Bolbochromus minutus Li & Krikken

Li, Chun-Lin, Yang, Ping-Shih, Krikken, Jan & Wang, Chuan-Chan, 2013, Three new species of Bolbochromus Boucomont (Coleoptera, Geotrupidae, Bolboceratinae) from Southeast Asia, ZooKeys 290, pp. 39-54 : 43-45

Bolbochromus minutus Li & Krikken sp. n. Figs 15, 713-1419

Holotype

male. THAILAND: Nakhon Nayok Prov.// Khao Yai Nat. Park., ca 700 m// 29. ix.-6. x. 1984// Karsholt, Lomholdt & Nielsen leg.//Zool. Mus., Copenha gen (deposited at the Universitetes Zoologiske Museum, Copenhagen, Denmark). The holotype (pinned) having both protarsi and right metatarsus broken.

Type locality.

Central Thailand: Nakhon Nayok Province, Khao Yai National Park, 14°26'N, 101°22'E (Fig. 23).

Description.

Holotype Male (Figs 1, 5, 7). Body length 5.8 mm; greatest width 3.5 mm. Form ovate, sides subparallel. Dorsum black with lateral margins of pronotum and elytron reddish black; irregular-shaped brownish orange markings located on sides of pronotum with exception of fovea (Fig. 7); size of elytral markings small, shape transversally irregular, across base of intervals 3-7, marking of interval 7 barely visible, (Fig. 1). Head:Labrum with anterior margin feebly triangularly concave centrally, sides notched. Clypeal apex rounded (Fig. 5), anterior margin beaded, surface coarsely punctate, punctures unevenly distributed, confluent or separated by less than 1 puncture diameter. Clypeofrontal suture absent. Vertex transversely, weakly convex at middle of base, punctures on surface more shallowly developed than those on clypeus, sparsely distributed. Thorax: Outline of pronotum generally rounded, surface coarsely punctate at center of lateral side of disc, with surrounding part impunctate, except for fovea; midline moderately indented, with shallow and inconspicuous punctures; both sides of midline and area in front of elytral base impunctate (Fig. 7); disc gradually declined anteriorly when viewed laterally (Fig. 7). Metasternal process poorly developed, narrowly separating middle coxae with anterior margin beaded. Scutellum with scattered secondary punctures, slightly longer than wide medially. Elytron:With 7 striae between suture and humeral umbone, stria 2 interrupted by stria 1 not reaching base, stria 5 terminating at basal one-ninth; interval 4 more convex and wider than others at basal one-fifth, interval 2, 5, and 6 less convex than others (Figs 1, 7). Legs: Protibia with 10 distinct teeth on outer margin, apical 3 teeth protruding, tip of apical tooth sharp and curved outwardly. Male genitalia: Length 1.6 mm. Parameres (Figs 13-14, 19) capsule-like, swollen overall when viewed laterally, weakly sclerotized laterally with medial and apical parts membranous; surface sparsely punctate, glabrous; longer in length than basal piece. Median lobe (Figs 13-14) trilobate; apex of dorsal sclerite largely swollen, shape rectangular; lateral sclerites downcurved (Fig. 19) with apex rounded swollen, more sclerotized and slightly shorter than dorsal sclerite; supporting sclerites elongate-oval. Internal sac invisible. Temones strongly sclerotized basally, shortly thickened to half of basal piece (Fig. 13). Basal piece with apical portion asymmetrical.

Female. Unknown.

Etymology.

The specific name is the Latin minutus which refers to the smallest body size of species currently known within Bolbochromus .

Diagnosis.

Bolbochromus minutus is similar to Bolbochromus plagiatus , but it can be distinguished based on the following combination of characteristics: smaller in body size ( Bolbochromus plagiatus larger, body length approximately 6.3 mm); punctures of pronotal midline shallow and sparsely distributed (densely coarse rugopunctures in Bolbochromus plagiatus ); elytral markings small across base of intervals 3-7 (large, across from stria 1 to epipleuron in Bolbochromus plagiatus ); tip of protibial apical tooth sharp and elongate (obtuse and not elongate in Bolbochromus plagiatus ).

Remarks.

Compared with other males in Bolbochromus species, Bolbochromus minutus can be easily separated from other similar species by the smaller body size, form of the elytral markings, and the punctures of the pronotal midline. In addition, the characteristics of the male genitalia are diagnostic.