Spirobranchus tetraceros ( Schmarda, 1861 )

Ben-Eliahu, M. Nechama & Ten Hove, Harry A., 2011, Serpulidae (Annelida: Polychaeta) from the Suez Canal- From a Lessepsian Migration Perspective (a Monograph) 2848, Zootaxa 2848 (1), pp. 1-147 : 88-95

Spirobranchus tetraceros ( Schmarda, 1861)

Fig. 33 , Table 5

Preliminary remarks. The nominal taxon, “ Pomatoceros triqueter ”, was reported from shallow fouling panels from Alexandria harbour and from various locations within the Suez Canal (see Mediterranean and Suez Canal Synonymy Sections below). That contradicts what is known of the ecology and depth preferences of Pomatoceros triqueter , a boreal-temperate taxon with an Atlantic-Mediterranean distribution in sublittoral depths (e.g., in the Levant Basin, samples from 38–67 m from Israel (N = 3), and from 119 m from Cyprus (N = 1) (authors’ unpubl. database). Along the coast of Israel and presumably also along the Mediterranean coast of Egypt, there are three rather similar species found in shallow habitats. Like Pomatoceros triqueter , all three have triangular tubes and calcareous opercular plates borne on winged opercular peduncles: Pomatoceros lamarckii ( Quatrefages, 1866) , an Atlantic-Mediterranean species ( Bianchi 1981), Spirobranchus tetraceros and Pomatoleios kraussii, Lessepsian migrant species ( Ben-Eliahu & ten Hove 1992) that may occur on biofouling panels, both of them present in the Suez Canal. Spirobranchus tetraceros is distinguished from the others by its more elaborate opercular spines and its fringed opercular wings (in most specimens) and special collar chaetae ( Figs 33A, D and E ). The opercular peduncles of both Pomatoceros lamarckii and Pomatoleios have wings with smooth margins. Pomatoleios kraussii has a somewhat concave opercular plate, frequently with a diagnostic sunken (internal) talon (ten Hove 1973 fig. 43); best seen when cleared in glycerine, and it lacks collar chaetae. Pomatoceros lamarckii has fine small limbate collar chaetae ( Ben-Eliahu & ten Hove 1992). Ghobashy et al. (1990) retroactively corrected citations of “ Pomatoceros triqueter ” for the Suez Canal to Spirobranchus tetraceros . However, given the presence of the similar taxon, Pomatoleios kraussii , we have placed question marks before the problematic citations.

Pomatoceros tetraceros Schmarda, 1861: 30 , pl. 21, fig. 129 [Type locality: New South Wales].

Spirobranchus tetraceros: ten Hove 1970b: 3–14 , figs 1–34 [redescription and synonymy; Red Sea, Indian Ocean: Natal; Persian Gulf; Malaysian Archipelago, Japan, Australia: Sydney, California:?Gulf of Catalina; tropical Pacific coast of America; Caribbean Sea; considered as absent thus far on the west coast of Africa (not found in two locations in Dakar, Senegal, by H.A. ten Hove in 1982); however, collected in 2007 in Dakar (H. Zibrowius, pers. comm.); Imajima 1979: 177–178, fig. 8 [ Japan]; Zibrowius 1979b: 133–134 [ France, Toulon Port, biofouling removed from the aircraft carrier “Foch”]; Imajima & ten Hove 1984: 51–52 [ Japan to Australia]; Wehe & Fiege 2002: 133–134 [Suez Canal, Red Sea, Gulf of Aden, Arabian Sea, Persian Gulf; list of references]; Zenetos et al. 2005: 73 [classified as an “established alien species” in the Mediterranean].

Eastern Mediterranean

Spirobranchus giganteus coutierei: Laubier 1966: 18–19 (fide ten Hove 1970b: 41–49) [ Lebanon: Beirut, 25–30 m, IX.65, on bryozoans and madreporarians; first Mediterranean record of this Lessepsian migrant].

Spirobranchus coutieri [ sic]: Amoureux 1976: 1054 [ Israel, Haifa Bay , 18 m, rocky substrates] .

