INTRODUCTION
Plocamopherus ocellatus Rüppell & Leuckart, Reference Rüppell and Leuckart1828 was described from a single individual collected in 1822 from coral in Tor on the Sinai coast of the southern Gulf of Suez. The species was meticulously described and illustrated (Rüppell & Leuckart, Reference Rüppell and Leuckart1828). While investigating the fauna and flora of the Sudanese coast of the Red Sea in 1904–1905, Cyril Crossland collected seven specimens on muddy bottoms in the Bay of Suez, in Suakim Harbour ‘on the boxes in which Pearl Oysters were kept’ and in Dongnab Harbour (Eliot, Reference Eliot1908). In 1924, three specimens were collected in the Suez Canal at the northern end of the Great Bitter Lakes and near Toussoum, and it was remarked ‘As it is a Red Sea form, not known from the Mediterranean, it has presumably migrated about 75 kilometres, or nearly halfway northwards along the Canal’ (O'Donoghue, Reference O'Donoghue1929). In 1977, over half a century later, the species was found for the first time in the Mediterranean: a single individual was collected by one of the authors (BSG) off Nitzanim, Israel, on the muddy bottom at a depth of 50 m (Barash & Danin, Reference Barash and Danin1982 (list), 1986). In 1998, a single specimen was photographed off Kaş, Turkey, amongst rocks at 8–10 m depth (Rudman, Reference Rudman2002). In 2000, 2002 and 2003, specimens were collected off Lebanon (Valdés & Templado, Reference Valdés and Templado2002; Crocetta et al., Reference Crocetta, Zibrowius, Bitar, Templado and Oliverio2013). In December 2011, eight specimens and many egg ribbons were observed in the Bay of Iskenderun on algae-covered rocky bottoms at 4 m depth (Çevik & Cavas, Reference Çevik and Cavas2012).
Since the first record dating back to 1977, no additional observations have been recorded from Israeli waters in the scientific literature, and yet a spate of recent finds seem to support the establishment of a local self-propagating population of P. ocellatus off the Israeli coast.
MATERIALS AND METHODS
The present account comprises opportunistic data collected during biodiversity assessment surveys of the hard bottom biota off the Mediterranean coast of Israel, and by recreational divers/underwater photographers during 2003–2015. Underwater surveys were carried out by scuba diving near several scuttled vessels used as wreck diving sites: ‘Zeev Hayam’ off Tel Aviv (34.43.44″N 32.03.41.1″E), 2003, 25 m depth, same location 2007, 2009 and March 2015; ‘Eitana’ off Nahariya (35.04.38.6″N 33.02.25.0″E), 2009, 30 m depth; ‘Nitzan’ off Achziv (33.02.234″N 35.04.245″E), December 2014, 26 m depth, same location, April 2015, 26 m depth. In addition, it was recently sighted on the breakwater of Ashdod Port, May 2015, 15 m depth. No specimens were collected.
RESULTS
SYSTEMATICS
Superfamily POLYCEROIDEA Alder & Hancock, Reference Alder and Hancock1845–1855
Family POLYCERIDAE Alder & Hancock, Reference Alder and Hancock1845–1855
Genus Plocamopherus Rüppell & Leuckart, Reference Rüppell and Leuckart1828
Plocamopherus ocellatus Rüppell & Leuckart, Reference Rüppell and Leuckart1828
(Figure 1A–F)
Plocamopherus ocellatus Rüppell & Leuckart, Reference Rüppell and Leuckart1828, Israel. (A) Off Achziv (33.02.234″N 035.04.245″E), April 2015, photo by Shevy B-S. Rothman; (B) off Tel Aviv (34.43.44″N 032.03.41.1″E), 2009, photo by Yoav Lavi; (C) egg ribbon, off Achziv (33.02.234″N 035.04.245″E), December 2014, photo by Yaron Halevi; (D) off Tel Aviv (34.43.44″N 032.03.41.1″E), March 2015, photo by Idan Loewenberg; (E) off Nahariya (35.04.38.6″N 033.02.25.0″E), 2009, photo by Omri Selner; (F) off Tel Aviv (34.43.44″N 032.03.41.1″E), October 2003, photo by Michael Levin.
