Species of Bolbelasmus are small to medium-sized (5.6–15.2 mm in body length) and can be recognized by the glossy, unicolored, reddish-brown to black dorsal surface; presence of a conical frontal tubercle with a rounded or bifurcated tip in males; transverse frontal carina present in females; eyes protruding, divided by a canthus anteriorly, canthus with anterior margin smooth; antennal club with first segment glabrous on inner side; pronotum usually quadrituberculate in major males (vestigial or reduced to bituberculate in minor males), females with transverse carina only; first elytral stria terminated by scutellum; parameres usually weakly sclerotized.

Holotype male. “China: Yunnan, Bangdashan (邦達山), 16.IX.2015. leg. Y.-T. Wang.” (glued on label, TARI), Taichung, Taiwan. Paratypes. 3♂♂, 1♀(TARI). same collecting data as the holotype. 1♀ (TARI). “China: Yunnan, Wudian (武甸), 17.IX.2014. leg. Y.-T. Wang”. 1♂, 2♀♀(TARI). “China: Yunnan, CCCC, Nabang (那邦), 21.VI.2017. leg. Y.-T. Wang”. 1♀ (CCLI). “China: Yunnan, Banggunjianshan (邦棍尖山), 19.IX.2015. leg. Y.-T. Wang”. 1♂ (CCLI). “China: Yunnan, Bangdashan (邦達山), 01.IX.2015. leg. Y.-T. Wang”. 2♂♂, 1♀(CCLI). “China: Yunnan, Ruili (瑞麗), 01.IX.2014. leg. Y.-T. Wang”.

Holotype male (Figs 3, 4). Body length 9.7 mm; width across humeri 6.0 mm. Dorsum moderately shiny. Head, pronotum and scutellum dark brown with elytra reddish brown. Head (Fig. 12): labrum with anterior margin crenulate, disc transversally rugose. Clypeus trapezoidal, surface densely rugopunctate; protrusion at basal angle moderately developed. Clypeofrontal suture well defined, distinctly curved in front of frontal tubercle. Frons with surface sparsely punctate, punctures fine, frontal tubercle vertically located in junction of suture, right-triangle in shape in lateral view. Eye prominent, canthus simple, not exceeding eye. Thorax: pronotum (Fig. 18) quadrituberculate, tubercles placed in a line, lateral tubercle greatly reduced in size; anterior face of median tubercles almost perpendicular to plane of pronotum; primary punctures coarse, moderately distributed on disc and intermixed with impunctate area, punctures between lateral margins of pronotum and fovea bigger and denser, posterior area between elytral humeri and suture impunctate except for four coarse punctures in front of scutellum, secondary punctures tiny, evenly scattered throughout surface of pronotum; frontal and lateral margins beaded, posterior margin beaded only in front of elytral humeri. Scutellum elongate, secondary punctures sparse throughout surface with a coarse puncture at center. Elytron (Fig. 24): elytral striae shallow, punctures mostly spaced 2–3 times diameters of punctures. Intervals slightly convex including sutural one, surface with scattered secondary punctures. Male genitalia (Figs 31, 32, 40).

Female (Figs 46, 47). Body length 7.7–10.0 mm; width across humeri 5.4–6.5 mm. Similar to male with minor differences in the form of strongly wrinkled surface of clypeus, transverse frontal carina trilobed, central lobe more prominent than lateral lobes, punctures on frons and vertex rugose, transverse pronotal carina feebly bilobed with lobes broadly developed, punctures on pronotal disc coarser and denser than males.

Variation in male. Dorsum brown, smaller body size, 6.6 mm in length and 5.2 mm in width across humeri, frontal tubercle less developed and not in junction of clypeofrontal suture, pronotal tubercles feebly convex, and number of coarse punctures arranged at pronotal posterior margin variable.