Spirobranchus tetraceros: Zibrowius & Bitar 1981: 159–160 [ Lebanon, Beirut, Zaitouné, 5 m, on bivalve, 23.IX.1978]; Ben-Eliahu 1991b: 518–524, fig. 2 [ Israel, Lebanon; Rhodes, Kallithea, 12.X.1970, HUJ-Poly-585—the earliest record indicating north-westward expansion to the Aegean Sea]; Ben-Eliahu & ten Hove 1992: 40–48 [ Israel, entire coast from north to south, 1–24 m]; Ben-Eliahu & Fiege 1996: 33–38 [western Levant Basin, Israel]; Selim 1997b: 94–96, figs 7a–c, 8a–e [ Egypt, Port Said, collected in 1988]; Ben-Eliahu & Payiatas 1999: 101, 119 [ Cyprus, Larnaca jetty, empty tubes, legit H. Zibrowius 1996; Famagusta harbour, Aya Napa, empty tube, legit M.N. Ben-Eliahu and G. Payiatas 1998, det. H. Zibrowius]; Zibrowius & Bitar 2003: 71 [ Lebanon]; Bitar 2005: 427 [ Lebanon, fouling communities, 5–20 m]; Ghobashy & Ghobashy 2005: 90–93 [Alexandria, Eastern Harbour on solid surfaces, citing Abd-Elnaby (2005) that S. tetraceros had become very common and was the most abundant serpulid in the harbour on rocks, concrete and metal surfaces, though H. elegans was still dominant on the fouling plates.]; Selim et al. 2005: 89–97 [reports replacement of Hydroides elegans as the dominant fouling serpulid species in Abu Kir Bay (Alexandria)]; Çinar 2006: 232, fig. 9 a–d, [Levant coast of Turkey, Iskenderun Bay, 0.1– 25 m on stones, IX.2005]; Abd-Elnaby 2009: 10 [Alexandria]; Selim 2009: 74 [Port Said].

? Pomatoceros triqueter not (Linnaeus), sensu Ghobashy & Selim 1976b: 303, 304 [Alexandria, Eastern Harbour, see preliminary remarks, above]; Ghobashy et al. 1980: 84, table 2 [Port Said]; El-Komi 1991a: 8, 12, tables 3, 4 [Alexandria, harbour]; El-Komi 1991b: 290–291, table 3 [Alexandria, harbour]; El-Komi 1992: 124, 128, tables 2, 4 [Alexandria, harbour]; El-Rashidy et al. 2009, 1 p. [Alexandria].

Suez Canal Spirobranchus tetraceros: Ben-Eliahu 1972a: 77 [eastern bank, several locations; 21.VI.1967, first reference from within the Suez Canal]; 1972c: 232, table 2; Ghobashy et al. 1986: 319–326, fig. 4 [Lake Timsah]; Ghobashy et al. 1990:

677–685 [Lake Timsah]; Ben-Eliahu 1991b: 519, fig. 2 [el Qantara-Km 45, Lake Timsah, Bitter Lakes]; Selim

1997b: 94–96, figs 7a–c, 8a–e [Suez Canal, “very abundant in all sites investigated”, i.e., El-Kab, Lake Timsah,

Deversoir, collected in 1988; for Lake Timsah, also citing Shalla (1985) and Mostafa (1992) (see App. Table 4)];

Emara & Belal 2004: 192–199 [pooled Lake Timsah and Bitter Lakes data]; Ghobashy & Ghobashy 2005: 91, 93

[referring to Ghobashy et al. (1986) and to Barbary (1992, see App. Table 4); Selim 2009: 74 [northern part of the canal]; Abd-Elnaby 2009: 10 [southern part of the canal].? Pomatoceros triqueter not (Linnaeus), sensu Ghobashy et al. 1980: 84, table 2 [El Tina, Isma’iliya]; Ghobashy & El-

Komi 1981a: 170 [Lake Timsah]; Ghobashy & El-Komi 1981b: 181 [southern canal]; Ghobashy 1984: 45 [Lake

Timsah]; Ghobashy & Ghobashy 2005: 91; 93 and referring to Ghobashy et al., 1980. In 1986, Spirobranchus tetraceros was first cited by this research group and all previous records of P. triqueter presumably refer to S. tetraceros . Spirobranchus sp. : Ghobashy 1984: 45 [Lake Timsah]; presumably S. tetraceros .? Spirobranchus giganteus not Pallas, sensu Selim 2009: 73 [Selim cited Fauvel (1933a, b) that referred to S. coutieri

( Gravier, 1908) and S. multicornis ( Grube, 1862) , both taxa synonymised with S. tetraceros , and thus Selim’s record is attributable to what we presently regard to be the S. tetraceros -complex].

