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Are Pinctada radiata and P. fucata only synonyms or really different species? The case of some Mediterranean populations 423

Table 1. Comparison of morphological characters in P. radiata and P. fucata.

Specimens collected on a removable contain- recorded, appeared here only during the last 5-6
ment boom allowed us to evaluate the growth rate years, showing a population dynamic typical of an
of the species: being the net completely clean at its alien species.
first installation, after four months, among fouling, But, if all the specimens constituting the large
four specimens were found. population reported as Meleagrina sp. by Mon-
The medium grown rate of this species in the E- terosato (1878) from Alexandria belong to the same
Sicily is 5.75 mm per month, which leaves us to species figured in Appolloni et al. (2018), this
believe that its expansion process in the Mediter- species was the earliest lessepsian species spreading
ranean Sea is very fast and facilitated by human ac- in the Mediterranean.
tivities. The disagreement of the present conclusions
with previous molecular studies (Barbieri et al.,
2015) according to us is attributable to the low
CONCLUSIONS number of specimens tested in these latter.
Probably previous records of P. radiata could be
According to differences in morphological char- related to P. fucata too, like that of Crocetta et al.
acters of the shell and soft parts the two populations (2009), who found “hundreds specimens” along the
of Sicilian Pinctada are here considered different. Calabrian shores, among which some at list were P.
One, which we call P. radiata, has ever been fucata (specimens figured in Crocetta et al., 2009
recorded in scattered localities along the Sicilian at figures 2O, Q).
rocky shores. This latter species is present in Aegean Sea, as
The second species, previously officially never could be argued by pictures furnished by Manousis