Isoplectron armatum subsp. armatum Hutton 1896
Creators: name: Hegg, Danilo
name: Morgan-Richards, Mary
name: Trewick, Steven A.
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Orthoptera
Rhaphidophoridae
Isoplectron
Isoplectron armatum
Isoplectron armatum armatum hutton, 1896

description: Isoplectron armatum armatum Hutton, 1896
Figs 3–4, 8, 10A, 11A–B, 12A, 13A, 14A–C, 17A–C, 21A–C
Isoplectron armatum Hutton, 1896: 237–238, pl. XIII fig. 18–18b.
Isoplectron calcaratum Hutton, 1896: 238, pl. XIII fig. 19, 19b. Syn. nov.
Setascutum ohauensis Richards, 1972: 163–165, fig. 5.1–5.6. Syn. nov.
Isoplectron armatum – Karny 1937: 230. –– Johns & Cook 2013: 17.
Isoplectron calcaratum – Karny 1937: 230. –– Johns 1977: 316, 318.
Isoplectron aciculatum – Bowie et al. 2006: 263–264, 267.
Diagnosis
A small to medium-sized rhaphidophorid with a body length between 9 and 14 mm, the hind tibiae about the same length as the body in males, approx. 10% shorter in females.
The most typical coloration is a mottled dark brown that blends in well with the bark of many New Zealand native trees, with pale spots on the mesonotum and/or the metanotum (Figs 12A, 21A), or on the first tergite. Colour morphs with a pale diamond on the back (Fig. 21B) or a pale longitudinal band (Fig. 21C) are also commonly encountered. The most characteristic trait of this species is a very conspicuous, weakly curved spine on the retrolateral inferior edge of the hind femur in adult males (Fig. 4A–C).
Isoplectron armatum armatum can only be differentiated from the other subspecies, I. armatum aciculatum, by examination of the adult male terminalia. The two subspecies, however, are allopatric, I. a. armatum being confined to New Zealand’s South Island, whereas I. a. aciculatum is only found in New Zealand’s North Island.
Isoplectron a. armatum can easily be confused with I. pallidum in Otago, where the two species are sympatric. Isoplectron pallidum, however, always has first and second hind tarsal segments armed with dorsal linear spines, whereas I. armatum always has first and second hind tarsal segments unarmed above. Adults of the species I. ferratum sp. nov. and nymphs of I. bicolor sp. nov. are also morphologically very similar to I. a. armatum. These two species, however, are only found in the north-west of New Zealand’s South Island, outside of the distribution range of I. armatum (compare Fig. 10A, C, E).
Etymology
' Armātus ’ (adj.) is Latin for ‘armed’ – with a very conspicuous spine on the retrolateral inferior edge of the hind femur in adult males.
Material examined (see also Supp. file 1: Table S1 and Figs S2–S 5)
Holotype NEW ZEALAND • ♂, adult; Dunedin (DN), Dunedin; 45.9° S, 170.5° E; 1896 or earlier; F.W. Hutton leg.; CMNZ 2021.17.3.
