Description of a new leafhopper species of the genus Longicornus (Hemiptera, Cicadellidae, Deltocephalinae) from China, with a revised key to species

Abstract A new leafhopper species Longicornus brevispinussp. nov. is described and illustrated from Yunnan Province, China. A key to distinguish all species of this genus is given, and a map showing the geographic distribution of all species is also provided. The type specimen of the new species is deposited in the Institute of Entomology, Guizhou University, Guiyang, China.


Introduction
established the genus Longicornus with L. flavipuncatus Li & Song, 2008 as its type species from China. This genus belongs to the tribe Scaphoideini of the subfamily Deltocephalinae based on the head being narrower than the pronotum, the frontoclypeus long and narrow, antennae long, and the forewing with one or more darkly pigmented reflexed veins in the vicinity of the outer anteapical cell (Zahniser and Dietrich 2013). Recently, Fang and Xing (2018) reviewed this genus and added two new species: L. furcatus Fang & Xing and L. biprocessus Fang & Xing, and considered L. flavipuncatus Li & Song, 2008 as a senior synonym of L. yunnanensis Xing & Li, 2011. So far, this genus includes five species, all from China.
During a study of the Chinese Deltocephalinae, we discovered another new species L. brevispinus sp. nov. from Yunan Province, China, which is described here. A key is also given to separate all five species of the genus. The type specimen of the new species is deposited in the Institute of Entomology, Guizhou University, Guiyang, China (GUGC).

Material and methods
Male specimens were used for the description and illustration. External morphology was observed under a stereoscopic microscope and characters were measured with an ocular micrometer. Color photographs were taken and stacked using a Nikon SMZ25 microscope. The genital segments of the specimens examined were macerated in 10% NaOH washed in distilled water and stored in glycerol. Male genital structures were drawn from preparations in glycerin jelly using a Leica MZ 12.5 stereomicroscope. Illustrations were scanned with a Canon CanoScan LiDE 200 and imported into Adobe Photoshop CS8 for labeling and plate composition.
Terminology of morphological and genital characters mainly follows Li et al. (2011) and Fang and Xing (2018). Absolute measurements, in millimeters (mm), are used for the body.

Longicornus Li & Song
Longicornus Li & Song, 2008: 27;Li et al. 2011: 110;Zahniser and  Description. Body robust, yellowish brown (Figs 1-4). Vertex with paired irregular dark brown short coalescing bands. Eyes black, ocelli pale yellow. Face marked with dark brown. Pronotum with irregular fuscous patches. Forewing brownish, with scattered hyaline areas, veins dark brown. Legs dark brown. Head including eyes slightly narrower than pronotum. Vertex with fore margin produced roundly, median length distinctly shorter than width between eyes. Ocelli located on anterior margin of vertex. Frontoclypeus distinctly longer than wide, anteclypeus expanded apically. Antennae arising near lower corner of eye. Pronotum with anterior margin roundly produced and posterior margin concave, longer than vertex. Mesonotum triangular, slightly shorter than pronotum, with transverse su-* Modified from Fang and Xing 2018   ture depressed. Forewing with four apical and three subapical cells, about 3 times as long as wide, appendix wide. Hind wing with three apical cells and two anteapical cells. Fore femur row IC with a row of short setae, row AM with 1 stout seta, 2 dorsoapical setae, and row AV with several short setae in basal half. Fore tibia with 4 macrosetae in row AD and numerous macrosetae decreasing in length toward the base in row AV. Hind femur broadened distally and slightly bowed, apical setal formula 2 + 2 + 1. Hind tibia flattened and nearly straight, row PD with 12 macrosetae decreasing in length toward the base; row AD with 10 long stout setae and 1-4 shorter stout setae between each long seta; metabasitarsomere with 4 platellae and 2 setae on apical transverse row.
Male genitalia: Pygofer longer than broad in lateral view, with many long macrosetae in posterior half (Fig. 5). Valve subtriangular (Fig. 6). Subgenital plate with wide base, narrowed posteriorly, with 6 setae along lateral margin, and mesal margin deeply concave near apex (Fig. 7). Style relatively narrow, apical process acute, turned laterally (Fig. 11). Connective articulated with aedeagus, Y-shaped with stem long (Fig. 10). Aedeagus very short and stout with base broad in lateral view, gradually tapered to apex in lateral view, with a pair of short and robust apical processes with truncate apex, gonopore apical (Figs 8,9).

Remarks.
The new species can be distinguished by the very short and stout aedeagus with a pair of short and robust apical processes with a truncate apex.
Etymology. The species name is derived from the Latin word "brevis" and "spinus", referring to the short apical processes of the aedeagal shaft.

Discussion
Species of Longicornus are all very similar in coloration and difficult to distinguish externally, but the structure of aedeagus are markedly different. This genus now includes five species which can be divided into two types based on the structure of aedeagus: 1) aedeagus with one pair of apical processes (L. brevispinus sp. nov., L. flavipuncatus and L. longus); 2) aedeagus with paired basal processes (L. furcatus and L. biprocessus). Longicornus furcatus has one pair of furcate aedeagal processes arising from the ventral margin near the base and L. biprocessus has two pairs of aedeagal processes medially on the dorsal margin of the shaft.
All species of Longicornus are distributed in southwest China (Oriental Region) and the species without apical processes of the aedeagus are distributed in the north of the region (Fig. 12). So far, this genus has not been recorded in the Palaearctic Region of China but it is highly likely that undiscovered species may be found there.