﻿A review of the sinica species group within the genus Lilioceris (Coleoptera, Chrysomelidae, Criocerinae)

﻿Abstract A new species group of the genus Lilioceris Reitter, 1913 is proposed and reviewed, the sinica group. It includes six species: L.gressitti Medvedev, 1958; L.rugata (Baly, 1865); L.sieversi (Heyden, 1887); L.sinica (Heyden, 1887); L.theana (Reitter, 1898) stat. nov.; and L.thibetana (Pic, 1916). Among them, L.theana is resurrected as a valid species from synonymy with L.rugata, and is newly reported from China. Redescriptions, an identification key, figures of habitus and male and female genitalia, geographic distributions, host plants, and habitats (if known) are provided for these species.


Introduction
Lilioceris Reitter, 1913 is the second largest genus of Criocerinae, includes approximately 150 species to date (Monrós 1960;Heinze and Pinsdorf 1962;Gressitt 1965;Warchałowski 2011;Bezděk and Schmitt 2017). The genus is widely distributed in tropical and subtropical parts of the world, with the highest species diversity in the Oriental Region. Species of Lilioceris are characterized by a more or less elongate body shape, of medium or small size (5-12 mm); the thorax is subcylindrical or subquadrate, without lateral margins, and the lateral sides constricted in middle; the tibiae has two spurs. Species of Lilioceris usually live in margins of forest or farmland habitats, and all life stages are associated with the host plant. Most of their host plants are from the families Smilacaceae, Dioscoreaceae, and Liliaceae (Jolivet 1988;Schmitt 1988), and a few Lilioceris species are economically important. Lilioceris is unquestionably monophyletic group within Criocerinae as shown by recent phylogenetic studies (Schmitt 1985;Matsumura et al. 2014). There are many taxonomic works focusing on regional species of the genus (e.g., Jacoby 1904Jacoby , 1908Gressitt and Kimoto 1961;Heinze and Pinsdorf 1962, 1963, 1964Kimoto and Gressitt 1979;Tishechkin et al. 2011;Warchałowski 2011;Xu et al. 2021), but still many species are difficult to identify based on existing keys, and therefore more revisionary work is needed. Tishechkin et al. (2011) proposed the impressa species group in the genus based on adults with a glabrous scutellum, flattened and short antennomeres 6-10 (wider than long), and strongly punctate elytral striae. Recently, when examining specimens of Lilioceris in the National Zoological Museum, Chinese Academy of Sciences, we found that some species were similar to members of the impressa species group, but differed in having cylindrical and longer antennomeres 6-10 (longer than wide). These species include L. gressitti Medvedev, 1958, L. rugata (Baly, 1865), L. sieversi (Heyden, 1887), L. sinica (Heyden, 1887), and L. theana (Reitter, 1898). We also found L. thibetana (Pic, 1916) to be very similar to L. gressitti Medvedev, and is not a member of the impressa group.
The primary purpose of this paper is to propose the Lilioceris sinica species group, and properly document the species included in this new group.

Materials and methods
The specimens from several museums and collections were examined. Collections cited in this article are indicated by the following abbreviations: Genitalia were soaked in warm 10% KOH for 1 h, and dyed in Chlorazol Black E. The basal orifice of the aedeagus was injected with 100% ethanol with a micro-injector until the internal sac was fully everted. The aedeagus with its everted internal sac was photographed using a large depth-of-field 3D digital microscope (Keyence VHX-1000C), and finally edited in Photoshop. A microvial with genitalia was pinned to the specimen from which the genitalia were removed for storage.
Body length (BL) was measured from the anterior margin of the labrum to the apex of the elytra; body width (BW) was measured along the greatest elytral width (EW); head length (HL) was measured along the anterior margin of the labrum to the posterior margin of tumid gena; head width (HW) was measured along the widest part of the head including eyes; pronotum length (PL) was measured along the median line of the pronotum; pronotum width (PW) was measured across the widest part of the pronotum; elytra length (EL) was measured along the suture from the base of the scutellum to the elytral apex.

