Pleioplectron triquetrum, Hegg & Morgan-Richards & Trewick, 2019

Hegg, Danilo, Morgan-Richards, Mary & Trewick, Steven A., 2019, Diversity and distribution of Pleioplectron Hutton cave wētā (Orthoptera: Rhaphidophoridae: Macropathinae), with the synonymy of Weta Chopard and the description of seven new species, European Journal of Taxonomy 577, pp. 1-46 : 19-20

Pleioplectron triquetrum sp. nov.

urn:lsid:zoobank.org:act:75D542D6-516C-4905-ABE0-3F14A89DCE72

Figs 2 A–B, 6D, 7D, 8J–L, 10J–L, 14F, 18D

Diagnosis

A small to medium-sized, dark-coloured inhabitant of the forests in the northeast of the South Island of New Zealand. The habitus is typical of Pleioplectron , chequered grey-brown in colour, with visibly banded legs and often with a dorsal median line. At the southern end of its range (Canterbury /North Canterbury), it could be most easily confused with P. simplex Hutton, 1896 , from which it is distinguished by the presence of a retrolateral apical spine on the fore femur, the darker colour and slightly smaller size. In northern Marlborough, it is most easily mistaken for P. auratum sp. nov., which is generally of lighter colour, but an examination of the terminalia is required to reliably distinguish the two species. Further inland and west, it could be confused with P. gubernator sp. nov., a smaller species that lacks the retrolateral apical spine on the fore femur.

Etymology

ʻ Trĭquĕtrus ʼ is Latin for ʻthree-corneredʼ or ʻtriangularʼ, after the triangular shape of the subgenital plate in the adult males ( Fig. 8J ).

Material examined (see also Table 5 in Supplementary Material)

Holotype

NEW ZEALAND • ♂, adult; Kaikōura (KA), Hinau Track; 42.349586° S, 173.566727° E; 200 m a.s.l.; 22 Oct. 2016; Danilo Hegg leg.; at base of tree in native forest; night search + insect net; NMNZ AI.037480 (prev. MPN CW3922 ).

Paratype

NEW ZEALAND • ♀, adult; North Canterbury (NC), Gore Bay, Tweedies Gully ; 42.862247° S, 173.3073717° E; 40 m a.s.l.; 7 Apr. 2018; Danilo Hegg leg.; on clay bank on side of track in native forest; night search + insect net; NMNZ AI.037481 (prev. MPN CW3846 ) .

Other material

NEW ZEALAND – Marlborough (MB) • 2 ♂♂, 2 ♀♀; Hanmer Springs, Fir Trail ; 42.50273° S, 172.84644° E; 500 m a.s.l.; 20 Dec. 2005; J. Goldberg and F. Wieland leg.; MPN CW386 to CW389 . – Kaikōura (KA) • 1 ♂, 2 ♀♀, 1 nymph; Hodder River ; 41.95700° S, 173.65023° E; 1150 m a.s.l.; 6 Apr. 2018; D. Hegg leg.; under boulders at bush-line; night search + insect net; MPN CW3826 , CW3827 , CW3858 , CW3916 • 1 ♂, 2 ♀♀; same collection data as for holotype; 28 Mar. 2016; MPN CW2870 to CW2872 • 1 ♂, 1 ♀, 2 nymphs; same collection data as for holotype; MPN CW3921 , CW3923 , CW3924 , CW3972 • 2 ♂♂, 1 ♀; same collection data as for holotype; 1 Apr. 2017; MPN CW3928 , CW3929 , CW3970 . – North Canterbury (NC) • 3 ♂♂, 2 ♀♀, 1 nymph; same collection data as for paratype; MPN CW3839 to CW3841 , CW3844 , CW3845 , CW3920 • 3 nymphs; Waipara, Tiromoana Bush Walk ; 43.09836° S, 172.84595° E; 150 m a.s.l.; 27 Sep. 2018; D. Hegg leg.; on clay bank on side of track; night search + insect net; MPN CW4084 to CW4086 .

Description

MEASUREMENTS. See Table 1.