Other material
NEW ZEALAND – Southland (SL) • 1 ♂; Kāmahi Reserve, Edendale; 46.32143° S, 168.73513° E; 60 m a.s.l.; 13 Nov. 2016; D. Hegg leg.; on tree trunk in native forest; night search + insect net; GenBank: PP155178; MPN CW3447. – Fiordland (FD) • 1 nymph; Eglinton River mouth; 45.16355° S, 167.82449° E; 200 m a.s.l.; 24 Dec. 2018; D. Hegg leg.; on tree trunk in native forest; casual find; MPN CW4283. – Dunedin (DN) • 1 ♀; Brockville, Dunedin; 45.8705° S, 170.4615° E; 250 m a.s.l.; 21 Jun. 1998; S. Trewick leg.; on footpath; casual find; MPN CW168 • 1 ♂; same data as for preceding; 13 Apr. 2007; B. Trewick leg.; inside house; casual find; MPN CW1920 • 1 ♂; Frasers Gully, Dunedin; 45.861° S, 170.461° E; 200 m a.s.l.; 17 Apr. 2017; S. Trewick and M. Morgan-Richards leg.; MPN CW3470 • 1 ♀; same data as for preceding; MPN CW3471 • 1 ♀; Ōpoho, Dunedin; 45.85431° S, 170.53385° E; 130 m a.s.l.; 30 Nov. 2016; D. Hegg leg.; on tree trunk in garden; night search + insect net; GenBank: PP155176; MPN CW3449 • 2 ♂♂; Duncan Rd, near Hampden; 45.36689° S, 170.72316° E; 460 m a.s.l.; 1 Oct. 2016; M. Morgan-Richards leg.; on clay bank; MPN CW3128, CW3130 • 1 nymph; same data as for preceding; MPN CW3127 • 1 ♂; Staircase Hut track, Waianakarua; 45.28210° S, 170.69724° E; 420 m a.s.l.; 3 Sep. 2016; D. Hegg leg.; on tree trunk in native forest; night search + insect net; MPN CW3159 • 5 ♀♀; same data as for preceding; MPN CW3161, CW3165, CW3166, CW3168, CW4923 • 1 nymph; same data as for preceding; MPN CW3167. – Central Otago (CO) • 3 nymphs; Wye Creek; 45.1384° S, 168.7623° E; 400 m a.s.l.; Nov. 2009; M. McDonald leg.; in native forest; night search; MPN CW1027, CW1029, CW1030 • 1 ♀; Piano Flat, Waikaia Forest; 45.55472° S, 169.02195° E; 220 m a.s.l.; 5 Mar. 2020; D. Hegg leg.; on tree trunk in native forest; night search + insect net; MPN CW4962 • 1 nymph; Nokomai River; 45.5148° S, 168.7091° E; 300 m a.s.l.; 12 Nov. 2022; D. Hegg leg.; on willow tree next to river; night search + insect net; GenBank: PP155185; MPN CW5565. – Otago Lakes (OL) • 1 spec. (hind leg only); Lake Dispute, Wakatipu; 45.050° S, 168.544° E; 450 m a.s.l.; Nov. 2004; P. Johns leg.; GenBank: PP155182; MPN CW192 • 2 specs (hind legs only); same data as for preceding; MPN CW193, CW194 • 2 ♂♂; same data as for preceding; M. Francis leg.; MPN CW251, CW252 • 4 nymphs; Sam Summers Walking Track; 45.0540° S, 168.5305° E; 450 m a.s.l.; Nov. 2009; M. McDonald leg.; in native forest; night search; MPN CW1024, CW1025, CW1031, CW1032 • 1 ♂; Bush Creek Track, Arrowtown; 44.9365° S, 168.8189° E; 400 m a.s.l.; Nov. 2009; M. McDonald leg.; in native forest; night search; MPN CW1033 • 1 nymph; Te Kere Haka Track, Kingston; 45.3247° S, 168.7157° E; 300 m a.s.l.; Nov. 2009; M. McDonald leg.; in native forest; night search; MPN CW1034 • 2 nymphs; Lake Sylvan; 44.7219° S, 168.3151° E; 400 m a.s.l.; Nov. 2009; M. McDonald leg.; in native forest; night search; MPN CW1026, CW1028 • 2 ♂♂; OBHS Lodge, Matukituki River; 44.49654° S, 168.77397° E; 400 m a.s.l.; 5 May 2017; D. Hegg leg.; on tree trunk in native forest; night search + insect net; MPN CW4932, CW4933 • 1 ♀; same data as for preceding; MPN CW4949 • 3 nymphs; same data as for preceding; MPN CW3444 to CW3446 • 1 ♀; Aspiring