Trochulus Chemnitz, 1786

Kneubuehler, Jeannette, Baggenstos, Markus & Neubert, Eike, 2022, On the verge of extinction - revision of a highly endangered Swiss alpine snail with description of a new genus, Raeticella gen. nov. (Gastropoda, Eupulmonata, Hygromiidae), ZooKeys 1104, pp. 69-91 : 69

Genus Trochulus Chemnitz, 1786

Trochulus biconicus (Eder, 1917)

Diagnosis.

Shell flattened and thin-walled, translucent, compressed in the direction of the axis; no trichome formation; whorls 5.5-6, gradually increasing so that the body whorl is only about twice as wide as the first whorl; the aperture is oblique, narrow, crescent-shaped; lip sharp, whitish and slightly reflexed; the four mucous glands are long, thick and pointed; penis and epiphallus are about the same length; the flagellum is barely separated from the epiphallus.

Differential diagnosis.

Raeticella gen. nov. differs from Trochulus by having a flat, biconical shell, devoid of any periostracal hairs, even in juveniles, and in having only four instead of occasionally six or eight (see Duda et al. 2014) mucous glands. It differs from Noricella by lacking a basal tooth, being devoid of any periostracal hairs, the absence of coarse ripples and the absence of an additional fold and bulge in the penial papilla, which occurs in N. oreinos ( Duda et al. 2014).

Etymology.

The name is derived from the Roman province of Raetia, which comprised within its larger expansion, the area of what is now known as eastern and central Switzerland. It also refers to the generic name, Noricella , which is another recently detected spin-off from Trochulus and whose name derives in part from the eastern border province of Raetia (Noricum - now Austria and Slovenia).