Gulf of Suez and Gulf of Aqaba

Spirobranchus contieri [sic]: Pixell 1913: 83–84, pl. 9, fig. 8 [Gulf of Suez: Suez; Red Sea: Suakin harbour; Indian Ocean: Zanzibar].

Spirobranchus jousseaumi [sic]: Potts 1928: 701 [Suez, Gulf of Suez] (synonymised with S. tetraceros by ten Hove 1970b: 4).

Pomatoceros coeruleus not (Schmarda), sensu Fauvel 1933a: 77 [Gulf of Suez St 24 ter, 60–80 m, 33º41'– 33º45'E, 27º48– 27º55' N, see Spirobranchus tetraceros sensu ten Hove 1970b , fide H. Zibrowius, pers. comm. (18.III.1971)]; Fauvel 1957: 10 [Gulf of Aqaba, Elat (see “Material examined”, below)].

Pomatoceros triqueter not (Linnaeus), sensu Fauvel 1933a: 78 [Gulf Suez (see Spirobranchus tetraceros sensu ten Hove 1970b , fide H. Zibrowius, pers. comm. 18.III.1971]; El-Komi et al. 1998: 16, 17 [Suez Bay, 1992–1993, on polystyrene fouling panels and buoys, previously examined Egyptian-identified material showed this name to have been used for S. tetraceros ]; Ghobashy & Ghobashy 2005: 91; 93 [citations from Suez Bay referring to El-Komi et al. 1998].

Spirobranchus giganteus not (Pallas), sensu Fauvel 1933a: 78–79 [Gulf of Suez: 7 stns, 35–[36–80] m; Gulf of Aqaba, 1 stn, 25 m, fide ten Hove (1970b: 4)]; Monro 1937: 317 [Arabian Sea]; Amoureux 1983: 369 [(part) Gulf of Aqaba, on algae, presumably S. tetraceros by habitat].

Spirobranchus jousseaumei: Fishelson & Rullier 1969: 102 [Musseri; redet. H.A. ten Hove 1990 S. tetraceros ]; Fishelson 1971: 122, table 3 [Gulf of Aqaba]; Amoureux et al. 1978: 151, fig. 16 S.j. [Gulf of Aqaba, Elat, Venezia lagoon, redet. herein due to the figure as S. coronatus , a member of the S. tetracero s–complex; both of these taxa appear to be present in the lagoon].

Spirobranchus polytrema not (Philippi), sensu Amoureux et al. 1978: 150–151, fig. 16 “ S.p.” [Gulf of Suez, Ras Kanisa; corrected to S. tetraceros herein, see remarks below].

Spirobranchus tetraceros: Ben-Eliahu 1991b: 519 , fig. 2 [Gulf of Suez, Gulf of Aqaba]; Selim 1997b: 94–96, figs 7a–c, 8a–e [Gulf of Suez, Port Taufiq, collected in 1988]; El-Komi et al. 1998: 16, 17 [Suez Bay, 1992–1993]; Hassan 1998: fig. p. 53 [Aqaba]; Ghobashy & Ghobashy 2005: 91, 93 [citations from Suez Bay referring to El-Komi et al. 1998].

Spirobranchus elatensis Pillai, 2009: 165–168 , figs 50a–f [Gulf of Aqaba; Elat; see Table 5, herein].

Red Sea proper-Indo-West-Pacific (excluding citations from Gulf of Suez and Gulf of Aqaba already given above) Serpula (Pomatoceros) multicornis Grube 1862: 67 , fig. 3; 1868: 639–640; 1870: 519 [all three records from Red Sea]. Pomatoceropsis coutierei Gravier 1905: 445–448 [Gulf of Aden: Djibouti and E. Aden; extensive description]; 1906a: pl. 8 figs 294–299 [Gulf of Aden]; 1906b: 114 [Gulf of Aden, Djibouti]; 1908: 125–130, pl. 8 figs 294–299, text-figs 482–487 [Red Sea, Musha Island].

