New species of Macropathinae from New Zealand. a) Crux boudica sp. nov., male, Rakiura (D. Hegg). b) Crux boudica sp. nov., female, Skippers Range (D. Hegg). c) Crux heggi sp. nov., male, Paparoa Range (D. Hegg). d) Crux heggi sp. nov., female, Saxon River (D. Hegg). Photo: Supplied
Three new species of wētā have been discovered in New Zealand's southern islands, all belonging to two new genera new to science.
Massey University professor in evolutionary ecology Steven Trewick detailed the discoveries in a newly published paper, Two new genera of tokoriro (Orthoptera: Rhaphidophoridae: Macropathinae) from Aotearoa New Zealand.
The new species are Crux boudica, Crux heggi and Occultastella morgana.
"Unfortunately, they're not giant ones, and perhaps that's why it's taken a little bit longer to encounter them," Trewick told RNZ's Morning Report on Tuesday.
"They're quite small, cryptic, but very pretty and interesting once you've seen that they're there."
Occultastella was found in the coal seam soils of Denniston Plateau on the West Coast. Trewick described its appearance as "startling". Its genus name means 'hidden star', and the species was named for orthopterist Mary Morgan-Richards, whom Trewick's paper said "contributed extensively on the ecology, systematics and taxonomy of New Zealand Rhaphidphoridae and Anostostomatidae" (different types of wētā).
"It's little, very dark and it has these extraordinary white flame markings on its head… There's some sort of economic history about that area," he said, referring to the region's mining industry, "so it was quite extraordinary finding a whole new not just species, but a whole new genus, at that location."
Crux boudica and Crux heggi were found on Rakiura / Stewart Island. 'Crux' is a constellation also known as the Southern Cross. The former was named after the Iceni queen who led an uprising against the conquering Romans in the first century CE "who apparently had that chariot with swords on her wheels".
"Well, the females of this species have this whole set of prongs and spikes sticking out from their bellies that must be something to do with them controlling the reproductive activity with males of that species.
"We've never seen them at it, but it's very formidable armoury… that's not normal in wētā. There are some other kinds of wētā where the females are, you know, dominant in controlling the reproductive activity, but they do it in other ways - by demanding natural gifts, presents from the males before they allow them to mate. But there seems to be a slightly different approach to the business."
Genus, plural genera, are the taxonomic grouping above species - for example, while lions and tigers are different species, they belong to the genus panthera - basically, big cats.
New species of Macropathinae from New Zealand. e) Occultastella morgana sp. nov., male, Buller River (T. Jewell). f) Occultastella morgana sp. nov., female, Cobb Valley (A. McDonald). Photo: Supplied
Crux heggi's species name came from orthopterist Danilo Hegg, "who collected specimens of this taxon and who has contributed extensively to revision of the New Zealand Rhaphidophoridae".
Trewick said the number of known wētā species was increasing "all the time", though none of those introduced in his new paper were giant, "unfortunately".
"The wētā that people are most familiar with are the tree wētā and obviously giant wētā, the species that we talk about - although most people won't encounter a giant wētā unless they're on a reserve island. But the majority of our diversity is in the group that we commonly call cave wētā, even though most of them don't live in caves. Most of them are in the forests, the native forests, up in the alpine zones in amongst the rocks, for instance.
"And we're talking, you know, something 70-plus species - and new stuff being discovered all the time, which is why we're sort of we're making a point of finding these species, because it is extraordinary in a country like New Zealand to be discovering new diversity even amongst fairly familiar kinds of organisms, like wētā."
He said research had now proved wētā were amongst the species which began thriving and evolving not long after New Zealand began to form over 16 million years ago.
"It does tell us something, because we have got fossil time-calibrated phylogenetics - so we've got some hypotheses now, some well-supported hypotheses about the patterns of diversification.
"And, so we can see that, particularly amongst these so-called cave wētā, the diversity starts increasing in the Miocene period - so that's about 16 to 19 million years ago when the New Zealand that we sort of recognise now started to form, started to come out of the ocean with the tectonic activity along the Alpine Fault and then diversification is kicking off then… very noticeably in wētā."
