Bolbochromus (Bolbochromus) dumogensis Krikken

Krikken, Jan & Li, Chun-Lin, 2013, Taxonomy of the Oriental genus Bolbochromus: a generic overview and descriptions of four new species (Coleoptera: Geotrupidae: Bolboceratinae), Zootaxa 3731 (4), pp. 495-519 : 509-512

Bolbochromus (Bolbochromus) dumogensis Krikken & Li, new species

( Figs. 7–8 , 25–27 , 46 , 51)

Material examined. Holotype male (BMNH) from Indonesia: Sulawesi Utara [North Sulawesi]: Dumoga-Bone NP, labelled ”R. Ent. Soc. Lond.\ PROJECT WALLACE\ B.M. 1985-10”, “1.”. Paratype female (BMNH) from same region, with same label, and additional data: February 1985, flight interception trap 3, plot D [?, illegible], ca 400m, lowland forest.

Identification. This species has 5 striae between the suture and the humeral umbone, like the preceding species. Compared to Bolbochromus celebensis , however, it has (in full-face view) larger eye foramina, due to its very slender, tapering eye canthi. Interocular part of frons, between ends of paraocular ridge on either side, with fine transverse ridge over fine paramedian denticles, not a full tubercle. General colour brown, head black. Anterolateral section of pronotum (full-face view) fully rounded, i.e., actually entire lateral border evenly rounded (non-angular). Body length roughly 8.0– 9.5 mm.

Description (holotype, male). Body length approximately 10 mm. Colour generally medium-brown, dorsum glossy, almost glabrous. Pilosity on underside and legs abundant, long, light brown.

Labrum with very vaguely emarginate anteromedian border, upper surface rugulate. Clypeal surface bordered by fine, widely arcuate perimarginal ridge, Clypeogenal angle hardly prominent. Clypeus and frons with abundant to dense, scattered, fine primary punctation, interspersed with minute secondary punctures. Eye canthus generally narrow, slender, anterior edge slightly, finely raised, widely arcuate from clypeogenal angle, tapering to temporal lobe; paraocular ridge (issuing from clypeogenal angle) fine, extending to lateral angle of low, transverse, interocular ridge; medial section of ridge with pair of very fine denticles (axial view). Eye foramen relatively large.

Pronotum moderately convex, gradually declivous in front, outline of marginate (raised) anterior border evenly arcuate; pronotal midline with punctate sulcus from near base to apex; anterolateral edge fully rounded (full-face view), entire lateral edge widely rounded to base. Pronotal surface with double punctation, primary punctation (size slightly variable) distinct, abundant around lateral fovea, also lining anterior and lateral marginal ridge; secondary punctation sparse, minute. Pronotal base immarginate on section between elytral stria 5 on either side (outline medially slightly expanded- rounded). Scutellum with scattered, very sparse double punctation.

Elytra with discal striae 1–5 reaching base between suture and humeral umbone; distinctly impressed, finely punctate; punctures separated by 4–7 puncture diameters, slightly crenulating interstriae. Elytral interstriae (on cross-section) moderately convex, interstria 1 distally slightly more convex; interstrial surface sparsely micropunctate. Punctures in juxtepipleural stria with long seta.

Protibia with 10 external denticles, proximally decreasing in size; apex unmodified, with robust, complanate, slightly tapering spur. Outer side of mesotibiae and metatibiae with 4+(1) and 3 arcuate anteapical fossorial elevations, respectively; their crest fringed with long, robust, acuminate spines; apical crest transversely subelliptic, with similar spines; terminal spurs long, apex blunt, slightly curved.

Aedeagus, Fig. 51; slender-elongate, slightly transparent-membraneous.

Measurements of respective parts in mm. Median length of head (full-face, excluding labrum and mandibles) 2.1, width 3.2. Median length of pronotum (dorsal) 3.6, maximum width 5.5. Median length of scutellum 1.0, maximum width 1.1. Sutural length of elytra (dorsal) 2.9, maximum width combined 5.9.

Variation and sexual dimorphism. Only two specimens available (male and female). Variation in size may well be larger than here indicated (see size range in B. celebensis ). The sexes are very similar.

FIGURES 37–44. Bolbochromus head (full-face). 37, B. nigriceps ; 38, B. celebensis ; 39, B. catenatus ; 40, B. niger ; 41, B. sulcicollis ; 42, B. ludekingi ; 43, B. walshi ; 44, B. laetus or near. Scale lines 1 mm.

Comments. The apparently limited occurrence of this unusual Bolbochromus versus the widespread B. celebensis suggests that the exploration for Bolbochromus in the archipelago is far from complete, and might have more surprises in store. One would expect more specimens to be available, as the Dumoga-Bone National Park was the focal area of Project Wallace.

Distribution. Indonesia: north Sulawesi.

Etymology. Name is derived from the type region.

Figures

FIGURES 1 – 8. Habitus of male Bolbochromus (oblique and lateral views). 1 – 2, B. nigriceps; 3 – 4, B. mindanaicus; 5 – 6, B. celebensis; 7 – 8, B. dumogensis. Scale lines 1 mm.

FIGURES 25 – 30. Bolbochromus holotypes, body parts, head (full-face), pronotum (dorsal), left elytron (dorsal). 25 – 27, B. dumogensis; 28 – 30, B. pumilus. Scale lines 1 mm.

FIGURES 45 – 46. Bolbochromus, anterolateral corner of pronotum (dorsolateral view). 45, B. celebensis; 46, B. dumogensis. Figs. 47 – 61. Aedeagus of Bolbochromus (various views). 47 – 49, B. laetus or near (47 upper side, 48 underside, 49 dextrolateral); 50, B. celebensis (upper side); 51, B. dumogensis (upper side); 52 – 53, B. nigriceps (52 upper side, 53 underside); 54, B. mindanaicus (upper side); 55, B. pumilus (upper side); 56 – 57, B. ludekingi (56 upper side, 57 underside); 58 – 59, B. sulcicollis (58 upper side, 59 dextro-lateral); 60 – 61, B. sinensis (60 dextro-lateral, 61 upper side of bent distal part). Scale lines 1 mm.