Pomatoceropsis jousseaumei Gravier 1906b: 114 , pl. 8 figs 292–293 [South Red Sea, Bab el Mandeb, Périm Island; Gulf of Aden, Djibouti];? Gravier 1908: 130–132, pl. 8 figs 292–293, text-figs 488–491 [South Red Sea, Périm Island; Gulf of Aden; queried because figures of aberrant specimens cannot be identified with confidence].

Spirobranchus contieri [sic]: Pixell 1913: 83 [Indian Ocean, Zanzibar].

Spirobranchus semperi: Pixell 1913: 82 [Red Sea; Indian Ocean, Zanzibar]; Wesenberg-Lund 1949: 359, fig. 47. [Persian Gulf].

Spirobranchus semperi var. aceros: Pixell 1913: 82–83 [Red Sea, Suakin, Agig Bay; Indian Ocean, Zanzibar, Maldives, Amirante Islands].

Spirobranchus giganteus not (Pallas), sensu Monro 1937: 317 [Arabian Sea]; Fishelson & Rullier 1969: 102 [part] [Red Sea, Eritrea, Entedebir, Umm Aabak, 3–4 m; on living or dead coral, 14 specs].

Spirobranchus giganteus var. arabica Monro, 1937: 317 , fig. 28 [Arabian Sea, South Arabian coast].

Pomatoceros caeruleus not (Schmarda), sensu Fauvel 1955b: 119 [Red Sea, Abulat Island ] .

Spirobranchus tetraceros: Day 1967: 802 , figs 38.3 l–n [Indian Ocean, Zanzibar]; Vine & Bailey-Brock 1984: 145–146, figs 6a–b [fig. 1c presumably also belongs to S. tetraceros ; Red Sea, Suakin harbour, Sanganeb Lagoon, Dunganab Bay]; Vine 1986: 91 and figure [Red Sea]; Ben-Eliahu 1991b: 519, fig. 2 [South Red Sea, Eritrea, Dahlak Archipelago]; Ishaq & Mustaquim 1996: 180–182, figs 10a–i [Arabian Sea, Pakistan, Karachi]; Abd-Elnaby 2009: 10 [Red Sea].

Spirobranchus jousseaumei: Fishelson & Rullier 1969: 102 [part] [Red Sea, Eritrea, on sponge; Bay of Melita, on coral (p.p. redet. herein as S. coronatus )].

Spirobranchus tetraceros complex: ten Hove 1994: 113–114 [Indian Ocean, Seychelles, Amirante Islands].

Material examined. Locations adjacent to the Suez Canal, Mediterranean side: Rhodes: 1 sample, littoral.— Cyprus: 1 empty tube, [3–5] m (H. Zibrowius, pers. comm.) .— Lebanon: common (H. Zibrowius, pers. comm.) .— Israel: 37 samples, 0.2–[3–18]– 31 m; first Israeli sample from Haifa Bay , 5.XI.1967, SLM 272, 27 m, det. M.N. Ben-Eliahu, INCNH unpublished data .

Suez Canal material reported herein: 57 samples, 137 specimens. Beets’ Great Bitter Lake samples: No triangular Spirobranchus tetraceros tubes appeared to be present on any of the shells.—Hebrew University- Smithsonian Expeditions, 1967–1973, 8 samples, 12 specs: el Qantara, Km 45: SLC 6, 1 spec.; SLC 31, 1 spec.; Lake Timsah, Km 78, opposite Isma’iliya: SBE 7, 1 spec.; SBE 8, 3 specs; Great Bitter Lake, east of Deversoir, Km 97, SLC 50, 1 spec.; SLC 61, 1 spec.; SLC 71, 1 spec.; Great Bitter Lake, SLC 123, 3 specs— Great Bitter Lake “Yellow Fleet” Biofouling Samples, January 13–20, 1975: 45 subsamples, 115 specs; Bremerhaven dry dock, 18.VI.1975, 2 subsamples, 2 specs, both individuals large, decayed.—Lake Timsah, legit, det. S.H. Shalla ca. 1984 Spirobranchus sp. , Conopomatus sp. , redet. H.A. ten Hove, ZMA V.Pol. 4997, 4998, 6 specs—El Tawan Beach, 10 / 19.XI.1988, legit S.B. Shazly, det. H.A. ten Hove, ZMA V.Pol. 3820, 2 specs.