Plocamopherus ocellatus Rüppell & Leuckart, Reference Rüppell and Leuckart1828; Eliot, Reference Eliot1908; O'Donoghue, Reference O'Donoghue1929; Barash & Danin, Reference Barash and Danin1986; Rudman, Reference Rudman2002; Valdés & Templado, Reference Valdés and Templado2002; Levin, Reference Levin2003, photo; Moradi, Reference Moradi2010, photo; Çevik & Cavas, Reference Çevik and Cavas2012; Nithyanandan, Reference Nithyanandan2012: 5, Figure 5; Crocetta et al. Reference Crocetta, Zibrowius, Bitar, Templado and Oliverio2013, Supplementary Data.
Colour in life: body colour ranges from brownish mauve (Figure 1E) to dark chocolate brown (Figure 1A) unevenly spread with spots of various size and shape, coloured rich yellow (Figure 1A) to orange (Figure 1B), with dark ring-like margins. Egg ribbons pale mauve (Figure 1C).
DISCUSSION
Plocamopherus ocellatus seems to be a very rare species: since it was first collected in 1822 just some 30 specimens were recorded in the scientific literature. It is native to the Red Sea and was recently recorded from the northern and southern Arabian Gulf (Moradi, Reference Moradi2010; Nithyanandan, Reference Nithyanandan2012). It was collected from the Suez Canal and from ‘stepping stone’ locales along the coast of the Levant (see above). Yet, these scant records provide some interesting information. It inhabits diverse habitats such as pristine coral reefs, muddy bottoms, algae-covered hard bottoms, polluted harbours, marinas and ship wrecks (Rüppell & Leuckart, Reference Rüppell and Leuckart1828; Eliot, Reference Eliot1908; Barash & Danin, Reference Barash and Danin1986; Levin, Reference Levin2003; Moradi, Reference Moradi2010; Nithyanandan, Reference Nithyanandan2012; Crocetta et al., Reference Crocetta, Zibrowius, Bitar, Templado and Oliverio2013; this paper), and having been collected in 1924 in the Great Bitter Lake, it is likely tolerant of high salinity (O'Donoghue, Reference O'Donoghue1929). As its pink egg ribbons were observed in December, both in Turkey (Çevik & Cavas, Reference Çevik and Cavas2012) and in Israel (Figure 1D) it is likely that it reproduces in the winter months, although individuals were observed year round. Crossland (fide Eliot, Reference Eliot1908: 104) observed ‘…that this species…suddenly appeared for a short time in great abundance and as suddenly disappeared, after depositing pink spawn…and is attached to Polyzoa.’ Indeed, it feeds on the arborescent bryozoan Bugula neritina (Linnaeus, Reference Linnaeus1758) (O'Donoghue, Reference O'Donoghue1929). Bugula neritina is a complex of three cryptic species, of which the cosmopolitan Type S is a common fouling species that has been known since the 18th Century in subtropical and tropical localities (Fehlauer-Ale et al., Reference Fehlauer-Ale, Mackie, Lim-Fong, Ale, Pie and Waeschenbach2014). It stands to reason that the recorded presence of P. ocellatus in ports and shipwrecks, both in the Red Sea and the Mediterranean where B. neritina provides a suitable habitat for the establishment success, is due to its association with the ubiquitous fouling bryozoan.
It is possible that P. ocellatus has been present off the Israeli coast at least since the late 1970s, and spread northward to Lebanon and Turkey, but occurred in such low numbers that it escaped attention until the population ‘bloomed’ recently, or that the earlier introduced population died out, and the millennial records from Turkey, Lebanon and Israel stem from a subsequent introduction through the Suez Canal.
The polycerid is known, like some of its cogeners, for its bioluminescent behaviour (Eliot, Reference Eliot1908; Vallés & Gosliner, Reference Vallés and Gosliner2006).
ACKNOWLEDGEMENTS
The authors are grateful to Roy Gevili, Yaron Halevy, Yoav Lavi, Michael Levin, Idan Loewenberg and Omri Selner for sharing their data and photographs, and Yair Yam, Putsker Diving Club, Nahariya, for helpful diving services. Oz Rittner, The Steinhardt Museum of Natural History and Israel National Center for Biodiversity Studies, edited the photographs. Sincere thanks to the librarians at the American Museum of Natural History, New York, US. The authors thank the unnamed reviewers for helpful comments.
