Distichopora violacea ( Pallas, 1766 )

Chakraborty, Oishinee, Raghunathan, C. & Chandra, Kailash, 2018, New record of Hydrozoa Distichopora violacea (Pallas, 1766) (Anthoathecata: Stylasteridae) from Andaman and Nicobar Islands, India, Zootaxa 4508 (3), pp. 439-442 : 439-440

Distichopora violacea ( Pallas, 1766) ( Fig. 2 )

For an exhaustive list of synonyms, refer to Boschma (1959) and Cairns (1983).

Material examined. One specimen 71 mm high and 112 mm wide, Rifleman Island (11.513950°N 92.646117°E), South Andaman, 06.xi.2015, 15 m deep (ZSI/ANRC-15940); one specimen 44 mm high and 68 mm wide, Craggy Island (13.226467°N 93.057450°E), North Andaman, 21.vii.2016, 8 m deep (ZSI/ANRC-15944); one specimen 19 mm high and 21 mm wide, Nancowry Island (07.997367°N 93.509483°E), Nicobar, 22.xii.2015, 20 m deep (ZSI/ANRC-15946).

Description. Colonies fan shaped. Branches blunt tipped in the plane of fan. Colony base usually broad and encrusting. Coenosteum violet, some with white faded tips. Coenosteum structure variable; tuberculate to linearimbricate. Gastropores and dactylopores do not form distinct cyclosystems but are arranged in pore rows restricted to lateral branches and sometimes occur on branch faces near base. Gastropores arranged unilinearly, flanked by dactylopores ( Fig. 2c ). Gastropores never lipped and usually round or polygonal in shape, 0.183 mm in diameter. Dactylopores arranged perpendicular to gastropores, forming longitudinal slits; 0.114 mm long and 0.061 mm wide. Gastrostyles present. Dactylostyles absent, ampullae superficial ( Fig. 2d ).

Distribution. India: Andaman and Nicobar Islands.

Elsewhere: Indo-Pacific. (GBIF 2017, Boschma 1959)

Lace corals are poorly studied in India as they are cryptic and small in size and predominantly occur in deep water, thus making them difficult to access. Also, no literature pertaining to their description or identification to the species level has been made so far from the Indian waters. The specimens were found from North Andaman to Nicobar, being frequent occurrence in that region. Of the 27 genera reported around the world ( Cairns 2015), only 2 genera have been mentioned from India ( Venkataraman et al. 2012; Sluka et al. 2011). This illustrates the need for further studies on hydrozoans in general, and the family Stylasteridae in particular, in order to document their diversity from Indian waters.

Figures

FIGURE 2. Distichopora violacea (Pallas, 1766). a, In situ photograph of specimen. b, Coenosteum. Scale equals 2mm. c, Characteristic pore rows showing gastropores (Gp), and datylopore (Dp). Scale equals 500 µm. d, Ampulla (Ap). Scale equals 2mm.