Locations adjacent to the Suez Canal, Red Sea side: 7 samples, shallow. Gulf of Suez, J.K. Lord Expedition 1870, det. H.A. ten Hove 1969 S. tetraceros (3 specs left under the original BM ( NH) number by HAtH, from a mixed sample of tubes, one Spirobranchus corniculatus (now BM ( NH) 1870.12.23.60), three S. tetraceros and 3 epibiontic species of Hydroides (now BM ( NH) 1870.12.23.61, 62, 63), first listed together under an unpublished ms. name by W. Baird), BM ( NH) 1870.12.23.31. Since both Spirobranchus taxa inhabit living coral, the sample was presumably from a coralligenous habitat; same, redet. H.A. ten Hove 1969 S. tetraceros, BM(NH) 1870.12.23.30, 2 specs—Gulf of Suez, legit R. MacAndrew, listed under an unpublished ms. name by W. Baird, redet. H.A. ten Hove 1969 S. tetraceros, BM(NH) 1869.7.8.42.—Gulf of Suez, Cambridge Expedition, R6, 6.XI.1924, det. F.A. Potts (1928: 701) Spirobranchus jousseaumi ; in 1986, Ben- Eliahu noted opercular wings reduced without crenellations, interradiolar membranes with unilobed processes, characteristic antler-like opercular spines; subsequent re-examination (in 2002) showed the operculum had been cut off at the base of the peduncle, and was missing, 1 spec., CUZM AN. I.1930.

Gulf of Aqaba: 10 samples, [0.2–1]– [6–8]–[20–25] –25. Elat, shallow up to 2 m, 1955, E55 / 441, legit H. Steinitz, det. P. Fauvel Pomatoceros coeruleus [sic], specimen lacked tube, operculum and collar chaetae; “branchia and collar characterized by dark indigo blue colour” ( Fauvel 1957: 10); redet. herein due to presence of interradiolar processes].

Red Sea: South Red Sea, 8 samples, 1– 27.4 –36.6 m, HUJ .

Indian Ocean: Seychelles, 11 samples, [1–7]– [4–8]–[12–15]– 45 m, ZMA, RMNH.

Suez Canal depth and substrates: shallow, 0.4–[3–4] m, on alga: Laurencia ; on sponge; on bivalves: Brachidontes pharaonis , Malvufundus regulus , Pinctada radiata and Spondylus spinosus ; barnacles; bryozoans; tunicates; rocks; artificial substrates: Canal walls, tin can submerged in mud; rubber fenders and iron frames.

Distribution. Circumtropical, but see Remarks. Red Sea: Gulfs of Suez and Aqaba. Lessepsian migrant to the Mediterranean: Israel, Lebanon, Cyprus, Turkey and Rhodes.

Colouration (Field notes for Lake Timsah specimen): Ventral side of operculum pink, dorsal side bluebrown. Radioles, from distal to proximal part, with white band, short blue band, white band, brown band, white band at base. Thorax dark red-brown. Noted very pink tube (Great Bitter Lake subsample Biv 11 [App. Table 2D]). One of us (HAtH) has the impression that individuals with bluish tubes that are buried in living corals and attached to dead Pocillopora damicornis (Linnaeus) skeletons may belong to a different taxon than the pink tube specimens found on various hard substrates, which might lend some support to Pillai’s (2009) distinction between S. tetraceros and S. semperi .

Remarks. The taxon Spirobranchus tetraceros as redefined by ten Hove (1970b) is presently considered to be a complex of species, with some taxa in the Indo-West-Pacific and another in the Caribbean ( Smith 1985; ten Hove & Kupriyanova 2009). Some of the Indo-West-Pacific species have been defined as “ S. tetraceros s. str., S. coronatus and S. decoratus ”, but, according to Smith (1985) there may be further subdivision that should be done within the taxon S. tetraceros “ s. str. ” based on characters such as the number of the main spines, colouration of the tube and the tube lumen, the extent of serration of filiform processes on the peduncular wings, and the presence and number of pairs of radiolar ocelli on the radioles.

