(Fig. 26)
Serpula (Pomatoceros) corniculata Grube, 1862: 66, fig. 5 [Java; original description].
Spirobranchus giganteus not (Pallas, 1766).— Straughan 1967 b: 245, fig. 14 e [Qld, Australia; in part, several of the synonyms included by Straughan belong to Sp. tetraceros]; Smith 1984 a: 461–483 [Magnetic, Orpheus and Lizard Island, Qld, Australia; larval development].
Spirobranchus giganteus sp. A, B, C.— Smith 1985: 24–37, figs 2 B–C, 3 A–F, 4 A–E, J–N, O –Q, 5 A–C, F–K, P–R, Table 1 [Lizard Island and other localities Qld, Australia; extensive descriptions, material partly studied by HtH in 1986].
Spirobranchus giganteus corniculatus. —ten Hove 1970: 24–32, 50 – 51, figs 63–73 [widely distributed in the Indo-West Pacific; including most of the extensive synonymy; Sp. paumotanus in the meantime has been reinstated and Sp. gardineri too is a full species, though Fauvel’s identifications –at least partly– belong to Sp. corniculatus]; Imajima & ten Hove 1984: 54 [Truk, Ponape, Majuro; Lizard Island]; Smith 1984 b: 951–955 [Magnetic Island, Qld, Australia; photoreceptors]; Marsden 1987: 71 - 64 [Heron Island, Qld, Australia; coral preference].
Spirobranchus gaymardi (Quatrefages, 1866).—Fiege & ten Hove 1999: 355 –364, figs 1–3 [redescription; Japan, Philippines, Indonesia, India, Australia (e.g., Lizard Island)].
Spirobranchus corniculatus. — Willette et al. 2015: figs 1, 2 [Australia, Fiji, Indonesia, Phillipines; DNA data].
Spirobranchus corniculatus -complex.— Hutchings 2008: 248, 250–251 [Great Barrier Reef, Australia].
Material examined. AM W. 201350 (11), North Ridge, 14 ° 40 'S, 145 ° 28 'E, coll. P. Hutchings, Jul 1977, det. H. ten Hove; AM W. 24045 (as Sp. gaymardi), Carter Reef, 14 ° 35 'S, 145 ° 35 'E, 15 m, coll. P. Hutchings, 10 Mar 1986, det. D. Fiege & H. ten Hove; AM W. 24046 (3, as Sp. gaymardi), SMF 6087 (2, as Sp. gaymardi), stn. 17, Palfrey Island, south of lighthouse, 14 ° 40 'S, 145 ° 28 'E, coral heads on sandy bottom, coll. H. ten Hove, P. Hutchings & M. Reid, 2 Mar 1986, det. D. Fiege & H. ten Hove; AM W. 27389, Carter Reef, 14 ° 35 'S, 145 ° 35 'E, coll. P. Hutchings, 10 Mar 1986; AM W. 28309 (2), between Lizard Head and Coconut Beach, 14 ° 40 'S, 145 ° 28 'E, undersides of boulders on rock, little sand, low tide, coll. H. ten Hove, 23 Jun 1983; AM W. 28433, Mermaid Cove, 14 ° 40 'S, 145 ° 28 'E, from crevices in dead coral, coll. H. ten Hove, 20 Jun 1983; AM W. 40282, Yonge Reef, back reef, 14 ° 36 'S, 145 ° 37 'E, 2 m, coll. P. Hutchings & P. Weate, 19 Jan 1975; AM W. 40283, same; AM W. 41739, Yonge Reef, back reef, 14 ° 36 'S, 145 ° 37 'E, in Millepora, coll. R. Smith, Nov 1985; AM W. 41741 (as Sp. gaymardi), Yonge Reef, reef flat, 14 ° 36 'S, 145 ° 37 'E, on Acropora palifera, coll. R. Smith, Nov 1985; AM W. 41746 (4, as Sp. gaymardi), Yonge Reef, 14 ° 35 'S, 145 ° 37 'E, coll. R. Smith, Dec 1983; AM W. 41753 (3, as Sp. gaymardi), same, coll. R. Smith, 5 Nov 1985; AM W. 41804 (as Sp. gaymardi), Yonge Reef, back reef, 14 ° 36 'S, 145 ° 37 'E, coll. R. Smith, Nov 1985; AM W. 41806, Yonge Reef, 14 ° 36 'S, 145 ° 37 'E, coll. R. Smith, 5 Nov 1985; AM W. 41808 (as Sp. gaymardi), Yonge Reef, back reef, 14 ° 36 'S, 145 ° 37 'E, in Porites lichen, coll. R. Smith, Nov 1985; AM W. 41810 (3, as Sp. gaymardi), Yonge Reef, 14 ° 36 'S, 145 ° 37 'E, coll. R. Smith, 5 Nov 1985; AM W. 41811 (as Sp. gaymardi), same, coll. R. Smith, Nov 1985; AM