boessneck (2011) was re-investigated here; it matches the type specimen from Baalbek quite well, it is somewhat larger than the specimens from Falougha.

Remark.

The correct generic affiliation of this species remained unclear until now. In his original description, Bourguignat compared it to his Helix camelina , which is a species of the Oxychilidae ; this text was uncritically copied by Pfeiffer (1859). Gude (1902) was the first to list it under the genus Monacha , but without any justification for doing so. Germain (1921), who remarked that this affiliation needs to be corroborated by an investigation of the genital organs, shared this point of view. Later, Pallary (1939) studied the type specimen and concluded that it should be classified within the genus Metafruticiola .