Hut track, Matukituki River; 44.50131° S, 168.68372° E; 400 m a.s.l.; 5 May 2017; D. Hegg leg.; on large rock; night search + insect net; MPN CW3771 • 1 ♂; Aspiring Hut, Matukituki River; 44.47580° S, 168.65914° E; 460 m a.s.l.; 6 May 2017; D. Hegg leg.; on beech tree branch; night search + insect net; GenBank: PP155181; MPN CW3454 • 1 ♂; same data as for preceding; MPN CW3999 • 3 ♀♀; South Mavora Lake; 45.31441° S, 168.17702° E; 630 m a.s.l.; 14 Mar. 2018; D. Hegg leg.; on tree trunk in native forest; night search + insect net; CW3802, CW4927, CW4928 • 2 ♀♀; South Mavora Lake; 45.29922° S, 168.17931° E; 630 m a.s.l.; 25 Jun. 2020; D. Hegg leg.; on tree trunk in native forest; night search + insect net; MPN CW4929, CW4930 • 1 nymph; Muddy Creek, Rees River; 44.69636° S, 168.46955° E; 520 m a.s.l.; 6 Sep. 2018; D. Hegg leg.; on tree trunk in native forest; night search + insect net; MPN CW4083. – Mackenzie (MK) • 1 ♂, holotype of Setascutum ohauensis; Lake Ōhau; 44.2° S, 169.8° E; 500 m a.s.l.; May 1958; OUSSA Otago University Science Students Association leg.; OMNZ IV7928 • 1 ♀, allotype of Setascutum ohauensis; same data as for preceding; OMNZ IV7929 • 1 ♂; Parsons Bush, Lake Ōhau; 44.24971° S, 169.81942° E; 540 m a.s.l.; 14 May 2017; D. Hegg leg.; on tree trunk in native forest; night search + insect net; GenBank: PP155184; MPN CW3506 • 6 ♂♂; same data as for preceding; MPN CW3503 to CW3505, CW5123 to CW5125 • 5 ♀♀; same data as for preceding; MPN CW3507, CW3508, CW5120 to CW5122 • 1 ♂; Governors Bush, Mt Cook Village; 43.73758° S, 170.09640° E; 750 m a.s.l.; 20 Oct 2017; D. Hegg leg.; on twig in native forest; night search + insect net; GenBank: PP155177; MPN CW3617 • 1 ♀; same data as for preceding; GenBank: PP155180; MPN CW3705 • 1 ♂; same data as for preceding; CW4960 • 1 ♂; same data as for preceding; 15 May 2018; D. Hegg leg.; MPN CW4961. – South Canterbury (SC) • 1 ♂; Raincliff Reserve, Ōpihi River; 44.16157° S, 170.99234° E; 150 m a.s.l.; 2 Jul. 2016; D. Hegg leg.; on Griselinia littoralis tree trunk; night search + insect net; GenBank: PP155175; MPN CW3112 • 1 ♂, 1 ♀; same data as for preceding; MPN CW3113, CW3114 • 1 ♂; Pioneer Park, Ōpihi River; 44.14562° S, 170.95329° E; 240 m a.s.l.; 27 Nov. 2022; D. Hegg leg.; on tree trunk in native forest; night search + insect net; MPN CW5554 • 4 ♂♂; Otaio Gorge; 44.52335° S, 170.92860° E; 330 m a.s.l.; 18 Mar. 2018; D. Hegg leg.; on tree trunk in native forest; night search + insect net; MPN CW5116 to 5119 • 2 ♀♀; same data as for preceding; MPN CW5114, CW5115 • 1 nymph; same data as for preceding; MPN CW3938 • 2 ♂♂; Peel Forest; 43.89631° S, 171.23491° E; 460 m a.s.l.; 2 Oct. 2020; D. Hegg leg.; on tree trunk in native forest; night search + insect net; MPN CW4965, CW4966 • 2 ♀♀; same data as for preceding; MPN CW4964, CW4967 • 5 ♂♂; Peel Forest; 43.899° S, 171.238° E; 400 m a.s.l.; 24 Feb. 2022; S. Trewick, M. Morgan-Richards and T. Trewick leg.; MPN CW5417, CW5418, CW5421, CW5422, CW5424 • 2 ♀♀; same data as for preceding; MPN CW5419, CW5423 • 1 nymph; same data as for preceding; MPN CW5420. – Mid Canterbury (MC) • 1 ♀; Cass Station; 43.033° S, 171.762° E; 600 m a.s.l.; 26 Feb. 2006; J. Whitfield leg.; GenBank: PP155172; MPN CW325 • 1 ♀; same data as