When we were finalizing the present paper, Pillai (2009) published his discussion on Spirobranchus . As he did with other taxa, Pillai split S. tetraceros sensu ten Hove (1970) (i.e., the S. tetraceros- complex) into about 8 different taxa, based on different character combinations ( Pillai 2009: 158, notably the discussion on p. 162). In order to evaluate this attempt to clarify the Spirobranchus tetraceros -complex, we compared the main characters used by Pillai with our material from the Suez Canal (see Table 5). By Pillai’s standards, the Suez Canal material is characterized by a unique combination of characters meriting the description of yet another species, intermediate between his definition of Spirobranchus tetraceros and S. semperi . Using Pillai’s criteria, ten Hove's (1970) figures, from a single Bahrain sample, should be named S. tetraceros (figs 23–24), S. semperi (figs 25–26, 28–29) and S. arabicus (figs 1–2, 15–16). We are not prepared to accept this approach since most of Pillai’s taxa are based upon single samples with 1– 6 specimens only and variability of various character states has not been studied by Pillai. For instance, Pillai’s (2009) description of S. elatensis , from the Gulf of Aqaba, was distinguished from S. tetraceros mainly by it’s conical operculum, based only on a single specimen. Our work is based on hundreds of samples, with several hundreds of specimens (admittedly not consistently enumerating all character states dealt with recently by Pillai). As regards S. tetraceros , we have found both conical and fully branched opercula and intermediate forms in the same Suez Canal samples, and consider them to belong to a single species (see Figs 33C–E ; see also ten Hove 1970, figs 6, 30 for a Caribbean population of what we nowadays would identify as the Caribbean S. dendropoma Mörch, 1863 ; cf. Smith 1985:66). We have noted that the presence / absence of papillae, and the shape of these papillae / fringes, seems to be dependent on their position, dorsal or more ventrally, in the radiolar circles. Without population studies, and without genetic support, we find Pillai’s splitting difficult to accept. Thus, we prefer not to adopt the classification given by Pillai (2009), but to retain the more “traditional” concept of this taxon as both in the present paper and Selim (1997b), thus synonymising S. elatensis with S. tetraceros s. str. A review of all the literature citations, taking into consideration Smith’s (1985) and Pillai’s (2009) hypotheses is not within the province of the present paper. However, when the review of this taxon will finally be carried out, it should comprise both morphological and genetic evidence from populations.

1) No. of spines sensu ten Hove 1970; in ten Hove & Kupriyanova (2009) these structures were referred to as horns,— 2) See Bailey-Brock (1985, fig.8e) or Pillai (2009, fig. 37c) and Fig. 33D . The character was never looked for consistently, but ten Hove’s unpublished notes mention it was present in material from New South Wales to Northern Territory, Australia,— 3) Information missing in Pillai (2009), but present in Bailey-Brock (1985: 204–207, fig. 8),— 4) Data from ten Hove's sketches of the types of S. coronatus ,— 5) From ten Hove's notes on the type material; the 4 th specimen from Heron Island, Queensland, Australia, det. S. coronatus by D. Straughan is a specimen exactly like S. " baileybrockae ”,— 6) Pillai (2009, figs 48b, c) suggest 1 medioventral (split in two) and two laterodorsal split in two; thus 6 horn tips,— 7) A double fringe was only figured before by Selim (1997b, fig. 7b); see Fig. 33D ,— 8 ) According to Pillai (2009: 178) four spines: 2 ventral spines and 2 dorsal ones with short mediodorsal tine. We interpret his figures 57c, d slightly otherwise,— 9) One also might argue that there are 4 opercular spines: 2 ventral ones split twice and two laterodorsal ones split twice of which the 1st branch is a short mediodorsal tine.

Regional citations given above are for the species complex as known subsequent to ten Hove (1970b). We should note, however, that fig. 16 S.j. of Amoureux et al. (1978: 150) from the Gulf of Aqaba, Elat, Venezia lagoon appears to be that of Spirobranchus coronatus ; thus, both S. tetraceros and S. coronatus are present in the northern Gulf of Aqaba. Spirobranchus polytrema not Philippi, sensu Amoureux et al. (1978: 150) is corrected to S. tetraceros based on the illustration marked S.p. in his fig. 16; thus the nominal taxon S. polytrema , was not a Mediterranean migrant to the Red Sea via the Suez Canal as stated by these authors.

