Onthophagus baiyericus 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 : 505-506

Onthophagus baiyericus Krikken & Huijbregts , new species

( Figs. 3 , 15 , 35–39 )

Type material. Holotype male (CMNC), from PNG: Baiyer River, 4000 ft, 6.viii.1974, S. Peck B281.

Diagnosis. Dorsum distinctly, finely punctate, not with micropunctation only (as in O. mimikanus ). Clypeal apex rounded(-truncate), margin not reflexed. Eye foramina very large, distinctly open behind, i.e., tapering posterior end of gena by far not reaching occipital side; interocular distance approximately 2.3 eye widths. Genal border rounded. Head and pronotum without any elevations. Generally brown(-black), dorsum shiny, not sericeous. Small, body length approximately 5 mm. Pygidium simply punctate. Females probably very similar, possibly with more rugulate-punctate clypeus, as in other species (see Variation and sexual dimorphism, below).

Description (holotype, male). Body length approximately 5 mm. Habitus convex, dorsum slightly deplanate. Color largely dark-brown, dorsally shiny; legs and ventral side brown. Dorsum glabrous, apart from microstubbles in fine punctures, underside with numerous pale-brown setae; dorsal punctation generally fine, scattered, sparse, denser on head.

Head shiny black-brown. Clypeal border widely, evenly rounded to narrowly, very slightly truncate apex (margin not reflexed); clypeal surface evenly, abundantly to densely, distinctly punctate; clypeogenal transition continuous at border; clypeogenal suture effaced; clypeofrontal transition without elevation. Genal border widely rounded in front, lateral tip rounded, posterior extension short, leaving lateral surface of eye distinctly exposed and undivided. Frontal surface virtually flat, punctation abundant, fine, more or less effaced, postfrontal surface slightly convex. Eye foramina broadly subelliptic, with 20–25 facet rows across widest point. Ratio interocular distance / maximum eye width approximately 2.3.

Pronotum black, shiny, moderately, evenly convex (lacking midline impression); anterior declivity gradual, unmodified; surface sparsely, evenly, very finely punctate throughout, micropunctation hardly distinct; anterior and lateral borders finely marginate; base very finely marginate; anterior section of lateral border straight (full-face view), anterolateral angle shortly rounded, subrectangular (slightly obtuse); posterior section of lateral border also straight (full-face view), posterolateral angle rounded off; pronotal lateral and basal borders widely rounded in dorsal view (basomedian angle obsolescent).

Elytra black-brown, shiny; scutellum indistinct, shape of base and apex unmodified; epipleuron glabrous, brown-black, shiny, with fine, scattered punctures. Elytra broad, with 8 straight to slightly curved, very fine striae; stria 7 evenly, very slightly curved in front, ending at humeral umbone; strial punctures very fine, mostly separated by 7–10 puncture diameters, finely crenulating interstriae. Interstrial surfaces slightly convex, scattered with sparse, fine 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 with numerous ocellate punctures (many with shorter setae). Abdominal ventrites moderately shiny, each laterally with more or less distinct row(s) of (irregularly annulate) punctures. Pygidium shiny brown, glabrous; base with transverse ridge, apex broadly marginate; surface evenly convex, with sparse to abundant, fine, simple punctation.

Legs generally shiny brown. Protibia robust, with 3+1 larger external denticles (distal 3 larger, acuminate), separated by some serration; proximal serration consisting of approximately 8 small denticles; apico-external denticle long, oblique to tibial axis; apico-internal angle unmodified, terminal spur small, elongate-acuminate, slightly 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 similar to profemora. 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 very fine claws; mesotarsomeres and metatarsomeres 1 long, almost 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: 10// 14/5/4 /2/4.

Parameres with tapering-convergent stalks rounded (full-face view), bent downward (lateral view), Fig. 15 .

Measurements in mm (dorsal view). Maximum width of head 1.5. Median length of pronotum 1.5, maximum width 2.4. Sutural length of elytra 2.4, maximum width combined 2.9.

Variation and sexual dimorphism. One male assigned to this species. Some similar brown females are excluded from allocation to this species, including one coming from the type locality; a side-by-side comparison shows for instance, clearly different eye foramen shapes.

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

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.