Hidden Diversity

Posted by Darren Ward @nzhymenoptera

New Zealand is a weird place for biodiversity. An estimated 20,000 invertebrate species live in New Zealand and at least 50% are undescribed. When discussed, perhaps most often mentioned is the ‘high degree of endemism’. This is the proportion of species found only in NZ and nowhere else in the world. Overall, about 90% of insect species in NZ are endemic.

What is far less appreciated is the number of new species still to be discovered and described. I am often asked ‘Are there still new species to be found in NZ?’ Yes, there are, and many hundreds of them.

Recently, twenty-four new species of Mecodema, a genus of large-bodied ground beetles, have been described (Seldon & Buckley 2019), with one species even from Clevedon in the northern Wairoa! This genus is highly diverse with species spread throughout mainland New Zealand, and on many offshore islands. Many species are found in relatively restricted geographic areas and their presence indicates past geological events which have shaped New Zealand; including, isolation from the mainland, diversification and adaption in alpine zones; and volcanic activity.

Just this week, a new species of parasitoid wasp, Sierola houdiniae, was described (see Magnacca 2019) from a single specimen, reared from the larvae of a caterpillar, Houdinia flexilissima, better known as “Fred the Thread”. The caterpillar is found in Waikato bogs and peatlands in the living stems of Sporadanthus ferrugineus, a large endemic New Zealand rush, and is considered a species of high conservation status.

Discovering such hidden diversity is an important part of understanding how the world works, but also gives a sense of wonder about the diversity of the weird and wonderful little critters around us.

Darren Ward is an entomologist in the New Zealand Arthropod Collection at Landcare Research, and a senior lecturer at the School of Biological Sciences, University of Auckland.

Seldon & Buckley. 2019. The genus Mecodema Blanchard 1853 (Coleoptera: Carabidae: Broscini) from the North Island, New Zealand. Zootaxa. doi.org/10.11646/zootaxa.4598.1.1

Magnacca. 2019. Two new species of Sierola Cameron (Hymenoptera: Bethylidae) from New Zealand and Australia. New Zealand Entomologist. doi.org/10.1080/00779962.2019.1602899

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