Resumen de Prima segnalazione di Crisilla perminima (Manzoni, 1868) in Mediterraneo

Tisselli Morena, Luigi Giunchi

• English

  Four specimens of Crisilla perminima (Manzoni, 1868) have been collected in a shell grit collected at 25 m depth close to Grotta Verde, Capo Caccia, Sassari (Sardinia Island). These specimens are 1.3-1.4 mm high and 0.7-0.8 mm wide. C. perminima was previously reported only from Canary Islands (Spain) and from Selvagem Islands (Portugal) and this is the first record of the species in the Mediterranean Sea. The nomenclature of this species has a tortuous history: it was in fact described as Rissoa (Setia) perminima Manzoni, 1868, then placed in Setia by Nordsieck (1979) and in Cingula s.l,. by Verduin (1984); in the current check-lists (e.g. CLEMAM) it is included in the genus Crisilla, opinion that we share. The protoconch of this species has about 1.5 whorls, with 7-8 very fine spiral striae. The teleoconch has 2 and 1/4 whorls and the sculpture is only formed by growth lines, clearly visible only on the last whorl. Since C.perminima has a lecitotrophic development, its introduction in the Mediterranean Sea could be explained only throughout anthropic activities, although the mechanism is presently unknown. The hypothesis of the presence of a sibling species in the Mediterranean has not been tested due to the scarcity of available material, but it deserves attention if this will become available.

• italiano

  Crisilla perminima (Manzoni, 1868) viene segnalata per la prima volta in Mediterraneo. In un campione di detrito prelevato a -25 m nei pressi della Grotta Verde, Capo Caccia, Sassari (Sardegna) gli autori hanno rinvenuto quattro esemplari di questa caratteristica specie.