Monotheca spinulosa ( Bale, 1882 )

Watson, Jeanette E., 2011, Review of the genus Monotheca (Hydrozoa: Leptolida) from Australia with description of a new species and a note on Monothecella Stechow, 1923, Memoirs of Museum Victoria 68, pp. 71-91 : 84-86

Monotheca spinulosa ( Bale, 1882)

Fig. 5A–G

Plumularia spinulosa Bale, 1882: 30 , pl. 15, fig. 8.— Bale, 1884: 139, pl. 12, figs 11–12.— Bale, 1888: 783, pl. 19, figs 11–13.— Von Lendenfeld, 1885a: 475.— Bartlett, 1907: 43.— Warren, 1908: 320.— Mulder and Trebilcock, 1910: 123, pl. 3, fig. 9, 9a.— Mulder and Trebilcock, 1916: 81, pl. 11, fig. 4.— Briggs, 1918: 34, 43.— Bedot, 1921: 29.— Blackburn, 1937: 368.— Blackburn, 1942: 116.— Pennycuik, 1959: 180.— Ralph, 1961c: 109.— Millard, 1962: 301.— Millard, 1966: 494.— Berrisford, 1968: 394.— Day, et al., 1970: 14,.— Watson, 1973: 188, figs 54, 55.— Millard, 1975: 401, fig. 125 E–J.— Millard, 1978: 196.— Watson, 1982: 107, fig. 4.11f–h.— Stranks 1993: 13.

Monotheca spinulosa . — Stechow, 1921: 260.— Stechow, 1923: 17.— Leloup, 1932: 160.— Millard, 1975: 401, fig. 125 E–J.— Millard, 1978: 196 — Hirohito, 1995: 278, fig. 96a–c.— Watson, 1996: 78.— Watson, 1997: 529.— Watson and McInnes, 1999: 111.— Watson 2003: 243, 252.— Vervoort and Watson, 2003: 369, 374. — Watson, 2005: 542.— Bouillon et al., 2006: 368.

Plumularia spinulosa var. obtusa . — Millard, 1957: 232.

Monotheca spinulosa var. obtusa . — Stechow, 1923d: 225.— Yamada, 1959: 78.

Material examined. NMV F59053 , microslide, Queenscliff Victoria, Bale collection, Museum Victoria, nominated as probable syntype by Stranks (1993) .

Material in a uthor’s collection: Stradbroke Island, south Queensland, on alga, depth 20 m, coll: J. Watson, 24 August 1975. Coniston Bay, Port Kembla, New South Wales, on bryozoan, depth 18 m, coll: J. Watson, September 1975. Gabo Island, Victoria, on ascidian Herdmania grandis and red algae under ledges, depth 12 m, coll: J. Watson, 15 February 1973. Port Phillip Heads, Victoria, on red alga, depth 10 m, coll: J. Watson, 9 January 1984. South (20 km) of Cape Bridgewater, Victoria, on red alga, depth 100 m, coll: V. Johnstone, from fishing trawl, 16 May 1969. Port Noarlunga, South Australia, on red alga, depth 10 m, coll: J. Watson, 10 February 1976. Abrolhos Islands, outer reef, Western Australia, on red alga, depth 15 m, coll: J. Watson, 17 October 1986. Karapuki Island, New Zealand, coll: D. A. Staples 14 September 1975 on red alga.

Description. Hydrorhizal stolons ribbon-like, flattened to substrate, outer flange with flexion joints in perisarc. Stems monosiphonic, to 5 mm high, basal stem region athecate, sometimes with two or three transverse nodes. Cauline internodes variable in length among colonies but typically moderately long and slender, straight to slightly curved, walls smooth, expanding slightly distally to apophysis, nodes transverse to slightly oblique, deeply constricted, an internal transverse septum below node.

Hydrocladia alternate, distal on internode, in one plane, borne on an upwardly directed apophysis, abcauline wall of apophysis a smooth extension of internode, distal node a deep transverse shoulder with internal septum behind node, a minute mound-shaped hydrostatic pore in axil beside a nematotheca. Hydrocladium with a short proximal athecate internode, distal node transverse, deeply constricted with an internal septum, occasionally an identical secondary athecate internode between the athecate and hydrothecate internode. Hydrothecate internode narrow, short, ending in a distal spine of variable length, projecting beyond hydrotheca.

Hydrotheca occupying most of internode; internode expanding distally as a prehydrothecal chamber between node and floor of hydrotheca, often a minute septum projecting backwards into chamber from floor of hydrotheca. Hydrotheca bonnet shaped, laterally compressed, adcauline wall rounded, set deep in internode, abcauline wall curved, proximally convex, straightening towards margin; margin delicate, deeply divided by a long V-shaped septum passing deeply backwards into hydrotheca, a minute triangular in septum in base of some hydrothecae. Hydranth with 12–14 tentacles.

Nematothecae bithalamic, moveable, all approximately of same size: one cauline, halfway along internode on opposite side to apophysis, one on internode in axil, one median inferior, base close to internode, twin laterals standing erect in front of hydrotheca, one at each side of distal spine, bases short, slightly inflated, cup deeply adcaudally excavated into a butterfly shape.

Male and female gonothecae large, one to several borne near base of stem, inserted on a short indistinct pedicel beside apophysis; body narrowly conical, facing upwards, walls smooth to weakly undulated, distally truncate, closed by a sheet of tissue, immature female gonophore with many ova.

Perisarc of stem and gonotheca moderately thick, thin on hydrothecal margin. Colonies colourless to white.

Figures

Figure 5. A–G, Monotheca spinulosa. A, part of stem; B, hydrocladium with short terminal spine; C, hydrocladium with long terminal spine; D, female gonotheca with ova; E, two views of twin lateral nematothecae; F, axillar nematotheca; G, median inferior nematotheca. Scale bar: A, 0.3 mm; B, C, 0.2 mm; D,1 mm; E–H, 0.1 mm.