HEAD. Frons dark brown, with very sparse setae; vertex glabrous and of variegated colour. Eyes dark. Fastigium dark, with a white spot on either side. Scapes and peduncles pale and pilose; antennae dark with occasional pale segments, covered in fine setae. Maxillari and labial palpi brown, with fine tomentum. In some sexually mature males, antennal segments have sensory hair tuffs as in P. simplex (see Fig. 5 ).

THORAX. Pronotum variegated dark brown with pale patches; dark with pale bars next to anterior and posterior margins; covered in sparse, fine tomentum. Anterior and lateral margins slightly rounded; posterior margin nearly straight.

LEGS. Moderately long; hind femora 10% to 20% longer than body in both males and females; hind tibiae 10% to 30% longer than body in females, 20% to 50% longer than body in males. Coxae and trochanters mottled light and dark brown. Fore and mid femora and tibiae with conspicuous alternating light and dark bands. Hind femora variegated; hind tibiae uniform dark colour. Fore coxae with a pronounced lateral spine. Fore femora without linear spines above or below but armed with one prolateral and one retrolateral spine at apex. Fore tibiae armed below, generally with two (up to four) linear spines on anterior edge and three (two to four) linear spines on posterior edge. Fore tibiae armed with two long spines below (one prolateral and one retrolateral) and two short spines above (one prolateral and one retrolateral) at apex. Mid femora without linear spines above or below, but armed with one prolateral and one retrolateral spine at apex. Mid tibiae armed below, with one to three linear spines on both anterior and posterior edges. Mid tibiae armed with two long spines below (one prolateral and one retrolateral) and two short spines above (one prolateral and one retrolateral) at apex. Hind femora armed with three to seven very small retrolateral linear spines below, and one retrolateral apical spine. Hind tibiae armed with 21 to 33 linear spines above, of varying length, on both anterior and posterior edges. Hind tibiae with two superior subapical spines (one prolateral and one retrolateral), two superior apical spines (one prolateral and one retrolateral), two inferior apical spines (one prolateral and one retrolateral) and two inferior subapical spines (one prolateral and one retrolateral). Superior subapical spines about twice as long as inferior subapical spines, inferior apical spines twice as long again; superior apical spines approximately three times as long as inferior apical spines. Hind tarsi with four segments, first and second segments with a pair of spines on distal end. First segment with 7–13 small dorsal, alternate spines. Second segment with 3–9 small dorsal, alternate spines. Second and fourth segments of approximately half of length of first segment, third segment one third of length of second and fourth segments.

ABDOMEN. Colour variegated brown/black, with a few lighter patches; covered in sparse, fine tomentum. Dorsal median line generally visible but thin and not very pronounced ( Figs 6D , 14F ).

MALE TERMINALIA. Cerci long, pointed at apex, dark brown colour, clothed in setae. Styli short and stumpy, extending about as far as end of subgenital plate. Subgenital plate forms a neat triangle, not keeled ( Fig. 8J ). Apex of subgenital plate visible from above, looking like a small alpine hat ( Fig. 8K ).

FEMALE TERMINALIA. Subgenital plate weakly bilobed, its lobes separated by a very shallow depression ( Fig. 10J ). Ovipositor reddish-brown, strongly curved upwards at apex, terminating in a very sharp point; relatively short (approximately three quarters of body length). Upper valve smooth above; lower valve with 4 to 6 strong teeth at apex on ventral edge ( Fig. 10 K–L). Dorsal view of terminalia as in P. simplex ( Fig. 12A ).

Figures

Fig. 2. Phylogenetic relationships of Pleioplectron Hutton, 1896 cave wētā based on mtDNA sequence. A. Bayesian analysis using a mtDNA sequence alignment of 1429 bp spanning the majority of COI, with a minimum individual sequence length of 1330. Posterior probabilities are shown by nodes. B. Maximum Likelihood tree using PhyML with a COI alignment that contained sequences ranging from 483bp to 1429 bp, although the majority were>850 bp at the 3′ end of the gene. C. Map of New Zealand entomological (Crosby) regions. These codes are indicated in the Material examined section for each species.

