Macrorhynchia phoenicea ( 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 : 303-305

Macrorhynchia phoenicea ( Busk, 1852)

( Fig. 2f , 6 a–f)

Plumularia phoenicea Busk 1852: 398–399 .

Aglaophenia phoenicea Bale 1884: 159 , pl. 15, figs 1–5, pl. 17, figs 1–4, pl. 19, fig. 31.

Lytocarpus phoeniceus Stechow 1909: 97 ; Billard 1913: 74, fig.60; Stechow 1913 b: 10, 95, figs 62–64; Jäderholm 1916: 7, fig. 4; Briggs 1918: 47; Jäderholm 1919: 25; Bedot 1921 a: 320; 1922: 151; Jarvis 1922: 354; Jäderholm 1923: 5; Nutting 1927: 233; Leloup 1930b: 10, text-fig. 7, pl. 2, fig. 1; Briggs & Gardner 1931: 194, fig. 5; Stephenson et al. 1931: 67; Leloup 1938b: 21; Vervoort 1946a: 328; Pennycuik 1959: 187; Redier 1964b: 147; Rees & Thursfield 1965: 177; von Schenck 1965: 942; Redier 1966: 93; Millard 1968: 254, 284; Millard & Bouillon 1973: 94; Millard 1975: 451, fig. 137D; 1978: 195 et seq.; Bouillon 1984: 106; Russell 1984: 105; Southcott 1987: 81.

Macrorhynchia phoenicea Stechow 1923 b: 19 ; 1923d: 241; 1925a: 259; Hakushi et al. 1957: 217, pl. 108, fig. 11; Yamada 1958: 51, 62; 1959: 85; Itô & Inoue 1962: 452, pl. 8, figs 88–93; Mammen 1967: 313, figs 108–109; Rho 1967: 347–348, fig. 8A–B; Hirohito 1969: 26; Edwards 1973: 587; Rho & Chang 1974: 147; Rho 1977: 279, 425, pl. 94, fig. 94; Hirohito 1983: 80; Rho & Park 1986: 102; Park 1990: 84; Ryland & Gibbons 1991: 555–557, fig. 23; Park 1992: 295; Bouillon et al. 1995: 38; Hirohito 1995 (English text): 299, fig. 106a-e; Irving 1995: 324, appendix 2; Watson 1996: 79; 2000: 68–70, fig. 59A–F; Schuchert 2003: 223–226, figs. 68–69; Di Camillo et al. 2009: 218–222, 216, fig. 6A–H, fig. 9A–M.

Macrorhynchia phoenacea Bakus et al. 1994: 176 (incorrect subsequent spelling).

Lytocarpus phoenicus Allen & Steene 1994: 51 , fig. (incorrect subsequent spelling).

Lytocarpus spectabilis Allman 1883: 43 , fig. 2, pl. 15.

Material examined. Stn. 1: 09.ix. 2017, 7 m; Stn. 3: 08.ix. 2017, 8 m; Stn. 7: 09.i. 2019, 6 m; Stn. 12: 21.ii. 2018, 5 m; Stn. 13: 20.x. 2017, 6 m; Stn. 14: 26.x. 2016, 6 m; Stn. 15: 19.ii. 2018, 3 m; Stn. 16: 10.i. 2019, 5 m; Stn. 17: 23.i. 2017, 6 m; Stn. 27: 07.x. 2016, 12 m; Stn. 35: 23.iii. 2018, 12 m; Stn. 40: 16.xii. 2016, 8 m; Stn. 41: 21.vii. 2018, 6 m; Stn. 44: 16.x. 2018, 11 m; Stn. 45: 15.x. 2018, 11 m; Stn. 47: 27.xii. 2017, 4 m.

Description. Colonies fan-like in appearance comprising three to four main stems arising from the hydrorhiza ( Fig. 6a ). Primary, secondary and even tertiary branching observed in large colonies ( Fig. 6d ). Branches polysiphonic thinning to monosiphonic in distal regions. Hydrocladia closely set, short, alternate to sub-alternate. Hydrocladia divided by transverse nodes, each node bearing one hydrotheca and three nematothecae; two laterals and one median inferior. Internode with two strong partial or complete internodal septa, the strongest near the base of hydrotheca and the partial present beneath the mid-adcauline wall. Two weak septa present below the wall of lateral nematothecae. Hydrothecae short with basal adcauline wall convex and fused to the lateral nematotheca distally ( Fig. 2f ). Abcauline wall convex and a strong, partial septum present in the hydrotheca. Partial septum arising from the free abcauline wall to the interior of the hydrotheca not reaching the adcauline side. Hydrothecal margin tilted away from the node and strongly everted with a pair of blunt cusps in the mid-lateral region with a smaller pair near the base of the lateral nematothecae. Median abcauline cusp, a small spine connecting with the intrathecal septum, and one, small adcauline cusp present in between the lateral nematothecae on the hydrothecal margin. Median nematotheca moderately long, tapering and reaches beyond the hydrothecal margin. Lateral nematothecae tubular, bent, narrowing towards their margin and overtopping the hydrotheca. At the base of the hydrocladium, two cauline nematothecae present. Cauline nematothecae tubular and shorter than the lateral nematothecae. Proximal nematotheca points along the hydrocladium and the distal nematotheca pointing along the hydrocaulus ( Fig. 6e ). Gonothecae are borne on modified hydrocladium ( Fig. 6f ).

Colour. Brown to dark brown in live colonies.

Remarks. The species is being reported from Indian waters after a 55-year hiatus and from Andaman and Nicobar Islands after a period of 108 years. This species was frequently encountered during the study with a bathymetric range of 4 to 12 m.

Associated fauna. The bivalve Pterelectroma physoides (Lamarck, 1819) ( Fig. 6c ). Hebella crateroides Ritchie, 1909 was found growing on Lytocarpus phoeniceus ( Busk, 1852) by Ritchie (1909) from Interview Island.

Substrate. The species over growing entire surfaces of rocks and boulders ( Fig. 6b ).

Distribution. Type locality; Torres Strait, Australia

India; Gulf of Mannar ( Thornely 1904; Gravely 1927), Lakshadweep Islands ( Borradaile, 1905), Andaman and Nicobar Islands ( Ritchie 1910a and present study), Neendakara at 10 fathoms (= 18.288 m), Tamil Nadu ( Mammen 1965b).

Elsewhere; Australia, Indonesia ( Di Camillo et al. 2009), Malay Peninsula, New Guinea, Philippines, South China Sea, Japan, Polynesia, tropical Indian Ocean, southern Africa, Kei Islands ( Schuchert 2003).

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 6. Macrorhynchia phoenicea. a, Colony at West Island. b, Colony overgrowing entire substrates at West Island. c, Bivalve, Pterelectroma physoides, on M. phoenicea at Elizabeth Bay. d, Hydrocaulus showing secondary branching. e, Hydrocaulus showing cauline nematothecae. f, Modified hydrocladia on hydrocaulus. Scale bar, d= 2mm, e=200µm, f= 1mm.