Review of the genus Apotrechus in China (Orthoptera, Gryllacrididae, Gryllacridinae)

Abstract In the present paper, the genus Apotrechus Brunner-Wattenwyl, 1888 is revised. Two new species from China are described and illustrated: Apotrechus quadratus sp. n. and Apotrechus truncatolobus sp. n.. A new key and the distributional data are given.


Introduction
The genus Apotrechus was proposed by Brunner-Wattenwyl (1888), with the type species Apotrechus unicolor Brunner-Wattenwyl, 1888. This genus resembles the genus Eremus Brunner-Wattenwyl, 1888, but differs from the latter in: smooth frons, spineless hind tibia and absence of male styli. Liu and Yin (2002) first studied Apotrechus in China, described one new species A. nigrigeniculatus. Liu and Bi (2008) gave a key of Apotrechus from China containing three species, and two new species A. digitatus and A. fallax were illustrated. Besides, Liu et al. (2010) also reported one new species A. transversus from Zhejiang. Subsquently, Guo and Shi (2012) reviewed this genus of China and also provided a key containing six species in China which included one new species A. bilobus, and one new combination A. parvospinus. Bian et al. (2014) provided a key to the species with one new species A. trilobus and the morphological photographs for five Chinese known species in this paper.
So far, the genus Apotrechus includes nine species in the world, among them, A. unicolor Brunner-Wattenwyl, 1888, A. swinhoei (Griffini, 1909), and A. illawarra Rentz, 1990 are recorded in Australia; A. insolitus (Walker, 1869) is distributed in Vietnam and others are recorded in China. In this paper, tow new species of Apotrechus are identified and described, namely Apotrechus quadratus sp. n. and A. truncatolobus sp. n., which are distributed in Guangxi.

Material and methods
All specimens of the genus were collected by light-trapping and net-catching from China. Adult specimens were preserved in 70% ethanol in the field, then removed and dried in the lab. The specimens were observed with the help of a Leica MZ 12.5 dissecting microscope and illustrated with the aid of a drawing tube attached to the microscope. Line drawings were made with Adobe Illustrator CS 6 graphic software. The length of the body was measured mesaby the distance between apex of fastigium verticis and posterior margin of tenth abdominal tergite, ovipositor by distance between base of subgenital plate and apex of ovipositor; pronotum, tegmina and hind femora by distance between summit of base and apex. All lengths are presented in millimeters. The venation nomenclature used in this paper is based on the interpretation of Karny (1937). All type specimens recorded here are deposited in the Shanghai Entomology Museum, the Chinese Academy of Sciences. Description. Male. Body medium sized. Wings absent. Fastigium of vertex rounded, about 2 times as wide as scape; eyes reniform, prominent; ocelli inconspicuous. Pronotum almost hexagon, paranota lower. Fore coxa with a spine, fore tibia on ventral surface with 5 pairs of spurs (included 1 pair of apical spurs); mid tibia without inner upper apical spur but with 4 pairs of spurs (included 1 pair of apical spurs) on ventral surface. Ventral surface of hind femur with 10-11 internal spines, but without external spine, hind tibia unarmed or with 1-2 minute spines on dorsal surface, bearing 3 pairs of apical spurs. 9 th abdominal tergite divided into two lobes, which bearing spine-like apex pointing downwards, epiproct medially furrowed (Fig. 5). Cerci shorter, conical; subgenital plate broad, hind margin split into two lobes, apex of lobes spine-like, curved inside (Fig. 6). Female. Unknown. Coloration. Body infuscate. Fastigium of vertex with darkish black longitudinal band; frons with 3 blackish longitudinal stripes, middle stripe broad, not connected with the longitudinal band of fastigium of vertex (Figs 1-2); inner margin of antenna foveolae and first segment with blackish spots. Pronotum with a darkish black longitudinal band in the middle and all margins black. Apex of fore and middle femora black, hind femur with a blackish longitudinal stripe on external surface, all tibiae darkish black on the base and apex.

Genus
Measurements. (length in mm)  Description. Female. Body large. Wings apterous. Fastigium of vertex roundly projected, about 2 times as wide as scape; eyes reniform, produced; ocelli faintly. Pronotum almost hexagon, lateral lobes longer than high. Fore coxa with a spine, fore tibia on ventral surface with 5 pairs of spurs (included 1 pair of apical spurs) but without inner upper apical spur; mid tibia on ventral surface with 4 pairs of spurs (included 1 pair of apical spurs). Hind femur on ventral surface armed 8 internal spines and 1-3 external spines; hind tibia on dorsal surface bearing 6 pairs of rather small spines and 2 pairs of apical spurs. Cerci shorter, conical; subgenital plate broad, square, and hind margin slightly concave (Fig. 9). Ovipositor short, curved upwards, apex blunt. Male. Unknown. Coloration. Body yellowish brown. Fastigium of vertex with 2 pairs of darkish black longitudinal bands; frons with 3 blackish longitudinal spots; inner margin of basal antenna and first segment with blackish spots. Lateral and fore margin of pronotum black, in the middle with a darkish black vertical stripe. Mesonotum and metanotum also with a black spot at middle parts (Figs 7-8). Hind femur with a blackish longitudinal stripe on external surface, all tibiae on base and apex darkish black.   Liu & Yin, 2002, but differs mainly in the the latter in body larger and subgenital plate of female with hind margin slightly concave.

Measurements. (length in mm)
Etymology. The specific epithet referrers to shape of female subgenital plate. Description. Male. Body medium sized. Wings absent. Fastigium of vertex rounded, about 2 times as wide as scape; eyes ovoid, prominent, ocelli inconspicuous. Cephalic margin of pronotum slightly projected, posterior margin slightly truncated, lateral lobes lower. Fore coxa with a spine, fore tibia on ventral surface with 5 pairs of spurs (included 1 pair of apical spurs); mid tibia without inner upper apical spur but on ventral surface with 4 pairs of spurs (included 1 pair of apical spurs); hind tibia without spine or on dorsal surface with 1-2 minute spines, with 3 pairs of apical spurs. Hind femur with 10-12 internal spines and 7-8 external spines on ventral surface. Lobes of 9 th abdominal tergite with roundly truncated apex (Fig. 20); cerci shorter, conical; subgenital plate broad, hind margin split into two lobes and with notch in the middle (Figs 18-19).
Coloration. Body yellowish brown, occiput slightly with darkish black. Frons without blackish longitudinal stripes; dorsal margin of abdominal with a darkish black longitudinal band in the middle (Fig. 17). Apex of fore femur, base and apex of tibiae slightly darkish black. Diagnosis. This new species almost the same as its congeners, but the frons without blackish longitudinal stripe; lobes of male 9 th abdominal tergite with roundly truncate apex.
Etymology. The specific epithet referrers roundly truncate lobes of male 9 th abdominal tergite.