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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

BIOGEOGHAPHIA - vol. XI - 7985 Principi e metodi delfanalisi biogeografica I Lepidotteri come strumento per la descrizione della B—diversita fra regioni italiane(qq‘) ALBERTO ZILLI E TOMMASO RACHELI Dz'partz'mem‘0 all Biologza Animale e dell’U0mo, Um'z2ersz'ta «La Sapienza», Roma SUMMARY Regional fidiverxity evaluation in Italy wit}; Lepidoptera A numerical analysis, according to the coefficient S“ of Baroni Urbani & Buser, carried out on 951 italian lepidoptera species reveals the homogeneity of peninsular Italy as far as this taxon is concerned. The data from single-link cluster analysis show a high degree of similarity at .75 among the areas. The grouping of regions into smaller units is not always univocal, in spite of the high number of tested species. Some different trends are therefore pointed out by analysing italian representatives of monophyletic taxa such as Noctuidae, Hesperioidea and Papilionoidea. INTRODUZIONE Una analisi biogeografica complessiva dei lepidotteri italiani non e rnai stata intrapresa anche se il livello di conoscenza della tassonomia e distribu- zione di molti gruppi di macrolepidotteri e piu che soddisfacente. L’idea del presente studio is scaturita dall’intenzione di compilare una banca dati sui lepidotteri italiani. Secondo Holloway & Jardine (1968) sia le metodiche nu- rneriche che i lepidotteri sono particolarmente validi per studi biogeografici. E stato quindi stimolante utilizzare i dati in nostro possesso per sottoporli ad analisi nurnerica. Abbiarno pertanto calcolato il coefficiente di similarita fra dati binari proposto da Baroni Urbani & Buser (1976) per valutare il grado di affinita faunistica tra varie regioni italiane usando i seguenti taxa: Noc- tuidae, Hesperioidea e Papilionoidea. I molti dati sulla distribuzione e la monofilia di questi tre taxa, singolarmente considerati (Kitching, 1984; Kri- stensen, 1976; Scott, 1985), li hanno fatti preferire come soggetto dell’indagi- ne. In virtu dell’aderenza del taxon da noi usato allo scenario vegetazionale, essendo i lepidotteri doppiamente interagenti con le piante (larva — pianta alimentare; imago - fiore), fino a casi ben documentati di coevoluzione (Ehr- lich l3: Raven, 1965; Edgar et al., 1974; Feeny, 1975; Ratchke & Poole, 1975; (*) Lavoro eseguito nell’ambito del «Gruppo nazionale di Biologia Naturalisticagg del C.N.R. e Mini- stero P.I. (40%). 233