Isoplectron maculatum, 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 : 44-46

Isoplectron maculatum sp. nov.

urn:lsid:zoobank.org:act:D7BC8F91-27ED-42D8-9E63-CE84613D39E3

Figs 3 , 8 , 10G , 12E , 13F , 15D–F , 18D–F , 20D , 22B

Diagnosis

Slightly smaller than the closely related I. serratum , it can only be differentiated from the latter species by examination of the male terminalia. The two species, however, are allopatric. I. maculatum sp. nov. has a chequered yellow/ black coloration in adults.

The distribution range of I. maculatum sp. nov. may overlap with Pharmacus montanus . Isoplectron maculatum is most easily differentiated from the latter species by the long, slender legs, the presence of dorsal linear spines on the first two segments of the hind tarsi and the serrated upper valve of the ovipositor.

Etymology

‘ Măcŭlātus ’ (adj.) is Latin for ‘speckled’, after the insect’s colour pattern.

Material examined (see also Supp. file 1: Table S6)

Holotype

NEW ZEALAND • ♂, adult; South Canterbury (SC), Middle Mt Peel ; 43.86312° S, 171.18167° E; 1350 m a.s.l.; 19 Apr. 2019; D. Hegg leg.; on rocky outcrop on ridgeline; night search + insect net; GenBank: PP155130; NMNZ AI.071892.

Paratype

NEW ZEALAND • 1 ♀, adult; same data as for holotype; NMNZ AI.071893 .

Other material

NEW ZEALAND – South Canterbury (SC) • 1 ♀; same data as for holotype; MPN CW5581 • 1 ♂; same data as for holotype; 27 May 2023; GenBank : PP155129; MPN CW5641 • 1 ♀; same data as for preceding; GenBank : PP155131; MPN CW5638 • 1 ♂; same data as for preceding; MPN CW5642 • 2 ♀♀; same data as for preceding; MPN CW5639 , CW5640 .

Description

MEASUREMENTS. See Table 1. Body longer by 1.4 mm (12%) in females.

HEAD. Very similar to I. serratum . Like in the latter species, the lower extremity of the vertex is black, but with two conspicuous pale spots between the fastigium and the eyes. Frons and clypeus pale, with vertical dark streaks below the eyes. Labrum pale. Scapes and pedicels variegated pale and grey; all other segments of the antennae brown.

THORAX. In adults, the pronotum, mesonotum and metanotum are chequered yellow / black ( Figs 12E , 22B ).

LEGS. Same as I. serratum .

ABDOMEN. Chequered yellow/ black ( Figs 12E , 22B ). In nymphs, the whole body tends to be coloured a dull grey / green.

MALE TERMINALIA. Suranal plate trapezoidal, not as heavily sclerotised as in I. serratum ( Fig. 15D ). Subgenital plate same as in I. serratum ; not as heavily sclerotised; with a double keel only in the distal half ( Fig. 15E ). Cerci short, on average 13% of body length, covered in sparse, mostly short hair; tapering gradually along their whole length and ending with a blunt tip at the apex. Styli slender, longer than subgenital plate. Paraprocts covered in dense, stout spinules on the inward-facing side; they are wider than the subgenital plate and are visible from below ( Fig. 15E ). Under the suranal plate there is a retractable cover which presumably protects the genitalia when not in use ( Fig. 20D ; compare with Fig. 15D ).

FEMALE TERMINALIA. Subgenital plate consists of two narrow, rounded lobes, covered in sparse hair; separated by a gap at least twice as wide as the lobe themselves ( Fig. 18D ). Ovipositor on average two thirds of body length; relatively straight and only lightly recurved upwards near the apex. Lower valve of ovipositor with 6 to 7 teeth below at the apex. Dorsal surface of upper valve heavily serrated in distal half ( Fig. 18E–F ).

Distribution and habitat

Isoplectron maculatum sp. nov. is currently only known from the alpine regions on Mt Peel in South Canterbury. It is most likely more widely distributed in the mountain ranges south of the Rangitata River, possibly as far west as the Two Thumb Range. Found almost exclusively on rock, where it feeds on lichen, it camouflages well with its background.

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. 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. 15. 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. serratum (Richards, 1972) comb. nov. The Gap, Torlesse Range (MPN CW3182). D–F. I. maculatum sp. nov., Middle Mount Peel, South Canterbury. D–E. MPN CW5638. F. MPN CW5640. G–I. I. virgatum sp. nov., Heaphy River, Kahurangi NP (MPN CW5622). J–L. I. ferratum sp. nov., Cave Brook, Gouland Downs, Kahurangi NP. J–K. Holotype (NMNZ AI.071896). L. MPN CW4953. Scale bars: 1 mm.

Fig. 18. Adult female terminalia of cave wētā in the genus Isoplectron Hutton, 1896. Left column: subgenital plate; central and right columns: ovipositor. A–C. Isoplectron serratum (Richards, 1972). Kahutara Saddle, Seaward Kaikōura Range (MPN CW5555). D–F. I. maculatum sp. nov. Middle Mount Peel, South Canterbury (MPN CW5642). G–I. I. virgatum sp. nov., paratype. Ces Clarke Hut, Paparoa Range (NMNZ AI.071895). J–L. I. ferratum sp. nov., paratype. Mt Stokes, Marlborough Sounds (NMNZ AI.071897). Scale bars: 1 mm.

Fig. 20. Retractable cover in adult male terminalia of cave wētā in the genus Isoplectron Hutton, 1896. A–B. I. pallidum (Richards, 1972) comb. nov. Crown Range Road (MPN CW5560). A. Dorsal view of retractable cover. B. Ventral view of subgenital plate and apex of retractable cover. C. I. serratum (Richards, 1972) comb. nov., dorsal view. Mt Altimarloch, Black Birch Range (MPN CW5588). D. I. maculatum sp. nov., holotype, dorsal view. Middle Mt Peel, South Canterbury (NMNZ AI.071892). Scale bars: 1 mm.

Fig. 22. Live Isoplectron Hutton, 1896 in their natural habitats. A. I. pallidum (Richards, 1972) comb. nov., adult ♀. Staircase Hut Track, Waianakarua. B. I. maculatum sp. nov., adult ♂. Middle Mt Peel, South Canterbury. C–F. I. serratum (Richards, 1972) comb. nov. C. Adult ♀. The Gap, Torlesse Range. D. Adult ♂. Mt Richmond, Richmond Range. E. Mating pair. Mt Altimarloch, Black Birch Range. F. Female nymph. Mt Altimarloch, Black Birch Range.