Pleioplectron Hutton, 1896

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 : 10-12

publication ID	https://doi.org/ 10.5852/ejt.2019.577
publication LSID	lsid:zoobank.org:pub:5ED633C5-4F9C-4F9D-9398-B936B9B3D951
DOI	https://doi.org/10.5281/zenodo.5625624
persistent identifier	https://treatment.plazi.org/id/03A487B7-251A-5026-A20F-FC9FFAA9B396
treatment provided by	Plazi
scientific name	Pleioplectron Hutton, 1896
status

Treatment

Genus Pleioplectron Hutton, 1896 View in CoL

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 View Fig ). 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 View Fig ). 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 View Fig A–B with Fig. 4 View Fig 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 View Fig ). 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 View 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 View 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 View 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 View 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 View Fig ). 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 View Fig View Fig View Fig View Fig ), 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 View Fig View Fig ).