Revision of the genus Ptomaphagus Hellwig from eastern Asia (Coleoptera, Leiodidae, Cholevinae)

Abstract The species belonging to the genus Ptomaphagus Hellwig, 1795 (Coleoptera, Leiodidae, Cholevinae, Ptomaphagini) from eastern Asia are assigned to three species groups. Group yasutoshii has a single species: P. (s. str.) yasutoshii Nishikawa, 1993 from Taiwan, China. Group nepalensis with three species: P. (s. str.) nepalensis Perreau, 1988 from Nepal and P. (s. str.) masumotoi Nishikawa, 2011 from Thailand are redescribed, and P. (s. str.) piccoloi Wang, Růžička, Nishikawa, Perreau & Hayashi, 2016 is recorded for the first time from China (Zhejiang). Group sibiricus with seven species, including two newly described Chinese ones P. (s. str.) funiu sp. n. from Henan, and P. (s. str.) haba sp. n. from Yunnan, and five known species: P. (s. str.) chenggongi Wang, Nishikawa, Perreau, Růžička & Hayashi, 2016, P. (s. str.) hayashii Wang, Růžička, Perreau, Nishikawa & Park, 2016, P. (s. str.) kuntzeni Sokolowski, 1957 (distribution records from Myanmar excluded), P. (s. str.) sibiricus Jeannel, 1934 and P. (s. str.) tingtingtae Wang, Nishikawa, Perreau, Růžička & Hayashi, 2016. Specimens of other undescribed species of the group sibiricus are also recorded, revealing a high diversity of this genus in eastern Asia, especially in central and north Sichuan, China, which essentially remains to be investigated. Relevant morphological characters of the examined species are illustrated with colour plates, and their known distributions are mapped. A key to species of Ptomaphagus from eastern Asia is provided.


Introduction
The genus Ptomaphagus belongs to the subtribe Ptomaphagina of the tribe Ptomaphagini (Leiodidae, Cholevinae) and was introduced by Hellwig (1795) based on a single species Tritoma sericea Fabricius, 1787 (= Silpha subvillosa Goeze, 1777) from Europe, which was fixed as the type species of the genus by monotypy. It is the most speciose genus (including 138 known species worldwide) in the tribe Ptomaphagini. However, the nominotypical subgenus, which is limited to the Palaearctic and north Oriental Regions has only 30 species (Perreau 2000, Nishikawa 2011, Wang et al. 2016a, 2016b, 2016c. Considering the fauna of China, only four representatives of the subgenus Ptomaphagus s. str. had been recorded from Taiwan Island, two of which were just recently described in a previous paper in this series (Wang et al. 2016b). For the vast mainland of China, there were no records of this genus before this study.
In this paper, two new species are described: Ptomaphagus (s. str.) funiu sp. n. from Henan Province, China and P. (s. str.) haba sp. n. from Yunnan Province, China. P. (s. str.) piccoloi Wang, Růžička, Nishikawa, Perreau & Hayashi, 2016 is recorded for the first time from China (Zhejiang Province). Several unidentified Ptomaphagus species from central and north Sichuan Province are discussed here also, without descriptions due to the limited number of available specimens. This reveals a high diversity in this region. Moreover, P. (s. str.) nepalensis Perreau, 1988 from Nepal and P. (s. str.) masumotoi Nishikawa, 2011 from Thailand are redescribed, and record of P. (s. str.) kuntzeni Sokolowski, 1957 from Myanmar is discounted. Relevant morphological characters of the examined species are illustrated with colour plates, and their known distributions are mapped. All species from eastern Asia are assigned to one of three species groups, and a key to all the investigated taxa is provided.

