Praecantrix silvatica, Hegg & Morgan-Richards & Trewick, 2024

Hegg, Danilo, Morgan-Richards, Mary & Trewick, Steven A., 2024, Revision of the New Zealand cave wētā genus Isoplectron Hutton (Orthoptera: Rhaphidophoridae), with synonymy of Petrotettix Richards and Setascutum Richards, and the description of a new genus, European Journal of Taxonomy 971, pp. 1-75 : 57-58

Praecantrix silvatica gen. et sp. nov.

Exclusively a forest dweller, widespread throughout New Zealand’s South Island, with known observations from Stewart Island/ Rakiura and the southern end of North Island ( Fig. 10B ), it may be encountered both in leaf litter on the forest floor and on tree trunks or in foliage, but appears to be primarily an arboreal species. With a body length under 10mm, this is the smallest species treated in this paper. Based on DNA analysis we recognize two subspecies, very similar in their overall habitus and nearly identical in the terminalia, but allopatric in their distribution. Praecantrix silvatica silvatica gen., sp. et subsp. nov. is found in the western regions of New Zealand’s South Island from Jackson Bay to Kahurangi National Park and the Marlborough Sounds, whereas Praecantrix silvatica lutea gen., sp. et subsp. nov. is found along the east coast from Stewart Island/ Rakiura to Wellington ( Fig. 10B ).

Praecantrix silvatica gen. et sp. nov. is most easily identified by its shiny look conferred by the glabrous body, by the clear, crisp line delimiting the white body under-parts and the black sides of the thoracic dorsal segments and of the abdominal tergites ( Fig. 23E ), and by the small number of dorsal linear spines on the hind tibiae (generally less than 15 pairs).

Praecantrix silvatica gen. et sp. nov. adults are most easily confused with nymphs of the larger Talitropsis sedilloti , another glabrous, shiny arboreal cave wētā with which it is sympatric. Talitropsis sedilloti , however, is rarely black on the dorsum and lacks the lateral black/ white line. Furthermore, an examination of the terminalia will quickly reveal if a specimen at hand is an adult of the smaller species or a nymph of a larger species – and Talitropsis sedilloti adults are nearly twice as large as those of Praecantrix silvatica gen. et sp. nov.

Figures

Fig. 10. Known distribution of cave wētā in the genera Isoplectron Hutton, 1896 and Praecantrix gen. nov. A–C. All of New Zealand. A. Isoplectron armatum Hutton, 1896. Solid shapes indicate material collected as part of this study; empty circles indicate additional locations of material examined by Hutton (1896). Shapes represent different subspecies: circle = Isoplectron armatum armatum Hutton, 1896; diamond = Isoplectron armatum aciculatum Karny, 1937. B. Praecantrix silvatica gen. et sp. nov. Shapes represent different subspecies: dark green square = Praecantrix silvatica silvatica gen., sp. et subsp. nov.; light green diamond = Praecantrix silvatica lutea gen., sp. et subsp. nov. D. Map of North Island. E–J. Map of South Island. F. Isoplectron serratum (Richards, 1972) comb. nov. Solid shapes indicate material collected as part of this study; empty diamonds indicate additional locations of material examined by Richards (1972). Scale bars: 200 km.

Fig. 23. Live Isoplectron Hutton, 1896 and Praecantrix gen. nov. in their natural habitats. A. Isoplectron virgatum sp. nov., adult ♀ on Astelia Banks & Sol. ex R.Br. leaf. Bob’s Hut, Matakitaki River. B. Isoplectron ferratum sp. nov. in black beech Fuscospora solandri (Hook.f.) Heenan & Smissen tree canopy. Cave Brook, Gouland Downs, Kahurangi NP.C. Isoplectron parallelum sp. nov., adult ♀ on flax Phormium tenax J.R.Forst. & G.Forst. flower. Wellington. D. Praecantrix saxicola sp. nov., adult ♀. Mt St Bathans, Central Otago. E. Praecantrix silvatica silvatica gen., sp. et subsp. nov. adult ♀. Mt Arthur Tablelands, Kahurangi NP. F. Praecantrix silvatica lutea gen., sp. et subsp. nov. adult ♀. Hinau Track, Kaikōura.