New records and checklist of Chilocorini (Coleoptera: Coccinellidae) from China

Abstract Background China is one of the countries with the greatest species diversity of Chilocorini (Coleoptera: Coccinellidae), including nearly forty-five percent of the known genera and fourteen percent of all described species in this tribe. Recently, we discovered three species previously not recorded in China. New information In this study, three species Priscibrumus uropygialis (Mulsant, 1853), Priscibrumus disjunctus Canepari, 1997 and Brumus octosignatus (Gebler, 1830) are documented for the first time in China. Brumus octosignatus is the first member of the genus Brumus Mulsant, 1850 recorded in China. Detailed descriptions, illustrations and distributions of these three species are provided. A checklist of Chinese Chilocorini is also given.


Introduction
The members of family Coccinellidae, commonly known as colourful and shiny beetles, predators of plant pests, contain 6000 species distributed worldwide (Vandenberg 2002). The tribe Chilocorini is well-known as a primary predator of coccids. Many species of this tribe are widely used as biological control agents. In recent years, phylogenetic and evolutionary studies of Chilocorini indicated that this tribe is a monophyletic group, closely related to the tribe Coccinellini (Magro et al. 2010, Seago et al. 2011, Escalona et al. 2017, Che et al. 2017 or Plotinini (Li et al. 2020). At present, Chilocorini contains 22 genera and more than 280 species distributed worldwide (Łączyński and Tomaszewska 2012, Li et al. 2020).
China is one of the countries with the greatest species of Chilocorini (Coleoptera: Coccinellidae), including 10 genera and 39 species (Li et al. 2017a). However, in Li et al. (2017a), the genus Brumus Mulsant was incorrectly recorded in the Chinese checklist of Chilocorini (no literature existed to indicate that the members of this genus were distributed in China). After a phylogenetic study of the Chilocorini, the genus Phaenochilus Weise was synonymised with Chilocorus Leach (Li et al. 2020).
In this study, we report for the first time in China the genus Brumus with the species Brumus octosignatus (Gebler, 1830), as well as the species Priscibrumus uropygialis (Mulsant, 1853) and Priscibrumus disjunctus Canepari, 1997. A revised checklist of Chinese Chilocorini is also provided, containing all nine genera and 42 species.

Materials and methods
Specimens, examined in this study, were collected in China (Tibet and Xinjiang) and deposited at the Department of Entomology, South China Agriculture University (SCAU), Guangzhou.
The newly-collected specimens of Priscibrumus disjunctus were identified based on the original species description (Canepari 1997). The specimens of the other two new Chinese records i.e. Priscibrumus uropygialis and Brumus octosignatus, were identified from the secondary descriptions and illustrations by Miyatake (1985) and Kovář (1997), respectively.
External morphology was observed with a dissecting stereomicroscope (SteREO Discovery V20, Zeiss). Male and female genitalia were dissected, cleared in 10% solution of sodium hydroxide (NaOH) by boiling for several minutes and examined with an Olympus BX51 microscope. Photographs of the genitalia and other morphological characters were taken with digital cameras (AxioCam HRc and Coolsnap-Procf & CRI Micro*Color), attached to microscopes using AxioVision Rel. ver. 4.8 and Image-Pro Plus ver. 6.0. Images were cleaned up and laid out in plates with Adobe Photoshop CS ver. 8.0. Terminology follows Ślipiński (2007).
Abbreviations TL = total length: length from apical margin of clypeus to apex of elytra TW = total width: width across both elytra at widest part TH = body height measured across the highest point of the elytra HW = head width in a frontal view PL = pronotal length: from middle of anterior margin to base of pronotum PW = pronotal width at widest part EL = elytral length: from apex to base including scutellum EW = elytral width, equal to TW

