Bolbochromus (Bolbochromus) mindanaicus 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 : 506-507

Bolbochromus (Bolbochromus) mindanaicus Krikken & Li, new species

( Figs. 3–4 , 31–33 , 54)

Material examined. Holotype male (IRSNB) from Philippines, labelled “Dapitan\ Mindanao\ Baker ”, “J.J.E. Gillet det., vend.:\ Bolboceras \ catenatus Lans. \ R.M.N.H. Belg. 10.640”. Paratypes: male (USNM) labellled “Kolambugan\ Mindanao\ Baker ”, female (FMNH) labelled “from Jolo I.\ Sulu Is” [ Philippines], “ex mouth and\ stomach preserved\ Rana m. leytensis”.

Identification. Small patterned species, body length roughly 6–7 mm. Postfrons with distinct, short, low transverse median ridge, its crest bifid (not simply conical); clypeus apicomedially slightly protuberant. Elytra with 7 striae between suture and humeral umbone. Eye foramina small (in full-face view), due to broad, arcuate eye canthi. Most of clypeus and frons abundantly to densely punctate. General colour glossy black, at least pronotal sides yellow, elytra usually with yellow prediscal patch and postdiscal streak(s), head black. Anterolateral section of pronotum (full-face view) obtusely angular. The structurally similar singletons (females, presumably same species group) seen from some Philippine islands other than Mindanao and Jolo are different in their colouration, and may represent different taxa. Aedeagus of B. mindanaicus with distinct parameres, simply elongate-convex (not with tips peeping from strongly sclerotised, brown ovoid capsule; note that B. catenatus -like Metabolbochromus with a colour pattern deceptively similar to B. mindanaicus were also seen from the Philippines!).

Description (holotype, male). Body length approximately 7 mm. Colour generally black, with symmetric (orange-)yellow markings on pronotum and elytra; dorsum glossy, almost glabrous. Pilosity on underside and legs abundant, long, light brown.

Labrum with slightly emarginate anteromedian border, limited by fine irregular ridge, upper surface with some large punctures. Clypeal surface bordered by fine, widely arcuate perimarginal ridge, with low apicomedian protrusion. Clypeogenal angle hardly prominent. Clypeus and frons with abundant to dense, scattered, distinct primary punctation, interspersed with few minute secondary punctures. Eye canthus with rugulate-punctate surface, generally broad, anterior edge slightly, finely raised, widely arcuate from clypeogenal angle, tapering to temporal lobe; paraocular ridge (issuing from clypeogenal angle) fine, low, extending to anterolateral angle of eye foramen. Clypeofrontal transition superficially impressed between clypeogenal angles; transverse, postfrontal ridge very short, bluntly bifid (pair of approximated points, axial view). Eye foramen relatively small.

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 obtusely angular, shortly rounded (full-face view), entire lateral edge widely rounded to base. Pronotal surface with double punctation, primary punctation (size slightly variable) distinct, abundant on lateral declivity (lateral fovea indistinct), also lining anterior and lateral marginal ridge; secondary punctation very sparse, minute. Pronotal base immarginate on section between elytral stria 7 on either side (outline medially simply rounded). Disc largely black, with central yellow, cordiform marking over midline impression; lateral declivity, to border, largely yellow. Scutellum black, with scattered, very sparse fine punctation and indistinct micropunctation.

Elytra with discal striae 1, 3, 4, 6, 7 reaching base between suture and humeral umbone; 2 and 5 anteriorly abbreviated, all distinctly impressed, distinctly punctate; punctures separated by 3–6 puncture diameters, slightly crenulating interstriae. Elytral interstriae (on cross-section) moderately convex, interstria 2 less convex than others; interstriae 3 and 4 distinctly broader than 2; interstrial surface sparsely micropunctate. Punctures in juxtepipleural stria with long seta. Interstriae 3–4 with distinct yellow prediscal patch (slightly behind elytral base); interstria 4 with elongate yellow postdiscal marking; interstriae 7 and 8 with very small yellow patch against humeral umbone.

Protibia with 8 external denticles, proximally decreasing in size; apex unmodified, with robust, complanate, slightly tapering spur. Outer side of meso- and metatibiae with 2+(1) arcuate anteapical fossorial elevations, their crest fringed with long, robust, acuminate spines; apical crest transversely subelliptic, with similar spines, slightly shorter; terminal spurs long, tapering, apex blunt.

Aedeagus, Fig. 54; slender, with pair of distinct, sclerotised, elongate-convex parameres with rounded tip.

Measurements of respective parts in mm. Median length of head (full-face, excluding labrum and mandibles) 1.2, width 2.2. Median length of pronotum (dorsal) 2.4, maximum width 3.9. Median length of scutellum 0.75, maximum width 0.95. Sutural length of elytra (dorsal) 2.9, maximum width combined 4.3.

Variation, sexual dimorphism, comment. One female similar to holotype assigned to this species, approximately 6 mm long, with some ecological notes—it was found in a frog ( Rana )—see label data above and note in introduction. The male paratype lacks the prediscal (orange-)yellow markings on the elytra, otherwise very similar.

Distribution. Philippines: Mindanao and, at least, nearby Jolo Island.

Etymology. Name is derived from the type region, adjective.

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 31 – 36. Bolbochromus holotypes, body parts, head (full-face), pronotum (dorsal), left elytron (dorsal). 31 – 33, B. mindanaicus; 34 – 36, B. sinensis. Scale lines 1 mm.