Looks like H. pusillum to me - but you can't easily work from images like this Mike - and I only know H. rubicundulum from one sighting at Ohau Tarns, a few garden plants I counted the chromosomes of and did DNA extractions from - all in 2001.. Suggest you ask the person who named it - Peter Heenan (heenanp@landcareresearch.co.nz)