A new species of Tachycines Adelung, 1902 (Orthoptera, Rhaphidophoridae, Aemodogryllinae, Aemodogryllini) from karst caves in Guizhou, China

Abstract Tachycines (Gymnaeta) trapezialissp. nov. (梯形裸灶螽) is described with specimens collected from Diaosiyan and Sanjiaoshan caves in Ziyun County, Guizhou, China. The unique trapezoidal shape of the epiphallus in males and the subgenital plate in females, which separate the new taxon from its congeners, are illustrated.


Introduction
During scientific expeditions to the proposed Ziyun Nature Reserve for Hume's pheasant (Syrmaticus humiae) in Ziyun County, Guizhou, China, nymphs and adults of a new species were collected in Diaosiyan and Sanjiaoshan caves in Ziyun County, Guizhou, China, in June and October of 2019.

Materials and methods
All specimens used in this study were preserved in 75% ethanol. Details of the morphology were studied under an Olympus SZ61 stereomicroscope. Male genitalia were preserved in mixture solution of ethanol and glycerin. Photographs were taken by an Olympus DP22 digital camera and processed with Adobe Photoshop CS6.
All specimens are deposited in the Institute of Karst Caves, Guizhou Normal University, Guizhou Province, China (IKCGZNU). The morphological terminology follows Qin et al. (2019).       Description. Male. Body medium-sized (Fig 5). Vertex divided into two conical tubercles (Fig. 1A, B). Ommateum normal, not reduced; ocelli visible. Legs elongate and slender; fore femur about 1.6-1.8 times longer than the pronotum, ventrally un- armed, internal genicular lobe with a small spine; external genicular lobe with one elongate movable spur; ventral side of fore tibiae with two external spurs and two internal spurs. Mid femur ventrally unarmed, internal, and external genicular lobes with one elongate movable spur respectively; ventral side of mid tibiae with one external spur and one internal spur. Hind femur without spines ventrally; hind tibiae with 55-60 outer spines and 54-58 inner spines, arranged in groups. Supra-internal spurs of hind tibiae not exceeding ventral apex of hind tarsus (Fig. 1C). Hind tarsus keeled ventrally and with one dorsal apical spine. Male genitalia with trapezoidal epiphallus, lateral sclerites and median process divided at apical fourth (Figs 2A, B, 3A, B).

Tachycines (Gymnaeta) trapezialis
Female. Other characters are similar to male (Fig. 6). Subgenital plate wider than long and with three lobes; median lobe large and nearly trapezoid with apex transverse, paired lateral lobes small and nearly triangular with blunt apex (Fig. 1D). Ovipositor (Fig. 1E) shorter than half the length of hind femur. Coloration. Body brown. Frons with two dark longitudinal bands (Fig. 1A). Pronotum and mesonotum margins dark brown. Apexes of abdominal tergites dark brown. Hind femur with darkish stripes laterally.
Etymology. The name refers to trapezoidal epiphallus in males.
Habitat. Individuals of the new species live in groups in subtropical karst caves (Figs 4, 7).

Discussion
Species distribution of the subgenus (Fig. 8) presents a complexity which may reflect the degree of troglomorphism and parapatry distribution. Many species of this subgenus were found both inside and outside of cave. Eyes of these species vary from fully developed to reduced or absent, as in the totally blind T. (G.) omninocaecus. The geographical distribution pattern might be explained by the evolutionary scenario of zones of secondary admixture following epigean dispersal among lineages diverged from allopatry, as proposed by Ketmaier et al. (2013).