Onthophagus aceroides 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 : 507-508

Onthophagus aceroides Krikken & Huijbregts , new species

( Figs. 2 , 14 , 30–34 )

Type material. Holotype male only (MBBJ), from Indonesia: Irian Jaya: Freeport Concession, 11.iii. 1997, R. Ubaidillah, Dpt 5-3, 97206, dry lowland forest, 4˚ 26’ 21” S–136˚ 52’ 59” E, 300 ft, dung pitfall trap.

Diagnosis. Clypeal border of this species evenly rounded; behind slightly, narrowly reflexed margin is a low, median longitudinal ridge. Head and pronotum without any further elevations. Clypeofrontal surface densely punctate. Pronotum distinctly, finely punctate, abundantly so on disc. Dorsum sericeous (finely microreticulate). Eye foramina large, closed behind, i.e., very narrow posterior end of gena reaching occipital side; interocular distance approximately 2 eye widths. Genal border rounded. Abdominal ventrites with row of fine punctures along base. Pygidium simply punctate. Generally dark-brown, shiny. Apparently slightly smaller than its relatives O. acerus and O. mimikanus , body length approximately 5 mm.

Description (holotype, male). Body length approximately 5 mm. Habitus convex, dorsum slightly deplanate. Color largely dark-brown, shiny, sericeous; legs lighter brown. Dorsum glabrous, microstubbles aside; underside with numerous pale-brown setae; dorsal punctation generally fine, scattered, sparse to abundant, denser on head.

Head shiny black-brown. Clypeal border widely, evenly rounded to apex, margin slightly, narrowly reflexed; clypeal surface densely, distinctly punctate(-rugulate), medially, behind apex, with low longitudinal ridge, surrounding surface slightly raised; clypeogenal transition continuous at border; clypeogenal suture vague; clypeofrontal transition without elevation. Genal border widely rounded in front, lateral tip rounded, posterior extension tapering and just reaching occipital side. Frontal and genal surface virtually flat, punctation abundant, fine, effaced on postfrontal surface, sericeous (microreticulate). Eye foramina broadly subelliptic, with 20–25 facet rows across widest point. Ratio interocular distance / maximum eye width approximately 2.

Pronotum brown, shiny, moderately, evenly convex (lacking midline impression); anterior declivity gradual, unmodified; surface abundantly, evenly, finely punctate throughout, sericeous; anterior and lateral borders finely marginate; base very finely marginate; anterior section of lateral border straight (full-face view), anterolateral angle shortly rounded, subrectangular; posterior section of lateral border very slightly sinuate, virtually straight (full-face view), posterolateral angle rounded off; pronotal lateral and basal borders widely rounded in dorsal view

Elytra brown, shiny; scutellum indistinct, shape of base and apex unmodified; epipleuron glabrous, brown, shiny, virtually impunctate. Elytra broad, with 8 straight to slightly curved, fine striae; stria 7 evenly, very slightly curved in front, ending at humeral umbone; strial punctures fine, mostly separated by approximately 5 puncture diameters, finely crenulating interstriae. Interstrial surfaces slightly convex, sericeous, scattered with sparse, minute punctation.

Antennal club yellow-brown, scapus unmodified. Mentum shallowly emarginate in front. Postocular area of propectus concave, posteriorly delimited by simple coxal-marginal ridge. Propectoral sides with numerous setabearing punctures. Metasternum shiny, anterior lobe very slightly prow-shaped in front, behind punctate-setose surface; metasternal lobe and disc with slight midline impression, micropunctate; metasternal flanks distinctly sericeous (microreticulate), with numerous ocellate seta-bearing punctures. Abdominal ventrites moderately shiny, each laterally with more or less distinct basal row of small (irregularly subocellate) punctures, several with seta. Pygidium matt (sericeous), glabrous; base with transverse ridge, apex distinctly marginate; surface evenly convex, with abundant, fine, distinct punctation.

Legs slender, generally shiny brown. Protibia robust, with 3+1 larger external denticles (distal 3 long, acuminate), distinctly separated by serration; proximal serration consisting of 7–8 small denticles; apico-external denticle slender, oblique to tibial axis; apico-internal angle unmodified, terminal spur strong, elongate-acuminate, curved; protibial underside with low longitudinal crest; protarsus slender. Profemur robust, underside shiny, with numerous seta-bearing punctures and some micropunctation. Mesofemoral and metafemoral undersides with fewer seta-bearing punctures, metafemur virtually glabrous. Mesotibiae and metatibiae slender, strongly dilated distad to transversely subelliptic crest, which is fringed with short fossorial spines below, and some long, fine spines above; externally with approximately 3 very slight, spine-bearing fossorial protrusions. Mesotarsi and metatarsi generally very slender, with fine sickle-shaped claws; mesotarsomeres and metatarsomeres 1 long, straight, unmodified, shorter than 2–5 combined. Terminal spurs on mesotibiae and metatibiae elongate-acuminate. Length proportions terminal spur//metatarsomeres 1–5 in approximate integers: 11// 12/5/3 /2/4.

Parameres with tips dilated-rounded (full-face view), strongly curved downward, Fig. 14 .

Measurements in mm (dorsal view). Maximum width of head 1.5. Median length of pronotum 1.8, maximum width 2.4. Sutural length of elytra 2.2, maximum width combined 2.8

Variation and sexual dimorphism. Only one male available.

Etymology. Name expresses similarity to O. acerus Gillet, 1930 .

Figures

FIGURES 1 – 8. Habitus (oblique view) of Onthophagus species, with indication of body length. 1, O. acerus, holotype ,, 6 mm; 2, O. aceroides, holotype, 5 mm; 3, O. baiyericus, holotype, 5 mm; 4, O. mimikanus, female holotype, 6 mm; 5, O. kokopygus, holotype, 3 mm; 6, O. daymanus, holotype, 4.5 mm; 7, O. kokocellosus, holotype, 4.5 mm; 8, O. bituberoculus, female paratype, Timika, 7 mm.

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 25 – 39. Onthophagus species, body parts. 25 – 29, O. acerus, holotype; 30 – 34, O. aceroides, holotype; 35 – 39, O. baiyericus, holotype. — Head (full-face) 25, 30, 35; pronotum (dorsal) 26, 31, 36; left elytron (dorsal) 27, 32, 37; protibia (upper side) 28, 33, 38; metatibia (underside) 29, 34, 39. Scale lines equal 1 mm.