Onthophagus rutriceps, Krikken & Huijbregts, 2012

Krikken, Jan & Huijbregts, Johannes, 2012, An unusual new Onthophagus from New Guinea (Coleoptera: Scarabaeidae: Scarabaeinae), Acta Entomologica Musei Nationalis Pragae 52 (2), pp. 425-431 : 426-431

Onthophagus rutriceps sp. nov.

( Figs. 1–17 )

Type material. HOLOTYPE: male ( RMNH), from “ PAPUA NEW GUINEA: Morobe Prov.: Saruwaged Mtns., Huon Peninsula, YUS Transect , 5 o 57’28”S 146 o 52’25”E, 600-950m, July 2011, T. Larsen ” . PARATYPES: 13 males and females, same label data as holotype ( NAIC, CMNC) ; 1 male, New Guinea [probably former German New Guinea: now Madang Prov.: Kani Mountains (cf. Fig. 15 ), year ca. 1900], v. Bennigsen [lgt.] ( NMPC) .

Diagnosis. Head of male with tip slightly bent upward, extended as “shovel”, apical crest shortly rounded; entire head surface lacking protrusions. Head of female shorter, with bisinuate, shortly reflexed clypeal apex and a pair of simple, pillar-like erect interocular horns; clypeofrontal ridge distinct, arcuate. Intercoxal lobe of metasternum just behind mesosternum with cariniform prow-shaped protrusion in both sexes (rounded in profile, pointed in ventral view). Head brown-black, remainder of body predominantly orange-yellow or more rufous, with symmetric brown-black markings. Pronotum of major males with forwardcurved postdiscal projection (“handle”), anterior pronotal declivity broadly deplanate (but surface not delimited by extra ridges). Anterolateral angles of pronotum acute. Pronotal base medially obtusely angular. Elytral striae virtually impunctate, odd discal interstriae convex, intervening even discal interstriae less convex and broader; interstrial surface (like most of dorsum) with indistinct micropunctation only. Legs robust. External protibial denticles of female not separated by serration, separating emarginations widely, evenly rounded; proximal serration limited; note other sexual differences in protibial shape (see below). Apical crests of meso- and metatibiae multi-sinuate-dentate, fringed with setae, lacking the more common shorter spines. Inner side of male protibial apex projecting angularly. Eyes darkish, foramina narrow, widely separated (interocular distance 10–11 single eye-widths). Dorsum virtually glabrous. Known body length 9–13 mm. Parameres ( Fig. 14 ) tapering, bent downward, distal (downward) upper side (“roof”) narrow, parallel-sided.

Description (holotype, male). Body length ca. 13 mm. Habitus robust, convex; colour generally yellow to orange, with symmetric brown-black markings; largely shiny, several parts more or less matt (sericeous, microreticulate). Dorsal side and pygidium virtually glabrous, seemingly almost impunctate (micropunctation and microsetae present, but inconspicuous); ventral side and legs with numerous long, yellowish setae.

Head black, shiny, with numerous inconspicuous micropunctures. Clypeus shovel-like: elongate forward, surface concave behind apex, sides marginate (well-defined margin finely punctate); lateral border virtually straight, converging to slightly reflexed tip, apical crest shortly rounded; clypeofrontal transition lacking ridge. Clypeogenal transition at border virtually continuous, fine suture curving from border onto frons; genal border very widely rounded, outer margin (anterior corner) crowded with fine punctation. Eye foramina narrowly elliptic, with ca 11 facet rows across widest point. Ratio interocular distance / maximum (transverse, single) eye width ca 10.

Pronotum moderately convex, broadly deplanate in front of short, forward-curved postdiscal projection; this projection slightly tapering, apex rounded, upper side of projection with slight longitudinal impression. Anterolateral surface of pronotum gradually, moderately declivous to very shallowly concave corner, anterolateral angle acute; anterior and lateral border of pronotum narrowly marginate; anterior section of lateral border virtually straight (full-face view), posterior section slightly sinuate; posterolateral angle rounded off to generally widely rounded, immarginate pronotal base; median section of base obtusely angular, finely marginate. Most of pronotal surface shiny orange, postdiscal projection and its immediate periphery black, basomedian surface also narrowly black; margins of pronotum narrowly infuscated; much of surface with inconspicuous micropunctation.

Elytra broad, largely yellow, more or less shiny; base and apex with broad transverse brownblack marking; scutellum indistinct, shape of elytral base and apex unmodified; epipleuron black, orange midway, glabrous. Elytra with 8 fine, distinct, straight to slightly curved striae, stria 7 hardly sinuate in front, extending to shiny humeral umbone; strial punctures obsolescent, hardly distinct. Elytral interstriae 1, 3, 5, 7, 8 convex, more shiny than less convex and broader interstriae 2, 4 and 6; interstrial micropunctation hardly distinct.