Taxonomy of the Lilioceris sinica species group
Diagnosis. Small size, length less than 9.5 mm. Head, antennae, and ventral surface black, legs black or with femora bicolored; pronotum yellow, brown, or dark brown, without metallic luster; elytra unicolored, red, brown, black, or blue, without bands or patches, without metallic luster. Antennae short, nearly 1/3 as long as body length, antennomeres 5-10 cylindrical, longer than wide, densely pubescent and punctate. Pronotum disc with punctures distinct, scattered, not aligned into rows in the middle. Scutellum lingulate, glabrous, at most pubescent along basolateral margins. Elytra with ten rows of completely punctate striae, punctures large, present at apex; intervals flat or convex at apex, without punctures. Mesosternal process short, perpendicularly connected with metasternite. Male genitalia with tegmen Y-shaped and slender, combined with second connecting membrane. Internal sac membranous, with dorsal, median, and ventral sclerites moderately sclerotized. Female genitalia with tergites 8 and 9 and sternites 8 and 9 sclerotized, posterior areas of tergite 8 and sternite 8 with dense setae, without apodemes.
Species of the Lilioceris sinica group are similar to those of Lilioceris impressa group in having glabrous scutellum, completely punctate elytral striae, and three moderately sclerotized sclerites in aedeagus. However, the most significant difference between the two groups is that antennomeres 6-10 are distinctly flattened and quadrate or even transverse  in the impressa group (Tishechkin et al. 2011), while obviously cylindrical  in the sinica group. Generally, body size in the impressa group (length 7.5-11.8 mm; mean 9.18 ± 0.20) is greater than that in the sinica group (length 6.0-9.0 mm; mean 7.13 ± 0.22).
We recognize six species belonging to sinica group based on examination of the type specimens and / or descriptions. As to the African Lilioceris treated by Heinze and Pinsdorf (1962), several species with a pronotum irregularly punctate, the elytra unicolored and strongly punctate, and the antennomeres 6-10 slightly longer than wide, probably fall into this group (e.g., L. cafra (Lacordaire, 1845), L. consobrina (Clark, 1866), L. latipennis (Clark, 1866), L. lumbwensis (Weise, 1926) L. puncticollis (Lacordaire, 1845), and L livida (Dalman, 1823)). These species will be treated when types are available to us in the future. Known host plants of the group are Dioscorea spp. (Dioscoreaceae).
Abdominal sternites with a row of pubescence, interrupted in the middle; lateral transverse impressions present on sternites 2-5, area outside the impression densely pubescent (Fig. 12C).
Legs slender; tibiae with dense punctures and pubescence; femora with dense pubescence on dorsal surface, with sparse pubescence on ventral surface.
Distribution. China (Yunnan, Sichuan, Guizhou). Remarks. Medvedev (1958) indicated that L. gressitti was similar to L. rugata (Baly, 1865), especially to L. rugata sparsipunctata Medvedev, 1958 (synonymized with L. sinica by Gressitt and Kimoto 1961), but differed by the smaller and narrower body, finer punctures on the pronotum, and less strong punctures on the elytra. In addition, it differs from L. sinica in the abdominal sternites having less pubescence. ( Diagnosis. Femora black; pronotum disc with large punctures; elytral punctures strong and not diminishing posteriorly, intervals convex apically; lateral side of metasternite nearly glabrous, without strip of pubescence; abdominal sternites smooth.
Abdominal sternites nearly smooth (Fig. 13C). Legs slender; tibiae with dense punctures and pubescence; femora with dense pubescence on the dorsal surface, with sparse pubescence on the ventral surface. Female reproductive organs ( Fig. 25A-C). Spiculum gastrale short, X-shaped, distal part strongly widened, apical margin straight; ovipositor with dense setae, distal part of ovipositor cylindrical and short, with a small protuberance; spermatheca small and greatly convoluted.
Host plant and habitat. This species feeds on Dioscorea japonica and D. tokoro (Kimoto, 1964). The habitat is unknown.
Distribution. Japan. Remarks. This species is similar to L. sinica, but differs from the latter by having its pronotal disc with strong and deep punctures, metasternite and abdominal sternites nearly smooth (in L. sinica, pronotal disc with fine and shallow punctures, lateral side of metasternite with a wide strip of pubescence, and abdominal sternites densely pubescent except the glabrous abdominal transverse impressions). In addition, the genitalia of L. rugata differ from those of L. sinica by posterior part of dorsal sclerite in dorsal view widely rounded, directed laterally (in L. sinica, posterior part of dorsal sclerite in dorsal view slightly narrowed at apex, more or less parallel-sided).  synonymized L. sinica with L. rugata, which is not justified in the light of the present study.
Lilioceris rugata is widely distributed in Japan, obviously isolated geographically from other species in China, Russian and Korea. The records of this species from Russia and Korea are questionable. We found some photographs identified as L. rugata on websites from Russia (https://www.zin.ru/animalia/coleoptera/eng/lilrugkm.htm) and Korea (https://blog.naver.com/onegunah/110021296278) that are actually L. theana. Cho and An (2020) recorded nine specimens of L. rugata collected from South Korea. They are probably also L. theana (see Cho and An 2020: 7, fig. 13). The materials of L. rugata from Russia and Korea need more study. ( Diagnosis. Pronotum brownish red, elytra black or dark blue, femora black; pronotum disc with fine punctures; elytral punctures large on basal half, diminishing posteriorly; metasternite almost glabrous; abdominal sternites have a row pubescence and the rest of area nearly smooth, transverse impressions present on sternites 2-5, area outside the impression with sparse pubescence.
Abdominal sternites with a distinct row of pubescence, sparse in the middle; lateral transverse impressions present on sternites 2-5, area outside the impression sparsely pubescent (Fig. 14C).
Legs slender; tibiae with dense punctures and pubescence; femora with dense pubescence on the dorsal surface, with sparse pubescence on the ventral surface.
Host plant and habitat. This species feeds on Dioscorea nipponica and D. polystachya in Beijing according to our observations; in addition, D. septemioba, D. batatas, and D. japonica are also its hosts (Park et al. 2012).
Legs slender; tibiae with dense punctures pubescence; femora with dense pubescence on the dorsal surface, with sparse pubescence on the ventral surface.
Host plant and habitat. (Figs 47-50) This species feeds on Dioscorea polystachya according to our field observation in Beijing (Fig. 49).
Legs slender; tibiae with dense punctures and pubescence; femora with dense pubescence on dorsal surface, with sparse pubescence on ventral surface.

