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3.2 Spreading of the invasive crab Percnon gibbesi along the Apulian coast

E. Prato & L. Papa

Palo di Capo Passero, Sicily-Italy (Relini et al., 2000);
subsequently, it spread rapidly to the the western and
eastern Mediterranean (Thesalou-Legaki et al., 2006).
Regarding Italian waters, after the report from Sicily (Re-
lini et al., 2000), the species spread rapidly along the Tyr-
rhenian coast and along the Ionian coast, Calabria and the
Apulia shores of Italy (Gennaio, 2014).
During SCUBA diving activities along Mar Grande
of Taranto (Apulia, Ionian sea), in the 2013-14 summer
season, five specimens of P. gibbesi were collected, to-
gether with another seven observed in July 2014 (Tab. 2).
Mar Grande of Taranto houses the shipyard of the Italian
Navy, the largest Italian mussel farms, as well as an ex-
panding trade port and is particularly exposed to the intro-
duction of non-indigenous species.
The five specimens captured were photographed,
measured and deposited in the collection of the CNR-
IAMC of Taranto (Fig. 6). The first specimen was col-
lected in June 2013. All specimens were recorded along
the shallow subtidal rocky shoreline (< 1 m), among boul-
ders and algae. This is the common habitat of P. gibbesi as
reported in previous observations).
This record fills a gap in the Mediterranean distribu-
tion of P. gibbesi and particularly in the Ionian Sea. Our
records together with those reported by Gennaio (2014)
from the Salentine shores suggest that populations are
already established along the Apulian coastline. Accord-
Fig. 6: Specimens of Percnon gibbesi from Taranto Gulf (Apu-
lia, Ionian sea, Italy). ing to Crocetta and Colamonaco (2008), the presence of a
few specimens suggests that this species has expanded its
Percnon gibbesi (H. Milne Edwards, 1853) is an inva- distribution range recently. Since the presence of this spe-
sive crab native of the Atlantic Ocean, which has spread cies in other surveyed areas is not confirmed, we can con-
to the Mediterranean Sea through the Strait of Gibraltar clude that further studies are necessary to monitor the new
by shipping and larval drift (Galil et al., 2002) or because populations that could settle, since the Taranto area seems
of accidental releases from the aquarium trade. to be conducive to the establishment of non-indigenous
The species was recorded for the first time in the cen- species and deserves greater attention, being a hotspot of
tral Mediterranean at Linosa, Pelagie Islands, and Porto alien biodiversity.

Table 2: Date, sampling site, geographic coordinates, number of Percnon gibbesi caught and observed along the coastline of Taranto
Gulf. Gender and morphometric measurements (width and length mm) are reported for the 5 captured specimens only.

Carapace
Geographic coordinates N individuals (mm)
Sampling sub-
Date site Latitude Longitude caught observed strate gender width length
Jun 2013 Saturo 40.3689778 N 17.3062133 E 1 rocky m 14 16.5
Sep 2013 Torricella 40.3134195 N 17.4713730 E 2 rocky m 29 32.5
rocky f 28 30
Jul 2014 Marina di Pulsano 40.3509431 N 17.3661446 E 1 4 rocky m 25 27
Jul 2014 Baia d’Argento 40.3616227 N 17.3372492 E 1 3 rocky m 25 28

Medit. Mar. Sci., 18/1, 2017, 179-201 185