The Sicilian (Crocidura sicula) and the Canary (C. Canariensis) shrew (Mammalia, Soricidae): Peripheral isolate formation and geographic variation

Abstract

The skull and mandible morphometries of two insular and endemic taxa (C. sicula and C. canariensis) from the Sicilian and Canary archipelagos, both having exactly the same karyotype were analysed by principal component and canonical variate analyses and related multivariate techniques. Information available in the literature was also employed to obtain a better approach to the systematics relationships in this taxon. Specimens of C. suaveolens, C. leucodon, C. wbitakeri and C. russula from the Mediterranean, and C. esuae from the Pleistocene of Spinagallo (Sicily) were used as references. The results of multivariate analyses of the metric and non-metric characters of the skull and mandible, coupled with data from the biochemical and cytotaxonomic literature, have provided unanimous results pointing to the marked phenetic similarity of the C. sicula and C. canariensis taxa, that are ascribable to the same monophyletic group. On paleobiogeographic grounds, it is suggested that both taxa are two relict peripheral isolates, so dating today’s disjointed distribution back to a colonization of the two archipelagos by a Maghrebi ancestral taxon, related to the C. esuae form, living in the Middle-Upper Pleistocene, and today probably extinct. In particular, the C. canariensis populations are morphologically very close to those of the smaller islands around Sicily (Marettimo, Gozo, Ustica), which have been isolated from Sicily for a long time; this could be explained by the similar adaptive responses on the islands and be caused by the Centrifugal Spéciation Model. These findings are considered sufficient to guarantee con- specificity between C. sicula and C. canariensis and to place the latter taxonomically as a subspecies of C. sicula. A recent typological classification of C. sicula is also discussed and refuted. © 1995 Taylor & Francis Group, LLC.