Materials and methods
Specimens were relaxed and softened in a hot saturated solution of potassium hydroxide for 4 minutes (for mounted dry specimens) or 8 minutes (for alcohol-preserved specimens), and then transferred to distilled water to rinse the residual potassium hydroxide off and stop any further bleaching. The softened specimens were moved into glycerine and dissected there to observe morphological details. After examination, the body parts were mounted on a glass coverslip with Euparal Mounting Medium for future studies. Habitus photographs were taken using a Canon macro photo lens MP-E 65mm on a Canon 550D. Observations, photographs, and measurements of morphological details were performed using an Olympus BX53 microscope with an Olympus DP73 camera. The final deep focus images were created with Zerene Stacker 1.04 stacking software. Adobe Photoshop CS6 was used for post-processing. Exact label data are cited, while authors' remarks and addenda are placed in square brackets; separate label lines are indicated by a slash (/), and separate labels are indicated by a double slash (//). Measurements are averages taken from 5 specimens. Habitus (Fig. 1A) elongated oval, regularly convex and sublustrous. Well pigmented: mostly blackish brown; mouthparts, basal three or four antennomeres and apical half of ultimate antennomere, protarsi, and apex of meso-and metatarsi more or less yellowish. Dorsum continually clothed with fine, recumbent, yellowish pubescence.  Insertions of pubescence on dorsal surfaces of pronotum, elytra and femora aligned along transverse striolations; interspace between two striolations glabrous.
Head transverse, HW/HL = 1.5. Clypeofrontal suture absent. Clypeus with anterior margin almost straight. Compound eyes well developed, EW/HW = 0.1. Antennae ( Fig. 2A) slender, AL/HW = 1.1; antennomere III shorter than II; VI with length/ width = 0.5; XI pear-shape. Pronotum ( Fig. 2B) transverse, widest just before hind angles, PW/PL = 1.5. Sides gently arched, gradually narrowing from posterior to anterior; hind angles slightly pro- Aedeagus (Fig. 3A) rather long and slender, with median lobe gradually narrowing towards a lanceolate apex and terminated to a widely subrounded knob in dorsal view; opening of genital orifice situated on dorsal surface, deeply cut inwards on preapical left margin of median lobe. Ventral surface of the apex of the median lobe (Fig. 3C) inserted with two ventrally oriented setae on the left side and three ventrally oriented setae on the right side; parameres narrow, reaching about apical 1/7 of median lobe, each apex ( Fig. 3D) with two long lateral setae and one shorter apical seta. In lateral view (Fig. 3B), median lobe slender, regularly bent ventrally, and gradually tapering to a round apex. Endophallus with stylus quite slender, a transverse nodule in middle region, a cheliform complex just below base of stylus, and a circular complex in the basal region.
Abdominal ventrite VIII (Fig. 4I) emarginate at posterior edge. Spiculum gastrale (Fig. 4J) of genital segment with about 1/5 of length protruding beyond anterior edge of epipleurite IX. Aedeagus (Fig. 5A) slender, with median lobe gradually narrowing towards an oblong apex and terminated to a shortly rounded knob in dorsal view; opening of genital orifice situated on dorsal surface, deeply cut inwards on preapical left margin of median lobe. Ventral surface of the apex of the median lobe (Fig. 5C) inserted with five ventrally oriented setae on the left side and six ventrally oriented setae on the right side; parameres narrow, reaching about apical 1/7 of median lobe, each apex ( Fig. 5D) with two long lateral setae and one similar apical seta. In lateral view (Fig. 5B), median lobe regularly bent ventrally but almost straight in apical half, and gradually tapering to a acuminate apex. Endophallus with stylus quite slender, a transverse nodule in middle region, a cheliform complex just below base of stylus, and a circular complex in the basal region.
Female. Similar to male in general appearance (Fig. 1D), including elytral apices (   7A) very short and stout, with median lobe gradually narrowing towards a widely lanceolate apex and terminated to a rounded knob in dorsal view. In lateral view (Fig. 7B), median lobe very thick, gently bent ventrally, and gradually tapering towards a thin apex.
