Siphonodictyon maldiviense

Siphonodictyon maldiviense (Calcinai, Cerrano, Sarà & Bavestrello, 2000)

(Figures 5 A–D)

Synonymy:

Aka maldiviensis Calcinai, Cerrano, Sarà, & Bavestrello 2000: 217, fig. 15; Calcinai, Cerrano, & Bavestrello, 2007: 1363, fig 4F–H & 6.

Material examined: 2 specimens, ZSI/ANRC–20961, June 19, 2018, Wall (a dive site), Havelock Island, Ritchie’s Archipelago, Coll. Preeti Pereira; 1 specimen, ZSI/ANRC–20965, May 26, 2017, Craggy Island, North Andaman, Coll. Preeti Pereira; 1 specimen, ZSI/ANRC– 20969, May 28, 2017, Trilby Island, North Andaman, Coll. Preeti Pereira; 1 specimen, ZSI/ANRC–20979, October 25, 2016, Durgapur (site I), North Andaman, Coll. M.P. Goutham-Bharathi; 1 specimen, ZSI/ANRC–20984, February 24, 2018, Ross Island, North Andaman, Coll. Smitanjali Choudhury; 1 specimen, ZSI/ANRC–20989, September 11, 2018, Sound Island, Middle Andaman (12°29.469′N, 92°57.660′E), Coll. Naveen Kumar Nigam.

Description: The sponge was found boring corals and the description is based only on fistules; fistulae projecting from the surface of substratum (2–3 cm in height and 0.5–0.9 cm in breadth) and are poly-tomously branched and tapering (Fig. 5A); fistulae white when alive, retaining the colour after preservation (Fig. 5B); consistency firm, almost brittle; oscules and ostia not visible.

Skeleton: The ectosomal skeleton is arranged in triangular meshes, 50–80 µm in diameter (Fig. 5C). The meshes are bounded by thick multi-spicular tracts comprising bundles of oxeas, with few oxeas projecting outside the fibres.

Spicules: Short, stout, hastate oxeas (Fig. 5D). See Table 3 for spicule morphometrics.

Distribution: This is the first record of Siphonodictyon maldiviense for Indian waters from the Andaman Nicobar Islands. This species was originally described by Calcinai et al. (2000) from Maldives in the Central Indian Ocean Islands province, Western Indo-Pacific realm. Lim et al. (2008) extended its distribution to the Sunda shelf in the Central Indo-Pacific realm.

Remarks: Siphonodictyon maldiviense is the second species of the genus Siphonodictyon to be reported from the Andaman and Nicobar Islands. Despite recorded from several localities in the Andaman Island group (n=6), spicule morphology of this species did not vary greatly spatially.