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BMC Evolutionary Biology 2008, 8:56 http://www.biomedcentral.com/1471-2148/8/56

record [22]. So far, no phylogeographic signature of the Bufo siculus n. sp
Pliocene subdivision of Sicily into two islands was Holotype
detected. The effective population size of mtDNA in Bufo An adult female, P215 (Museum of Terrasini, Palermo,
siculus n.sp., as inferred from θ (Fluctuate) is small (Table Figure 5a, c), collected November, 17, 2006, by M. Lo
2). Valvo, Monte Pellegrino reserve (38.170 N, 13.351 E),
Palermo, Sicily, Italy; for nomenclature and morphologi-
The distribution analysis indicated an observed distribu- cal description: Additional files 2 and 4.
tion in the B. siculus clade that was unimodal and visually
congruent with the distribution of expected values for a Paratypes
sudden population expansion, although not quite statisti- ZFMK 85896 (juv., topotypic, M. Lo Valvo leg. 2005),
cally significant (Figure 3f, p = 0.077). The distribution for ZFMK 85778 (ad. male, Sicily, Monte Carbonara region,
this clade is extremely compressed to the left, indicating W. Haas leg., ca. 1991, GenBank EU497506), ZMB 69556
very low numbers of mismatches and low variance. This (juv. female, EU497501) and MVZ 250741 to MVZ
profile may indicate an even more recent expansion in 250743 (two juv. and one subad. female, EU497502 to
this group than in the mainland B. balearicus group. The EU497504): Italy, southeastern Sicily, mouth of San
Fluctuate analysis also did not statistically permit rejection Leonardo River, M. Lo Valvo leg. 2005; MZPA A95 (adult
of a no-growth scenario for this clade, and Tajima's D did female, La Fossa, NW Sicily, A. Sicilia leg. 2006,
not fit the expectation for an expanded population. EU497598); NME A 1490/08 (adult male, La Fossa, NW
Sicily, F. Marrone leg.). For morphometric details of two
However, the high similarity among mtDNA haplotypes adult paratypes see Table 5 in Additional file 4.
across the entire island is consistent with the known high
mobility of green toads, exemplified by fast post-Pleis- Diagnosis
tocene re-colonization of northern Europe by two haplo- A medium- to large-sized green toad that differs from all
type groups [28]. The current range of B. siculus appears to other, especially all circum-Mediterranean green toad spe-
follow a pattern known in another Sicilian endemic, the cies, by its distinct mitochondrial haplotype group. Bufo
lizard Podarcis wagleriana, that is widespread across Sicily siculus exhibits strong variability in coloration with adult
but absent in the very northeast [42,73].

Our data reveal taxonomic identity (B. siculus) of toads on
Favignana Island (loc. 25) and Ustica Island (loc. 24);
green toads on the Aeolian Islands may be members of the
geographically proximate B. balearicus (see Additional file
3 for further comments on Circum-Sicilian islands).
Detection of Calabrian B. balearicus haplotypes in north-
eastern Sicily (loc. 20) suggests their relatively recent inva-
sion; either during Pleistocene sea level lows [72], by
rafting across the narrow Strait of Messina, or possibly by
human introduction. It remains unknown whether both
taxa (B. balearicus and B. siculus) occur in sympatry in
northern Sicily as range maps suggest [42], and whether
they would hybridize, given the considerable mtDNA and
breeding-phenology differences. Bioacoustic data in the
potential contact zone will also help to illuminate this
question.

Description of a new species
Mitochondrial and nuclear, morphometric and other pre-
liminary biological data show that green toads from most
speci
Figure 5
Holotype of Bufo siculus n.sp. and chromosomes of the new es
of Sicily represent a separate lineage. Sicilian green toads Holotype of Bufo siculus n.sp. and chromosomes of
have been physically separated by the Strait of Sicily from
the new species. (a, c) Holotype of Bufo siculus n.sp. (P215,
their closest African relatives for long evolutionary peri- Museum of Terrasini, Palermo), adult female, in life (Photo:
ods. In order to acknowledge these facts, and to raise the M. Lo Valvo). (b) Somatic metaphase from a paratype (MVZ
potential conservation status of this form, which repre- 250742), southeastern Sicily, San Leonardo River, with 2n =
sents an island endemic, we hereby describe it as a new 22 chromosomes (Photo: M. Stöck).
species.

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