Lytocarpia brevirostris ( Busk, 1852 )

Chakraborty, Oishinee & Raghunathan, C., 2020, Notes on seven Aglaopheniids (Cnidaria: Hydrozoa: Aglaopheniidae) from Andaman and Nicobar Islands with three new records to India, Zootaxa 4790 (2), pp. 291-317 : 298-300

Lytocarpia brevirostris ( Busk, 1852)

( Fig. 2c , 3 d–f)

Plumularia brevirostris Busk, 1852 ; 397.

Aglaophenia brevirostris Kirchenpauer, 1872: 27 ; Bale, 1884: 169; Kirkpatrick, 1890: 611; Bale, 1913: 135.

Plumularia vitana Kirchenpauer, 1872: 34 .

Aglaophenia maldivensis Borradaile, 1905: 843 ; Billard, 1913: 91.

Thecocarpus brevirostris Billard, 1910: 51 ; 1913: 89; Briggs, 1918: 34, 45; Stechow, 1919: 137; Bedot, 1921 a: 332; 1922: 157; Jarvis, 1922: 350; Pennycuik, 1959: 187; Rees & Thursfield, 1965: 186; Millard, 1968: 254; Vasseur, 1974: 158; Millard, 1975: 454; 1978: 199; Tang, 1991: 32–33.

Lytocarpia brevirostris Stechow, 1922:151 ; 1923: 245; Ryland & Gibbons, 1991: 545–546; Bouillon et al., 1995: 36; Irving, 1995: 324; Watson, 2002: 347; Vervoort & Watson, 2003: 306; Gravier-Bonnet and Bourmaud, 2012: 106, 114, 120; Di Camillo et al., 2012: 525.

Material examined. Stn. 27: 07.x. 2016, 11 m; Stn. 30: 06.x. 2016, 10 m; Stn. 33: 06.x. 2016, 18 m; Stn. 35: 23.iii. 2018, 13 m; Stn. 48: 28.xii. 2017, 13 m.

Description. Colonies pinnate with second order of branching ( Fig. 3d ). Hydrocaulus polysiphonic and hydroclades alternately arranged. Hydrocaulus divided into internodes; internodes bearing hydrocladial apophyses. Hydrocladial apophysis always associated with one anteriorly placed mamelon and two large nematothecae with double opening, one inferior nematotheca and one axillary anterior nematotheca ( Fig. 3f ). Hydrocladia segmented by oblique nodes with overlapping hydrothecae. Hydrotheca elongate with one prominent abcauline tooth and six lateral teeth, adcauline tooth absent ( Fig. 2c ). Adcauline hydrothecal wall more or less straight and abcauline hydrothecal wall sinuous. Hydrotheca with a short intra-thecal septum towards the lower adcauline side. Single hydrotheca associated with two lateral nematothecae and one median inferior nematotheca. Lateral nematothecae directed upwards. Median nematotheca adnate to the hydrotheca for half its length and the rest free, directed away from the hydrotheca. Median inferior nematotheca not reaching the hydrothecal margin in length. Reproductive structures observed as closed corbulae that replaced the hydrocladium ( Fig. 3e ). Corbulae bears six to eight leaf-like ribs. Corbulae axis divided into segments by oblique nodes; first segment with a hydrotheca and three nematothecae; one median inferior and two laterals. Proximal portion of each rib with a hydrotheca and two lateral nematothecae, median inferior nematotheca absent. Subsequent portion of the ribs with numerous nematothecae.

Colour. Yellow, in live colonies

Remarks. In the present study, the species was recorded beyond the depth of 10 m up to 13 m. In terms of bathymetric distribution of the species, it has been recorded as stenobathic between 12–30 m ( Gravier-Bonnet and Bourmaud, 2012) from Baa atoll. In another study, from Bunaken Marine National Park, Indonesia, the species was recorded to have a wide vertical distribution, being more abundant in the extremes and rare in the 10–30 m depth range ( Di Camillo et al. 2011). The species is a new record to Indian waters.

Substrate. The colonies were observed to be growing on rocks, boulders and in crevices.

Distribution. Type locality; off Cumberland Island, Queensland.

India; Andaman and Nicobar Islands (Present study).

Elsewhere; South Pacific Islands, Northern Australia, tropical Indian Ocean from India to Africa (Di Camillo et al. 2012).

Figures

FIGURE 2. Illustrations of hydrothecae. a, Aglaophenia cupressina Lamouroux, 1816. b, Gymnangium hians (Busk, 1852). c, Lytocarpia brevirostris (Busk, 1852). d, Lytocarpia delicatula (Busk, 1852). e, Macrorhynchia philippina Kirchenpeuer, 1872. f, Macrorhynchia phoenicea (Busk, 1852). g, Monoserius pennarius (Linnaeus, 1758). Scale bar, a, b, g= 200µm, c, d, e, f, h, i=100µm.

FIGURE 3. a–c, Gymnangium hians. a, In-situ photo of colony at Paget Island. b, Gonothecae arranged in two rows on the hydrocaulus. c, associated bivalve, Pterelectroma physoides, attached to the main stem. d–f, Lytocarpia brevirostris. d, In-situ photo of colony at Sir Hugh Ross Island. e, Gonothecae borne on modified hydrocladia. f, Hydrocaulus showing cauline nematothecae. Scale bar, b, e= 2mm, c= 5mm, f= 200µm