Remarks.
In original labels, the type locality is 'Thibet, Trianatang'. There are at least three villages with similar pronunciation to Trianatang, first village 'Qiunatong' is in Gongshan county, northwestern Yunnan (28.09655°N, 98.57368°E, 1816 m), very close to Tibet; the second village 'Qunatang' is in Zayü county, Tibet (28.33884°N, 98.58602°E, 2460 m), and the third village 'Qunatang' is in Mêdog county, Tibet (29.46423°N, 95.74406°E, 2084 m). They are not far from each other, and all are possibilities to be the type locality of 'Trianatang'.
Lilioceris thibetana was formerly placed in the impressa group (Tishechkin et al. 2011), probably due to its similarity with Lilioceris malabarica as stated in original description by Pic (1916). In the holotype, the antennae are missing, so it is difficult to determine whether it belongs to the impressa group or the sinica group based on the antennae. Fortunately, we have three specimens from Yunnan which fit well with  the type in body size, body color, punctures on pronotum and elytra, pubescence on metasternites and abdominal sternites, and in the shape of the aedeagus (compared with the illustration of Tishechkin et al. 2011: fig. 29). However, their antennomeres 5-10 are all cylindrical so we moved L. thibetana into the sinica group.
This species is similar to Lilioceris gressitti, but differs by having the metaventral disc nearly smooth (in L. gressitti, the metaventral disc has a narrow pubescent strip).  Furthermore, in L. thibetana, the spiculum gastrale is Y-shaped, slightly wider in the distal part, and the apical margin is rounded, while in L. gressitti, the spiculum gastrale is X-shaped, strongly widened in the distal part, and the apical margin is straight.