Onthophagus ofianus Krikken & Huijbregts

Krikken, J. & Huijbregts, J., 2013, New Guinea Onthophagus: taxonomy of ten small, unicolored new species (Coleoptera: Scarabaeidae: Scarabaeinae), Zootaxa 3619 (5), pp. 501-525 : 517-518

Onthophagus ofianus Krikken & Huijbregts , new species

( Figs. 12, 24 , 86–91 )

Type material. Holotype male (CMNC) from PNG: Brown River, 30 mi N Port Moresby, 900 m, 15–16.vi.1974, S. Peck. Paratypes listed in Appendix 1.

Diagnosis. Frons with distinct transverse ridge, base of conically thickened lateral ends of this ridge virtually reaching eye. Anterior margin of clypeus with low, reflexed, rounded lobe. Female with slight clypeofrontal ridge. Pronotum with anteromedian protrusion, in major males taking the form of a median longitudinal plate (angulate, in lateral view). Color shiny brown or black. Dorsal surface glabrous, punctation remarkably sparse, minute. Pygidium simply punctate, with several long setae. Body length usually 4–5 mm.

Description (holotype, male). Body length approximately 4.5 mm. Habitus convex, dorsum slightly deplanate. Color largely medium-brown, shiny, underside and legs more light-brown or yellow. Dorsum with sparse to abundant, scattered, fine or minute punctation, lacking distinct setae or shorter bristles, underside with numerous pale-brown bristles and longer setae.

Head brown, entirely minutely, sparsely punctate. Clypeal border very widely rounded from virtually uninterrupted clypeogenal transition to broadly reflexed, rounded anterior lobe, margin on either side not sinuate; marginal surface of clypeus slightly wrinkled; clypeogenal suture vague; clypeofrontal transition without elevation. Gena without distinct lateral tip, fully rounded, posterior extension tapering, reaching occipital side. Frontal surface between anterior part of eyes with pair of subconical tubercles, close to from edge of eyes, interconnected by straight lamina, its crest sharp, slightly undulate (full-face view). Eye foramina narrowly subelliptic, with approximately 12 facet rows across widest point. Ratio interocular distance / maximum eye width approximately 9.

Pronotum brown, shiny, with scattered, sparse, fine to minute punctation, more distinct on disc and lateral declivities; surface evenly, strongly convex (lacking midline impression); anterior declivity with narrow, longitudinal plate-like protrusion, angulate (i.e., virtually rectangular in profile), its base slightly dilated to apical border of pronotum, surface slightly concave on either side; anterior and lateral borders finely marginate; base extremely finely marginate; anterior section of lateral border almost straight (full-face view), anterolateral angle shortly rounded, subrectangular (full-face view); posterior section of lateral border very widely rounded (full-face view), without angle continuing to basal border; pronotal lateral and basal borders widely rounded in dorsal view.

Elytra dark-brown, shiny; scutellum indistinct, shape of base and apex unmodified; epipleuron brown, slightly shiny, with row of seta-bearing punctures. Elytra broad, with 8 fine, distinct, straight to slightly curved, striae; stria 7 evenly, very slightly curved in front, ending at humeral umbone; strial punctures fine, on disc mostly separated by 5–10 puncture diameters, very slightly crenulating interstriae. Interstrial surfaces slightly convex, with scattered, sparse, simple micropunctation.

Antennal club brown, scapus unmodified. Mentum shallowly emarginate in front. Postocular area of propectus very slightly concave, matt, posteriorly delimited by simple coxal-marginal ridge. Propectoral sides with numerous weakly-defined, seta-bearing punctures. Metasternum moderately shiny, anterior lobe convex in front; metasternal disc with slight midline impression, very finely, abundantly punctate; metasternal flanks shiny, with numerous small, seta-bearing ocellate punctures. Abdominal ventrites shiny, each with more or less distinct row of setabearing punctures, anal ventrite with distinct row of seta-bearing punctures. Pygidium with general surface evenly convex, shiny yellow-brown, sparsely, finely punctate, laterally with several seta-bearing punctures; base with transverse ridge, apex marginate.

Legs slender, generally shiny brown. Protibia robust, with 3+1 larger external denticles (distal 3 long, slender, acuminate, proximal one small but distinct), distinctly separated by serration; proximal serration consisting of 8 small denticles; apico-external denticle oblique to tibial axis; apico-internal angle unmodified, terminal spur fine, long, tapering, slightly curved; protibial underside with low longitudinal crest; protarsus slender. Profemur robust, underside shiny, with numerous (partly seta-bearing) fine punctures. Mesofemoral and metafemoral undersides yellow, with some fine, seta-bearing punctures. Mesotibiae and metatibiae slender, dilated distad to transversely subelliptic crest, which is fringed with short fossorial spines below, and some long, fine spines above; externally with approximately 3 slight, spine-bearing fossorial protrusions; mesotibia slightly sinuate internally. Mesotarsi and metatarsi generally slender, with fine sickle-shaped claws; mesotarsomeres and metatarsomeres 1 long, straight, unmodified. Terminal spurs on mesotibiae and metatibiae long, tapering. Length proportions terminal spur // metatarsomeres 1–5 in approximate integers: 12// 13/4/3 /2/5.

Parameres short, membraneous roof projecting, with distinct tips tapering, directed downward (lateral view), Fig. 24 .

Measurements in mm (dorsal view). Maximum width of head 1.6. Median length of pronotum 2.4, maximum width 2.7. Sutural length of elytra 2.2, maximum width combined 2.9.

Variation and sexual dimorphism. Female has clypeus transversely rugulate and with slight, virtually straight clypeofrontal ridge, not reaching clypeogenal borders. Variation mainly in the development of the forebody protrusions: both interocular ridge and anteromedian pronotal protrusion may be lower than in holotype. Body color varies from brown to black.

Etymology. Named after the type locality; to be treated as masculine noun.

Figures

FIGURES 13 – 24. Parameres (lateral view) of Onthophagus species. 13, O. acerus, holotype; 14, O. aceroides, holotype; 15, O. baiyericus, holotype; 16, O. daymanus, holotype; 17, O. kokopygus, holotype; 18, O. kokocellosus, holotype; 19, O. bituberoculus, holotype; 20, O. kukali, holotype; 21, O. kokodentatus, holotype; 22 – 23, O. dissidentatus, paratype, Wau (22), paratype. N Port Moresby (23); 24, O. ofianus, holotype. Scale lines (on top of relevant parameres) equal 0.5 mm.

FIGURES 74 – 91. Onthophagus species, body parts. 74 – 79, O. kokodentatus, holotype (73 – 78), female paratype Iora Creek (79); 80 – 85, O. dissidentatus, holotype (80 – 84), female paratype N Port Moresby (85); 86 – 91, O. ofianus, holotype (85 – 89), female paratype Manari (91). Head (full-face) 74, 79, 80, 85, 91; pronotum (dorsal) 75, (dorsal, with rear view of frontovertexal protrusions) 81, 87; left elytron (dorsal) 76, 82, 88; protibia (upper side) 77, 83, 89; metatibia (underside) 78, 84, 90. Scale lines equal 1 mm.