Bolbochromus (Bolbochromus) vespertialis, Liao, 2024

Liao, Weiqi, 2024, A new species of Bolbochromus Boucomont, 1909 (Coleoptera: Geotrupidae: Bolboceratinae) from Guangdong, China, Zoological Systematics 49 (3), pp. 276-279 : 276-278

Bolbochromus (Bolbochromus) vespertialis sp. nov.

Material examined. Holotype ♂, CHINA, Guangdong, Zhanjiang , 21.1569°N, 110.3074°E IV.2023, Weiqi Liao leg. Paratype. 1♂, same data as holotype. All types are deposited in Aquatic Organisms Museum of Guangdong Ocean University .

Description. Holotype ( Figs 1–4 ). Body length 7.8 mm; largest width 5.7 mm, ovate, sides parallel. Dorsum color glossy, black; symmetric brownish-orange markings on elytra and both sides of pronotum, except in basal fovea ( Figs 2–3 ). Head covered with coarse punctures evenly, distributed; labrum approximates a rounded, smooth trapezoid with a central depression; clypeal apex broadly arcuate, slightly elevated, anterior margin smooth, lateral margins intersect ocular canthus at an obtuse angle; margin of ocular canthus decreasing in width backwards, completely including and dividing eye into two parts, lower half slightly larger than upper half; clypeofrontal suture obscure ( Fig. 4 ), middle of vertex with a distinct transverse bimodal carina ( Figs 1, 4 ).

Pronotum. In dorsal view, pronotum approximated as an ellipse with a slightly flattened anterior edge and a slightly bulging posterior edge ( Fig. 1 ). Surface coarsely punctures distributed over outer two-thirds of surface of disc, except in transverse region adjacent to basal fovea ( Figs 2–3 ), smaller punctures distributed in midline and on leading edge of disk, rest of area with no punctures or a small random distribution with fine punctures (mainly concentrated in marginal areas) ( Fig. 2 ). Midline moderately indented, transverse “H” shaped area from both sides of midline to base of prothorax is smooth and free of punctures ( Fig. 1 ). In lateral view, disc with an approximate parabolic shape ( Fig. 3 ), anterolateral angle of pronotum obtuse and approximates a right angle, posterolateral angle of pronotum less prominent and rounded; lateral margin between two angles fringed with setae underneath ( Fig. 3 ). Scutellum smoothy, narrow, line angle between two edges in front half of part greater than line angle in back half, surface with scattered nearly invisible punctures ( Fig. 1 ).

Elytron. Thirteen punctate striae distributed on each elytron, uniformly distributed longitudinally; sutural stria extends upward from scutellum to terminate at elytral base; extension of stria 2 interrupted by a sutural stria, and intersection of two smooth and free of punctures; stria 5 slightly shorter than stria 2 and fails to extend to elytral base; striae 8 and 9 equal in length, extending to humeral umbone and then disappearing; stria 10 connects humeral umbone and continues below, significantly longer than striae 8 and 9, but not extending to elytral base; stria 12 terminating at stria 13, slightly longer than stria 11, significantly shorter than striae 8 and 9; stria 13 more twisted than others, with deeper and more pronounced punctures, situated in reflexed lateral margin of elytron, almost touching elytral base. Setae sparsely and uniformly distributed in area between stria 13 and outer edge. Interstriae 1, 3, and 4 are slightly more elevated than others, with interstria 1 protruding to most pronounced degree; interstriae 3, 5 slightly wider than remaining interstrial ( Figs 1–3 ).

Legs. Tibia slightly curved, puberulent, dorsal setae slightly shorter than ventral surface; protibia with 9 crescent-shaped teeth along outer margin, gradually enlarged from base to apex, 3 teeth near apex significantly larger than last 6, medial apex margined by a slightly curved slender spine ( Fig. 2 ).