Diagnosis
Priscibrumus can be distinguished from other genera of the tribe Chilocorini by the following combination of characters: body densely covered with short, greyish pubescence; antenna composed of 10 antennomeres, with terminal antennomere very small and embedded in the penultimate antennomere; pronotal basal margin entirely bordered with submarginal line; base of pronotum and elytra contiguous all along their length; elytral epipleura narrow, more or less horizontal and without foveae; abdominal postcoxal lines almost complete; mid and hind tibiae with two apical spurs. Body oval, moderately convex. Head black, densely covered with short, greyish pubescence. Mouthparts and antenna black. Pronotum black, densely covered with short, greyish pubescence. Scutellum black. Elytra reddish-brown, with two pairs of broadly black stripes: outer stripes approximately 2/5 width of elytra, 3/4 length of elytra; inner stripes situated on suture, almost as long as elytra, distinctly broadening at base and weakly broadening at apex, densely covered with extremely short, greyish pubescence ( Fig. 1a-c). Underside black except elytral epipleura brownish-yellow, densely covered with short, greyish pubescence. Abdominal postcoxal lines incomplete, arcuate. Posterior margin of male abdominal ventrite 5 slightly emarginate at middle and of ventrite 6 distinctly emarginate (Fig. 1d).

Priscibrumus disjunctus
Male genitalia: penis slender, penis capsule with short outer and inner arm, apex of penis truncate with membranous appendage (Fig. 1e-f). Tegmen stout, penis guide narrow at base, parallel along basal 1/3, after that, gradually broadening to basal 2/3, then narrowing to apex in ventral view; penis guide in lateral view, widest near base, gradually narrowing to apex; parameres distinctly longer than penis guide with dense short setae on the inner sides and distal end with a group of short setae in lateral view ( Fig. 1g-h).

Diagnosis
This species can be distinguished from other species of Priscibrumus by the following combination of characters: elytra reddish-brown, with two pair of broadly black stripes, inner stripes situated on suture, almost as long as elytra; parameres distinctly longer than penis guide.
Male genitalia: penis slender, penis capsule with short outer arm and long inner arm, apex of penis truncate with membranous appendage (Fig. 2e-f). Tegmen stout, penis guide parallel along 2/3 length, then gradually narrowing to apex in ventral view; penis guide in lateral view, widest at base, parallel along 2/5 length, then gradually narrowing to apex; parameres as long as penis guide with dense long setae on the inner sides and distal end with a group of long setae in lateral view (Fig. 2g-h).

Diagnosis
This species can be easily distinguished from other species of Priscibrumus by the following combination of characters: elytra reddish-brown, with a pair of black spots at elytral apex; parameres as long as penis guide.
Male genitalia: penis slender, penis capsule with short outer and long inner arm, apex of penis acute with membranous appendage (Fig. 3e-f). Tegmen stout, penis guide narrow at base, widest at basal 1/2, then gradually converging to blunt tip, symmetrical in ventral view; penis guide in lateral view, widest at base, parallel along basal 1/3, after that gradually converging to apex; parameres nearly as long as the penis guide with dense short setae on the inner sides and distal end with a group of short setae in lateral view (Fig. 3g-h).

Diagnosis
This species can be easily distinguished from other species of Brumus by the following combination of characters: pronotum with a black spot at central of basal margin; elytra orange-yellow, with four pairs of black spots; parameres nearly as long as the penis guide.  Barovskij 1927, Mader 1955, Bielawski 1975, Bielawski 1984, Kovář 1997 and Xinjiang, China (present study) (Fig. 4).

Discussion
The genus Priscibrumus was erected by Kovář (1997), when he revised Exochomus and Brumus Mulsant, 1850 from the Palearctic Region. This revision was a huge contribution to our understanding of the relationships between Exochomus and its closely-related genera. Until now, Priscibrumus only contained seven species which mainly occur in the Pamir Mountains, especially in the western part of the Himalaya Mountains (Kovář 1997, Poorani 2002. Priscibrumus himalayensis (Kapur) was the first member of this genus recorded in China (Tibet) by Hu et al. (2013).
Brumus was considered a junior synonym of Exochomus by Ślipiński and Giorgi (2006). Subsequently, Kovář (2007) (Li et al. 2020). Actually, Brumus can be easily distinguished from Exochomus by the following characters: elytral epipleuron more or less horizontal; tarsal claws without basal tooth, only slightly swollen at base. In Exochomus, the outer part of elytral epipleuron is distinctly descending; and the tarsal claws have a large triangular tooth at the base.