Onthophagus (Indonthophagus) aeneopiceus d’Orbigny, 1902

Ziani, Stefano, 2024, Historical and morphological review of the subgenus Indonthophagus Kabakov, 2006 of Onthophagus Latreille, 1802 (Coleoptera: Scarabaeidae: Scarabaeinae: Onthophagini), Insecta Mundi 2024 (38), pp. 1-42 : 5-7

Onthophagus (Indonthophagus) aeneopiceus d’Orbigny, 1902

( Fig. 3 )

Onthophagus aeneopiceus d’Orbigny 1902: 156 ; d’Orbigny 1905: 488; d’Orbigny 1913: 376; d’Orbigny 1922: 609; Boucomont and Gillet 1927: 151; Balthasar 1963: 263; Balthasar 1969: 65; Ferreira 1972: 557; Balthasar 1972: 22; Zunino 1975: 153; Barbero et al. 1998: 243; Schoolmeesters 2023; Ziani and Keith 2023: 1 .

Type locality. “ Erythrée ” [ Eritrea].

Type material. Holotype, a minor ♂, fixed by monotypy, examined by photos, in d’Orbigny collection ( MNHN).

Diagnostic features. Length 4.0 to 6.5 mm. Colour dark brown, moderately shiny, with distinct isodiametric microreticulation, elytra sometimes with dark red irregular humeral spots, clypeal sides dark red. Antennae yellow. Dorsal pubescence pale-yellow.

Head short, clearly wider than long, with clypeus broadly round, only very feebly sinuate anteriorly, sides not sinuate; clypeofrontal carina distinct and bent backward, slightly closer to the base of the horn than to the anterior margin of clypeus; occipital carina extended in a long horn arising between the eyes, where it is broad, broader than clypeofrontal carina, and flat, directed backward, tapering gradually to the extremity and following the curvature of pronotum, with moderately long yellow setae mainly at sides, in major males, reduced to a narrow straight lamina in minor males (holotype); clypeal surface with very transversely rugose, setigerous punctures, frontal surface doubly sparsely punctate.

Pronotum convex, declivous anteriorly, with a distinct anteromedian depressed area in major males (in minor male (holotype) without depression) and a small hardly distinguishable posterolateral dull area on either side near pronotal posterior angles; anterior angles distinctly produced, sides not sinuate behind them in dorsal view; dorsal surface setigerously punctate, punctures sub-regular in distribution, separated by 1-2 diameters on disc, smaller and more spaced on the anteromedian furrow; each puncture bears a small granule at its anterior margin, and a long pale-yellow seta, slightly longer that those on clypeus.

Elytral striae shiny, distinctly impressed, with punctures slightly larger than strial width and barely crenulating interstrial sides; interstriae flat to barely convex, all rather regularly granulate; granules slightly smaller than strial punctures; posterior margin of each granule with a small, indistinct, setigerous puncture; setae pale-yellow, thin, as long as pronotal ones.

Pygidium with rather regularly distributed, setigerous punctures; setae yellow, long, thin.

Males with protibial spur clearly bent downward apically, and with a small denticle strongly curved downward on the inner angle of protibial apex.

Female not examined. According to d’Orbigny (1913), females have the occipital carina extended in a backward bent lamina, placed between the eyes, in the middle of them, and a pronotal anteromedian transverse gibbosity, sometimes very slightly divided in two lobes.

Male genital armature. Parameres short, apices bent ventrally, obviously diverging apically, without basolateral plate denticle, round at apex ( Fig. 3b–c ); endophallus with the presence of accessory endophallites, two evident raspulae and a bracket-shaped lamella copulatrix, very thin ( Fig. 3d ).

Distribution. Eritrea ( d’Orbigny 1902). Sudan, Ethiopia, Kenya ( d’Orbigny 1913). Ivory Coast ( Balthasar 1969, doubtful record). Yemen ( Ziani and Keith 2023).

Material examined. Eritrea: “Erythrée” [Eritrea], examined by photos (holotype ♂ of O. aeneopiceus, MNHN ) . Yemen: Ibb gov., W of Jabal Hadish , 30.iii.1976, R. Naviaux leg. 1 ♂ ( DKCC) ; Ibb gov., 5 km SW Najd al Jumai - Wadi Maytam 1600 m, 13°52’28″N 44°17’45” E, 26-27.x.2005, D. Král leg. 1 ♂ ( NMPC) .

Historical review. Despite O. aeneopiceus being described more than a century ago, its nomenclatorial and systematic history is relatively poor. According to d’Orbigny (1902), the holotype, a male, the sole available specimen for the description, was collected in Eritrea. Eleven years later, d’Orbigny (1913), evidently after examining further material, specified the presence of a long curved backward cephalic horn in major males, described the female and added other localities from three more countries. Balthasar (1963), whilst specifying that O. aeneopiceus was an Afrotropical species, hypothesized its presence also in the Palaearctic Africa. Balthasar (1969) reported the species for Ivory Coast, but this record, completely off the known distribution area of the species, was rightly regarded dubiously by Schoolmeesters (2023). Lastly, Ziani and Keith (2023) published the first record for the Palaearctic ecozone (sensu Löbl and Löbl 2016) after two males collected in Yemen.

Remarks. Ziani and Keith (2023), although preferring not to insert O. aeneopiceus in any known subgenus of Onthophagus , pointed out the similarity between the lamella copulatrix and the overall structures inside the endophallus of O. aeneopiceus with those of O. mopsus .

It is noteworthy that O. aeneopiceus is, so far, the sole species belonging to the group in which the male protibial spur is sinuate, clearly bent downward apically. This characteristic is common in those Onthophagus species somehow associated with burrows or nests of small mammals ( Ziani and Gudenzi 2009). Only further investigation will be able to clarify whether the biology of this species is connected to pholeophily.

Figures

Figure 3. Onthophagus (Indonthophagus) aeneopiceus d’Orbigny, 1902 [major ♂: Yemen, Ibb gov.]. 3a) Dorsal habitus. 3b) Parameres, lateral view. 3c) Parameres, dorsal view. 3d) Endophallus. AcS: accessory endophallites. LC: lamella copulatrix. Rs: raspulae. Photos by A. Degiovanni, edited by G. Fiumi [from Ziani and Keith (2023)].