for preceding; MPN CW326 • 1 ♀, 1 nymph; Wainui, Banks Peninsula; 43.817° S, 172.903° E; 20 m a.s.l.; 30 Nov. 2012; B. Taylor-Smith and M. Morgan-Richards leg.; night search; GenBank: PP155173, PP155174; MPN CW2135, CW2195 • 1 ♀; Hinewai Reserve, Banks Peninsula; 43.81489° S, 173.02740° E; 300 m a.s.l.; 22 Sep. 2018; D. Hegg leg.; on tree branch in native forest; night search + insect net; MPN CW4924 • 1 ♂; Hamilton Hut, Harper River; 43.12903° S, 171.62762° E; 800 m a.s.l.; 12 Sep. 2020; D. Hegg leg.; on tree trunk in native forest; night search + insect net; MPN CW4963. – North Canterbury (NC) • 1 ♀, holotype of I. calcaratum; Eyreton, Canterbury; 43.4° S, 172.5° E; 50 m a.s.l.; 1896 or earlier; F.W. Hutton leg.; CMNZ 2021.17.6 • 2 ♀♀; Tiromoana Bush Walk, Waipara; 43.09185° S, 172.85077° E; 220 m a.s.l.; 27 Sep. 2018; D. Hegg leg.; on clay bank on side of track; night search + insect net; MPN CW4925, CW4926 • 1 ♀; Tweedies Gully, Gore Bay; 42.86225° S, 173.30737° E; 20 m a.s.l.; 7 Apr. 2018; D. Hegg leg.; in blackberry shrub; night search + insect net; GenBank: PP155183; MPN CW3933. – Kaikōura (KA) • 1 ♂; Mt Fyffe Track, Kaikōura; 42.349° S, 173.571° E; 300 m a.s.l.; 17 Jan. 2006; J. Goldberg leg.; GenBank: PP155169; MPN CW391 • 1 ♀; same data as for preceding; MPN CW390 • 1 ♂; Hinau Track, Kaikōura; 42.34977° S, 173.56725° E; 200 m a.s.l.; 28 Mar. 2016; D. Hegg leg.; on tree trunk in native forest; night search + insect net; GenBank: PP155171; MPN CW2874 • 1 ♀; same data as for preceding; GenBank: PP155170; MPN CW2873 • 3 ♂♂; same data as for preceding; MPN CW2875 to CW2877 • 1 ♀; same data as for preceding; MPN CW2878 • 1 nymph; same data as for preceding; Jan. 2017; MPN CW3451 • 1 ♂; same data as for preceding; 3 Jul. 2020; MPN CW4934 • 2 ♀♀; same data as for preceding; MPN CW4939, CW4940 • 1 ♂; Kaiterau Trail, Kaikōura; 42.34121° S, 173.56832° E; 560 m a.s.l.; 4 Jul. 2020; D. Hegg leg.; on tree trunk in native forest; night search + insect net; MPN CW4938 • 3 ♀♀; same data as for preceding; MPN CW4935 to CW4937 • 1 ♂; Puhi Puhi Bush, Kaikōura; 42.27014° S, 173.73771° E; 160 m a.s.l.; 15 Oct. 2020; D. Hegg leg.; on tree trunk in native forest; night search + insect net; MPN CW5156 • 1 nymph; Kahutara Saddle, Seaward Kaikōura Range; 42.32241° S, 173.42870° E; 1200 m a.s.l.; 1 Apr. 2017; D. Hegg leg.; on clay bank on side of track; night search + insect net; GenBank: PP155179; MPN CW3452. – Marlborough (MB) • 1 ♂; Renwick, Wairau Valley; 41.52725° S, 173.84760° E; 50 m a.s.l.; 28 Sep. 2018; D. Hegg leg.; on tree trunk near river; night search + insect net; MPN CW4942 • 1 ♀; same data as for preceding; MPN CW4943 • 1 ♂; Renwick, Wairau Valley; 41.51304° S, 173.83856° E; 50 m a.s.l.; 5 Oct. 2018; S. Trewick and M. Morgan-Richards leg.; MPN CW4296 • 1 ♀; same data as for preceding; MPN CW4297 • 7 ♂♂; Southerland Stream Track, Blenheim; 41.54806° S, 173.96524° E; 60 m a.s.l.; 5 Oct. 2018; S. Trewick and M. Morgan-Richards leg.; MPN CW4298, CW4299, CW4301 to CW4303, CW4308, CW4309 • 5 ♀♀; same data as for preceding; MPN CW4300, CW4304 to CW4307 • 1 ♂; Waihopai River, Wairau Valley; 41.52456° S, 173.73504° E; 80 m a.s.l.; 19 Oct. 2018; D. Hegg leg.; on tree trunk near river; night search + insect net; MPN CW4941.
