Pomatostegus actinoceras Mörch, 1863

(Fig. 14 D)

Pomatostegus actinoceras Mörch, 1863: 400, figs 16–17 [Philippines; original description].

Pomatostegus actinoceras . — Willey 1905: 314, pl. 8, figs 3–4 [Sri Lanka]; Augener 1914: 152 –155 [as actinoceros; Australia, Shark Bay]; Pillai 2009: 109 –112, figs 9a–e & 10a–e [as actinoceros; Kimberley, WA]; Humann & Deloach 2010: 71 [Indo-West Pacific; colour photograph]; Bailey-Brock et al. 2012: 975, fig. 5A–K [Marshall Islands].

Pomatostegus stellatus not (Abildgaard, 1789).— Dew 1959: 41–42, fig. 14A–G [Qld, Australia; Solomon Islands]; Johanssson 1918: 10–12 [Australia, WA]; Pillai 1960: 23–25, fig. 9a–d [Sri Lanka]; 1971: 94 [same]; Straughan 1967a: 38 [Qld, Australia]; Straughan 1967b: 237 [same]; Straughan 1967c: 224 [NT, Australia]; Imajima 1977: 101–102, fig. 7a–k [Ogasawara Islands, Japan]; 1982: 51 [Palau and Yap Islands]; 1987: 80 [Okinawa, Japan]; Mak 1982: 608 [Hong Kong]; Imajima & ten Hove 1984: 54 [Truk Islands, Ponape and Majuro Atoll]; 1986: 9 [Gilbert Islands (Kiribati) and the Solomon Islands]; Stock 1988: 217 [Lizard Island, Qld, Australia; parasitized]; Nishi 1993a: 12, table 1 [Okinawa, Japan]; 1993b: 19, table 1 [same]; 1995: 29–31, fig. 1h [same]; 1996: 312 [same]; Fiege & Sun 1999: 131–133, fig. 19a–f [Hainan Island, China].

Material examined. AM W.28348, Carter Reef, 14°40'S, 145°28'E, coll. P. Hutchings, 10 Mar 1986, det. H. ten Hove; AM W.44540, MI QLD 2390; AM W.47311, Day Reef, Fore Reef, 14°28'18"S, 145°31'48"E, coral rubble, 10 m, coll. M. Blazewicz-Paskowycz, 13 Feb 2009; ZMA V.Pol. 4754, stn.22, between Osprey Island & beach of Resort, intertidal at low tide, from below large boulders on rocky bottom, coll. H. ten Hove & P. Hutchings, 6 Mar 1986; ZMA V.Pol. 4755, Palfrey Island, SE point, sandy beach, intertidal, small cobble, 0.5 m above ebb tide level, probably cast ashore, coll. H. ten Hove, 19 Jun 1983.

Diagnosis. Tube thick, opaque, white, triangular in cross-section; a strong median keel with blunt teeth and two or more lateral rows of well-defined teeth. Peduncle broad with lateral wings terminating in pointed tips. Operculum a column with 2–6 chitinous plates with frilled margins stacked one above the other; diameter of plates decreases upwards (distally). Circlets of 10–12 spines present at the basis of each disk, except for the first chitinous plate (Fig. 14 D).

Remarks. There tend to be more of “free” circlets of spines, without accompanying wide plates in the Indo- Pacific P. actinoceras as opposed to the Caribbean P. stellatus . Figure 14 D suggests 3 discs surmounted by 2 or 3 starlets of spines, also compare Rullier 1974 (Cuba) versus Fiege & Sun 1999: 132, fig. 19 (China) and Imajima 1977: 101, fig. 7 (Japan); it seems to be one of the morphological differences between these two species.

Distribution. Indo-West Pacific distribution, including Southern Japan, Micronesia and Australia, China, Sri Lanka.