Contribution to the genus Xanthocorus Miyatake (Coleoptera, Coccinellidae, Chilocorini)

Abstract The genus Xanthocorus Miyatake, 1970 consists of three species from China, including two new species described here: Xanthocorus nigrosuturalis sp. n. and Xanthocorus mucronatus sp. n. A key to identification of species is given. Diagnoses, detailed descriptions, illustrations, and distributions are provided.

The genus Xanthocorus was monotypic until recently. It was only recorded from China (Miyatake 1970;Pang and Mao 1979;Pang et al. 2004;Ren et al. 2009) and without any new species added in recent decades. In this paper two new species of Xanthocorus from China are described bringing to three, the number of known species in the genus. A diagnosis of the genus and a key to its known species are also given.

Material and methods
Specimens examined in this study were collected in China. Type specimens designated in the present paper are deposited at the Department of Entomology, South China Agriculture University (SCAU), Guangzhou, and the Institute of Zoology (IOZ), Chinese Academy of Science, Beijing.
External morphology was observed with a dissecting stereoscope (SteREO Discovery V20). The following measurements were made with an ocular micrometer: TLtotal length, length from apical margin of clypeus to apex of elytra; TW-total width, width across both elytra at widest part; TH-total height, from the highest part of the beetle to elytral outer margins; HW-head width in frontal view, head widest part; PLpronotal length from the middle of anterior margin to the base of pronotum; PW-pronotal width at widest part; EL-elytral length, from the apex to the base including the scutellum; EW-elytral width, equal in TW. Morphological terms of the Coccinellidae follow Ślipiński (2007) and Ślipiński and Tomaszewska (2010).
Male and female genitalia were dissected, cleared in 10% solution of NaOH by boiling for several minutes, and examined with an Olympus BX51 microscope. Photographs of the morphological characters of the genitalia were generated with digital cameras (AxioCam HRc and Coolsnap-Procf & CRI Micro*Color), attached to microscopes using AxioVision Rel. 4.8 and Image-Pro Plus 6.0 to capture images, and photographs were cleaned up and laid out in plates with Adobe Photoshop CS 8.0.
Body almost circular, moderately convex. Head yellow with black vertex in male, entirely black in female. Mouthparts and antennae brown, sparsely covered with short, greyish pubescence. Pronotum black, only anterior angles and anterior margin yellow. Scutellum black. Elytra yellow, only elytral bead black (Fig. 2a-c). Underside black except inner part of elytral epipleura yellow and abdominal ventrites brownish black, sparsely covered with short, greyish pubescence.
Male genitalia: penis slender, penis capsule with short outer and inner arms, apex of penis bifurcate with membranous appendage (Fig. 2e-f). Tegmen stout with penis guide slightly asymmetrical in ventral view and widest at base with sides parallel from base to 1/2 length, then gradually converging to blunt apex in lateral view. Parameres stout, distinctly longer than penis guide, densely covered with long setae at inner surfaces and apices with group of long setae in lateral view ( Fig. 2g-h).
Remarks. The Chinese specimens of this species studied were identical with the illustrations and descriptions of adult and male genitalia given by Miyatake (1970). Diagnosis. This species resembles Xanthocorus nigromarginatus, but can be distinguished from it by having slightly elongate body; black pronotum with only anterior  (Miyatake, 1970). a antenna b mandible c labium d maxilla e prosternum f meso-and metaventrite g metendosternite h front leg i hind leg j tarsal claws. Scale bars: 0.1 mm. angles yellow; elytra yellow with black elytral lateral margin, anterior margin and suture (Fig. 3a-c); slender parameres (Fig. 3g). In X. nigromarginatus, body almost circular, pronotum black except anterior angles and anterior margin yellow; elytra yellow, only elytral lateral margin black (Fig. 2a-c); parameres stout (Fig. 2g).
Body broadly oval, moderately convex. Head and mouthparts black. Antenna brownish yellow, sparsely covered with short, greyish pubescence. Pronotum black with anterior angles yellow. Scutellum black. Elytra yellow with black elytral bead, anterior margin and suture (Fig. 3a-c). Underside black except inner margins of elytral epipleura yellow. Abdominal ventrites brown, sparsely covered with short, greyish pubescence.
Male genitalia: penis slender, penis capsule with short outer and inner arms. Apex of penis bifurcate with membranous appendage (Fig. 3e-f). Tegmen stout with penis guide distinctly asymmetrical in ventral view and with sides parallel from base to 2/3 length, then abruptly converging to blunt apex in lateral view. Parameres slender, strongly constricted at base, expanded toward apex, distinctly longer than penis guide, densely covered with long setae at inner surfaces and apices with group of long setae in lateral view (Fig. 3g-h).
Male genitalia: penis slender, penis capsule with short outer and inner arms. Apex of penis strongly narrow with membranous appendage (Fig. 4e-f). Tegmen stout with penis guide with parallel sided from base to 1/2 length, then gradually converging to blunt apex in ventral view; in lateral view, penis guide widest at base, gradually constricted to apex. Parameres strongly constricted at base and expanded toward apex, longer than penis guide, densely covered with long setae at the inner sides and distal end with a group of long setae in lateral view (Fig. 4g-h).
Distribution. China (Yunnan) (Fig. 5). Etymology. The species name is derived from Latin and refers to the pointed apex of penis.