W. 41816 (2, as Sp. gaymardi), Lizard Island, 14 ° 40 'S, 145 ° 27 'E, in Porites, coll. R. Smith, 1983; AM W. 41817 (as Sp. gaymardi), Yonge Reef, back reef patch, 14 ° 36 'S, 145 ° 37 'E, in Stylophora pistillata, coll. R. Smith, 8 Nov 1985; AM W. 41818 (2, as Sp. gaymardi), Yonge Reef, 14 ° 35 'S, 145 ° 37 'E, coll. G. Kelly & R. Smith, Dec 1983; AM W. 41826 (2, as Sp. gaymardi), Mrs Watsons Bay, off Chinamans Ridge, 14 ° 40 'S, 145 ° 27 'E, coll. R. Smith, 8 Jan 1983; AM W. 41836 (2), lagoon, 14 ° 40 'S, 145 ° 27 'E, coll. R. Smith & D. Randall, 20 Jan 1983; AM W. 41742 (2), Yonge Reef, back reef, 14 ° 36 'S, 145 ° 37 'E, in Acropora palifera, coll. R. Smith, 11 Nov 1985; AM W. 41821 (4), Yonge Reef, back reef patch, 14 ° 36 'S, 145 ° 37 'E, in Acropora palifera, coll. R. Smith, 11 Nov 1985; AM W. 41834 (2), Waining Reef, back reef area, 14 ° 27 'S, 145 ° 13 'E, in Porites, coll. R. Smith, Dec 1983; AM W. 41886 (3, as Sp. gaymardi), Yonge Reef, back reef, 14 ° 36 'S, 145 ° 37 'E, in Porites, 10 m, coll. R. Smith, Nov 1985; AM W. 41913 (3, as Sp. gaymardi), Mrs Watsons Bay, off Chinamans Ridge, 14 ° 40 'S, 145 ° 27 'E, in Porites, coll. R. Smith, 26 Jul 1985; AM W. 41931 (2, as Sp. gaymardi), Yonge Reef, 14 ° 35 'S, 145 ° 37 'E, coll. R. Smith, Dec 1983; AM W. 41933 (as Sp. gaymardi), Mrs Watsons Bay, off Chinamans Ridge, 14 ° 40 'S, 145 ° 27 'E, in Porites, coll. R. Smith, 8 Jan 1983; AM W. 41934 (2, as Sp. gaymardi), Lizard Island, 14 ° 40 'S, 145 ° 27 'E, coll. R. Smith; AM W. 41936 (2, as Sp. gaymardi), Yonge Reef, back reef patch, 14 ° 36 'S, 145 ° 37 'E, in Porites sp. and Porites lichen, coll. R. Smith, 11 Nov 1985; AM W. 41938 (as Sp. cruciger), Yonge Reef, 14 ° 36 'S, 145 ° 37 'E, in Acropora pistillata, coll. I. Dight & R. Smith, 15 Jan 1985; AM W. 41940 (as Sp. cruciger), Waining Reef, back reef area, 14 ° 27 'S, 145 ° 13 'E, 5 m, coll. R. Smith, Dec 1983; AM W. 41941 (2, as Sp. cruciger), North Point, 14 ° 39 'S, 145 ° 27 'E, coll. R. Smith, 8 Jan 1983; AM W. 41942 (as Sp. cruciger), Yonge Reef, reef flat, 14 ° 36 'S, 145 ° 37 'E, on old Tridacna gigas shell, coll. R. Smith, Nov 1985; AM W. 42026 (7, as Sp. gaymardi), Mrs Watsons Bay, off Chinamans Ridge, 14 ° 40 'S, 145 ° 27 'E, in Porites, coll. R. Smith, 26 Jun 1982; AM W. 42028 (4, as Sp. cruciger), Yonge Reef, reef flat, 14 ° 36 'S, 145 ° 37 'E, in Porites, coll. R. Smith, Nov 1985; AM W. 42034 (as Sp. gaymardi), Yonge Reef, back reef, 14 ° 36 'S, 145 ° 37 'E, in Millepora, coll. R. Smith, Nov 1985; AM W. 42035, Mrs Watsons Bay, off Chinamans Ridge, 14 ° 40 'S, 145 ° 27 'E, coll. R. Smith; AM W. 42043 (as Sp. cruciger), Yonge Reef, back reef bommie crest, 14 ° 36 'S, 145 ° 37 'E, coll. R. Smith, 11 Nov 1985; AM W. 42101 (many), Howick Group, Coquet Island, in natural harbour, below lighthouse, 14 ° 32 ' 24 "S, 144 ° 59 ' 47 "E, in Porites, coll. R. Smith, Dec 1983; AM W. 42103 (2), Mrs Watsons Bay, off Chinamans Ridge, 14 ° 40 'S, 145 ° 27 'E, coll. R. Smith, 1983; AM W. 42105 (2), Mrs Watsons Bay, off Chinamans Ridge, 14 ° 40 'S, 145 ° 27 'E, coll. R. Smith, 8 Jan 1983; AM W. 45041, MI QLD 2406; AM W. 45042, MI QLD 2406; AM W. 45043, MI QLD 2406; AM W. 45044, MI QLD 2406; AM W. 45045, MI QLD 2406; AM W. 45046, MI QLD 2406 (2); AM W. 45428, MI QLD 2447; AM W. 45429, MI QLD 2447; AM W. 47318, North Direction Island, Deep Reef slope, 14 ° 44 ' 36 "S, 145 ° 30 ' 54 "E, coral rubble, 