Isoplectron sp. Hawkes Bay ©Mike Lusk Male (top) female (bottom) Icm scale bar

Isoplectron are small but relatively robust cave weta that mostly inhabit forest, expecially among the damp litter and decaying logs. The genus has been overlooked due to its small size and cryptic nature, and additional species are likely to exist.

Isoplectron calcaratum Hutton, 1897
The legs are hairy, with the hind femora dilated and "armed below with a single, long, nearly straight spine on the inner edge, near the middle.”
Body length: 13mm   Pronotum: 3mm Thorax: 6mm   Abdomen: 6mm 
Ovipositor: 7mm. Antennae: 50mm.
Legs:   Fore: 19mm. Mid: 20mm. Hind: 40mm
Locality: Wellington, in blossoms of Metrosideros scandens. North Canterbury, among dead wood. Mohi Bush, Hawke’s Bay. Palmerston North. Bideford, Wairarapa.

Isoplectron armatum Hutton, 1897
The legs are hairy, with the hind femora dilated and "armed below with a two strong curved spines and some smaller ones on the indder edge near the middle.”
Body length: 12mm. Pronotum: 4mm  Thorax: 7mm  Abdomen: 7mm Width at Mesonotum: 4mm.
Legs:   Fore tibia: 6mm. Hind tibia: 12mm. Hind femur: 12mm.
Antennae: “tawny”.          
Locality: Dunedin.
Notes: “Legs very hairy. Fore and middle femora unarmed below; hind femora much dilated, armed below with two strong curved spines, and some smaller ones on the inner edge near the middle.”

At least two other species from Nelson and Wellington were noted in the 1930s but details of their appearance and distribution are few. Other species are likely to be described in this genus, and some existing taxa need to be renamed including Talitropsis irregularis, the type specimen of which is an immature individual from Auckland. The supposedly alpine genus Setascutum is a synonym of Isoplectron.


  • Hutton F.W. 1897 The Stenopelmatidae of New Zealand. Transactions and Proceedings of the New Zealand Institute 29: 208-242