Monacha (Monacha) obstructa (L. Pfeiffer, 1842)

Neubert, Eike & Bariche, Michel, 2013, On the Monacha species of Lebanon (Gastropoda, Hygromiidae), ZooKeys 311, pp. 1-18 : 9-10

Monacha (Monacha) obstructa (L. Pfeiffer, 1842) Figs 9, 10

Helix obstructa L. Pfeiffer, Symbolae ad Historiam Heliceorum II: 35 [Tripoli]. 1842

Specimens examined.

NMBE 508032/12, Jazire, Nahr al Qasimiyah (part of the Litani), 33.32°N, 35.288°E, 15 m alt., 18.08.2008; NMBE 508031/32, Nahr al Damour, 33.704°N, 35.452°E, 20 m alt., 18.08.2008; NMBE 508030/7, Nahr el Kalb, Jeita Grotto, cave entrance, 33.944°N, 35.641°E, 90 m alt., 16.08.2008; AUBM-MOLL0492/1, Campus of the American University Beirut, 33.9016°N, 35.4781°E, 26.09.2009.

Diagnosis.

shell small, cream white, aperture with thick white labial callus, umbilicus closed, forming a characteristic funnel-shaped “pseudo-umbilicus”.

Description.

shell medium sized, spire broadly conical and somewhat elevated; protoconch consisting of 1.5 smooth whorls; teleoconch cream white, with faint riblets and a malleate sculpture (compare to Monacha syriaca ), and evenly rounded whorls; last whorl slightly bending towards the aperture; aperture broadly oval, reinforced by a thick white labial callus, well discernible from the outside as a thick white callosity; peristomial rim sharply bounded, red; umbilicus closed, but last whorl forming a characteristic funnel-shaped “pseudo-umbilicus”.

Measurements (Fig. 9): H = 6.68; D = 11.83; PH = 4.2; PD = 5.85.

Distribution.

In Lebanon this species seems to be quite restricted, probably because it is confined to more arid or steppe-like areas like central Syria, where it is one of the most abundant snail species. These environmental conditions are not present in the western part of Lebanon with its humid and steep mountain slopes. However, it is the most widespread species within Monacha . Its distribution ranges from Egypt to Pakistan, and Turkey to Saudi Arabia ( Neubert 1998), probably because it can be easily distributed by human activities.

Remarks.

This species is unmistakable for its funnel-shaped “pseudo-umbilicus”. Subadult shells can be differentiated from Monacha syriaca by the uniformity of its cream white shell.