New record of the Seychelles dragonet Synchiropus sechellensis Regan , 1908 from the Mediterranean : accidental entrance or Lessepsian immigration ?

The Seychelles dragonet Synchiropus sechellensis Regan, 1908 is reported for the fourth time from the Mediterranean and for the first time from Cyprus. This addition expands its distribution in the Mediterranean further from the Gulf of Antalya on the Turkish coast and the islands of Rhodes and Kastellorizo in Southeastern Aegean, placing a question mark whether this species was accidentally introduced in the Mediterranean as initially hypothesized, or it actively entered from the Indo-Pacific through the Suez Canal (Lessepsian immigration) and may have been overlooked in areas closer to the Canal. The basic measurements of the specimen caught in Cyprus, as well as an updated list of all Lessepsian fish species reported from Cyprus are given.


Introduction
Due to its proximity to the Suez Canal, Cyprus is highly affected by Lessepsian immigration.An earlier estimate (Michailidis 2010) showed that Lessepsian fish constitute up to 10% of the biomass of the local artisanal landings in Cyprus, while more recent data (Cyprus Department of Fisheries and Marine Research 2016) raise this percentage to 20%.So far, 36 Lessepsian fish species are known from Cyprus, with the most recent studies being those of Iglesias and Frotté (2015) with 7 new species (Parupeneus forsskali was confirmed by Chartosia and Michailidis 2016) and Crocetta et al. (2015) who reported Cheilodipterus novemstriatus (Rüppell, 1838).
In this study, the occurrence of a new Red Sea fish species is reported from Cyprus: the Seychelles dragonet Synchiropus sechellensis Regan, 1908.This species is widely distributed in the Indo-West Pacific and the Red Sea (Fricke 2002).The first report of the species from the Mediterranean was for an individual caught in the Gulf of Antalya (Turkey) in April 2014 (Gökoğlu et al. 2014).The species was then documented in the nearby Greek waters of Kastellorizo (September 2014) and Rhodes (February 2016) (Kondylatos et al. 2016).Dragonets of the family Callionymidae are benthic fishes occurring in the upper 900 meters of temperate, subtropical, and tropical oceans (Fricke 2002).Of the 42 species in the genus, only Synchiropus phaeton (Günther 1861) is common along the Mediterranean Sea coasts (including Cyprus), mainly on muddy bottoms at depths of 99-650 m (Froese and Pauly 2016).The present report of Synchiropus sechellensis raises the known number of Lessepsian fish species in Cyprus to 37 (Table 1).

Methods
On 28 March 2016, a male Synchiropus sechellensis individual (Figure 1) was caught in a trammel net (36 mm inner mesh eye opening) set at a depth of 40 m in the area of Moni Cyprus (34.691ºN 33.202ºE) (Figure 2).The species and sex were identified  (Bleeker, 1855) 1964 (Demetropoulos and Neocleous 1969) established Upeneus pori Ben-Tuvia and Golani, 19892004(Tzomos et al. 2010) established according to Fricke (1983Fricke ( , 2006)).Standard fin spine and fin rays counts were made.Morphometric measurements were taken using digital calipers.The specimen is preserved at the Department of Fisheries and Marine Research of Cyprus, in 90% ethanol solution.

Results and discussion
The specimen of Synchiropus sechellensis matches the description given by Gökoğlu et al. (2014)  Fricke (1981).The depth of collection in Cyprus (40 m) falls within the same range as in Gökoğlu et al. (2014) (30-50 m) and only slightly deeper than those (3 and 10-30 m) reported by Kondylatos et al. (2016).
The finding of S. sechellensis in Cyprus is the fourth record of the species in the Mediterranean, following those in Turkey and Greece hints at establishment of the species in the area.The new finding also challenges the view of Gökoğlu et al. (2014) that the species may have been accidentally introduced to the Mediterranean by marine traffic and shipping activities, a view that was logically based on the fact that only one specimen was found in the Mediterranean, and it was collected at a substantial distance from the Suez Canal.The distance between the new and the previous findings suggests that S. sechellensis may have entered the Mediterranean through the Suez Canal, and that its absence from locations closer to the entrance may be incidental and due to the species' rarity and small size.
As supported by previous studies for other marine regions (e.g.Karachle et al. 2016), there is no doubt that fish species diversity in the Eastern Mediterranean, and likewise that in Cyprus, is changing.The extent to which non-indigenous species may affect the ecological balance remains to be seen; thus, as suggested in the past, continuous monitoring is essential.

Figure 2 .
Figure 2. Map of the Eastern Mediterranean with the capture location of Synchiropus sechellensis (black dot).

Table 1 .
Lessepsian fish species reported from Cyprus up to May 2016.