Abdominal ventrite VIII (Fig. 6I) simply subrounded at posterior edge. Spiculum gastrale of genital segment (Fig. 6J) with about 1/3 of length protruding beyond anterior edge of epipleurite IX. Aedeagus (Fig. 7A) very short and stout, with median lobe gradually narrowing towards a widely lanceolate apex and terminated to a rounded knob in dorsal view; opening of genital orifice situated on dorsal surface, deeply cut inwards on preapical left margin of median lobe. Ventral surface of the apex of the median lobe (Fig.  7C) inserted with 5 ventrally oriented setae on the left side and 6 ventrally oriented setae on the right side; parameres narrow, reaching about apical 1/5 of median lobe, each apex (Fig. 7D) with 2 lateral setae and 1 similar apical seta. In lateral view (Fig.  7B), median lobe very thick, gently bent ventrally, and gradually tapering towards a thin apex. Endophallus with stylus quite slender, a subelliptical nodule in middle region, a cheliform complex just below base of stylus, and a circular complex in the basal region.
Female. Similar to male in general appearance (Fig. 1G), including elytral apices (Fig. 6H), but distinguished by the following characteristics: protarsi (Fig. 6D)   Abdominal ventrite VIII (Fig. 8I) distinctly emarginate at posterior edge. Spiculum gastrale of genital segment (Fig. 8J) with about 1/3 of length protruding beyond anterior edge of epipleurite IX. Aedeagus (Fig. 9A) long and slender, with median lobe gradually narrowing towards a lanceolate apex and terminated to an obtusely rounded knob in dorsal view (Fig. 9B); opening of genital orifice situated on dorsal surface, deeply cut inwards on preapical left margin of median lobe. Ventral surface of the apex of the median lobe (Fig. 9D) inserted with 6 ventrally oriented setae on both sides; parameres narrow, reaching about apical 1/5 of median lobe, each apex ( Fig. 9E) with 2 lateral setae and 1 shorter apical seta. In lateral view (Fig. 9C), median lobe slender, regularly bent ventrally but abruptly stronger in apical part, and gradually tapering towards a thin apex. Endophallus with stylus quite slender, a subelliptical nodule in middle region, a cheliform complex just below base of stylus, and a circular complex in the basal region.
Female. Similar to male in general appearance (Fig. 1I), including elytral apices (Fig. 8H), but distinguished by the following characteristics: protarsi (Fig. 8D) simply Etymology. The specific epithet is from the Chinese name (in Pinyin) of the type locality "Habashan", and means "flower of gold" in the Naxi language.

Other undescribed species of group sibiricus
Certain female specimens of Ptomaphagus from eastern Asia are possibly assigned to the right species group, but they cannot be identified at species level without the corresponding male individuals; this problem concerns especially females from the group sibiricus. The male aedeagus is the most crucial character for separating species.
The following Ptomaphagus species numbered as spp. 1, 2 and 3 have similar spermathecae, all curved in distal part and coiled in proximal part. Ptomaphagus spp. 4-8 with only one or two specimens respectively. What is surprising is the syntopic occurrence of four species (spp. 5-8) on a single mountain, Micang Shan (part of the Qinling Mountain Range), even at the same collecting point. For female specimens from the same region, their spermathecae are all curved in the distal part and coiled in the proximal part, similar to each other but with slight differences. Therefore, in consideration of limited specimens and the uncertainly of matching female and male specimens, we refrain from describing these species here and only provide illustrations of their aedeagi in Fig. 10, until such time as more specimens become available from this region. Remarks. Szymczakowski (1964) reported this female specimen as belonging to Ptomaphagus (s. str.) kuntzeni. However, Nishikawa (2011) and Wang et al. (2016a) disputed his identification. After dissecting it, we found that the spermatheca is curved in the distal part and coiled in the proximal part, but P. (s. str.) kuntzeni is so far the only species in the group sibiricus in which the spermatheca is not coiled in proximal part. Thus P. (s. str.) kuntzeni is excluded from the list of known fauna of Myanmar.