Spirobranchus gardineri Pixell 1913

Spirobranchus gardineri Pixell, 1913

(Fig. 28A, B)

Spirobranchus gardineri Pixell, 1913: 81 –82, fig. 7a–f [Providence Reef, N. of Madagascar; original description].

Spirobranchus gardineri. — Fauvel 1933a: 79 [Gulf of Suez, Red Sea; diagnosis]; 1933b: 143 [same];? Straughan 1967b: 243 – 244, fig. 14a [Qld; diagnosis and figure not typical]; Pillai 1971: 100 –101 [Sri Lanka; diagnosis]; Fiege & ten Hove 1999: 362 –363 [in part; discussion and mention of 2 taxa under this name; the material from South China Sea belongs to Sp. richardsmithi]; Fosså & Nilsen 1996: 140, 148 [Seychelles; colour photograph]; 2000: 142, 146 [same]; Smith 1985: 40 – 44, figs 2E–F, 3G–H, 4E, T–W, 5N [Lizard Island, Australia; partim, not variant types 1 and 2].

Spirobranchus giganteus corniculatus not (Grube, 1862).— Bailey-Brock 1985: 203 –204, fig. 6a–c [Fiji; diagnosis].

Spirobranchus tetraceros not (Schmarda, 1861).— Erhardt & Moosleitner 1995: 872 [the colour photograph clearly is not Sp. tetraceros but Sp. gardineri by spiraled branchiae and opercular set-up].

Material examined. AM W.201840, Carter Reef, 14°40'S, 145°28'E, coll. P. Hutchings, 10 Mar 1986, det. H. ten Hove; AM W.28292 (2), stn.16, North Point, 14°40'S, 145°28'E, sloping reef with mainly dead, thinly silted corals, coll. H. ten Hove, P. Hutchings & M. Reid, 1 Mar 1986; AM W.41752, Yonge Reef, 14°35'S, 145°37'E, coll. R. Smith, 5 Nov 1985; AM W.41755, same, back reef bommie, coll. R. Smith, 5 Nov 1985; AM W.41756, same, coll. R. Smith, Nov 1985; AM W.41790, same, back reef, in Porites lichen, coll. R. Smith, Nov 1985; AM W.41805, same, in Millepora, coll. R. Smith, Nov 1985; AM W.41809, same, coll. R. Smith, Nov 1985; AM W.41832, same, back reef, in Millepora, coll. R. Smith, Nov 1985; AM W.41844, same, back reef, in Millepora, coll. R. Smith, Nov 1985; AM W.41919 (2), same, back reef, in Millepora, coll. R. Smith, Nov 1985; AM W.41921, Waining Reef, back reef area, 14°27'S, 145°13'E, coll. R. Smith, Dec 1983; AM W.41954, Yonge Reef, 14°35’S, 145°37’E, coll. R. Smith, Dec 1983; AM W.42032 (4), same, back reef, 14°36'S, 145°37'E, in Porites lichen, coll. R. Smith, Nov 1985; AM W.45089, MI QLD 2424; AM W.45412, MI QLD 2424; AM W.45430, MI QLD 2446; AM W.47299, Day Reef, Fore Reef, 14°29'S, 145°33'E, coral rubble, 4–10 m, coll. M. Blazewicz-Paskowycz, 19 Feb 2009; AM W.47314, Fore Reef, 14°26'54"S, 145°30'00"E, coral rubble, 10 m, coll. N. Bruce & M. Blazewicz-Paskowycz, 21 Feb 2009; ZMA V.Pol. 3578, Yonge Reef, 14°35'S, 145°37'E, coll. R. Smith, 5 Nov 1985.

Diagnosis. Opercular plate bearing a (fairly long) column ending in a pair of latero-dorsal spines and a bifid medioventral spine, all with tips curved away from the opercular plate. Latero-dorsal spines each bear one pair of short spinules and two unpaired ones, the largest one located latero-ventrally, and the other three located subterminally. Peduncle with wide distal wings with entire edge (no processes).

Remarks. Spirobranchus gardineri resembles Sp. richardsmithi in having a column arising from distal plate and bearing three spines/processes distally. However, the three distal processes in Sp. gardineri are less elaborate, and are all directed anteriorly, away from the opercular plate, while the ventral bifurcate spine as well as the proximal side spinules of the two latero-dorsal spines are recurving towards the opercular plate in Sp. richardsmithi. This was noted for the first time by Smith (1985: 43–47, fig. 3G–H versus I–L), and formalized in a new description by Pillai (2009: 154–158). All records from before the last date should be checked whether or not they belong to Sp. gardineri sensu stricto; we have only given references where the identity is clear from either description or figures.

Pillai (2009: 182–184, fig. 60A–G) describes as Spirobranchus sp. 6 a single specimen from the South China Sea with an operculum almost intermediate between those of Sp. gardineri and Sp. richardsmithi, however, more complicated in that the two dorsal spines are bifid as well as the ventral one, which is pointing upward as in Sp. gardineri. It remains to be seen if this falls within the (as yet poorly documented) variability of Sp. gardineri or indeed merits a specific status.

Distribution. North of Madagascar, widely distributed in the Indo-West Pacific.