Dragmacidon durissimum (Dendy, 1905)

(Fig. 2, 6)

Thrinacophora durissima Dendy, 1905:187

Sigmaxinella durissima .— Dendy 1922: 113

Axinella durissima .— Burton 1959: 259

Dragmacidon durissima .— Hallmann 1917: 639; Alvarez & Hooper 2002: 735 Dragmacidon durissimum .— Alvarez & Hooper 2009: 28

Material examined. ZMA Por. 0 0 460, Philippines, Sulu Archipelago, anchorage off N Ubian, Sulu Islands, 6.125°N, 120.433°E, 23 m depth, 28 June 1899, coll. Siboga Expedition. ZMA Por. 0 0 461, Indonesia, Banda anchorage, Maluku, 4.5398°S, 129.9084°E, 9 m depth, 22 November 1899, coll. Siboga Expedition. ZMA Por. 18621, Thailand, Ko Thai-ta-Mun, South of Ko Si-chang, Chonburi, Chon Buri, 13.1024°N, 100.8077°E, 5 m depth, 19 September 2001, coll. Sumaitt Putchakarn.

Description. Shape (Fig. 6 A). Massive, hemispherical.

Colour. Beige in ethanol.

Oscula. Inconspicuous, flushed, irregularly distributed, up to 5 mm diameter.

Surface. Papillose, uniformly covered with small short processes, blunt, with a dermal membrane stretching over conules.

Skeleton (Fig. 6 B). Plumoreticulated with multispicular tracts, packed with spicules in all directions, vaguely plumose or plumo-echinated, 150–350 µm thick, connected by shorter and thick tracts nearly at right angles, forming an irregular reticulation of oval and large meshes. Main tracts projecting through surface and ending in surface conules or short processes.

Spicules (Fig. 6 C–D, Table 5). Oxeas, 247.8–381 µm x 8.7–19 µm; Styles 196.3–370 µm x 8.9–20.7 µm; trichodragmata up to 15 um long, rare (Fig. 6 C).

Specimen Locality Oxeas Styles Tricodragmata

ZMA Por. 460 Philippines 247.8–364.1µm 196.3–338.4µm ~ 15x5–10 µm

(320.8±28.1) (274.7±34.3)

x 8.7–16µm (12.8±1.8) x 8.9–20.7µm (14.1±2.7)

ZMA Por. 461 Maluku 283–381µm (334.7±21.2) 241.2–370.7µm

(292.5±30.9)

x 10.3–19µm (12.5±1.9) x 9.7–18.2µm (13.5±2.1)

ZMA Por. 18621 Thailand 232.6–361.5µm 182.8–547.6µm

(298.7±34.7) (322.4±79.3)

x 9.7–16.9µm (13.4±1.7) x 8.3–18.8µm (14.4±2.8)

QM G 300181 * Ashmore Reef, 229.8–312.7µm (283.2±18) 203.1–312.5µm 15– 20 x5–10 µm

WA by 7.4–19µm (13.4±3.1) (251.8±33.4) by 11.7–

16.4µm (13.7±1.2)

*Data from Alvarez & Hooper (2009)

Remarks. The material examined agrees in all its characteristics with Dragmacidon durissimum . It is very similar to D. austral e, in external and skeletal characteristics but can be differentiated from it by the presence of trichodragmata. As previously indicated (Alvarez & Hooper 2009) these species are similar to the Western Atlantic D. reticulatum and the West African D. lunaecharta (Ridley & Dendy, 1886) which are also distinguished by the presence of trichodragmata in the latter.

Distribution. Based on the material examined the distribution of Dragmacidon durissimum can be extended to Indonesia (i.e MEOW Banda Sea), Philippines (i.e. MEOW Palawan/ North Borneo) and Gulf of Thailand (Fig. 2). These and records from Alvarez & Hooper (2009) indicate that this Indian Ocean species, has a wider distribution than previously thought.