Isoplectron armatum aciculatum Karny, 1937

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 : 30-35

Isoplectron armatum aciculatum Karny, 1937

Figs 3 , 5 , 8 , 10A , 12B , 13B , 14D–F , 17D–F , 21D

Isoplectron aciculatum Karny, 1937: 230 .

Isoplectron calcaratum – Hutton 1896: pl. XIII fig. 19a.

Diagnosis

Morphologically very similar to Isoplectron armatum armatum , it can only be differentiated from the latter by examination of the adult male terminalia or by DNA analysis. Other minor differences between the two subspecies are a larger body size and longer legs in I. a. aciculatum (see Table 1), and frequently (but not always) an additional spine on both the prolateral and retrolateral inferior edges of the hind femur in the northern subspecies. The two subspecies, however, are allopatric, I. a. aciculatum being confined to the southern regions of New Zealand’s North Island, between Wellington, Tongariro and Gisborne, whereas I. a. armatum is only found in South Island.

Isoplectron armatum aciculatum could be confused with several species in the genus Neonetus ; it is most easily differentiated from these by the slender, elongated shape of the hind femora, which are armed with a prominent spine underneath, and by the absence of a prolateral spine at the apex of the fore and mid femora.

Etymology

The Latin word ‛ăcĭcŭla ’ translates as ‘hair pin’. Named after the shape of the conspicuous spine on the retrolateral inferior edge of the hind femur in adult males.

Material examined (see also Supp. file 1: Table S2)

Holotype

NEW ZEALAND • ♂, adult; Wellington (WN), Wellington; 41.3° S, 174.8° E; 1903 or earlier; G.V. Hudson leg.; OUMNH ENT-ORTH097.

Representative female

NEW ZEALAND • ♀, adult; Hawke’s Bay (HB), Mohi Bush Reserve ; 39.85485° S, 176.89542° E; 450 m a.s.l.; 10 May 2023; D. Hegg leg.; on tree trunk in native forest; night search + insect net; NMNZ AI.071888 .

Other material

NEW ZEALAND – Wellington (WN) • 1 ♂ subadult, paratype of I. calcaratum ; Wellington ; 41.3° S, 174.8° E; 1896 or earlier; F.W. Hutton leg.; CMNZ 2021.17 .7 • 1 ♀; Ahumairangi Town Belt, Wellington ; 41.26896° S, 174.76929° E; 250 m a.s.l.; 9 Apr. 2022; D. Hegg leg.; in Veronica shrub; night search + insect net; MPN CW5606 • 1 ♀; Queen Elizabeth II Park, Paekākāriki ; 40.96758° S, 174.97745° E; 40 m a.s.l.; 10 Jul. 2016; J. Nisbet leg.; in wētā motel on tree trunk; Genbank: PP155156; MPN CW3033 • 1 ♂; same data as for preceding; MPN CW3034 • 2 ♀♀; same data as for preceding; MPN CW3029 , CW3030 • 2 nymphs; same data as for preceding; MPN CW3031 , CW3032 • 1 ♂; Turitea Road, Palmerston North ; 40.41496° S, 175.66401° E; 120 m a.s.l.; 28 Aug. 2004; S. Trewick leg.; on the ground; casual find; MPN CW139 • 1 ♂; same data as for preceding; 3 Apr. 2016; S. Trewick and M. Morgan-Richards leg.; in wētā motel on tree trunk; GenBank: PP155155; MPN CW2869 • 1 ♂; same data as for preceding; MPN CW2868 • 1 ♂; same data as for preceding; 19 Mar. 2017; GenBank: PP155154; MPN CW4625 • 1 ♀; same data as for preceding; GenBank: PP155162; MPN CW4624 . – Wairarapa (WA) • 1 ♀; Bideford ; 40.86653° S, 175.86795° E; 150 m a.s.l.; 18 Sep. 2004; S. Trewick and M. Morgan-Richards leg.; on rotting log; GenBank: PP155159; MPN CW156 • 1 ♂; same data as for preceding; MPN CW154 • 1 ♀; same data as for preceding; MPN CW155 . – Rangitikei (RI) • 1 ♀; Big Hill Stream Track, Ruahine Range ; 39.58789° S, 176.33173° E; 500 m a.s.l.; 2011; M. Lusk leg.; MPN CW1634 . – Hawke’s Bay (HB) • 1 ♂; Cape Sanctuary, Cape Kidnappers ; 39.66073° S, 177.04288° E; 160 m a.s.l.; 14 Mar. 2011; M. Lusk leg.; in rifleman nest box; GenBank: PP155161; MPN CW1626 • 1 ♂; same data as for preceding; 16 May 2011; M. Lusk leg.; under kānuka bark; GenBank: PP155158; MPN CW1635 • 1 ♂; same data as for preceding; 14 Jun. 2011; GenBank: PP155157; MPN CW1961 • 2 ♀♀; same data as for preceding; Sep. 2011; MPN CW1809 A, CW1809B • 1 ♂; Kuripapango Track, Kaweka Range ; 39.380° S, 176.334° E; 500 m a.s.l.; 27 Feb. 2012; M. Lusk leg.; MPN CW1884 • 1 ♀; Lorenbrey, Kahurānaki Rd ; 39.8200° S, 176.8465 °E; 160 m a.s.l.; Sep. 2011; M. Lusk leg.; MPN CW2075 • 1 ♂; Ngaruroro River terrace; 39.36934° S, 176.32052° E; 520 m a.s.l.; 11 Mar. 2014; M. Lusk leg.; in mānuka /kānuka forest; GenBank: PP155160; MPN CW2657 . – Gisborne (GB) • 1 ♂; Okitu Bush Scenic Reserve ; 38.66506° S, 178.09982° E; 50 m a.s.l.; 9 Mar. 2023; R. Kleinpaste leg.; photograph only; iNaturalist 150680236 . – Taupō (TO) • 1 ♀; Marshalls Road, Ohakune ; 39.39469° S, 175.39605° E; 580 m a.s.l.; 5 Apr. 2023; D. Hegg leg.; on tree trunk on road side; night search + insect net; MPN CW5644 • 1 gynandromorph; same data as for preceding; 7 May 2023; GenBank: PP155165; MPN CW5645 • 1 ♂; same data as for holotype; 12–14 May 2023; in wētā motel; GenBank: PP155167; MPN CW5647 • 1 ♀; same data as for preceding; GenBank: PP155166; MPN CW5648 • 1 ♀; same data as for preceding; GenBank: PP155168; MPN CW5649 • 1 ♀; same data as for preceding; GenBank: PP155164; MPN CW5650 • 1 ♂; Marshalls Road, Ohakune ; 39.39518° S, 175.39726° E; 580 m a.s.l.; 13 May 2023; D. Hegg leg.; on tree trunk on road side; night search + insect net; GenBank: PP155163; MPN CW5646 .

