Scarabaeidae, Latreille, 1802

Krell, Frank- Thorsten, 2006, Fossil Record And Evolution Of Scarabaeoidea (Coleoptera: Polyphaga), The Coleopterists Bulletin (mo 5) 60, pp. 120-143 : 127-128

Scarabaeidae : PROTOTROGINAE Nikolajev 2000 a (L Cretaceous)

Diagnosis: Mesocoxae elongate, contiguous; mesotibia with two transverse keels; elytra covering pygidium; five visible sternites; lateral margins of sternites forming sharp edges. Remarks: According to Nikolajev, the taxon is diagnosed by symplesiomorphies only (in respect to Trogidae ). Since Nikolajev classifies Trogidae , Geotrupidae , and Scarabaeidae as subfamilies (of Scarabaeidae 5 Scarabaeoidea without Lucanidae and Passalidae ), his Prototroginae should be upgraded to family level to be consistent with the current classification ( Lawrence et al. 2000; Scholtz and Gebennikov 2005). However, since Prototroginae are diagnosed solely by symplesiomorphies ( Nikolajev 2000 a) and are likely to be paraphyletic, I refrain from formally giving it the new status of a family. Nevertheless, there are no extant scarabaeoids with five visible sternites and tibiae with two transverse keels.

Scarabaeidae : Melolonthinae : CRETOMELOLONTHINI Nikolajev 1998 (L Cretaceous) Diagnosis: Labrum not covered by clypeus; clypeus without anterior border; anterior border of pronotum leathery; Radius 1 (5 RA3) and R3 (5 RA4) apically approximated (but not fused); meso- and metatibia with single transverse carina; apical spurs of meso- and metatibia close-set; pygidium free; two last abdominal spiracles on sternites; six visible sternites. Remarks: All diagnostic characters seem to be plesiomorphic with respect to Melolonthinae (wing venation) or even Scarabaeidae . Cretomelolonthinae might be paraphyletic as defined.

Scarabaeidae : Aclopinae ?: HOLCOROBEINI Nikolajev 1992 (U Jurassic–L Cretaceous) Diagnosis: Medium-sized body; mandibles and labrum exposed; outer margin of protibia with three denticles; meso- and metatibia with two transverse keels; mesocoxae contiguous; each elytron with ten ‘dot-like grooves’; radius gradually thinning toward apex and running along frontal margin of hind wing; radius sector (5 RA4) curving smoothly without joining radius (5 RA3). Remarks: Nikolajev (2004) integrated the Holcorobeini into Aclopinae although two characters do not fit his own diagnosis of this subfamily: the tarsi of Holcorobeini are not or only slightly longer than the tibia (much longer in Aclopinae with the exception of Xenaclopus Arrow ), and the meso- and metatibiae can have more than one keel on the outer side (one keel in Aclopinae with a rudimentary second in Xenaclopus ). Moreover, the metaventrite and coxae are much smaller in the fossils than in extant Aclopinae .