Bolbelasmus chifengi is morphologically similar to B. concavisuturalis, but can be distinguished from the latter by the coarser and denser primary punctures on the pronotal disc (finer and scattered in B. concavisuturalis), elytral intervals evenly convex (elytral intervals flat with sutural interval concave in B. concavisuturalis) and by the longer parameres (shorter in B. concavisuturalis).

Southern Yunnan, China (Fig. 52).

Bolbelasmus chifengi sp. nov. is named after Dr Chi-feng Lee, the curator of the Department of Applied Zoology, Taiwan Agriculture Research Institute, Taichung, Taiwan, who kindly provided materials used in this study.

Holotype male. “Mon-Angget, near Chiangmai, North Thailand, 31-V-1990, K. Masumoto leg.” (glued on label, NSMT). Paratypes. 1♂ (ZMUC) “Northern Thailand, Doi Sutep, 21.6.1958, B. Degerbøl leg., Pr. 548 (1.7.59)”. 1♀ (NSMT) “Doi Suthep, Chiang Mai, Thailand, 15-VIII-1989, Y. MANIT leg.”

Holotype male (Figs 1, 2). Body length 10.2 mm; width across humeri 6.3 mm. Dorsum distinctly shiny. Head, pronotum and scutellum reddish brown with elytra brown in color. Head (Fig. 11): labrum with anterior margin crenulate, disc transversally rugose. Clypeus trapezoidal, surface densely rugopunctate; protrusion at basal angle reduced. Clypeofrontal suture well defined, distinctly curved in front of frontal tubercle. Frons with surface sparsely punctate, punctures fine, frontal tubercle vertically located in junction of suture, triangular in lateral view. Eye prominent, canthus simple, not exceeding eye. Thorax: pronotum (Fig. 17) quadrituberculate, tubercles situated in a line, lateral tubercle smaller; anterior face of median tubercles almost perpendicular to surface of pronotum; primary punctures weakly defined, sparse on disc except between lateral margin of pronotum and fovea, these coarser and denser, line in front of scutellum with a coarse puncture, secondary punctures tiny, evenly scattered on surface of pronotum; frontal and lateral margins beaded, posterior margin beaded only anterior to humeri of elytra. Scutellum elongate, secondary punctures sparsely distributed. Elytron (Fig. 23): elytral striae shallowly impressed, punctures mostly spaced 2–3 times diameters of punctures. Intervals flat, with sutural interval weakly concave, surface scattered with secondary punctures. Male genitalia (Figs 29, 30, 39).

Figures 1–6. 

Dorsal and lateral views of male Bolbelasmus spp. 1, 2 B. concavisuturalis sp. nov.sp. nov., holotype 3, 4 B. chifengi sp. nov., holotype 5, 6 B. meridionalis.

Figures 7–10. 

Dorsal and lateral views of male Bolbelasmus spp. 7, 8 B. korshunovi 9, 10 B. yutangi sp. nov., holotype.

Figures 11–16. 

Scanning electron micrographs of heads of male Bolbelasmus spp. 11 B. concavisuturalis sp. nov. 12 B. chifengi sp. nov. 13 B. meridionalis 14 B. korshunovi 15 B. yutangi sp. nov. 16 B. coreanus. Scale bar: 1 mm.

Female paratype (Figs 44, 45). Body length 9.8 mm; width across humeri 5.8 mm. Similar to male with minor differences in the form of strongly wrinkled surface of clypeus, transverse frontal carina trilobed, central lobe more prominent than lateral lobes, punctures on frons and vertex rugose, transverse pronotal carina feebly bilobed, lobes broad, punctures on pronotal disc coarser and denser than those of males.

Male paratype. The single male paratype is smaller in body size, 9.4 mm in length and 5.1 mm in width across humeri, frontal tubercle less developed and with three coarse punctures along pronotal posterior margin in front of scutellum.

Bolbelasmus concavisuturalis sp. nov. is morphologically similar to B. coreanus, but can be distinguished from the latter by having denser punctures along the midline of the pronotum (Fig. 17) (sparser punctures in B. coreanus (Fig. 22)), punctures in elytral striae moderately developed (Fig. 23) (punctures weakly developed in B. coreanus (Fig. 28)) and ventrally curved parameres (straight in B. coreanus).