Description

MEASUREMENTS. See Table 1. No sexual dimorphism in body length.

HEAD. Same as in Isoplectron a. armatum .

THORAX. Same as in Isoplectron a. armatum ( Fig. 12B ).

LEGS. Same as in Isoplectron a. armatum , only longer (see Table 1). Hind femora most frequently armed with three retrolateral ventral linear spines; one of these very conspicuous, weakly curved. This spine is present in both males and females, but is much larger and more pronounced in males. Two prolateral ventral linear spines are generally also present but are much smaller.

ABDOMEN. Mottled dark brown, with pale dorsal spots on the sides of the first tergite ( Figs 12B , 21D ). Colour morphs with a pale diamond on the back or a pale longitudinal band are also commonly encountered.

MALE TERMINALIA. Subgenital plate similar to that in Isoplectron a. armatum , but glabrous at apex, and with a much wider keel ( Fig. 14E ); also shallower and not as strongly folded upwards at the edges, meaning that from the sides one can see through the gap between the subgenital plate and the paraprocts ( Fig. 14F ). Cerci one quarter of body length, covered in long hairs; tapering gradually along their whole length and ending with a blunt tip at the apex. Styli slender, covered in sparse setae, reaching to the apex of the subgenital plate. Paraprocts covered in dense, stout spinules at the apex; short but wide and protruding beyond the perimeter of the subgenital plate on the sides ( Fig. 14D ), visible from below ( Fig. 14E ).

FEMALE TERMINALIA. Subgenital plate consists of two small, rounded, asymmetrical lobes, covered by sparse hair at the apex; the two lobes separated by a small gap and not touching at the vertex ( Figs 17D ). Ovipositor same as in Isoplectron a. armatum ( Fig. 17E–F ).

Figures

Fig. 3. A. Phylogenetic relationships of six genera of New Zealand Rhaphidophoridae Walker, 1869 inferred from whole mitochondrial genome sequences using Maximum Likelihood approach and 1000 bootstraps. B. Map of New Zealand, showing locations of specimens of Isoplectron Hutton, 1896 and Praecantrix gen. nov. used in phylogenetic analyses (Figs 6–7). Colours correspond to different genera: red = Isoplectron; green = Praecantrix. Two letter codes indicate the New Zealand entomological regions (Crosby et al. 1998). These codes are reported in the Material examined section for each species.

Fig. 5. Isoplectron armatum aciculatum Karny, 1937. A–B. Adult male terminalia. A. Ngaruroro River terrace, Hawke’s Bay (MPN CW2657). B. Holotype, New Zealand (OUMNH ENT-ORTH097). C. Dorsal view of insect. Holotype, New Zealand (OUMNH ENT-ORTH097). Scale bars: 1 mm. Images B–C ©Oxford University Museum of Natural History, published with permission.

Fig. 8. Gene tree for the eight morphologically identified species of Isoplectron Hutton, 1896 using Maximum Likelihood analysis of ~850 bp of mtDNA (COI) from 86 specimens. Node support labels are the result of 1000 ML bootstrap replicates.