Antenna with 9 antennomeres; club lamellae unmodified, yellow-brown, covered with light pubescence; scapus in front with fine, longitudinal ridge. Mentum in front deeply excised; labial palpi with very small segment 4 distinct. Prosternum, mesosternum, mesepimeron black. Propectoral sides with fine coxal-marginal ridge widely curving forward, but not reaching border; surface abundantly hemipunctate-setose, laterally yellow. Intercoxal lobe of metasternum distinctly prow-shaped in front, flanked by numerous fine seta-bearing punctures; metasternal disc shiny, yellowish, virtually glabrous, smooth (micropunctation and their microsetae aside); flanks and adjacent metepisterna sericeous, and abundantly, finely hemipunctate-setose. Abdominal ventrites largely yellow, subsericeous, sides with row of fine, seta-bearing punctures; anal ventrite glabrous, medially black. Pygidium very slightly convex, yellow, shiny, apex black; margins narrowly raised, well defined, black; pygidial base with fine transverse ridge; surface with inconspicuous micropunctation.

Legs robust, tibiae and tarsi generally shiny brown, femora largely yellow (base and apex infuscated); coxae largely black. Protibia with 3+1 broad external denticles, separated by some serration; proximal serration consisting of ca. 5 separate small denticles, remainder of proximal edge continuous; apico-external denticle oblique to tibial axis; terminal spur slightly curved, elongate-tapering; protibial underside with longitudinal crest, ending apico-internally at accrete, projecting angle; protarsus unmodified. Profemoral underside with numerous punctures bearing long seta, mesofemoral underside with fewer seta-bearing punctures, metafemoral underside glabrous. Meso- and metatibiae dilated distad to oblong, sinuatedentate apical crest, which is fringed with long setae; external tibial side with 3 distinct sets of seta-bearing fossorial protrusions, remaining surface with numerous long setae. Terminal spurs on meso- and metatibiae elongate-tapering, their tips blunted-curved (metatibial spurs of holotype largely worn away). Tarsi generally slender, with unmodified sickle-shaped claws; meso- and metatarsomeres 1 long, straight, unmodified; length proportions of metatarsomeres 1–5 in approximate integers: 30/10/7/5/12.

Body part measurements of male holotype in mm (dorsal view): Maximum width of head 3.3. Median length of pronotum 4.6, maximum width 6.2. Sutural length of elytra 4.4, maximum width combined 6.6.

Body part measurements of female paratype pictured (dorsal view): Maximum width of head 3.2. Median length of pronotum 4.2, maximum width 5.8. Sutural length of elytra 4.3, maximum width combined 6.3. Length proportions of terminal spur versus metatarsomeres 1–5 in approximate integers: 25/32/10/6/5/11.

Variation and sexual dimorphism. Females with pair of long, erect pillar-like horns between eyes, tip of horns rounded off, horns circular on cross-section, their base set slightly away from eye foraminal edge (distance from eyes virtually equal to distance between them). Clypeus short, edge generally rounded, but tip distinctly bisinuate, margin narrowly reflexed. Clypeofrontal ridge distinct, widely evenly arcuate, angularly reaching distinct clypeogenal suture. Clypeal surface transversely braided rugulate, frons in front of horns transversely rugulate-punctate. Pronotal discal protrusion shifted forward, somewhat transverse, not projecting forward as “handle”; anterior discal surface more convex than in male; pronotal punctation minute, generally more distinct than in male. Female protibia lacking apico-internal projection; upper side with well defined depressed parts externally delimited by extra ridge along non-serrate inter-dental emarginations.

Male clypeal extension and length of pronotal projection less in smaller males, real minors with reduced, simply prominent discal protrusion. Extension of elytral brown-black markings varies, basal and apical markings may be broadly connected over lateral declivity. Pronotum may be entirely yellow-orange. Frontal horns of minor females shorter, but still very distinct.

Colours vary slightly: yellow may be more rufous, black may be brownish-black. Approximate body length 9–13 mm.

Biology. Onthophagus rutriceps sp. nov. occurred from 700–950 m a. s.l. in primary rainforest. Although the species was most abundant at about 700 m, it was not collected at lower elevation (600 m), which may have been due to habitat disturbance. It did not occur at all above 950 m. Despite trapping with rotting fruit and carrion at the same sites, the species was only attracted to pitfall traps baited with human dung (T. H. Larsen, pers. comm. 2012).

Etymology. Latin contraction, meaning shovel-headed Onthophagus .

Distribution. Papua New Guinea: Huon Peninsula and possibly adjacent regions.

Figures

Figs. 1–9. Habitus of Onthophagus rutriceps sp. nov., male holotype (1–5), female paratype (6–9), body length ca. 13 and 10 mm, respectively. Oblique, dorsal, lateral, ventral, frontodorsal views.

Figs. 10–15. Body parts and labels of Onthophagus rutriceps sp. nov., male holotype (10–11), female paratype (12–13), male paratype (14, 15, ex NMPC). 10 – head, full-face view; 11–12 – protibia upper side; 13 – metatibia underside; 14 – parameres, lateral view; 15 – text of four labels (Bennigsen male). Scale lines equal 1 mm.

Figs. 16–17. Field photos. Onthophagus rutriceps sp. nov., male left (16), female right (17). (Photo T. H. Larsen).