Dear Mehmet

First specimens appeared 1983 before the Israeli and South-Turkish coast.
She should have introduce through oil tankers from the Persian Gulf into the
Mediterranean. Meanwhile the species has there strongly spreaded and has
also been determined before Cyprus and Rhodes already.
This into the Mediterranean penetrated (artificially) species was at first
described as Strombus decorus raybaudii by Nicolay & Manoja 1983. This
Determination was sure somewhat rash, because for the evolution of a real
subspecies much more time be necessary as since the opening of the Suez
Canal. The name S.decorus raybaudii must therefore be considered as synonym.
The question is now, whether the taxon S. decorus persicus as subspecies is
well-founded.
In the Indian Ocean occurs S. decorus Roeding (1798). In 1821 Swainson
descriped S.persicus from the Persian (Arabian) Gulf. Later, this taxon was
considered a subspecies (Abbott 1960; Walls 1980) of decorus. Following
Moolenbeek & Dekker this species is common in the Arabian Gulf with a few
doubtful records outside this area, one record from Aden (Melvill & Standen,
1901) and one from the northern Red Sea (Mienis, 1974). The shell figured by
Sharabati, 1984, pl.7 fig.6, is referable to S. decorus decorus and its Red
Sea provenance is doubtful. From the coast of Oman, S. decorus persicus is
mentioned by Bosch & Bosch (1982).
Wawra & Sattmann (1988) have compared the radulae of decorus decorus from
Zanzibar with those of S. decorus raybaudii from the Mediterranean. As they
examined the lateral teeth only, the relationship between the two taxa is
still not fully understood. Moolenbeek & Dekker concluded that more
material, especially of S. decorus persicus, should be examined. Accordingly
they have sent some species of Oman for further research to Dr. Wawra.
They write further: "In November 1991, marine molluscs were collected in
several intertidal areas of the Sultanate of Oman. In the southern province
of Dhofar strombids seem to be rare, a phenomenon which may be partly
explained by the influence of cold-water upwellings. Further north, towards
Muscat, that influence diminishes and the number of strombid species
increases. One of the more familiar strombids that can be found there is
usually called Strombus decorus persicus Swainson 1821 (Abbotts, 1960; Walls
1980). However, after examination of the shell morphology and radular
characteristics of S. decorus from Kenya and S. decorus persicus from Oman,
it is concluded that these taxa represent different species."

Literature about it:
ABBOTT, R.T. 1960.  The genus Strombus in the Indo-Pacific. - Indo-Pacific
Mollusca 1 (2): 33-146.
BOSCH, D. & BOSCH, E. 1982  Seashells of Oman. London, pp. 1-206.
BOSCH, D. & BOSCH, E. 1989  Seashells of Southern Arabia. Muscat: 1-124.
KRONENBERG, G. & BERKHOUT, J. 1984.  Strombidae. - Vita Marina, 31 (1-6):
sect. Buikpotigen 263-362.
KRONENBERG, G. & BERKHOUT, J. 1986.  Addenda en Corrigenda. - Vita Marina
(Buikpotigen): 363-368.
MELVILL, J.C. & STANDEN, R. 1901  The Mollusca of the Persian Gulf, Gulf of
Oman, and Arabian Sea, as evidenced mainly through the collections of Mr.
F.W. Townsend, 1893-1900; with descriptions of new species. - Proc. Zool.
Soc. Lond. [1901]: 327-460.
MIENIS, H.K. 1974, A checklist of Strombidae drom the Sinai-area of the Red
Sea. - Inf. Soc. Malac. Belge 3 (8-9): 115-117.
MOOLENBEEK, R.G. & DEKKER, H. 1993.  On the identity of Strombus decorus and
Strombus persicus, with the description of Strombus decorus masirensis n.
ssp. and a note on Strombus fasciatus. - Vita Marina, 42 (1): 3-10.
NICOLAY, K. & MANOJA, E.R. 1983.  Strombus (Conomurex) decorus raybaudii n.
ssp. - La Conchiglia XV (176-177): 17-18.
SHARABATI, D. 1984.  Red Sea shells. London, pp. 1-128
WALLS, J.G. 1980  Conchs, Tibias and Harps. Neptune, pp. 1-191.
WAWRA, E. & SATTMANN, H. 1988 Bemerkungen zur Radula von Strombus decorus
(Roeding 1798) (Gastropoda: Prosobranchia) aus dem Mittelmeer. - Ann.
Naturhist. Mus. Wien 90: 357-360.

Cordially
Gert