On the generic separation of Ovatella Bivona, 1832 and Myosotella Monterosato, 1906 (Pulmonata: Ellobiidae)

Morphological and anatomical evidence is presented leading to conclude that Ovatella Bivona, 1832 and Myosotella Monterosato, 1906 must be separated at the genus level. Shell morphology: the punctuations on the first three whorls of the teleoconch and the single row of periostracal hairs, even in the body whorl, in Myosotella contrast with the striate aspect of the teleoconch and the whole coverage of the body whorl by periostracal hairs, at least in juveniles, in Ovatella. The apertural dentition in Myosotella consistently shows the first parietal tooth as definitely strongest, whereas in Ovatella the posterior parietal tooth is as strong or even stronger than the anterior one; a callus usually present on the outer lip of Ovatella is absent in Myosotella. Anatomy: Myosotella has a monolithic, compact mandible, which contrasts with the tripartite, fibrous mandible of Ovatella. The presence of a well developed pallial gland in Ovatella and the morphology of the penial papilla also distinctively separate this taxon from Myosotella. Basic similarities between both taxa (hermaphroditic genital opening, short open sperm groove, wide visceral nerve ring) are interpreted as symplesiomorphies, and are in accordance with the trends observed with the remaining genera of the Pythiinae