Hydroides longispinosa Imajima, 1976a

(Fig. 6)

Hydroides longispinosa Imajima, 1976a: 240 –246, fig. 5 [Ogasawara Islands, Southern Japan].

Hydroides centrospina Wu & Chen, 1981a: 354 –355 [South China Sea; description].

Hydroides centrospina . — Meng et al. 1994: 46, figs 3, 1–9 [Hainan Island, South China Sea]; Sun & Yang 2000: 119 [South China Sea]; Sun et al. 2015: 46 –50, Fig. 14 [Qld, NSW, Australia].

Hydroides longispinosa . — Imajima 1977: 95 [Ogasawara Islands, South Japan, fouling buoy]; 1982: 46 [Palau Islands, fouling boat]; 1987: 78 [Okinawa, Japan]; Hutchings & Murray 1982: 1031, 1034, 1035 [Lizard Island, experimental settling on dead coral substrate]; Imajima & ten Hove 1984: 48 [Ponape Island; Lizard Island, Qld, material of Hutchings & Murray; discussion]; 1986: [Gilbert Islands, Solomon Islands]; Hutchings 1984: 232 –233 [Lizard Island, Qld; settling]; 1985: 246– 247 [same]; Meng et al. 1994: 46 [Hainan Island, South China Sea; name]; Sun & Yang 2000: 124, figs G–K [Yellow Sea].

Hydroides longispinosus . — Bailey-Brock 1987: 282 [Tonga]; Fiege & Sun 1999: 116 –118 [Hainan Island, South China Sea]; ten Hove & Kupriyanova 2009: 53 [name]; Bailey-Brock et al. 2012: 969, 972, fig. 4D [Enewetak, Rongelap, Marshall Islands].

