Glaresis

Glaresis is a genus of beetles, sometimes called "Enigmatic scarab beetles", in its own family, the Glaresidae. It is closely related to, and was formerly included in, the family Scarabaeidae. Although its members occur in arid and sandy areas worldwide (except Australia), only the nocturnal adults have ever been collected (typically at lights), and both the larvae and biology of Glaresis are as yet unknown. Due to their narrow habitat associations, a great number of these species occur in extremely limited geographic areas, and are accordingly imperiled by habitat destruction.

Glaresis Temporal range: Aptian–Recent PreꞒ Ꞓ O S D C P T J K Pg N
Glaresis hespericula
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Coleoptera
Suborder:	Polyphaga
Infraorder:	Scarabaeiformia
Superfamily:	Scarabaeoidea
Family:	Glaresidae Kolbe, 1905
Genus:	Glaresis Erichson, 1848
Species
>80; see text

These beetles are small, 2.5–6 mm long, and have the stocky appearance typical of fossorial scarabs, with short, heavy, spurred legs. Color ranges from tan to dark brown, and the back is covered with short setae.

Efforts to raise glaresids in the laboratory were undertaken in the 1980s by C. H. Scholtz and others, but were unsuccessful.

Glaresis was originally classified with Trogidae (originally a subfamily within Scarabaeidae), and has many characteristics of "primitive" scarabaeoids, but no affinities to any of the other primitive groups; recent work suggests that they may in fact belong in Trogidae. Scholtz argued that Glaresis is the most primitive type of scarabaeoid, but more recent research indicates that the Pleocomidae hold this position. The species in North, Central, and South America have been revised by Robert Gordon and Guy Hanley, January 2014, in the journal Insecta Mundi.

Fossil species

• †Glaresis burmitica Cai and Huang 2018 Burmese amber, Myanmar, Cenomanian
• †Glaresis orthochilus Bai et al. 2010 Yixian Formation, China, Aptian
• †Glaresis tridentata Bai et al. 2014 Yixian Formation, China, Aptian

"Glaresis" cretacea Nikolajev 2007 from the Aptian aged Zaza Formation in Russia is considered questionable, with Cai and Huang 2018 considering it to have no diagnostic characters of the family.