Monoserius pennarius (Linnaeus, 1758)

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 : 305-306

Monoserius pennarius (Linnaeus, 1758)

( Fig. 2g , 7 a–c)

Sertularia pennaria Linnaeus, 1758: 813 .

Aglaophenia spicata Lamouroux, 1816: 166 ; Billard, 1909: 329.

Plumularia banksia Gray, 1843: 294 ; Billard, 1910: 48.

Aglaophenia secunda Kirchenpauer, 1872: 35 ; Marktanner-Turneretscher, 1890: 273; Billard, 1909: 329.

Aglaophenia crispate Kirchenpauer, 1872: 36 ; Billard, 1909: 329.

Lytocarpus secundus . Allman, 1883:42; Jaderholm, 1903: 298; Billard, 1908 c: 940.

Lytocarpus fasciculatus Thornely, 1904: 123 .

Lytocarpus pennarius . Billard, 1909: 329; Ritchie, 1910a: 19.

Hemicarpus fasciculatus . Billard, 1913: 83.

Hemicarpus banksi . Bale, 1924: 263.

Monoserius fasciculatus . Leloup, 1932: 165; Vervoot, 1941: 228; Mammen, 1965b: 310.

Monoserius banksii . Ralph, 1961: 56.

Monoserius pennarius . Mammen, 1965b: 307; Schuchert, 2003: 229.

Material examined. Stn. 32: 21.ii. 2017, 18 m; Stn. 46: 22.xii. 2015, 10 m.

Description. Colony fragment, 9.5 cm, with a polysiphonic main stem and pinnately arranged side branches. Side branches alternate and directed at almost 90° to the main stem. Side branches feather-like in appearance with dense hydrocladia alternately arranged ( Fig. 7a ). Main stem and side branches polysiphonic. Hydrocladia straight, stiff and segmented by transverse nodes. Each node with one hydrotheca and two slightly developed internal ribs originating from the rear side of the hydrotheca but not reaching the other side of the node. Hydrothecae campanulate with a compeletely adnate adcauline side ( Fig. 2g ). Hydrothecal opening perpendicular to the hydrocladial axis. Hydrothecal rim with one abcauline tooth and 4–5 lateral cusps on either side. Median inferior nematotheca half the length of the hydrotheca, with a crenulated rim. Lateral nematothecae small, cup-shaped with their opening directed upwards. Gonocladia, modified hydrocladium bearing gonothecae, straight ( Fig. 7c ). First segment bearing hydrotheca, rest of the segments bearing short branches called nematocladia. Nematocladia with two rows of adnate nematothecae. Goncladial axis also bears nematothecae. Gonothecae absent.

Colour. The main stem is brown in colour with white coloured hydrocladia.

Remarks. In the present study, the dimensions of the hydrothecal depth and diameter at the mouth were recorded as 0.27mm and 0.14mm, respectively. These dimensions are identical to the specimens observed by Ritchie (1910) from Andaman Islands. Although, only two specimens were examined during the study, this species is easily identified based on the overall colony structure ( Fig. 7a ) hydrothecal structure ( Fig. 2g ) and its characteristic gonocladium ( Fig. 7c ). both the specimens were recorded at depths below 10 m, i.e., 10 and 18 m.

Associates. Unidentified sea anemone was observed attached to the basal stalk of the colony ( Fig. 7b ).

Substrate. The species was observed growing in sandy bottom with a mass of roots for anchorage.

Distribution. Type locality; unknown.

India; Gulf of Mannar ( Thornely 1904), Andaman and Nicobar Islands ( Ritchie 1910a and present study), Mouth of Hoogly (Leloup 1932) and Kerala ( Mammen 1965b).

Elsewhere; Ceylon, Indonesia, Philippines, Sothern Japan, Palau, New Zealand ( 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 7. Monoserius pennarius. a, Colony at Trinket Island. b, Sea anemone on the hydrocaulus. c, Modified hydrocladia. Scale bar, c= 2 mm.