Two new species of Chilocorus Leach, 1815 from Laos (Coleoptera Coccinellidae Chilocorini)

Abstract Background Chilocorus Leach, 1815 the largest genus of Chilocorini, contains more than 80 species, mainly preying on Coccoidea. Many species of Chilocorus are economically important as they are widely used as biological control agents. New information In this study, two new species of the genus Chilocorus Leach are described from Laos: C.toulakhomianus Li & Wang, sp. n. and C.vientianicus Li & Wang, sp. n. Diagnoses and detailed descriptions of the new species are given. Each species is illustrated in detail, including genitalia. Distribution maps are presented.


Introduction
Chilocorus Leach, 1815 the largest genus of Chilocorini, contains 81 species in the recent world checklist (Li et al. 2018). However, morphological characters of the genus Chilocorus are relatively heterogeneous at species level. Chapin (1965) considered Chilocorus as a non-monophyletic genus. Miyatake (1970), who studied East-Asian species, subdivided Chilocorus into seven groups depending on the characters of the pronotal oblique line, prosternal process, prosternal hypomeral foveae, elytral epipleural foveae and elytral outer margin. Recently, the molecular and morphology-based phylogenetics of Chilocorini indicated Chilocorus as not a monophyletic group. Four other genera ( Phaenochilus Weise, Anisorcus Crotch, Egius Mulsant and Simmondsius Ahmad & Ghani) were recovered as embedded in the clade of Chilocorus; meanwhile, these four genera were synonymised with Chilocorus (Li et al. 2020b).
Untill now, there is scarce literature to investigate and research Coccinellidae species in Laos. Prior to the prsent study, except for C. politus Mulsant, 1850 (Li et al. 2018), no other Chilocorini species was recorded in this country. This paper adds two new species to the world fauna of this genus from Laos. These two new species are extremely similar to C. politus in body shape and colouration.

Materials and methods
Specimens, examined in this study, were collected in Laos. Type specimens of the new species are deposited at the Department of Entomology, South China Agriculture University (SCAU), Guangzhou.
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
The genus Chilocorus can be distinguished from the other genera of the tribe Chilocorini by the following combination of characters: body with dorsum glabrous, rarely with pubescence; outer elytral margin slightly reflexed, without distinct bead; antenna stout, composed of 7 or 8 antennomeres (Fig. 1e); terminal maxillary palpomere elongate, from 1 to 2 times as long as basal width, with sides nearly parallel or moderately expanded to apex (Fig. 1f); prosternal process long, narrow and subparallel without carina (Fig. 1d); legs with stout femora, tibiae with a triangular tooth at basal 1/3, without tibial spurs ( Fig. 1i-j); tarsal claws stout, with approximately rectangular basal tooth, about 1/2-2/3 as long as claw (Fig. 1k).
Male genitalia: penis slender, penis capsule with long outer and short inner arm, with spiral texture from apical 1/5 to apical 1/3, apex of penis truncate with membranous appendage (Fig. 1m-n). Tegmen stout, penis guide slightly narrow at base, gradually broadened up to basal 1/2, abruptly tapering from apical 1/4 to apex, slightly asymmetrical in ventral view; penis guide in lateral view, widest at base, 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. 1  o-p).

Diagnosis
This species is very similar to C. politus and species C. vientianicus, sp. n. in the body size and colouration, but can be distinguished from them by penis with spiral texture from apical 1/5 to apical 1/3; penis guide widest at base, gradually converging to apex in lateral view. Furthermore, this species also can be distinguished from C. vientianicus, sp. n. by coxites with straight outer and inner margins. In C. vientianicus, sp. n., coxites outer margin is almost straight, but inner margin is distinctly concave near apical 1/3.

Etymology
The specific epithet is named after Toulakhom, the type specimen collector of this ladybird.
Male genitalia: penis slender, penis capsule with long outer and short inner arm, apex of penis truncate with membranous appendage (Fig. 2e-f). Tegmen stout, penis guide narrow at base, guide slightly narrow at base, gradually broadened up to basal 1/2, abruptly tapering from apical 1/4 to apex, approximately symmetrical in ventral view; penis guide in lateral view widest at base, parallel along basal 5/8, after that abruptly 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. 2g-h).

Diagnosis
This species resembles C. toulakhomianus, sp. n. in the body size and colouration, but can be distinguished by the following characters: apex of penis truncate with membranous appendage, without spiral grain; penis guide widest at base, parallel along basal 5/8, after that abruptly converging to apex in lateral view; coxites elongate outer margin almost straight, inner margin distinctly concave near apical 1/3.

Etymology
The specific epithet is named after Vientiane, the type locality of this ladybird.

Discussion
The species deversity of Chilocorini have been investigated in detail in many countries of East and Southeast Asia, such as China, Japan, Vietnam etc (Kamiya 1959;Miyatake 1970;Hoáng 1983;Li et al. 2020a). However, Chilocorini and even Coccinellidae in Laos are poorly taxonomically studied. In this paper, we describe two new species adding them to the world fauna of Chilocorus from Laos. As the largest genus of Chilocorini, the morphological characters of Chilocorus are relatively heterogeneous at species level. Compared with Asian fauna species, these two new species and their similar species C. politus can be easily distinguished by the following two characters: dorsum brownish-red without any spots; terminal maxillary palpomere moderately expanded to apex, the length nearly equal to the width.