Northern Thailand (Fig. 52).

Concavi- (L.) = concave, -suturalis (L.) = suture. In reference to the concave sutural intervals of the elytra.

Korean Peninsula; China (Anhui, Zhejiang, Kweichow, Szechuan, Yunnan); Taiwan.

The detailed distribution of B. coreanus in China requires further investigation, particularly those from southwestern areas. Based on a large number of Bolbelasmus specimens recently collected from Yunnan and neighboring areas, we found no representatives of B. coreanus among them. Therefore, we reserve a decision about whether B. coreanus occurs in Yunnan, Thailand and India, as recorded by Krikken (1977). Voucher specimens from the areas mentioned above are required.

(5♂♂). 2♂♂ (ZMUC). Thailand: Loei Province, Phu Luang Wildlife Sanctuary, 8.–14.x.1984, 700–900 m, Karsholt, Lomboldt & Nielsen leg., Pral Siaw, 1923-9-33, Paūl Fogh/ Coll. Roseberg. 3♂♂ (NSMT). Sansai, Chiang Mai, Thailand, 17. VI. 1993.

Figures 17–22. 

Scanning electron micrographs of pronota of male Bolbelasmus spp. 17 B. concavisuturalis sp. nov. 18 B. chifengi sp. nov. 19 B. meridionalis 20 B. korshunovi 21 B. yutangi sp. nov. 22 B. coreanus. Scale bar: 1 mm.

Body length, males, 6.8–9.0 mm, greatest width at pronotal base 4.4–5.7 mm; females, 7.1–8.7 mm in length, 4.3–5.6 mm in width (Zinchenko 2016). Bolbelasmus korshunovi is distinguished from the other Oriental Bolbelasmus species by elytral sutural intervals that are moderately convex, primary punctures sparsely distributed either side of the center of the pronotum, and shapes of the parameres.

Thirteen type specimens were designated in the original description of the species (Zinchenko 2016), 12 of them collected from June to August, and the holotype during November. Accordingly, the temporal activity of adults is likely at least half the year during both rainy and dry seasons. This is identical to the sympatric species, B. meridionalis.

Northern Thailand.

Bolbelasmus korshunovi inhabits plains to low-elevational montane areas and occurs sympatrically with B. meridionalis in northern Thailand.

Northern India.

Based on the collecting data from the monotypic specimen, B. krikkeni occurs in mid-elevation forests above 1000 m and is unique compared to its congeners that usually inhabit plains to low-elevation montane areas in the region. No additional specimens have been recorded since the publication of the original description.

(11♂♂, 8♀♀). 1♂ (NSMT). Thailand: Sansai, Chiang Mai, 17. VI. 1993 (1 male at NSMT). 9♂♂, 7♀♀ (NSMT); same locality, 12-V-1996. 1♀ (NSMT); near Chiang Mai, N Thailand, VII-1996, native collector. 1♂ (NSMT). Taiwan: Formosa, Heito, 10-VII-1941, H. Kondo/Sizumu Nomura Bequest, 1981.

Figures 23–28. 

Scanning electron micrographs of elytra of male Bolbelasmus spp. 23 B. concavisuturalis sp. nov. 24 B. chifengi sp. nov. 25 B. meridionalis 26 B. korshunovi 27 B. yutangi sp. nov. 28 B. coreanus. Scale bar: 1 mm.

Body length, males, 6.1–8.2 mm, greatest width at pronotal base, 3.7–5.0 mm; females, 5.6–8.2 mm in length, 3.3–5.2 mm in width. Both B. meridionalis and B. minutus constitute a distinctive group among southeastern Asian congeners based on sharing the distinctly convex elytral sutural intervals and the tips of the parameres acute and curved ventrally in lateral view. Due to a lack of further material being available of the later species, B. meridionalis and B. minutus can only be separated by the shape of male genitalia and the lateral margin of the pronotum in B. meridionalis, which is more widely explanate than that of B. minutus.

