FIRST RECORD OF THE RETICULATED DRAGONET , CALLIONYMUS RETICULATUS VALENCIENNES , 1837 ( ACTINOPTERYGII : CALLIONYMIFORMES : CALLIONYMIDAE ) , FROM THE BALEARIC ISLANDS , WESTERN MEDITERRANEAN

Background. The reticulated dragonet, Callionymus reticulatus, was originally described based on a single specimen, the holotype from Malaga, Spain, south-western Mediterranean, probably collected before 1831. The holotype is now disintegrated; the specific characteristics are no longer discernible. The species was subsequently recorded from several north-eastern Atlantic localities (Western Sahara to central Norway), but missing in the Mediterranean. Material and methods. Specimens of C. reticulatus were observed and collected during two cruises in 2014 and 2016 in the Balearic Islands off Mallorca and Menorca. The collected specimens (8 females) have been deposited in the collection of the Hebrew University of Jerusalem (HUJ). All individuals of C. reticulatus were collected from beam trawl samples carried out during the DRAGONSAL0914 in September 2014, and during the MEDITS_ES05_16 bottom trawl survey in June 2016, on shelf and slope bottoms around the Balearic Islands. Both surveys used a ‘Jennings’ beam trawl to sample the epi-benthic communities, which was the main objective of the DRAGONSAL0914 and a complementary objective in the MEDITS_ES05_16. The ‘Jennings’ beam trawl has a 2 m horizontal opening, 0.5 m vertical opening and a 5 mm diamond mesh in the codend. Trawls had duration of 1 to 3 min of effective sampling (bottom time) at a speed of 2 knots. Catches were sorted out to species and standardized abundances of callionymid species (individuals per 500 m2) were obtained by calculating the sampled surface (distance covered × beam trawl horizontal opening). Results. Callionymus reticulatus is recorded from the Balearic Islands for the first time; the specimens are described and illustrated. Conclusions. The new record confirms that the species is still extant in the Mediterranean. A key to Mediterranean callionymid fishes is provided to distinguish C. reticulatus from other species of the family in the area. The callionymid fish fauna of the Mediterranean now comprises 11 species, including three Lessepsian migrants originating from the Red Sea.


INTRODUCTION
Dragonets (family Callionymidae) are a group of benthic living fishes occurring in the upper 900 metres of all temperate, subtropical, and tropical oceans of the world, and a few species are found in estuarine and freshwater habitats (Fricke 1983a).They are characterised by a depressed body, a triangular head when seen from above, the large eyes, situated dorsally on the head, the presence of a preopercular spine which is bearing additional spinules and/or serrae, the gill opening reduced to a small pore, absent swim bladder, two dorsal fins (the first with thin, flexible spines, the second with soft rays), and jugular pelvic fins which are separated from each other, but each connected with the pectoral-fin base by a membrane.The Atlantic species of the family were revised by Fricke (unpublished ** ), who distinguished 18 valid species-group from the area, including seven species from the western Mediterranean.Nakabo and Hartel (1999) raised Foetorepus dagmarae (Fricke, 1985) and Foetorepus valdiviae (Trunov, 1981) to the species level and described "Foetorepus goodenbeani Nakabo et Hartel, 1999" (In the present paper assigned to the genus Synchiropus).Fricke (2002), in a checklist of callionymid fishes, listed a worldwide total of 182 valid species in 10 genera.Subsequently, several additional species were described, including Protogrammus alboranensis Fricke, Ordines, Farias et García-Ruiz, 2016 from the Alboran Sea, south-western Mediterranean by Fricke et al. in Farias et al. (2016)."Callionymus sanctaehelenae Fricke, 1983" was synonymised with Callionymus bairdi Jordan, 1888 by Fricke (2002).Synchiropus sechellensis Regan, 1908 was reported as a Lessepsian migrant in the eastern Mediterranean by Gökoğlu et al. (2014), and Diplogrammus randalli Fricke, 1983, another Lessepsian migrant in the eastern Mediterranean, by Seyhan et al. (2017).
During recent surveys of fishes of the northern Balearic Islands in 2014 and 2016, several populations of Callionymus reticulatus Valenciennes, 1837 were discovered, which represent a new record of the species from the island group, and the first record from the Mediterranean since the collection of the holotype from Malaga (Spain) before 1831.Several specimens were collected; they are described in the present paper.The species is compared with allied species, and its distribution is discussed.

