Isoplectron bicolor Hegg & Morgan-Richards & Trewick 2024, sp. nov.
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 bicolor

description: Isoplectron bicolor sp. nov.
urn:lsid:zoobank.org:act: EBEFE4F1-4F9B-4173-AF54-A53151132217
Figs 3, 8, 10E, 12C, 13C, 14G–I, 17G–I, 21E–F
Diagnosis
The largest species in the genus Isoplectron; in the adult form, it is unmistakeable due to its characteristic coloration, with tawny head, thorax, fore and mid legs and hind femora, which contrast with the near black abdomen and hind tibiae (Fig. 21E). Nymphs could be easily mistaken for those of I. ferratum sp. nov., with which it is sympatric, and with I. armatum. The latter species however is not found within the distribution range of I. bicolor sp. nov.
Etymology
‘ Bĭcŏlor ’ (adj.) is Latin for ‘two-coloured’ – because of the unique contrasting coloration, tawny in the front and black in the back.
Material examined (see also Supp. file 1: Table S3)
Holotype NEW ZEALAND • ♂, adult; Nelson (NN), Cave Brook, Gouland Downs; 40.89153° S, 172.35449° E; 620 m a.s.l.; 4 Feb. 2018; D. Hegg leg.; on tree trunk; night search + insect net; NMNZ AI.071889.
Paratype NEW ZEALAND • 1 ♀, adult; Nelson (NN), Chaffey Hut, Cobb River; 41.09600° S, 172.57535° E; 880 m a.s.l.; 26 Dec. 2020; D. Hegg leg.; on tree trunk; night search + insect net; NMNZ AI.071890.
Other material
NEW ZEALAND – Buller (BR) • 1 ♀; Nina Hut, Nina Valley; 42.46573° S, 172.32202° E; 760 m a.s.l.; 15 Mar 2015; in sink outside hut; photograph only; iNaturalist 1909084. – Nelson (NN) • 1 nymph; same data as for holotype; 20 Apr. 2016; GenBank: PP155151; MPN CW2991 • 1 ♂; same data as for holotype; GenBank: PP155152; MPN CW3758 • 1 ♂; Mt Arthur Tablelands; 41.18500° S, 172.64370° E; 1180 m a.s.l.; 8 Feb. 2018; D. Hegg leg.; in beech tree canopy; night search + insect net; GenBank: PP155153; MPN CW3760 • 1 ♂; same data as for preceding; 24 Dec. 2020; MPN CW5346 • 3 nymphs; same data as for paratype; MPN CW5195, CW5197, CW5198 • 1 ♂; same data as for paratype; 5 Jan. 2022; MPN CW5357.
Description
MEASUREMENTS. See Table 1. The only female collected has a body longer than any of the examined males by two to six millimetres.
HEAD. As per generic description. Vertex tawny with dark streaks. A dark patch extends behind the posterior margin of the eye. Frons pale, with dark vertical stripes below the scapes of the antennae. Scapes of antennae tawny. All other segments of the antennae are reddish.
THORAX. Pronotum, mesonotum and metanotum tawny with complex dark pattern (Fig. 12C).
LEGS. All leg segments are tawny, except for the hind tibiae, which are near black in adults. Hind tibiae of same length as body in females, up to 50% longer than body in males. 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 nine to seventeen prolateral ventral linear spines, very small, and four to eight strong retrolateral ventral linear spines. 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. Hind tibiae armed with 12 to 16 dorsal linear spines on both the anterior and the posterior edge (Fig. 13C). 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 hind tarsal segment occasionally armed with a few dorsal linear spines. Second tarsal segment unarmed except at the apex.
ABDOMEN. Typically dark, near black in adults, although a tawny diamond may extend from the thorax into the first few tergites (Figs 12C, 21E). Nymphs often have a diamond pattern on the back (Fig. 21F).
MALE TERMINALIA. Subgenital plate with central lobe at least twice as long as lateral lobes, glabrous, with visible keel at centre (Fig. 14H). Cerci with alternating tawny and dark bands; 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, extending beyond the apex of the subgenital plate. Paraprocts with pronounced lateral lobes at the apex, which is covered in dense, stout spinules (Fig. 14G). The paraprocts project beyond the apex of the subgenital plate and are therefore visible from below (Fig. 14H).
FEMALE TERMINALIA. Subgenital plate consists of two large, elongated lobes, flat at the vertex, which is covered in short hair (Fig. 17G). Ovipositor three quarters of body length, tapering and curving upwards gradually along its whole length. Lower valve of ovipositor with 6 teeth below at the apex. Dorsal surface of upper valve finely serrated in distal half (Fig. 17H–I).
Distribution and habitat
A cryptic, arboreal insect, confined to the north-west regions of New Zealand’s South Island between Lewis Pass and Kahurangi National Park (Fig. 10E). It is believed to live primarily in the tree canopy in native forests.
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 35-39, DOI: 10.5852/ejt.2024.971.2761, http://zenodo.org/record/14451786