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. 12. Dorsal view of cave wētā in the genera Isoplectron Hutton, 1896 and Praecantrix gen. nov. A–I. Isoplectron. A. I. armatum armatum Hutton, 1896, adult ♂. Parsons Bush, Lake Ōhau (MPN CW5123). B. I. armatum aciculatum Karny, 1937, adult ♀. Ohakune (MPN CW5644). C. I. bicolor sp. nov., adult ♂. Mt Arthur Tablelands (MPN CW3760). D. I. serratum (Richards, 1972) comb. nov., adult ♂. The Gap, Torlesse Range (MPN CW3182). E. I. maculatum sp. nov., holotype, adult ♂. Middle Mt Peel, South Canterbury (NMNZ AI.071892). F. I. ferratum sp. nov., holotype, adult ♂. Cave Brook, Gouland Downs (NMNZ AI.071896). G. I. virgatum sp. nov., adult ♀. Cave Brook, Gouland Downs (MPN CW3794). H. I parallelum sp. nov., adult ♀. Ahumairangi Town Belt, Wellington (MPN CW5598). I. I. pallidum (Richards, 1972) comb. nov., adult ♂. Mt Kyeburn, Danseys Pass (MPN CW3456). J–L. Praecantrix. J. P. silvatica silvatica gen., sp. et subsp. nov., adult ♂. Mt Arthur Hut (MPN CW5390). K. P. silvatica lutea gen., sp. et subsp. nov., adult ♂. Peel Forest (MPN CW4968). L. P. saxicola gen et sp. nov., holotype, adult ♂. Mt Wakefield (NMNZ AI.071904). Scale bar: 10 mm.

Fig. 13. Left hind tibia of cave wētā in the genera Isoplectron Hutton, 1896 and Praecantrix gen. nov., adult ♂, dorsal view. A–I. Isoplectron. A. I. armatum armatum Hutton, 1896. Parsons Bush, Lake Ōhau (MPN CW5123). B. I. armatum aciculatum Karny, 1937. Ohakune (MPN CW 5646). C. I. bicolor sp. nov., holotype. Cave Brook, Gouland Downs (NMNZ AI.071889). D. I. pallidum (Richards, 1972) comb. nov. Duffers Saddle, Old Woman Range (MPN CW5385). E. I. serratum (Richards, 1972) comb. nov. The Gap,Torlesse Range (MPN CW3182).F. I. maculatumsp. nov., holotype. Middle Mt Peel, South Canterbury (NMNZ AI.071892). G. I. virgatum sp. nov. Cave Brook, Gouland Downs (MPN CW3776). H. I. ferratum sp. nov., holotype. Cave Brook, Gouland Downs (NMNZ AI.071896). I. I. parallelum sp. nov. Ahumairangi Town Belt, Wellington (MPN CW5569). J–K. Praecantrix J. P. silvatica lutea gen., sp. et subsp. nov. McLean Falls, Catlins Forest (MPN CW3901). K. P. saxicola gen et sp. nov., holotype. Mt Wakefield (NMNZ AI.071904). Scale bar: 5 mm.

Fig. 14. Adult male terminalia of cave wētā in the genus Isoplectron Hutton, 1896. Left column: dorsal view; central column: ventral view (subgenital plate); right column: lateral view. A–C. I. armatum armatum Hutton, 1896. A–B. Kaiterau Trail, Kaikōura (MPN CW4938). C. Pioneer Park, Ōpihi River (MPN CW5554). D–F. I. armatum aciculatum Karny, 1937. Ohakune. D. MPN CW5647. E–F. MPN CW5646. G–I. I. bicolor sp. nov., Cave Brook, Gouland Downs. G–H. Holotype (NMNZ AI.071889). I. MPN CW3758. J–L. I. pallidum (Richards, 1972) comb. nov. J, L. Staircase Hut track, Waianakarua River (NMNZ AI.071891). K. Mt Kyeburn, Danseys Pass (MPN CW3455). Scale bars: 1 mm.

Fig. 17. Adult female terminalia of cave wētā in the genus Isoplectron Hutton, 1896. Left column: subgenital plate; central and right columns: ovipositor. A–C. Isoplectron armatum armatum Hutton, 1896. South Mavora Lake (MPN CW4927). D–F. I. armatum aciculatum Karny, 1937. Ohakune. D. MPN CW5648. E–F. MPN CW5650. G– I. I. bicolor sp. nov., paratype (NMNZ AI.071890). Chaffey Hut, Cobb River. J–L. I. pallidum (Richards, 1972) comb. nov. Duffers Saddle, Old Woman Range (MPN CW5387). Scale bars: 1 mm.

Fig. 21. Live Isoplectron Hutton, 1896 in their natural habitats. A–C. I. armatum armatum Hutton, 1896. A. Adult ♂ showing the most common habitus, dark brown back with two pale patches on the metanotum. Raincliff Reserve, Ōpihi River, South Canterbury. B. Adult ♂ with diamond-shaped dorsal pattern. Hinau Track, Kaikōura. C. Adult ♀ with broad longitudinal dorsal band. Pioneer Park, Ōpihi River, South Canterbury. D. I. armatum aciculatum Karny, 1937, adult ♀. Ohakune. E–F. I. bicolor sp. nov. E. Adult ♂. Mt Arthur Tablelands, Kahurangi NP. F. Male nymph. Chaffey Hut, Cobb River.