Plumularia meretricia Watson, 1973

Watson, Jeanette E., 2018, Some Hydroids (Cnidaria, Hydrozoa) from the Great Australian Bight in the collection of the South Australian Museum, Zootaxa 4410 (1), pp. 1-34 : 17-18

Plumularia meretricia Watson, 1973

Figure 7D–F

Plumularia meretricia Watson, 1973: 191 , figs 61–74.— Watson, 2011: 71.— Bouillon et al., 2006: 370.

Material examined. SAM H2536, one microslide. Near South Australia – Western Australia border, depth 180 m, trawl, coll: R. Southcott 1/07/1988 .

Description. Part of infertile branched colony, longest branch 10 mm. Hydrorhizal stolons tubular, perisarc thick, rugose. Stem, branch and hydrocladial internodes long, cylindrical, smooth, sometimes with transverse septa.

Hydrocladia sub-alternate, apophysis short, strong, with inflated transverse distal node. First hydrocladial internode moderately long, usually deeply divided by two to five transverse segments ending in transverse distal node. When more than one hydrotheca on the hydrocladium, hydrothecate internodes are separated by a long cylindrical internode without internal septa.

Hydrothecate internode short, hydrotheca occupying distal half, two incipient septa in base of internode and two above at base of hydrotheca. Hydrotheca deep bowl-shaped, margin circular, rim thin, not everted.

FIGURE 7A–F.

7A–B. Synthecium elegans Allman, 1872 . A, part of hydrocladium. B, hydrocladial internode and hydrothecae. 7C, Synthecium subventricosum Bale, 1914 , hydrocladial internodes and hydrothecae. 7D–F, Plumularia meretricia Watson, 1973 . D, part of branched stem. E, apophysis and branch hydrotheca. F, hydrotheca, anterior view, angle of view showing partly visible lateral nematothcae.

Nematothecae all similar in shape and size, short, moveable, base robust, cup wide, circular, slightly adcaudally excavated. Median inferior set well back on hydrothecate internode, twin laterals not reaching hydrothecal margin, One nematotheca proximal on athecate internode, one or two cauline nematothecae (usually lost but marked by foramen on stem internode), one nematotheca in axil of stem and hydrocladium, and a prominent dome-shaped hydrostatic pore with circular orifice on apophysis.

Perisarc of stem and branch thick, perisarc of hydrotheca thinning towards margin.

Hydrorhiza, width 88–144 Stem width 96–104 Branch width 40–56 Hydrocladium

first athecate internode length 80–144 succeeding athecate internode length 192–280 hydrothecate internode length 392–440 width at node 56–60 Hydrotheca

abcauline wall, length 100–128 adcauline wall free length 40–48 width of margin (lateral view) 156–180 Nematotheca

length of base 30–40 depth of cup 20–21 Remarks. This description of Plumularia meretricia supplements that of Watson (1973). The material is much damaged.

Distribution. Eastern Great Australian Bight.