Fig. 8. Adult male terminalia of cave wētā in the genus Pleioplectron Hutton, 1896. Left column: ventral view (subgenital plate); central column: dorsal view; right column: lateral view. A–C. P. simplex Hutton, 1896, Hinewai Reserve, Banks Peninsula. A–B. MPN CW4109. C. MPN CW4118. D–F. P. hudsoni Hutton, 1896, Otaki Forks, Tararua Forest Park (MPN CW3890). G–I. P. thomsoni (Chopard, 1923) comb. nov., Trotters Gorge, Otago (MPN CW3780). J–L. P. triquetrum sp. nov., Hinau Track, Kaikōura. J, L. MPN CW3922. K. MPN CW3928. M–O. P. auratum sp. nov. M, O. Whites Beach, Rarangi (MPN CW4295). N. Waihopai River, Blenheim (MPN CW4146). Scale bars = 1 mm.

Fig. 5. Pleioplectron simplex Hutton, 1896, adult ♂, Hinewai Reserve, Banks Peninsula (MPN CW4109). Detail of antenna showing sensory hairs. Scale bar = 1 mm.

Fig. 6. Dorsal views of cave wētā in the genus Pleioplectron Hutton, 1896. A. P. simplex Hutton, 1896, adult ♀, Helicopter Hill Track, Craigieburn (MPN CW3914). B. P. thomsoni (Chopard, 1923) comb. nov., adult ♂, Claremont Bush, South Canterbury (MPN CW4115). C. P. gubernator sp. nov., adult ♀, Mt Arthur (MPN CW4056). D. P. triquetrum sp. nov., adult ♂, Hinau Track, Kaikōura (MPN CW3928). E. P. auratum sp. nov., adult ♂, Whites Beach, Rarangi (MPN CW4295). F. P. rodmorrisi sp nov., adult ♂, Hodder River, Inland Kaikōura Range (MPN CW3824). G. P. hudsoni Hutton, 1896, adult ♂, Karori, Wellington (MPN CW3564). H. P. caudatum sp. nov., adult ♂, Brewster Hut Track, Haast Pass (MPN CW4049). I. P. flavicorne sp nov., adult ♂, Brewster Hut Track, Haast Pass (MPN CW4055). J. P. crystallae sp nov., adult ♀, Cave Brook, Gouland Downs (MPN CW3991). Scale bar = 10 mm.

Fig. 14. Live Pleioplectron Hutton, 1896 in their natural environments. A–B. P. simplex Hutton, 1896, Hinewai Reserve, Banks Peninsula. A. Adult ♀ feeding on a small native snail Flammulina zebra (Le Guillou, 1842). B. Adult ♂. The different colouration is due to individual variation, not sexual dimorphism. C–D. P. thomsoni (Chopard, 1923) comb. nov. C. Adult ♂ in natural cave, Trotters Gorge, Otago. D. Adult ♀ in mining tunnel in Bannockburn, Central Otago, where a population of nearly white colour exists. E. P. hudsoni Hutton, 1896, adult ♀, Otaki Forks, Tararua Forest. F. P. triquetrum sp. nov., ♂, Hinau Track, Kaikōura.

Fig. 10. Adult female terminalia of cave wētā in the genus Pleioplectron Hutton, 1896. Left column: subgenital plate; central and right columns: ovipositor. A–C. P. simplex Hutton, 1896, Hinewai Reserve, Banks Peninsula (MPN CW4114). D–F. P. hudsoni Hutton, 1896, Karori Ecosanctuary, Wellington. D. MPN CW3554. E–F. MPN CW3552. G–I. P. thomsoni (Chopard, 1923) comb. nov. G. Pioneer Park, Opihi River, South Canterbury (MAPN CW3913). H–I. Trotters Gorge, Otago (MPN CW4007). J–L. P. triquetrum sp. nov., Tweedies Gully, Gore Bay (MPN CW3846). M–O. P. auratum sp. nov., Renwick, Blenheim. M. MPN CW4120. N–O. MPN CW4119. Scale bars = 1 mm.

Fig. 12. Adult female terminalia of cave wētā in the genus Pleioplectron Hutton, 1896, dorsal view (suranal plate). A. P. simplex Hutton, 1896, Hinewai Reserve, Banks Peninsula (MPN CW4114). B. P. crystallae sp. nov., Salisbury Lodge, Mt Arthur (MPN CW3941). C. P. caudatum sp. nov., Brewster Hut Track, Haast Pass (MPN CW4040). Scale bars = 1 mm.