Isoplectron parallelum, 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 : 53-56

publication ID	https://doi.org/ 10.5852/ejt.2024.971.2761
publication LSID	lsid:zoobank.org:pub:F82472D1-595D-4DB7-A463-513B94BE85D9
persistent identifier	https://treatment.plazi.org/id/03AF8780-FFBD-FF80-BE43-57D55BEBFD40
treatment provided by	Plazi
scientific name	Isoplectron parallelum
status	sp. nov.

Treatment

Isoplectron parallelum sp. nov.

urn:lsid:zoobank.org:act:577A6714-3C40-4422-A145-4A299C18B287

Figs 3 View Fig , 8 View Fig , 10D View Fig , 12H View Fig , 13I View Fig , 16A–C View Fig , 19A–C View Fig , 23C View Fig , 24A–C View Fig

Diagnosis

A small rhaphidophorid (body length 9 to 12 mm) characterised by the presence of six to eight longitudinal stripes on the back. Very similar to Talitropsis poduroides in morphology and habitat use, it can only be differentiated from this species by examination of the male terminalia or of the female sternites and sub-genital plate ( Fig. 24 View Fig ). While Talitropsis poduroides is widely distributed in North Island, the two species appear to be allopatric.

Isoplectron parallelum sp. nov. is also very similar to I. virgatum sp. nov. in morphology and habitat use and can only be differentiated from the latter species by examination of the male terminalia, or by the number of ventral protuberances on the female sternites (compare Figs 15G View Fig and 16A View Fig , Figs 18G View Fig and 19A View Fig ). Isoplectron parallelum also always has a retrolateral spine at the apex of the mid femur, a trait that is usually absent in I. virgatum . The latter species, however, is confined to South Island, which makes confusion between the two species unlikely.

Etymology

‘ Părallēlus ’ (adj.) is Latin for ‘parallel’, because of the longitudinal parallel stripes on the insect’s back.

Material examined (see also Supp. file 1: Table S9)

Holotype

NEW ZEALAND • ♂, adult; Wellington (WN), 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; NMNZ AI.071898. GoogleMaps

Paratype

NEW ZEALAND • 1 ♀, adult; same data as for holotype; NMNZ AI.071899 GoogleMaps .

Other material

NEW ZEALAND – Wellington (WN) • 1 ♂; Newlands, Wellington ; 41.233° S, 174.827° E; 150 m a.s.l.; 16 Apr. 2006; S. Trewick leg.; on Eucalyptus tree; casual find; GenBank: PP155119; MPN CW362 GoogleMaps • 1 ♂; same data as for preceding; GenBank: PP155120; MPN CW363 GoogleMaps • 1 ♀; Zealandia Ecosanctuary, Wellington ; 41.30554° S, 174.73678° E; 250 m a.s.l.; 8 May 2006; R. Goudswaard leg.; MPN CW410 GoogleMaps • 1 ♀; Rangitautau Reserve, Wellington ; 41.33716° S, 174.82203° E; 60 m a.s.l.; 16 Oct. 2020; D. Hegg leg.; on Phormium tenax flower; night search + insect net; GenBank: PP155118; MPN CW5131 GoogleMaps • 4 ♂♂; same data as for holotype; MPN CW5566 to CW5569 GoogleMaps • 2 ♀♀; same data as for holotype; MPN CW5596 , CW5598 GoogleMaps • 1 ♀; Days Bay, Wellington ; 41.27566° S, 174.90748° E; 100 m a.s.l.; 2 Oct. 2023; S. Trewick leg.; on Melicytus ramiflorus leaves; night search; GenBank: PP155108; MPN CW5657 GoogleMaps .

Description

MEASUREMENTS. See Table 1. Sexual dimorphism in body length, with females being larger by 1.4 mm (15%).

HEAD. Vertex pale with four brown lines running from the fastigium to the anterior margin of the pronotum, two above the eyes and two near the centre. Dark streaks run from the posterior margin of each eye to the pronotum, resembling the temples in a pair of sun-glasses. Frons, clypeus and labrum pale, with two vertical dark stripes below the scapes of the antennae. Scapes and pedicels variegated; all other segments of the antennae pale.

THORAX. Pale with brown dorsal lines running along the length of the thorax and continuing into the abdomen ( Fig. 12H View Fig ).

LEGS. Sexual dimorphism present. The hind tibiae are about the same length as the body in both males and females. Since females are larger than males, their hind tibiae are also longer, by approximately the same amount. 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 or two retrolateral and prolateral ventral linear spines, the retrolateral ones being larger. Fore tibiae armed with two pairs of ventral linear spines, and with one pair of ventral apical spines. A retrolateral dorsal spine at the apex of the fore tibia is usually present. 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. Hind tibiae armed with about 17 dorsal linear spines (min 14, max 22) on both the anterior and the posterior edge ( Fig. 13I View Fig ). Hind tibiae armed at the apex with two ventral apical spines, two dorsal apical spines and two dorsal sub-apical spines; the dorsal apical spines are largest. Ventral sub-apical spines are always absent. First and second segments in hind tarsi always unarmed except at the apex.

ABDOMEN. Tergites pale, with dorsal brown stripes running longitudinally along the whole length of the insect from the pronotum to the terminalia ( Figs 12H View Fig , 23C View Fig ). In females only, the seventh sternite is equipped with two ventral protuberances; the eighth sternite with one ventral protuberance ( Fig. 19A View Fig ).

MALE TERMINALIA. Suranal plate trapezoidal with conspicuous hair tufts on the two posterior corners; the posterior margin is bent inwards in a V-shape ( Fig. 16A View Fig ). Subgenital plate pear-shaped; covered in very sparse, thin tomentum except near the base on the sides, which are glabrous; with a double keel in the basal half, turning into a single keel in the distal half ( Fig. 16B View Fig ). Cerci on average 20% 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 short and stumpy, not reaching to the apex of the subgenital plate. Paraprocts narrow, tapering right from the base to a blunt tip at the apex; glabrous ( Fig. 16A View Fig ).

FEMALE TERMINALIA. Subgenital plate consists of two bulging, rounded lobes, joined at the base and diverging at the apex; glabrous on the inner surface, covered in stout hair on the outer surface ( Fig. 19A View Fig ). Ovipositor short, 55% to 60% of body length; moderately recurved upwards from the base to the apex; lower valve with 7 to 11 teeth below at the apex; dorsal surface of upper valve serrated in distal third ( Fig. 19B–C View Fig ).

Distribution and habitat

Only known from Wellington and surrounds (North Island). Isoplectron parallelum sp. nov. is mainly found on the elongated leaves of shrubs in the genera Phormium and Astelia , where the insect’s habitus blends in with the leaf’s longitudinal nervature.