Onthophagus kokodanus kokodanus, Krikken, Jan & Huijbregts, Johannes, 2012

Krikken, Jan & Huijbregts, Johannes, 2012, Taxonomy of new relatives of Onthophagus catenatus Lansberge, 1883 from New Guinea (Coleoptera, Scarabaeidae, Scarabaeinae), ZooKeys 251, pp. 49-67 : 58-61

Onthophagus kokodanus kokodanus subsp. n. Figs 5-614, 1933-38

Type-material.

41 males and females, 4 collection records. Holotype male (CMNC) from Papua New Guinea: 34 mi E Port Moresby, Kokoda Trail, 2000 ft, 17-18.vii.1974, S. Peck, T43-44.

Paratypes: Papua New Guinea: Kokoda Trail, 34 mi E Port Moresby, 17-18/vii/1974, Peck, 2000ft, 6 spm., incl. holotype, in CMNC. Kokoda Trail, 30-34 mi E Port Moresby, 16-17/vii/1974, Peck, 2200ft, 4 spm., in CMNC. Kokoda Trail, 34 mi E Port Moresby, 17-18/vii/1974, Peck, 2200ft, 17 spm., in CMNC. 16-17/vii/1974, Peck, 2200ft, 14 spm., in CMNC.

Diagnosis.

The pair of interconnected, basally broad (in axial view), plate-like vertexal horns in the major male, with the median conical tubercle just in front, constitutes the primary feature of this subspecies - at least in major males. Lateral border of pronotum distinctly rounded at about 0.4 of length behind anterolateral angle (not angular, in dorsal view, Fig. 34). Pronotum with blunt bisinuate rim behind broadly depressed, more or less concave anterior declivity, all this reduced in minors. Clypeofrontal ridge low, slightly arcuate, ends on either side angularly connected at clypeogenal ridge. Most of dorsal side finely to minutely, sparsely, evenly punctate. Clypeal tip distinctly, broadly reflexed, apical border bisinuate. Dorsal eye parts broadly elliptic, separated by slightly over three eyewidths. Elytra sericeous, virtually matt, sparsely micropunctate; strial punctures very fine, widely separated, all similar, not stronger caudad. Pygidium sparsely to abundantly, very finely punctate. Colour generally black-brown, moderately shiny, without metallic lustre. Body length usually 10-12 mm.

The presence of an isolated conical protrusion right in front of the horns is shared with other New Guinea species, like Onthophagus heurni Gillet, 1930 and joliveti Paulian, 1973, which may be confusing. The males of both these species, however, have on their horns, which are more or less erect, a distinct basal-internal lobe or denticle, and their eyes are narrow.

Description

(holotype, male). Body length ca 12 mm. Habitus generally convex, robust. Colour of dorsal side (brown-)black, generally moderately shiny, elytra sericeous; ventral parts largely black, matt (microreticulate); legs dark-brown, shiny. Dorsal side and pygidium virtually glabrous (apart from any inconspicuous micro-stubbles); ventral side and legs with numerous long, light-brown setae.

Clypeal border broadly, distinctly marginate, sides virtually straight from genae to bisinuate, reflexed, shortly lobiform apex; clypeal surface shiny, with sparse, minute punctation; clypeogenal transition at border obtusely angular (anterolateral corner of gena slightly elevated), on either side with straight ridge to slightly arcuate, distinct clypeofrontal ridge. Genal and frontal surface minutely punctate as on clypeus; genal border evenly, widely rounded. Vertex between posterior end of eyes with pair of long, complanate, basally very broad horns, connected at base, with distinct conical tubercle medially on anterior side; horns strongly directed laterad (beyond eyes, in axial view), evenly curving upward to tapering, blunt tip, inner edge of horns sinuate (in axial view); horn surface also minutely, sparsely punctate. Frontal disc limited by fine frontogenal ridge, on either side extending along eye. Dorsal eye parts widely elliptic, with ca 28 facet rows across widest point. Ratio of interocular distance to maximum (transverse) eye width ca 3.2.

