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4. SLOVENIA

4.1 Brachidontes pharaonis in the Adriatic Sea - a distributional review with the first record from Slovenia

F. Crocetta, V. Pitacco & L. Lipej
Brachidontes pharaonis (Fischer, 1870) (Mollusca: noticed for local researchers. Unfortunately, both papers
Bivalvia: Mytilidae) is a small-sized mussel native to the do not display the putative specimens, or provide addi-
Indo-Pacific that since 1876 has spread to the Mediter- tional details or the repository holding the sampled mate-
ranean Sea. Originally confined to the eastern Mediter- rial (if existing), and therefore we are prone to consider
ranean, it soon invaded the central part of the basin, with these records as incorrect or based on mere misidentifica-
stable populations in Malta and Italy (Sicily and Calabria) tions for other mytilid species. This also seems to be con-
and there are records from Corsica and the Adriatic Sea. firmed by both additional incorrect distributional data pre-
During benthic studies on Adriatic molluscan com- sented in Sarà et al. (2013) [e.g. presence of B. pharaonis
munities, a single specimen of B. pharaonis was found at in Naples (Italy) and Taranto (Italy) as based on Crocetta
5 m depth in Cape Strunjan (Slovenia, northern Adriatic et al. (2009), where no traces of such distributional data
Sea) (45.5347222° N, 13.6027777° E) (Fig. 15), in asso- are present, and absence in Messina (Italy), from where
ciation with a colony of Cladocora caespitosa (Linnaeus, this taxon is known since at least 1977 (Di Natale, 1982)].
1767). With the aim to first record it from Slovenia, we In turn, while carrying out our bibliographic review, we
analyzed the published literature on this taxon, and no- also noticed opposite contrasting event: Rinaldi (2012)
ticed that statements on its Adriatic distribution are quite presented some Mytilaster lineatus (Gmelin, 1791) sam-
confused and often conflicting, and may easily cause un- pled in 2009 in Pialassa Baiona (Italy) (E. Rinaldi & G.
certainties for non-specialists. This also led us to carry out Servello, pers. comm.), which in reality are B. pharaonis.
a brief review of its local distribution.
The first record from the Adriatic basin dates back to Taking into account the present finding and the biblio-
<1998, when De Min & Vio (1998) recorded this species graphic review, only three confirmed records exist from
from its northern areas, namely from Savudrija (Croatia). the Adriatic Sea so far: one from Croatia (<1998: De Min
The above cited record has been considered the only one & Vio, 1998), one from Italy (2009: Rinaldi, 2012 as M.
from the Adriatic Sea untill very recently, when two arti- lineatus) and one from Slovenia (August 2012: this pa-
cles practically simultaneously potentially broadened its per). All these records are linked by the finding of one or
distribution in the area: i) Sarà et al. (2013) stated a wide a small number of specimens, and despite additional re-
but punctual Adriatic distribution, with records from both search at the three sites, no follow-up exists from Croatia
Venice and Bari (Italy), and Split (Croatia); ii) Galil & (F. Crocetta & E. Vio, unpublished data), Italy (E. Rinaldi
Goren (2014) considered it as widespread from the Istrian & G. Servello, unpublished data) or Slovenia (L. Lipej
Peninsula to Split (Croatia), but did not take into account & V. Pitacco, unpublished data). In the light of these re-
the records listed by Sarà et al. (2013). sults and despite the repetitive findings listed above, B.
These two statements left us astonished, as the Medi- pharaonis must be considered as casual in the Adriatic
terranean Sea, with its long-lasting tradition of malaco- Sea. In addition, the three records do not seem to be relat-
logical research, is daily explored by a large number of ed, and are only presumably based on casual introduction
malacologists and marine biologists, and such a wide dis- events by ship transportation through ballast waters or as
tribution of a targeted alien species cannot have gone un- a fouler of ship keels.

Fig. 15: A-B. Brachidontes pharaonis (Fischer, 1870) from Slovenia. A. The entire specimen. Scale bar: 1 mm. B. A magnification
of the hinge teeth of the right valve. Scale bar: 0.5 mm.

Medit. Mar. Sci., 18/1, 2017, 179-201 191