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 : 86

Monotheca spinulosa , measurements, (µm)

Remarks. A microslide (NMV F59053) in the Bale collection of Museum Victoria labelled ‘ Plumularia spinulosa Bale 1882 , Queenscliff’ was nominated as a probable syntype by Stranks (1993). As this is the only known specimen, by monotypy it is the holotype of the species.

The position of the cauline nematotheca varies between colonies, typically being about halfway along the internode but sometimes only one-third the distance up from the proximal node. The position of the cauline apophysis is also somewhat variable, ranging from well below to close to the distal node. The axillar hydrostatic pore is very small and is only seen with careful searching.

Stechow (1923) erected the var. obtusa for morphotypes with a blunt terminal hydrocladial spine and Ralph (1961b) erected the var. spinulosa for material from New Zealand with a long terminal spine. Later studies, including the present one, suggest the length of the spine is very variable. Watson (2005) suggested it may be a response to environmental conditions and evidence from this study supports this conclusion, specimens with the longest spines being from deeper, less turbulent habitat.

M. spinulosa is a very small species with a preference for a substrate of flabellate red algae.

Type locality. Queenscliff , Victoria, Australia .

Known distribution. Temperate southern Australia to southeast Queensland, Lord Howe Island, New Zealand, Japan, South Africa, south Atlantic. Littoral to 100 m.