Monacha (Monacha) nummus (Ehrenberg, 1831)

Neubert, Eike & Bariche, Michel, 2013, On the Monacha species of Lebanon (Gastropoda, Hygromiidae), ZooKeys 311, pp. 1-18 : 6-9

Monacha (Monacha) nummus (Ehrenberg, 1831) Figs 4, 5, 8

Caracolla nummus Ehrenberg, Symbolae Physicae: 8 [Syrien]. 1831

Helix oxygyra Charpentier, Zeitschrift für Malakozoologie, 4: 131 [Bei Nahr und Kelb [sic!], zwei Lieues nördlich von Beirut, an Felsen]. 1847

Type specimens.

oxygyra: syntype in MZL.

Specimens examined.

NMBE 508022/6, Nahr Ibrahim, Chouene, trail Chouene–Chouwan Lake, 34.081°N, 35.785°E, 450 m alt., 20.08.2008; NMBE 508021/2, Nahr Ibrahim, at the road between Chouaya and Yahchouch, 34.064°N, 35.728°E, 780 m alt., 20.08.2008; NMBE 508020/3, Nahr Ibrahim, 34.079°N, 35.679°E, 80 m alt., 20.08.2008; NMBE 508018/1, Qanater al Zbeideh, Nahr Beirut, 33.85°N, 35.556°E, 80 m alt., 19.08.2008; NMBE 508017/5, Nahr Abu Ali close to Seraad, 34.382°N, 35.93°E, 630 m alt., 19.08.2008; NMBE 508016/20, Nahr el Kelb, Jeita Grotto, cave entrance, 33.944°N, 35.641°E, 90 m alt., 16.08.2008; NMBE 508015/4, Nahr el Kelb, road to Jeita Grotto, limestone slope, 33.947°N, 35.637°E, 115 m alt., 16.08.2008; NMBE 506357/1, Wadi Abadieh, 33.8434°N, 35.6344°E, 310 m alt., 28.10.2011; NMBE 506356/4, Kfar Hbab, 34.006°N, 35.6552°E, 113 m alt., 27.10.2011; NMBE 506355/3, Kfour, 34.0348°N, 35.6952°E, 817 m alt., 27.10.2011; NMBE 506354/12, Adma, 34.0166°N, 35.6489°E, 85 m alt., 27.10.2011; NMBE 25953/5, Beirut, 33.8526°N, 35.4296°E, coll. A. Vogt ex Bohny; AUBM-MOLL 0466/9, AUBM-MOLL0478/1, AUBM-MOLL0480/13, Nahr el Kelb, 33.9547°N, 35.5975°E, 30 m alt., 26.09.2009; AUBM-MOLL0468/8, AUBM-MOLL0470/2, AUBM-MOLL0489/1, Ghazir, 34.0302°N, 35.6701°E, 326 m alt., 25.10.2009; AUBM-MOLL0476/5, Jeita, 33.9448°N, 35.6387°E, 88 m alt., 26.09.2009; AUBM-MOLL0552/2, Nahr Ibrahim, 34.0824°N, 35.802°E, 780 m alt.; AUBM-MOLL 0343/10, Nahr el Kelb, coll. Pallary; AUBM-MOLL0344/19, Tripoli, 34.4314°N, 35.8184°E, coll. Pallary; AUBM-MOLL0345/9, Jounieh, 33.3896°N, 35.6323°E, coll. Pallary.

Diagnosis.

shell large, biconvex, periphery with a sharply bounded keel, umbilicus narrowly opened, broad periomphalum.

Description.

shell large and flat, biconvex, shell colour grey to brown; protoconch consisting of two smooth whorls; teleoconch whorls with a dense pattern of white ribs, that extend to the glossy underside of the shell; suture marked by a white sutural thread; ca. six regularly increasing whorls, periphery with a sharply bounded crimped keel, sometimes spire stepped because of whorls attaching somewhat below the keel during shell growth; last whorl not descending; aperture obliquely oval with an acute palatal edge, sometimes with a faint white lip; peristomial rim sharply bounded and simple; umbilicus always open, narrow, with a broad periomphalum.

Measurements. Syntype oxygyra: H = 5.91; D = 15.55; PH = 3.73; PD = 8.84. Fig. 5: H = 6.53; D = 16.15; PH = 3.39; PD = 8.67.

Distribution.

This species seems to be restricted to coastal regions in Lebanon.

Remarks.

This species can easily be confused with other keeled species known from the Levante area. To illustrate the differences, shells of Monacha (Monacha) spiroxia (Bourguignat, 1868) (Fig. 6) and Monacha (Monacha) carinata Hausdorf, 2000 (Fig. 7) are given. They differ in that the last has a larger shell with a more flat spire and a less pronounced keel. So far, these two species have only been recorded from the Hatay province of Turkey, while Monacha (Monacha) nummus seems to be restricted to Lebanon. Monacha (Monacha) spiroxia differs from Monacha (Monacha) nummus by being smaller, having a white lip in the aperture, a much narrower umbilicus and a teleoconch sculpture of small granules.