Lepidoptera species with a western and eastern distribution in the Mediterranean: reasons for a disjunction

Biogeographia — vol. XX — 1999 (Pubblicato il 31 ottobre 1999) Biogeografia del|‘AnatoIia Lepidoptera species with a western and eastern distribution in the Mediterranean: reasons for a disjunction ALBERTO ZILLI Museo Civico di Zoologizz, Via U. Aldroz/zlndi, 18 — [-001 97 Roma (fmly) Key words: biogeography, Mediterranean, Lepidoprera, distributional patterns. SUMMARY A brief review ofLepidoprera species occurring at both extremities ofthe Mediterranean region and absent in the middle is given. It is suggested that determinants producing such an ‘escatomediterra.nean' distributional pattern were the most diverse. INTRODUCTION The common practice of ascribing a species’ distribution to a convenient standardised distributional pattern (e.g., Muller, 1974; La Greca, 1964, 1975; Vigna Taglianti et al., 1993) while analysing the faunal composition of a given area is sometimes hampered by species showing unusual or bizarre distributions. In fact, they may not comfortably fit with predetermined schemes, also in case these were empirically produced by superimposing actual distributions of a high number oftaxa. Inquiries about the standardised pattern that should be tributed to these ‘oddly distributed’ species are therefore often addressed. The observation that some species of butterflies and moths occur at both extremities of the Mediterranean region and are absent from the middle, thus not corresponding With any of the standardised patterns commonly in use for this area, gave the impetus for reviewing Lepidoptera species showing congruence in such a disjunction. Surprisingly, the number ofcases showing a similar pattern is so high that further research should ascertain whether this state of affairs is restricted to this group of insects or occurs in other animal taxa. EXAMPLES The following review synthetically outlines the distribution of some Lepidoptera species that in the Mediterranean region occur only in Western (\W) and Eastern (E) areas, or in regions ecogeographically related to the latter ones. In order to