Material examined. AM W.201323, between Yonge and Lizard Island, 14°40'S, 145°28'E, 15 m, coll. P. Hutchings, Jan 1983; AM W.16981, near Bird Islet, 14°40'S, 145°28'E, 7 m, coll. P. Hutchings & P. Weate, det. H. ten Hove; AM W.16986, near Bird Islet, 14°40'S, 145°28'E, 7 m, coll. P. Hutchings & P. Weate, det. H. ten Hove; AM W.16987, near Bird Islet, 14°40'S, 145°28'E, 7 m, coll. P. Hutchings & P. Weate, det. H. ten Hove; AM W.20155 (2), Turtle Beach, lagoon, 14°40'S, 145°28'E, coll. G. Anderson, 22 Jun 1982, det. C.J. Watson; AM W.27388, lagoon between Bird and South Island, 14°41'S, 145°28'E, 15 m, coll. C. Watson & P. Hutchings, 12 Mar 1986, det. H. ten Hove; AM W.41749, Yonge Reef, 14°35'S, 145°37'E, coll. R. Smith, 5 Nov 1985; AM W.41968, lagoon, 14°40'S, 145°27'E, coll. P. Hutchings & P. Weate; AM W.41969, coll. P. Hutchings & P. Weate, 16 Jan 1976; AM W.41970, lagoon, 14°40'S, 145°27'E, coll. P. Hutchings, Jan 1982; AM W.41971, same, coll. P. Hutchings, Jan 1982; AM W.41972, same, coll. P. Hutchings, Jan 1982; AM W.41973, lagoon, 14°40'S, 145°27'E, coll. P. Hutchings & P. Weate; AM W.42328 (2), off Chinamans Head, 14°40'S, 145°27'E, 7 m, coll. P. Hutchings, 28 Jul 1977; AM W.42059, off South Island, stn.G244, coll. E. Kupriyanova & G. Rouse, 2 Nov 2005; AM W.42327, lagoon, 14°40'S, 145°27'E, coll. P. Hutchings & P. Weate, 1976, det. E. Kupriyanova; AM W.42329, lagoon drop-off, 14°42'S, 145°28'E, 7.7 m, coll. P. Hutchings & P. Weate, 6 Nov 1976, det. E. Kupriyanova; AM W.42330, off Chinamans Head, 14°40'S, 145°27'E, 7 m, coll. P. Hutchings & P. Weate, 8 Jan 1977, det. E. Kupriyanova; AM W.42331, lagoon, 14°40'S, 145°27'E, coll. P. Hutchings & P. Weate, 1 Aug 1977, det. E. Kupriyanova; AM W.42332 (2), fringing reef between Bird Islet and South Island, 14°40'S, 145°28'E, 12 m, coll. P. Hutchings & P. Weate, 11 Jan 1977, det. E. Kupriyanova; AM W.42333, near Bird Islet, 14°40'S, 145°28'E, 12 m, coll. P. Berents & P. Hutchings, Sep 1976, det. E. Kupriyanova; AM W.44224, MI QLD 2368; AM W.44226, MI QLD 2367 (6); AM W.45085, MI QLD 2424 (50); AM W.45096, MI QLD 2435 (50); AM W.45424, MI QLD 2447 (6); AM W.46531, Bird Islet, front reef, Fore Reef, 14°41'48"S, 145°27'54"E, coral rubble, 3 m, coll. C. Watson, 8 Feb 2009; AM W.46532, same; MAGNT W025500 (many), North Point, mid shelf of Fore Reef, 14°38'42"S, 145°27'12"E, coral rubble, 2 m, coll. C. Watson, 12 Apr 2008; MAGNT W025509, Yonge Reef, 14°34'30"S, 145°36'18"E, coll. C. Glasby, 20 Apr 2008; MAGNT W025512 (2), North Point, mid shelf of Fore Reef, 14°38'42"S, 145°27'12"E, coral rubble, 2 m, coll. C. Watson, 12 Apr 2008; MAGNT W025513 (10), Palfrey Island, Fore Reef, 14°41'36"S, 145°26'24"E, dead Pocillopora sp. head, 10 m, coll. S. Smith, 15 Apr 2008; MAGNT W025515, North Point, mid shelf of Fore Reef, 14°38'42"S, 145°27'12"E, coral rubble, 2 m, coll. C. Watson, 12 Apr 2008; SAM E3600, stn.G238, east lagoon near Bird Islet, coll. G. Rouse & E. Kupriyanova, 31 Oct 2005; ZMA V.Pol. 3446 (20), near Bird Islet, grid C, experimental fouling panels, coll. P. Hutchings & P. Weate, det H. ten Hove 1981, retained from AM W.16984–6; ZMA V.Pol. 4962 (2), stn.20, reef front North of South Island, sloping reef outside lagoon & sandy bottom below, 10–17 m, coll. H. ten Hove, P. Hutchings & M. Reid, 5 Mar 1986; ZMA V.Pol. 4965 (10), stn.17, Palfrey Island, south of lighthouse, 14°40'S, 145°28'E, coral heads on sandy bottom, 7 m, coll. H. ten Hove, P. Hutchings & M. Reid, 2 Mar 1986; ZMA V.Pol. 4966 (10), stn.18, lagoon near East entrance, sheltered side of reef, near sandy bottom, 2–20 m, coll. H. ten Hove, 3 Mar 1986.

Diagnosis. Opercular verticil with 13–15 spines equal in size (no larger dorsal spine) curved outward, with pointed tips, each verticil spine with 4–6 pairs of lateral spinules directed obliquely outwards. All verticil spines also with 4–6 accessory teeth arranged in a single row on inner side. Central tooth longer than verticil spines, may be smooth, but mostly bearing numerous randomly placed small teeth distally. Funnel not chitinized, with 15–20 blunt-tipped radii. Grooves separating radii extending 1/3 of funnel length (Fig. 6).

Remarks. The species can be distinquished from H. elegans by the distinctly shorter central verticil spine. Material of Fiege & Sun (1999) included specimens with smooth central spines in the verticil, but one specimen with two opercula showed one smooth central spine and one with lateral pinnules. Because the smooth central spine, the main distinctive character of H. centrospina Wu & Chen, 1981a, clearly shows intraspecific variability, Fiege & Sun (1999: 118) synonymised Hydroides centrospina with H. longispinosa .

Distribution. Indo-West Pacific, from Qld, Australia to South Japan and Micronesia, South China, Ponape Island, Tonga.