Description
MEASUREMENTS. See Table 1. No sexual dimorphism in body length.
HEAD. As per generic description. Vertex mottled brown with pale patches. Black streaks run from the posterior margin of each eye to the pronotum, resembling the temples in a pair of sun-glasses. Frons pale, with dark vertical stripes below the scapes of the antennae. Scapes and pedicels of antennae pale with thin brown streaks. All other segments of the antennae are reddish (Fig. 11A–B).
THORAX. As per generic description. The most typical coloration is a mottled dark brown with pale patches on the mesonotum and/or the metanotum (Figs 12A, 21A). A narrow pale dorsal stripe (Fig. 21B) or a broad pale dorsal band (Fig. 21C) running across all three thoracic segments is also commonly seen.
LEGS. Fore and mid femora approximately half as long as body. Hind tibiae same length as body in males, 15% shorter in females. Fore femora always unarmed at the apex. Mid femora armed with one retrolateral spine at the apex; prolateral apical spine absent. Hind femora armed with one to three retrolateral ventral linear spines; one of these very conspicuous, weakly curved (Fig. 4A–C). This spine is present in both males and females, but is much larger and more pronounced in males. Up to two prolateral ventral linear spines are present on occasion but are much smaller. Fore tibiae armed with two pairs of ventral linear spines, and with one pair of ventral apical spines. Mid tibiae armed with two pairs of ventral linear spines, one pair of ventral spines and one retrolateral dorsal spine at the apex. A prolateral dorsal spine at the apex of the mid tibia is always absent. Up to two retrolateral dorsal linear spines on the mid tibiae may be present but only rarely. Hind tibiae armed with about 15 dorsal linear spines (min 11, max 20) on both the anterior and the posterior edge (Fig. 13A). Hind tibiae armed at the apex with two ventral sub-apical spines, two ventral apical spines, two dorsal apical spines and two dorsal sub-apical spines. The dorsal apical spines are always largest, whereas the ventral sub-apical spines are smallest. First and second segments in hind tarsi always unarmed except at the apex.
ABDOMEN. Typically mottled dark brown (Figs 12A, 21A), occasionally with pale dorsal spots on the sides of the first tergite. Colour morphs with a pale diamond on the back (Fig. 21B) or a pale longitudinal band (Fig. 21C) are also commonly encountered.
MALE TERMINALIA. Subgenital plate with central lobe three times as long as lateral lobes, covered with sparse, short setae at the apex, and with a visible keel at the centre (Fig. 4D–F). The subgenital plate’s central lobe is visibly folded upwards on the sides near the apex (Fig. 14A). Cerci on average 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 and always contained entirely within the perimeter of the subgenital plate both in length and in width (Fig. 14A). The paraprocts are therefore never visible from below (Fig. 14B).
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 4G–I, 17A). Ovipositor on average three quarters of body length, relatively straight in the basal half, tapering and moderately recurved upwards in the apical half. Lower valve of ovipositor with 6 to 8 teeth below at the apex. Dorsal surface of upper valve finely serrated in distal half (Fig. 17B–C).
Distribution and habitat
Isoplectron armatum is an arboreal cave wētā, common and widespread in dry forests in New Zealand’s South Island from Southland to the Marlborough Sounds (Fig. 10A). It is frequently encountered in urban parks and gardens. It is most easily found hiding under bark on tree trunks, often in groups of up to ten individuals; also in artificial wētā motels (Bowie et al. 2006; pers. obs.).
description: Published as part of 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, pp. 1-75 in European Journal of Taxonomy 971 on pages 23-30, DOI: 10.5852/ejt.2024.971.2761, http://zenodo.org/record/14451786