Onthophagus kokosquamatus, 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 : 62-65

Onthophagus kokosquamatus sp. n. Figs 9-11, 2145-49

Type material.

15 males and females, 4 collection records. Holotype male (CMNC) from Papua New Guinea: 34 mi E Port Moresby, Kokoda Trail, 2000 ft, 16-17.vii.1974, S. Peck, T43-45.

Paratypes: Papua New Guinea: Kokoda Trail, 30-34 mi E Port Moresby, 16-17/vii/1974, Peck, 2200ft, 2 spm., in CMNC. Kokoda Trail, 34 mi E Port Moresby, 16-17/vii/1974, Peck, 2200ft, 4 spm., incl. holotype, in CMNC. 17-18/vii/1974, Peck, 2200ft, 4 spm., in CMNC. Kokoda Trail, Kauai River, Manari, 12-14/viii/1976, Kukal, 700m, rain forest: dung, 5 spm., in CMNC.

Diagnosis.

The strongly rugulate-punctate pronotum, with the peculiar squamiform texture on the anterior gibbosity, together with its large size, should distinguish Onthophagus kokosquamatus from its relatives, or for that matter, any known Papuasian congeners. Bases of both vertexal horns interconnected by robust ridge topped with distinct forward angle. Lateral margin of pronotum distinctly angular at about 0.4 of length behind anterolateral angle (Fig. 46). Pronotal surface behind horns with numerous long setae. Distinctly arcuate clypeofrontal ridge well developed, its ends on either side angularly connected at clypeogenal ridge. Clypeogenal border obtusely angular (full-face view). Clypeal tip distinctly, broadly reflexed, apical crest bisinuate. Dorsal eye parts elliptic, less broad than in the preceding species, separated by about 4.5 eye widths. Most of head surface abundantly, finely punctate; female clypeus transversely rugulate. Elytral interstriae on disc sparsely, indistinctly punctate, lateral interstriae more densely punctate; strial punctures very fine, widely separated, all similar. Pygidium very densely, distinctly punctate. Metasternum superficially prow-shaped in front, behind transverse rim. Colour generally black-brown, without any metallic lustre (elytra lacking reflections shifting in relation to angle of view). Male and female very similar. Body length usually 11-12 mm. For smaller potential relatives, cf. comments below.

Description

(holotype, male). Body length ca 11.5 mm. Habitus convex, robust. Colour of dorsal side black, generally moderately shiny, forebody heavily (rugulate-)punctate; ventral parts largely black, partly shiny, strongly punctate; legs brown-black, shiny. Dorsal side and pygidium locally with some longer light brown setae (apart from inconspicuous micro-setae); ventral side and legs with numerous long, light-brown setae.

Clypeal border broadly, distinctly marginate, sides virtually straight from genae to apex, the latter bisinuate, reflexed, shortly lobiform; clypeal surface shiny, with abundant, fine punctation; clypeogenal transition at border obtusely angular, on either side with straight ridge to arcuate, very distinct clypeofrontal ridge. Genal surface finely, abundantly punctate as on clypeus, surface, like sides of clypeus, superficially transverse rugulate; genal border evenly, widely rounded. Vertex between posterior end of eyes with pair of long horns, which are convex in front, basally broad, and are connected at base by high, medially angulate ridge (axial view); horns strongly directed laterad (over eyes), evenly curving upward to tapering (on posterior side thickened) tip, their surface abundantly, very finely punctate. Frontal disc finely, abundantly punctate between slight genal sutures. Dorsal eye parts broadly elliptic, with 13-15 facet rows across widest point. Ratio of interocular distance to maximum (transverse) eye width ca 4.5.

Pronotum generally strongly convex; disc slightly convex (midline impression virtually effaced by heavy punctation); anteromedian surface strongly, evenly bulbous from disc forward; sides, behind horns of head, distinctly concave (with numerous long, decumbent setae), sloping down to anterolateral corner; anterior and lateral borders of pronotum marginate; anterior section posteriorly, at ca 0.4 of total length, with distinct angle, border very slightly concave; anterolateral angle rectangular, rounded; posterior section of lateral border strongly sinuate, posterolateral angle distinct; base medially slightly marginate along very obtuse basomedian angle. Most of pronotal surface densely rugulate-punctate, rugulation on anteromedian bulb squamiform (like reptile skin); anterolateral concavities largely smooth, many punctures on anterolateral surface looking like small horseshoes.

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

Antennal club light-brown, scapus unmodified. Mentum shallowly emarginate in front. Prothoracic sides with coxal-marginal ridge distinct, curving forward onto lateral border, most of surface densely annulate-punctate-setose. Anterior lobe of metasternum slightly convex (very slight median ridge in front), abundantly hemi-punctate-setose; disc abundantly, finely punctate; metasternal sides and adjacent parts matt, densely to crowdedly annulate-punctate-setose. Abdominal ventrites matt, laterally all crowdedly annulate-punctate-setose. Pygidium black, distal part shiny, with dense, distinct, simple punctation, with very few longer 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 protruding, rounded (upper side view), 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 sinuate-subelliptic crest, which is fringed with fine fossorial spines and 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 15, 14, 6, 4, 3, 4.

Parameres narrow, with narrow spatuliform tip (dorsal view), tapering, curved downward (lateral view), Fig. 21.

Measurements in dorsal view: maximum width of head 3.5 mm, median length of pronotum 4.5 mm, maximum width 6.2 mm, sutural length of elytra 4.9 mm, maximum width of combined elytra 6.5 mm.

Variability and sexual dimorphism.

General body shape of both sexes is very similar. Female clypeus transversely rugulate throughout. Small morphs have less developed horns and obsolescent intervening median angle. Body length 10.5-12 mm.

Comments.

Some smaller Onthophagus (up to ca 8 mm long) with narrow dorsal eye parts and satin-iridescent elytra, from various parts of New Guinea (including the Bismarck Islands), are superficially similar to Onthophagus kokosquamatus , for instance by their completely rugulate-punctate pronotum and pair of curved vertexal horns (in both sexes). These include Onthophagus irianus Balthasar, 1969 and novaeirlandiae Balthasar, 1969 (cf. his key couplet 78/79). By the shifting light reflections from their elytral disc, absent in kokosquamatus, they are reminiscent of species in the Papuasian group of species around Onthophagus iris Sharp, 1875. A study of this group is under way, and in that context the position of these smaller kokosquamatus-like forms and other potential relatives will certainly be reconsidered.

Etymology.

Specific epithet was derivedfrom geographic origin of the new species and peculiar squamiform pronotal sculpture.