MATERIALS AND METHODS
Materials of Callionymus reticulatus from the Balearic Islands are deposited in the Hebrew University, Jerusalem (HUJ).Counts and measurements followed Hubbs and Lagler (1947), fin-ray counts follow Fricke (1983b); the classification follows Eschmeyer et al. (2017), references according to Fricke (2017), collection acronyms follow Fricke and Eschmeyer (2017).The fish collection of the İzmir Katip Çelebi University, Turkey is abbreviated IKC.
Colour of fresh, female specimens: body above lateral line cream, back with six dark saddle-like areas, surrounded by white spots, lower sides of body white; upper half of pectoral-fin base with dark grey blotch, lower half with two white spots; eye dark grey.First dorsal mostly dark grey, membranes ventrally pale; second dorsal translucent, with oblique rows of dark blotches, membranes with a distal dark grey margin.Anal fin with a narrow distal dark band.Pectoral fins translucent; pelvic fins pale, with two series of dark grey blotches.Caudal fin pale, with three series of dark grey blotches.
In the course of the DRAGONSAL 2014 Cruise in the Balearic Islands, numerous specimens of Callionymus reticulatus were observed south and west of Mallorca but not retained (see Table 2, Fig. 3); just 4 small females collected at station 34 are available for this study.While the species appeared to be very common in September 2014, it was scarcely found at the stations with the previously highest abundance during the MEDITS_ES05 Cruise in June 2016.The reason of the disappearance from many stations remains unknown.Seasonal migrations for spawning or feeding could be one explanation for such differences.According to Fricke in Whitehead et al. (1986Whitehead et al. ( : 1090) ) the species reproduces in March-June in the North Sea.If spawning takes place at the same period in the Mediterranean and it involves some migration to other areas this could be the explanation for such a scarcity of individuals.
The new record of Callionymus reticulatus from the Balearic Islands confirms that this species is extant in the Mediterranean Sea, and expands the known distribution range by 700 kilometres towards the northeast into the Mediterranean; this is the second Mediterranean region for which the presence of this otherwise Atlantic species could be confirmed.A total of 10 species of callionymid fishes is now known to occur in the Mediterranean Sea, including two Lessepsian immigrants of Red Sea origin which have invaded through the Suez Canal.
Callionymus reticulatus inhabits coarse sand bottom, with a grain size similar to the size of the spots on the back and sides of the specimens; the species was found near Mallorca at depths of 46-68 m, significantly deeper than in the north-eastern Atlantic; Atlantic depth records based on SMNS materials range from 11-57 m.A reason for this deeper occurrence may be due to a slightly higher water temperature in the Mediterranean compared to the same depths in the north-eastern Atlantic and the presence of red algae communities such as maërl and Peyssonnelia beds which dominate the coarse sand circalittoral bottoms of the Balearic Islands down to 80 m depth (Ballesteros 1994, Ordines and Massutí 2009, Barberá et al. 2012).In this sense, there seems to be a clear habitat partitioning between C. reticulatus and C. maculatus in the area sampled during the DRAGONSAL0914 survey.Callionymus reticulatus showed high abundances that decreased with depth until it disappeared deeper than 68 m, whereas C. maculatus begun to appear at 78 m depth (Fig. 4), in coincidence with the disappearance of red algae beds and the beginning of bare sandy-mud bottoms.The red algae beds of the south west of Mallorca seem to play a key role to juvenile and small fish species, which show their highest abundances in these bottoms.Both, shelter availability, due to the higher structural complexity of these beds compared to bare sandy mud bottoms, and feeding opportunities, they show high abundances of small invertebrates as well, seem to be the main traits explaining juvenile and small fish preferences for these habitats (Ordines et al. 2011).The population of C. reticulatus in the Balearic Islands seems to be positively affected by these habitats as well.

ACKNOWLEDGEMENTS
We would like to thank the following persons for information, loan of specimens, or permission to examine

Fig. 3 .Fig. 4 .
Fig. 3. Map of the study area.Circles represent the 57 beam trawl stations DRAGONSAL0914 which place in the south shallow shelf off Mallorca Island; Squares represent the 13 beam trawl stations sampled during MEDITS_ES05_16, which were located on the shelf and upper slope off Mallorca and Menorca; Black circles and squares represent samples at which Callionymus reticulatus appeared; The 50, 100, 200, and 500 m isobaths are shown