Resumen de Note su alcune specie mediterranee del genere Mitrella Risso, 1826: (Gastropoda, Muricidae)

Stefano Chiarelli, Pasquale Micali, Paolo Quadri

• English

  Authors dealt with some Mediterranean species of the genus Mitrella, studying shells as well as colour of the mollusc soft parts and operculum. Mitrella species are mainly littoral, they show a remarkable variability of colour patterns and also the protoconch dimensions are variable within the same population. Shell thickness, slenderness and whorls profile are usually variable depending from type of biocoenosis and depth.Considering that shell colour and general form have been used in the past as diagnostic characters it is not surprising that many taxa have been based on local forms, living in particular areas like the Gulf of Gabes (Tunisia). Columbella lanceolata Locard, 1886 is considered good species, distributed in central and western Mediterranean. In the Gulf of Gabes this species shows a remarkable variability of colours and forms, mainly with slender and thin shells. In western Mediterranean M. scripta is rare, while M. lanceolata is frequent. In some Sicilian localities M. lanceolata and M. scripta are sympatric, without intermediate forms. These two species may be separated by the colour pattern of shell and soft parts, while the shell shape is usually very similar. Mitrella spelta Kobelt, l889 based on specimens from the Gulf of Gabes and M. syrtiaca Pallary, 1906 based on specimens from Tripoli (Libya) are considered to be only colour variations of M. lanceolata.Mitrella acuta Kobelt, 1889, Columbella decollata Brusina, 1865 and Columbella crossiana Réduz, 1851 are considered synonyms of M. gervillii (Payraudeau, 1826). Mitrella acuta was based on the form living in the Gulf of Gabes and seems to be restricted to this area and western Mediterranean. M. gervillii has a wide bathimetric distribution from littoral to about 100 m depth on red coral, so exhibit many forms and colour variations. Observations on three living specimens of M. gervillii from eastern Sicily, showed a direct correlation between shell and soft parts colour: both are dark or light brown. Columbella pediculus Kobelt, 1895, M. vatovai Coen, 1937 e M. aradusana Pallary, 1938, three species very similar to Mitrella coccinea (Philippi, 1836) = C. brisei Brusina, l970 arediscussed. Synonimy is likely but not proved. Mitrella coccinea seems to be distributed in all the Mediterranean sea, living on rocky and detritic bottoms.

• italiano

  Gli Autori passano in rassegna alcune specie mediterranee del genere Mitrella, basandosi anche sull’esame delle parti molli e dell’opercolo. Columbella lanceolata Locard, 1886 è considerata specie valida, distribuita nel Mediterraneo centrale e orientale, mentre M. scripta (Linné 1758) è rara nel Mediterraneo orientale. In alcune località della Sicilia le due specie sono simpatriche. La distinzione specifica è basata principalmente sul colore della conchiglia e delle parti molli. Mitrella spelta Kobelt, 1889 e M. syrtiaca Pallary, 1906 sono considerati semplici colorazioni di M. lanceolata. Columbella decollata Brusina, 1865, Columbella crossiana Réduz, 1851 e Mitrella acuta Kobelt, 1889 sono considerati sinonimi di M. gervillii (Payraudeau, 1826). Columbella brisei Brusina, 1870, Columbella pediculus Kobelt, 1895, M. vatovai Coen, 1937 e M.aradusana Pallary, 1938 sono affini a Mitrella coccinea (Philippi, 1836), la sinonimia è probabile. La notevole variabilità, l’ampia distribuzione e l’adattamento ad ambienti sia litorali che profondi hanno dato vita alla ricchezza di forme, colorazioni e sinonimi.