Bolbochromus (Bolbochromus) nomurai Li & Krikken, 2013

Gao, Hao, Geshev, Georgi A. & Yang, Qiao-Zhi, 2025, Contributions to the genus Bolbochromus Boucomont, 1909 (Coleoptera: Geotrupidae: Bolboceratinae) from China, with the description of a new species, Zootaxa 5566 (2), pp. 381-390 : 386-388

Bolbochromus (Bolbochromus) nomurai Li & Krikken, 2013

( Figs. 2A–D , 4C–D , 5G–I , 6F )

Bolbochromus nomurai Li et al., 2013: 47 ; Krikken & Li 2013: 500, table 1 (checklist); Nikolajev et al. 2016: 35.

Type locality. “ Northern Vietnam: Son La Province, Deo Pha Din , 21°70’N, 103°50’E ”.

Type material examined. None.

Additional material examined (6♂♂, 2♀♀, 2 unsexed specimens). 3♂♂, 2♀♀ ( CFYS), Gasa Town (Ŕ洒 Dz), Yunnan Province, China, IX.2020, local collector leg .; 1♂ ( CQZY), Gasa Town (Ŕ洒Dz), Xishuangbanna Prefecture, Yunnan Province, China, V.2020, local collector leg .; 1♂ ( CHG) Puwen Town (üĸDz), Xishuangbanna Prefecture, Yunnan Province, China, VII.2022, local collector leg .; 1♂ ( CBHH), Diqing Prefecture , Yunnan Province, China, by trap, VIII.2019, local collector leg .; 2 specimens ( CBHH), Mangyun (Ệ允), Dehong Prefecture, Yunnan Province, V.2020, local collector leg .

Description of the females. General ( Figs. 2C–D , 4D ): Length 6.7–7.8 mm, maximum width at pronotum posterior to middle (3.9–4.0 mm). Body convex, dorsum glossy. Color: Head black. Middle of disk more testaceous than the rest of pronotum. Scutellum testaceous. Elytra bicolored testaceous and black. Sutural interstria dark brown along entire length; all striae black. Head: Dorsal surface covered with coarse punctures, glabrous. Vertex of head with faint, transverse tubercle. Frons along inner margins of eyes barely raised. Clypeus broadly arcuate anteriorly; middle of anterior margin with low tubercle; margin of ocular canthus evenly arcuate; ocular canthus completely bisecting eyes. Antenna testaceous, with 11 antennomeres, antennomere 1 longer than any of 2–8, antennomere 2 elongated and thick, antennomeres 3–8 gradually thickening, antennomeres 9–11 elliptically swollen, inner face of antennomere 9 with glabrous plate. Pronotum: Each lateral third with scattered large punctures, central third impunctate except anteriorly; smaller secondary punctures distributed along lateral margins. Disc with distinctly impressed, median longitudinal groove terminating before reaching anterior and posterior margins, entire length with sparse punctures. Anterior triangular flat area with small punctures in front of mid-longitudinal impression. Lateral foveae barely impressed, with several punctures. Anterior angles obtuse. Anterior and lateral margins with border terminating on basal margin at level of humeral umbone of elytra; lateral margins fringed with setae underneath, visible from above. Scutellum: Shiny, with extremely fine, nearly invisible punctures along anterior margin. Distinct border on both sides relative to the elytra. Elytra: Each elytron with 13 punctate striae, all evenly punctate along their lengths; with 7 striae between suture and humeral umbone. Sutural stria runs parallel to scutellum and terminates at elytral base, interrupting stria 2 before elytral base; stria 5 ending before elytral base; striae 8 and 9 terminating on humeral umbone, not reaching elytral base; stria 10 extending around and below humeral umbone, longer than striae 8 and 9, not reaching elytral base; stria 11 terminating at elytral mid-length, well before elytral base; stria 12 reaching elytral base. Stria 13 with very deep punctures, situated in reflexed lateral margin of elytron, reaching elytral base. Reflexed lateral margin of elytra with setae of two lengths, long and short setae irregularly alternate, sparsely and evenly scattered between punctures of stria 13, long setae largely located at anterior, short setae more numerous than long setae. Elytral interstriae slightly convex; surface smooth, micropunctures almost invisible. Elytral apices acuminate. Ventral face of epipleuron black, with single row of setae. Legs: Protibia with 9 teeth along outer margin, gradually increasing in size from base to apex, with distal 3 teeth much larger than preceding. Apical mesotibial spurs adjacent to each other, unequal in length, with inner spur longer than outer spur; apical metatibial spurs subequal in length, spaced apart by basal width of a spur.

Variation. The brownish-orange marks on the male elytra varies distinctly, which vary from absent ( Fig. 6F ) to having a small brownish-orange band in striae 2–6 ( Fig. 2A ).

Sexual dimorphism. The two sexes show distinct sexual dimorphism in color pattern on the body. Males have a black body and brownish-orange marks on both sides of the pronotum, while the elytra are with or without oval brownish-orange marks near the base. The female body is generally testaceous, with small black marks near the margins of the pronotum, while the elytra have black or brown marks near the margins and suture.

Measurements. Body length: male 7.1–8.2 mm, female 6.7–7.7 mm; body width: male 4.0– 4.9 mm, female 3.8–4.3 mm.

Distribution. China: Yunnan; Vietnam.

Remarks. This species is the only species possessing sexual dimorphism in this study, although such phenomenon is seen in some other congeneric species, such as Bolbochromus mindanaicus Krikken & Li, 2013 ( Krikken & Li 2013; Li et al. 2019). Additionally, the material from Dehong Prefecture, Yunnan is unexpected, similar to those discussed in the remarks section of B. sunfengyii Gao & Yang , new species. For the same reason, this distribution should be confirmed with additional material.

Figures

FIGURE 2. Habitus of Bolbochromus nomurai Li & Krikken, 2013. A–B, male (Xishuangbanna, Yunnan); C–D, female (Xishuangbanna, Yunnan); A, C, dorsal view; B, D, ventral view.

FIGURE 4. Habitus of Bolbochromus species in oblique view. A–B, Bolbochromus sunfengyii Gao & Yang, new species; A, holotype; B, female paratype; C–D, Bolbochromus nomurai Li & Krikken, 2013; C, male (Xishuangbanna, Yunnan); D, female (Xishuangbanna, Yunnan); E–H, Bolbochromus sinensis Krikken & Li, 2013; E, male (Nanchang, Jiangxi); H, female (Lishui, Zhejiang); not to scale.

FIGURE 5. Aedeagus of Bolbochromus species.A–C, A*–C*, Bolbochromus sunfengyii Gao & Yang, new species (holotype), images denoted by an asterisk are enlarged version from A–C; D–F, Bolbochromus sinensis Krikken & Li, 2013 (Nanchang, Jiangxi); G–I, Bolbochromus nomurai Li & Krikken, 2013 (Xishuangbanna, Yunnan); A, A*, D, G, dorsal view; B, B*, E, H, lateral view; C, C*, F, I, ventral view; scale bar 0.2 mm.

FIGURE 6. Habitus of Bolbochromus species. demonstrating color variations on the dorsal surface in dorsal view. A–E, Bolbochromus sunfengyii Gao & Yang, new species (Xishuangbanna, Yunnan); F, Bolbochromus nomurai Li & Krikken, 2013 (Xishuangbanna, Yunnan).