脊背厚角金龜

Li et al. (2008) excluded B. meridionalis from the registered Taiwan fauna due to the lack of verified records. During the present study, we examined a male B. meridionalis specimen housed in NSMT bearing identical labels as the paratype of the species collected in Heito (now Pingtung) by the late Japanese coleopterist, Yushiro Miwa. We therefore confirm the record of B. meridionalis in Taiwan, though it has been lacking in reports of the genus for 90 years. Consequently, the conservation status of B. meridionalis in Taiwan is in urgent need of study, along with that of B. minutus Li & Masumoto, 2008 and Bolbotrypes davidis (Fairmaire, 1891). These species are restricted to habitats in highly urbanized areas and/or intensively farmed plains of Taiwan.

Indonesia (Java); eastern China; Thailand; Vietnam; Taiwan.

Bolbelasmus meridionalis has the widest known distribution among congeners in the region in eastern and southeastern Asia. Also, the records from Java for the holotype and paratypes indicated that it is the only member from the Sunda Islands of the genus.

Taiwan.

Bolbelasmus minutus was described from a pair of specimens collected during 1931, and no further records of the species have been recorded. This species occurs sympatrically with B. meridionalis and B. nativus in the plains of southern Taiwan.

Taiwan (southern areas and Lanyu island); Japan (Iriomote, Ishigaki and Tarama islands, Okinawa Prefecture).

Bolbelasmus nativus was originally described based on a single male from Taiwan. Ochi and Masumoto (2005) treated the population distributed on a few small islands near Taiwan as a subspecies, B. nativus ishigakiensis.

Japan (Amami oshima and Okinawa island).

Populations of B. shibatai are restricted to a few small islands in the southwestern archipelagos of Japan. Males possess strongly sclerotized parts of the parameres that can be distinguished from the similar species, B. coreanus.

Holotype male. “Myanmar: Bago Region, Moe Yin Gyi, CCCC, 21.V.2017. leg. Y.-T. Wang.” (glued on label, TARI). Paratypes. 1♀(TARI). data as the holotype. 5♂♂ (TARI). “China: Yunnan, Wudian (武甸), 17.IX.2014. leg. Y.-T. Wang”. 1♀ (CCLI) “China: Yunnan, Banggunjianshan (邦棍尖山), 18.IX.2015. leg. Y.-T. Wang”. 6♂♂ (CCLI). “China: Yunnan, Bangdashan (邦達山), 01.IX.2015. leg. Y.-T. Wang”. 1♂ (CCLI). “China: Yunnan, Ruili (瑞麗), 15.IX.2014. leg. Y.-T. Wang”. 1♂ (NSMT). “Doi Saket, Chiang Mai, Thailand, 12-X-1989, Y. MANIT leg”. 1♂ (NSMT). “Doi Mon Unggate, Samoeng Distr., Chiang Mai Prov., Thailand, 18-VII-1989, Y. MANIT leg”.

Holotype male (Figs 9, 10). Body length 9.3 mm; width across humeri 5.9 mm. Dorsum moderately shiny. Head, pronotum and scutellum dark brown with elytra reddish brown. Head (Fig. 15): labrum with anterior margin crenulate, disc transversally rugose. Clypeus trapezoidal, surface densely rugopunctate; protrusion at basal angle moderately developed. Clypeofrontal suture well defined, slightly curved in front of frontal tubercle. Frons with surface moderately punctate, punctures coarse, frontal tubercle vertically located at center of disc, triangular when viewed laterally. Eye prominent, canthus simple, not exceeding eye. Thorax: pronotum (Fig. 21) quadrituberculate, tubercles placed in a line, lateral tubercle greatly reduced in size; anterior face of median tubercles almost perpendicular to plane of pronotum; primary punctures coarse, dense on disc with small impunctate area in front of middle of posterior margin, punctures between lateral margins of pronotum and fovea bigger and denser, scattered coarse punctures distributed along posterior margin with seven punctures in front of scutellum, secondary punctures tiny, evenly scattered on surface of pronotum; frontal and lateral margins beaded, posterior margin beaded only in front of elytral humeri. Scutellum elongate, fine punctures sparsely distributed on surface. Elytron (Fig. 27): elytral striae shallowly impressed, punctures mostly spaced by 1–3 times diameters of punctures. Intervals slightly convex, including sutural interval, surface with scattered secondary punctures. Male genitalia. Figs 37, 38, 43.