2 m, coll. C. Watson; SAM E 3608, Ser 90, stn.G 230, North Point, 14 m, scuba, coll. G. Rouse & E. Kupriyanova, 25 Oct 2005; ZMA V.Pol. 4027 (5, as Sp. gaymardi), stn. 21, south of South Island, 14 ° 42 'S, 145 ° 28 'E, sloping silty reef, little coral cover, 18–20 m, coll. H. ten Hove & P. Hutchings, 6 Mar 1986, det. D. Fiege & H. ten Hove; ZMA V.Pol. 4028 (8, as Sp. corniculatus), stn. 18, lagoon near east entrance, sheltered side of reef, near sandy bottom, 2–20 m, coll. H. ten Hove, 3 Mar 1986; ZMA V.Pol. 4840 (5, as Sp. corniculatus -complex), stn. 16, North Point, sloping reef, mainly dead, slightly silted corals, 3–17 m, coll. H. ten Hove, P. Hutchings & M. Reid, 1 Mar 1986; ZMA V.Pol. 4851 (as Sp. corniculatus -complex), North Reef, 14 ° 40 'S, 145 ° 27 'E, underside of boulders on rock, low tide, little sand, coll. H. ten Hove, 22 Jun 1983; ZMA V.Pol. 4852 (2, as Sp. cruciger), Yonge Reef, depth 8–10 m, from dead & living corals, coll. H. ten Hove, 21 Jun 1983; ZMA V.Pol. 4853 (as Sp. corniculatus), between Research Point & Freshwater Beach, in lagoon, subtidally, dead coral cobbles on sand, 1 m, coll. H. ten Hove, 16 Jun 1983.
Diagnosis. Spiral branchiae. Peduncular wings with entire edge. Opercular endplate with two dorso-lateral antler-like spines originating from a short common stem, often each spine with 2–3 secondary spinules and with basal short, dorsal tine; medio-ventral spines may be present. Spine morphology very variable, dorsal tines may be short and broad, with blunt abraded tips and meeting above the midline (“ Sp. gaymardi ” morphotype); all opercular spines may be small, and tines, if present, narrow (“ Sp. corniculatus ” morphotype); dorso-lateral spines may be long, unabraded thin dorsal tines terminating in sharp spinules and spaced widely apart, and the medio-ventral spine long and branching (“ Sp. cruciger ” morphotype).
Remarks. Based on analysis of nuclear and mitochondrial markers, Willette et al. (2015) concluded that the Spirobranchus corniculatus- complex of morphospecies identifiable by their opercula mainly (see Smith 1985 for further differences), which includes Sp. corniculatus sensu stricto, Sp. cruciger and Sp. gaymardi (Smith’s 1985 Sp. giganteus sp. A, sp. C and sp. B respectively) is a single, morphologically variable species widely distributed across the Indo-Pacific. We have followed this genetic appraisal here and synonymized the former morphospecies. However, sampling in the study of Willete et al. (2015) was limited to the Central Indo-Pacific, excluding the West and East Indo-Pacific regions. According to unpublished observations of one of us (HtH), the " cruciger "and " gaymardi " morphotypes are very common on the Red Sea, but “ corniculatus ” type opercula are very uncommon. The range of variation given for the " gaymardi " morphotypes from the Central Indo-Pacific is enormous as compared to that in the Red Sea. Further molecular studies are needed to determine whether or not the specimens from the Red Sea belong to different species as those found in Indo-Pacific. In view of the remarks given with the generic diagnosis, the many mistaken identifications (see for instance above, Spirobranchus giganteus not (Pallas, 1766) — Straughan 1967 b), the difficulties in interpreting figures as (if) given in the literature, we have refrained from an extensive synonymy.
Distribution. Central Indo-West Pacific.