Variations on a theme, Part II

I have finally decided to change the appearance of the blog title by including some pictures of its namesake, which in actuality deserves a post all to itself.

The genus Muticaria Lindholm, 1925 from the peculiar family of landsnails knows as the Clausiliidae (door snails), is endemic to Sicily and Malta. Only one species exists on Malta, consisting of four main forms variously regarded in contemporary literature as varieties (Giusti et al., 1995) or actual subspecies (Nordsieck, 2007). Likewise, two main forms exist on Sicily, also regarded either as varieties of the same (Giusti et al., 1995) or as altogether different species (Beckmann, 1990).

The entity endemic to the Maltese Islands, namely Muticaria macrostoma (Cantraine, 1835) has, since the Pleistocene, diverged into local and very characteristic (though hybridizing) varieties, two of which are extremely limited in distribution. The typical forms are shown below.

I would like to thank Mr. He Jing for the excellent photographs and also for the permission to use them.

Muticaria macrostoma macrostoma (Cantraine, 1835) - Ħ'Attard

Muticaria macrostoma mamotica (Gulia, 1861) - Munxar

Muticaria macrostoma oscitans (Charpentier, 1852) - Dingli

Muticaria macrostoma scalaris (Pfeiffer, 1848) - Mistra

References:

Beckmann, K.-H., 1990. Beiträge zur Kenntnis der Landmolluskenfauna Siziliens mit der Beschreibung von Muticaria neuteboomi spec. nov. (Gastropoda: Pulmonata: Clausiliidae). Basteria, 54 (1/3): 75-85.
Giusti F., Manganelli G. & Schembri P.J., 1995. The non-marine molluscs of the Maltese Islands. Monografie Museo Regionale di Scienze Naturali, Torino, 15: 1-608.
Nordsieck, H., 2007. Worldwide door snails (Clausiliidae), recent and fossil. Hackenheim: Conchbooks, 214 pp.
Schembri, P.J. & Sultana, J. (eds.), 1989. Red Data Book for the Maltese Islands. Malta: Department of Information, pp. i-viii + 1-142 + 8 pl.