Figures 29–38. 

Male genitalia of Bolbelasmus spp. (29, 31, 33, 35, 37, dorsal views; 30, 32, 34, 36, 38, ventral views) 29, 30 B. concavisuturalis sp. nov. 31, 32 B. chifengi sp. nov. 33, 34 B. meridionalis 35, 36 B. korshunovi 37, 38 B. yutangi sp. nov. Scale bar: 0.3 mm.

Figures 39–43. 

Male genitalia of Bolbelasmus spp., lateral views 39 B. concavisuturalis sp. nov. 40 B. chifengi sp. nov. 41 B. meridionalis 42 B. korshunovi 43 B. yutangi sp. nov. Scale bar: 0.2 mm.

Female (Figs 50, 51). Body length 8.4–8.7 mm; width across humeri 5.1–5.3 mm. Similar to male with minor differences in the form of strongly wrinkled surface of clypeus, transverse frontal carina trilobed, central lobe more prominent than lateral lobes, punctures on frons and vertex rugose, transverse pronotal carina feebly bilobed, with lobes broadly developed to reduced, bigger punctures on pronotal disc denser than those of males and scutellum with 1 or 2 bigger punctures.

Figures 44–51. 

Dorsal and lateral views of female Bolbelasmus spp. 44, 45 B. concavisuturalis sp. nov., paratype 46, 47 B. chifengi sp. nov., paratype 48, 49 B. meridionalis 50, 51 B. yutangi sp. nov., paratype.

Variation in male. Male paratypes differ from the holotype in the following respects: smaller body size, 6.6 mm in body length and 5.2 mm in width across humeri, frontal tubercle less developed and not in junction of clypeofrontal suture, pronotal tubercle feebly convex, reduced, and number of coarse punctures along pronotal posterior margin variable.

Bolbelasmus yutangi is similar to B. nativus in sharing the frontal tubercle location at the center of the frons as well as having smaller parameres. It can be distinguished from the latter by the weakly convex basal angle of the clypeus (distinctly bulging in B. nativus), primary punctures densely distributed on the disc (almost impunctate along the middle of disc in B. nativus), sutural interval convex, similar to discal intervals (distinctly more convex than discal intervals in B. nativus) and parameres with the tips tapered (parameres broader at tips in B. nativus).

Eastern Myanmar, northern Thailand and western Yunnan, China (Fig. 52).

Figure 52. 

Distribution map of the eastern and southeastern Asian Bolbelasmus species. Question marks indicate doubtful distributional records.

Bolbelasmus yutangi sp. nov. is named after Mr Yu-tang Wang, a beetle enthusiast of Taiwan, who collected most of the material used in this study.

Described from Vladivostok, Russian Far East.

Bolbelasmus orientalis was described from one male and one female. Krikken (1977) examined both type specimens and found that the female allotype to be a minor male. Also, he noted that the species has no direct affinity with three congeners, B. coreanus, B. meridionalis and B. nativus, which are geographically close to B. orientalis but are allied to the western Palaearctic B. unicornis. Bezborodov and Koshkin (2014) doubted the locality label attached to the type specimens because there were no additional records of the species documented in Russia or nearby territories other than that of type specimens. We, therefore, exclude B. orientalis from the Bolbelasmus fauna in the eastern Palaearctic and the Oriental regions.