A review of the genus Sinocentrus Yuan (Hemiptera, Membracidae, Centrotinae) with description of a new species from China

Abstract A new species of the treehopper genus Sinocentrus Yuan, S. brevicornis Li & Chen, sp. nov. from China, is described and illustrated. A checklist and key to species of the Sinocentrus are provided.


Introduction
The treehopper genus Sinocentrus was established by Yuan (Yuan and Chou 2002) with only its type species, S. sinensis Yuan, 2002, known from one female specimen. The genus was originally placed in the tribe Leptocentrini by Yuan and Chou (2002), but Wallace and Deitz (2004) moved Sinocentrus to incertae sedis, because specimens were not examined in their study and the morphological characteristics were confounding.
Herein, a new species, Sinocentrus brevicornis Li & Chen, sp. nov. from China, is described and illustrated. As a result of this act, the genus Sinocentrus now contains two species. A key based on morphological characteristics to distinguish species is provided as well as a map of their geographic distributions.

Materials and methods
General morphological terminology follows Deitz (1975) and Dietrich et al. (2001) except morphology of the female genitalia, which follows Mejdalani (1998). Dry male specimens were used for the descriptions and illustrations. External morphology was observed under a stereoscopic microscope and characters were measured with an ocular micrometer. Measurements are given in millimeters; body length was measured from the apex of the head to the apex of the forewing in repose. Habitus photographs were taken using a NIKON SMZ 25 digital camera and multiple layers were stacked using Helicon Focus 6. The genital segments of the specimens examined were macerated in 10% NaOH and drawn from preparations in glycerin jelly using a Leica MZ 12.5 stereomicroscope. The photographs and the illustrations were imported into Adobe Photoshop CS5 for plate composition and labeling.
The type specimens examined are deposited in the Institute of Entomology, Guizhou University, Guiyang, Guizhou Province, China.
Remarks. This genus can be distinguished from other oriental Centrotinae genera by the following characters: pronotum highly developed, strongly inflated with anterior part evenly rounded, glabrous with minute punctures and no obvious pubescence, suprahumeral horns extended laterad, posterior pronotal process elevated far above scutellum, scutellum emarginate.

Checklist and distributions of species of
Coloration. General color black with scattered yellow setae. Eyes pale brown with yellow border in males, pale yellow with black markings in females (Figs 5, 6), ocelli yellow hyaline. Basal one-third of scutellum dark brown, covered with yellowish-white setae, preapical region yellowish-brown with apical white. Forewing pale yellow hyaline, one-fifth of basal, veins and apical limbus black. Hindwing veins pale brown. Thorax black with pale yellowish pubescence; coxae black with yellow pubescence; trochanter, femur, tibia and tarsus yellowish-brown and tarsal claw dark brown. Abdomen reddish-brown with yellow pubescence, basal part of abdomen with a yellow spot of pubescence, apices of terga and sterna pale yellowish.
Head and thorax. Head in anterior view wider than long, ratio: 2.11:1. Vertex with dorsal and ventral margins slightly arcuated and wave-shaped respectively, with wrinkles on surface and a weak median longitudinal carina. Eyes and ocelli oval, ocelli slightly closer to inner margins of eyes less than to each other. Frontoclypeus distinct and trilobed, margin with sparse setae, apices of lateral and median lobes on same plane, more than half of median lobe extending beyond towards ventral margin of vertex, and apex dorsally slightly upturned. Apex of metopidium convex in anterior view. Posterior pronotal process ending at more than half of forewing cell M 3+4 (last apical cell). Humeral angles triangular with apices somewhat blunt. Suprahumeral horns short, width between horns apices nearly half length of body. Scutellum humped basally, large punctures present, longer than wide, apex extended antero-dorsally male, curved ventrally in female (Figs 2, 4), posterior margin deeply emarginate. Mesotho-  racic femur without ablateral and adlateral cucullate setae. Metathoracic leg cucullate setae row II irregular.

Female genitalia.
Sternite VII (Fig. 20) in ventral view with posterior margin concave, lateral margins convex and surface with setae. Pygofer (Figs 18,19) in lateral view irregularly quadrilateral, with setae; in ventral view oblong, base slightly acute. Anal tube (Figs 18, 19) small and oval. Valvifer I (Fig. 21) semicircular and thin; valvulae I knife-shaped, apical three-fourths of dorsal surface sculptured, ventral surface of the apex with a row of small toothed processes. Valvifer II (Fig. 23) shoe-shaped in lateral view, dorsal margin membranous. Basal part of valvulae II (Fig. 22) connected to the apex of "sole", ramus slender, parallel-sided and evenly curved in basal two-thirds, apex slightly broadened with two indistinct and widely spaced dorsal preapical tooth processes; the one-third of apical broaden slightly. Gonoplac (Fig. 23) connected to base of "sole", apical third expanded, ventral margin with setae.
Head and thorax. Head wider than long. Vertex with dorsal margin arched and ventral margin oblique. Eyes oval. Ocelli hyaline, slightly closer to the inner margin of eyes less than to each other. Frontoclypeus distinct and trilobed, the apex of lateral lobes and the median lobes on the same plane, two-thirds of median lobe extending beyond towards ventral margin of vertex. Pronotum with dense setae and punctures. Humeral angles large, apices blunt. Suprahumeral horns leaflike pyramidal, horizontally extended laterally, width between suprahumeral horns apices nearly as long as body length . Nearly median part of the posterior pronotal process concave and touching forewing, apical upward, with four carinas. Scutellum short, wider greater than length, posterior margin round emarginate. Forewing with opaque sclerotization  at basal one-eighth, Venation similar to that of S. brevicornis. Metathoracic trochanter without spines and tibia with 3 rows of cucullate setae.
Male. Unknown. Distribution. China (Yunnan). Note. While holotype was not examined, an online image of the holotype (Fig. 28) and detailed Chinese description were available.

Discussion
In their phylogeny and genus-level revision of Centrotinae, Wallace and Deitz (2004) were unable to examine specimens of Sinocentrus and treated the genus as Centrotinae, incertae sedis.
We provide the following additional details on Sinocentrus: (1) frontoclypeus distinct (indistinct in Centrotypini); (2) posterior pronotal process elevated far above the scutellum, entirely exposed (straight at base, partially covers the scutellum in Centrotypini); (3) male lateral plate with short dorsoapical lobe extending dorsally, style clasp angled ventrally; style shank with arch at central section (angled dorsally; style shank with significant arch medially in Centrotypini); (4) mesothoracic femur without ablateral and adlateral cucullate setae; metathoracic leg cucullate setae row II irregular. Although the above characteristics can suggest that the genus is related to Leptocentrini, the shape of the female second valvulae closely align S. brevicornis with the tribe Centrotypini. Given these mixed affinities, we follow Wallace and Deitz, in treating Sinocentrus as Centrotinae, incertae sedis. Proper tribal placement may be affirmed by future phylogenetic analyses of combined morphological and molecular data.