The Suez Canal population appears to belong to a single taxon ( Figs 27A–E ), a fouling species characterised by small peduncular wings with a pointed tip, generally fringed ( Figs 27A, D, E ), sometimes with a double fringe (clearly visible in Fig. 33D , right wing; see note Table 5); interbranchial membranes usually with unilobed processes and the specimens examined from the Levant Basin of the Mediterranean appear to belong to the same taxon, known also from the Gulf of Aqaba and the Gulf of Suez (Ben-Eliahu 1991, fig. 2). Examination of live material from Elat showed two dense rows of bright crimson ocelli with minute lenses on each side of the rachis of the radioles (base of prostomium not looked for in this live specimen), suggesting the Elat population might be the same as Smith’s “ Spirobranchus tetraceros species C” ( Smith 1985, Table 5). Selim (1997b fig. 7) remarked and illustrated the polymorphism of the operculum of S. tetraceros , and we have also included examples in Figs 33A–E . Ten Hove (1970b: 4, 48) noted that Pixell (1913) had dealt with the variability of Spirobranchus tetraceros opercula of the C. Crossland collection in the Natural History Museum, London by giving them a variety of names (see synonymy above).

In their ranking of the Lessepsian migrants within the category, “Worst Invasive Species”, Zenetos et al. (2005) appear to underestimate the importance of Spirobranchus tetraceros , known from Beirut from 1965 ( Laubier 1966, as Spirobranchus giganteus coutierei ), and as far as Rhodes already in 1970 (Ben-Eliahu 1991, collected by the “Biota” project). Selim et al. (2005) reported that S. tetraceros had replaced Hydroides elegans as the dominant fouling species in Alexandria Mediterranean waters, such that it amply fulfils the criterion “having an serious impact on diversity” ( Zenetos et al. 2005).

Figures

FIGURE 8. Hydroides heterocerus. Variability in forms of opercula from different regions: A–D. Operculum of specimen from the Great Bitter Lake aggregate removed by J.P. Taasen from the M/S “Münsterland” after its journey to the Hapag-Lloyd dry dock in Bremerhaven (18.VI.1975, 7 m). A—Lateral view, B–D—Apical views, B—Focus on tips of verticil spines, C—Focus on basal spinules of verticil, D—Enlargement of marginal teeth of funnel; the expansion of the tips of the marginal teeth in “D” is intermediate between “E” and “F,” E—“Bowling-pin-shaped” radii with blunt or even stubby tips, specimen from Little Bitter Lake opposite Kabrit (sample SLC 123), F—More expanded, “T”-shaped tips found in specimen from the Sudanese Red Sea (BM(NH) 1972.23, legit C. Crossland, 1904–1905). Lessepsian migrants with marginal radii like “D” or like “E”. Scale: 1 mm.

FIGURE 27. Comparison of Salmacina spp. from the Suez Canal, Gulf of Suez, and Gulf of Aqaba. A—Salmacina incrustans from Great Bitter Lake, spec. 10-3, thoracic uncini both (F+1) = 3, left uncinus detailed F:3:3:3:3:4:4 (compare Fig. 23), B—Salmacina not dysteri (Huxley) from Gulf of Suez (32°44’–32°47’ E., 28°49’–28°54 N., 25–30 m, legit R. Ph. Dollfus, Stn 11, 8.XII.1928, coralligenous sand, det. P. Fauvel (1933a: 80, 1933b: 143), generalised herein to Salmacina sp.; thoracic uncini from second torus of single (minute) specimen, apical part of uncini covered by a flap; F:4:5:5:? (left uncinus) and F:4:6:6:6:? (right uncinus), C—Collar chaeta fin, blade broken off, D—Intertwining, netlike tube aggregation from which minute specimen was removed, E—Thoracic mru-type uncini of Salmacina specimen from Gulf of Aqaba (from Elat). Magnifications: A—12,000 x, B, C—10,000 x, E—8,000 x.

FIGURE 33. Variability in opercula of Spirobranchus tetraceros specimens from the Great Bitter Lake “Yellow Fleet”. A—Fringed wings of opercular peduncle visible on specimen to the right, B—¾ lateral view of tube with partly emerged operculum, C—Lateral view of conical form of operculum, without antler-like spines (subsample Bry1), D—Lateral view of conical operculum with antler-like spines; fringes (even a double one) seen on wings (D–E, subsample Ships Hulls Poly 24), E—Frontal view of operculum with spines; fringes seen on wings. Scales: 1 mm.