Pleioplectron Hutton 1896
Creators: name: Hegg, Danilo
name: Morgan-Richards, Mary
name: Trewick, Steven A.
Publisher: name: Zenodo
Year: 2019
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Orthoptera
Rhaphidophoridae
Pleioplectron

description: Genus Pleioplectron Hutton, 1896
Pleiplectron Hutton, 1896: 232.
Weta Chopard, 1923: 234. syn. nov.
Etymology
Not explained by Hutton. ʻ Pleios ʼ = ʻmanyʼ, ʻ plectron ʼ = ʻplectrumʼ in Greek (most likely an analogy for the dorsal spines on the hind tibiae, which are shaped like a plectrum). The hind tibiae are armed with many dorsal spines, more numerous than in other genera Hutton would have been familiar with. Pleioplectron is neuter gender.
Description
With ten species in the genus, it is difficult to isolate morphological characters that apply to every species of Pleioplectron. Here, we focus on characters that fit either all species, or only some, but are not found in other genera, and comment further on the differentiation of Pleioplectron from other genera of New Zealand Rhaphidophoridae in the Discussion.
Small- to medium-sized cave wētā (body length of adults 8.5 to 20 mm) found mainly in leaf litter in forests, occasionally in caves or above the tree-line, on the two main islands of New Zealand.
Head broad, nearly oval. Scapes of antennae sexually dimorphic in all species, very broad in males, thinner in females (Fig. 4). Segments of antennae fitted with sensory hairs in sexually mature males of three species (Pleioplectron simplex Hutton, 1896, P. rodmorrisi sp. nov. and P. triquetrum sp. nov.), a character not seen in other genera of Rhaphidophoridae (Fig. 5). Eyes approximately 1.2 mm across on longest dimension regardless of size of animal, strongly bulging and appearing disproportionately large in smaller species (compare Fig. 4 A–B with Fig. 4 C–D). Maxillary palps of varying length, with moderately dense covering of hair.
Dorsal body colour patchy or chequered brown in most species, light/tawny in one species (Pleioplectron thomsoni (Chopard, 1923) comb. nov.), very dark/nearly black in some others (P. gubernator sp. nov. and P. caudatum sp. nov.). Two species (P. rodmorrisi sp. nov. and P. crystallae sp. nov.) with more varied and vibrant colouration. Most species with a prominent yellow median line along length of dorsum (Fig. 6). Lateral edges of pronotum with a pronounced rim and bent upwards in all species.
Leg length varies strongly among species and between individuals within a species. In some species, males tend to have longer legs than females. The difference in leg length between sexes does generally not exceed 20%, and is mostly less important than individual variation. Apical spines: all species have one anterior spine at the apex of the fore femur; four out of ten species additionally have a posterior spine at the apex of the fore femur (Table 1). All species have both an anterior and a posterior spine at the apex of the mid femur. The hind femur has a retrolateral apical spine in five out of ten species (Table 1). All species have four apical spines at the apex of both fore and mid tibia, and at the apex of the hind tibia a pair of dorsal apical spines, a pair of dorsal sub-apical spines and a pair of ventral apical spines. Four out of ten species additionally have a pair of ventral sub-apical spines at the apex of the hind tibia (Table 1). The dorsal apical spines on the hind tibia are very long, generally at least twice or three times the length of ventral apical spines. Linear spines: fore and mid femur generally unarmed, except in Pleiplectron auratum sp. nov. and P. rodmorrisi sp. nov. Hind femur generally armed below; the number of spines varies both within and between species. Fore tibia always unarmed above; mid tibia generally unarmed above, except in Pleioplectron rodmorrisi sp. nov. Fore and mid tibia armed below, with one to three pairs of linear spines; the number varies both within and between species. The hind tibia is always armed above with two parallel rows of 20 or more (up to 50) linear spines; only P. crystallae sp. nov. has fewer than 20 dorsal spines in each row (Table 1). Linear spines on the hind tibiae are socketed but not articulated, very variable in size on the same animal, randomly smaller and larger without obvious pattern (Fig. 7). Additionally, two species (P. auratum sp. nov. and P. crystallae sp. nov.) have one or more (up to four) pairs of much larger, possibly articulated dorsal spines on the hind tibiae. Fore and mid tarsi: all segments unarmed. Hind tarsi: always armed above with a variable number of small spines on both the first and the second tarsal segment. The spines on the hind tarsi are most often alternate, meaning that if a spine is on the posterior edge, there is no corresponding spine in the same position on the anterior edge, and vice versa.
Male and female terminalia are species specific (Figs 8–11), yet they have common structures and elements in all species except for Pleioplectron rodmorrisi sp. nov. The male suranal plate is generally square on the posterior edge and covers all genital structures above. The male subgenital plate varies in shape between triangular and tri-lobed, but is often short, exposing three complex layers of genital structures in a ventral view. The female subgenital plate is rounded, bi-lobed or tri-lobed, at times small and largely hidden by the last sternite. The upper valve of the ovipositor is smooth in all species of Pleioplectron; the lower valve has few (up to ten) strong, well visible teeth near the apex (Figs 10–11).
description: Published as part of 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, pp. 1-46 in European Journal of Taxonomy 577 on pages 10-12, DOI: 10.5852/ejt.2019.577, http://zenodo.org/record/3552088