Male genitalia. Length 2.2 mm. Parameres capsule like ( Figs 6–7 ), slightly concave near one-half of apex, swollen in center, dorsal medial and posterior margins are sclerotized, membranously connected to basal piece; surface smooth and glabrous ( Figs 6–8 ). Median lobe trilobate, outer edge of dorsal sclerite rolled inward ventrally to form a luminal structure with a folded inner wall and a pennaceous apex ( Figs 8–9 ). Lateral sclerites apexes nearly intersecting; with contiguous series of teeth, pointing toward dorsal sclerite ( Fig. 10 ).

Variation. Variation occurs mainly on the pronotum and elytra portion. Elytral brownish-orange markings sometimes occur only at the base ( Fig. 5 ), the amount of marking color also varies then the common individuals. The black spots located in the basal fovea are sometimes slightly upward, blending with the basal black areas of the disc to form a band of mottling ( Fig. 5 ).

Etymology. The species name “ vespertialis ” indicates that the elytral black basal area of the common individual is modified by a brownish-yellow mottled pattern exhibiting a shape resembling that of a bat's wing, the root of the word is taken from the Latin for bat.

Diagnosis. Of all 22 species of the subgenus Bolbochromus distributed in the Oriental Region (Krikken & Li, 2013; Selking, 2019), seven species, are close in appearance to the new species, namely B. sinensis Krikken & Li, 2013 , B. ryukyuensis Masumoto, 1984 , B. minutus Li & Krikken, 2013 , B. nomurai Li & Krikken, 2013 , B. malayensis Li & Krikken, 2013 , B. plagiatus (Westwood, 1852) , B. mindanaicus Krikken & Li, 2013 . And two species, B. sinensis and B. laetus (Westwood, 1852) are closely distributed (Southern China).

The new species can be externally separated from them by following: 1) Clypeal traits with apex broadly arcuate, slightly elevated; anterior margin curved, smooth (vs. apex subrectangulared in B. sinensis and B. mindanaicus , rounded in B. plagiatus and B. minutus ; anterior margin not smooth, with convexity in B. nomurai , B. mindanaicus and B. ryukyuensis , completely beaded in B. malayensis ). 2) Elytral markings divided into two parts, the larger across base of striae 1–9 and interval 10, toothed in shape (vs. 3 teeth in all, occurring at intervals 1–2, intervals 4–5 and intervals 7–8; tapering toward lateral margins); the other, smaller, across elytron back edge of striae 2–4 and interval 4, approximating a narrow triangle ( Figs 1, 3 ) (vs. undivided in B. minutus , B. nomurai , B. ryukyuensis and B. plagiatus ; elytral base marking with no dentate prominence in B. sinensis and B. mindanaicus , elytral base marking cross over strae 1–8, not over 9 in B. malayensis ). In male genitalia, the new species is distinguished from others by: Parameres capsule like, slightly concave near one-half of apex, swollen in the center (vs. slenderer in B. sinensis and B. laetus , abruptly bent in B. sinensis ); median lobe trilobite (vs. aculeated in B. sinensis and B. laetus ); dorsal sclerite with apex slightly exceeds parameres (vs. significantly in B. sinensis , completely wrapped in B. laetus ).

Acknowledgments I would like to thank Maofu Chen for providing valuable specimens and taking fine images for this study. Also, thanks Yike Ren for contacting and getting me access to the microscope from Fisheries College of Guangdong Ocean University. Finally, thanks to Jilin Li for help with the adjustment and collage of the images in this article.

Weiqi Liao

College of Agricultural Sciences, Guangdong Ocean University, Guangdong 524088, China; E-mail: [e-mail]

Figures

Figures 1–5. Bolbochromus vespertialis sp. nov. 1. Holotype male, dorsal view. 2. Holotype, left fronto-lateral view. 3. Holotype, left lateral view. 4. Dorsal view of head. 5. Paratype male, dorsal view. Scale bars: 1–3, 5=5 mm; 4=1mm.

Figures 6–10. Male genitalia of Bolbochromus vespertialis sp. nov. 6. Dorsal view. 7. Ventral view. 8. Left fronto-lateral view. 9. Ventral view, dorsal sclerite. 10. Ventral view, lateral sclerite. Scale bars: 6–7=0.5mm.