Pronotum generally strongly convex, surface shiny; disc posteriorly slightly convex (midline impression virtually effaced), anterior surface broadly depressed, medially shallowly concave up to posterior, strongly bisinuate, transverse protrusion coming from disc forward; anterior and lateral borders of pronotum marginate; anterior section of lateral border slightly concave; anterolateral angle rectangular, shortly rounded; posterior section of lateral border slightly sinuate, posterolateral angle rounded; base medially finely marginate along very obtuse basomedian angle. Most of pronotal surface finely, sparsely punctate, anterior depression minutely, sparsely punctate, this punctation interspersed with vague micropunctation.

Elytra generally weakly shiny to matt (sericeous); scutellum indistinct in dorsal view, shape of base and apex unmodified; anterior half of epipleuron distinctly punctate-setose. Elytra broad, with 8 straight to slightly curved, fine, distinct striae; stria 7 distinctly sinuate in front, extending onto shining humeral umbone; strial punctures very fine, widely separated (ca 10 puncture diameters), hardly crenulating interstrial edges. Interstrial surfaces virtually flat to very slightly convex (from disc to lateral declivity of elytra), with sparse, inconspicuous micropunctation.

Antennal club light-brown, scapus unmodified. Mentum shallowly emarginate in front. Prothoracic sides with coxal-marginal ridge distinct, curving forward onto lateral border, much of surface annulate-punctate-setose, including large, seta-bearing hemi-punctures. Anterior lobe of metasternum slightly convex, abundantly punctate-setose, disc micropunctate; metasternal sides and adjacent parts matt, abundantly to densely annulate-punctate-setose. Abdominal ventrites sericeous, each laterally with strip of seta-bearing annulate punctures. Pygidium black, weakly shiny (sericeous), with sparse to abundant, shallow, very fine punctation, without macro-setae; surface slightly convex, base with transverse ridge, apex marginate.

Legs very robust. Protibia with 3+1 larger external denticles (distal 3 longer, sub-acuminate), separated by some serration; proximal serration consisting of 5-6 smaller denticles; apico-external denticle oblique to tibial axis; apical edge slightly rounded, with strong, acuminate, down-curved spur; protibial underside with low longitudinal crest; protarsus unmodified. Profemur robust, underside finely punctate, and with numerous larger seta-bearing hemi-punctures. Meso- and metafemoral undersides also finely punctate, with fewer large seta-bearing hemi-punctures. Meso- and metatibiae strongly dilated distad to transversely subelliptic crest, which is fringed with fine fossorial spines and longer setae; external side with ca 4 sets of distinct, spine-bearing fossorial protrusions. Tarsi generally slender, with well-developed sickle-shaped claws; meso- and metatarsomeres 1 straight, unmodified. Spurs on meso- and metatibiae elongate-acuminate. Relative length proportions of metatibial spur to metatarsomeres 1-5: ca 14, 17, 6, 4, 3, 6.

Parameres narrow (dorsal view), tapering, curved downward (lateral view), Fig. 19.

Measurements in dorsal view: maximum width of head 3.7 mm, median length of pronotum 4.4 mm, maximum width 6.4 mm, sutural length of elytra 4.8 mm, maximum width of combined elytra 6.7 mm.

Variability and sexual dimorphism.

Strongly varying in the development of the vertexal armature. Females have a complex transverse vertexal ridge (Fig. 38), not the variably long horns like in males (note the minor male in Fig. 15, and beware of extremely minor males looking like females, as in the next subspecies). Female vertexal ridge with sides laterally obtusely angulate, thence sloping to eye, medially with robust knob; pronotum with pair of blunt, forward protrusions topping anterior declivity. Body length 9-12 mm.

Etymology.

Name refers to the Kokoda Trail, the type locality; to be treated as masculine noun.