Ancognatha Erichson, 1847

Moore, Matthew R., Cave, Ronald D. & Branham, Marc A., 2018, Synopsis of the cyclocephaline scarab beetles (Coleoptera, Scarabaeidae, Dynastinae), ZooKeys 745, pp. 1-99 : 39-41

Ancognatha Erichson, 1847

Type species.

Ancognatha scarabaeoides Erichson, subsequent designation by Casey 1915: 111.

Valid taxa.

22 species.

The 22 species of Ancognatha are distributed from the southwestern United States south to Argentina (Fig. 52). The species diversity in the genus is concentrated in north and western South America and in Mexico, west of the Isthmus of Tehuantepec. Biological information on Ancognatha species is lacking, and almost nothing is known about the natural history of adults. In Meso- and Central America, Ancognatha species are associated with premontane, lower montane, and montane tropical forests with some species being collected at elevations from 2,000 to 3,500 m above sea level ( Ratcliffe 2003, Ratcliffe and Cave 2006, Ratcliffe et al. 2013). This pattern also holds in South America. Several Ancognatha species have been recorded from elevations over 4,000 m in Peru and northern Chile (Mondaca 2016, Figueroa and Ratcliffe 2016). Some South American Ancognatha species can be very large for the tribe. For example, A. matilei Dechambre from Colombia is up to the 36 mm long ( Dechambre 2000). Adults are attracted to lights at night.

Larvae are described for four Ancognatha species ( Ritcher 1966, Ramírez-Salinas et al. 2004, Vallejo and Morón 2008, Neita-Moreno and Morón 2008). South American larval descriptions are largely based on material collected in agroecosystems, and thus the natural ecology of Ancognatha immatures is poorly known. Mondaca (2016) reported the larvae of A. aymara Mondaca feeding on grass roots high in the altiplano steppe of northern Chile.

Ancognatha species can be recognized by the following combination of characters: 1) dorsal coloration variable, from all or partially black or testaceous, to light brown with variable dark maculae; 2) body convex and not strongly anteroposteriorly or dorsoventrally compressed; 3) clypeal apex rounded to parabolic, never truncate or emarginate; 4) frontoclypeal suture incomplete medially; 5) males with anterolateral margin of the mandibles without teeth; 6) mandibular apices narrow and elongated, recurved dorsally; 7) mandibular molar area with rows of circular micropunctures; 8) apical margin of mentum narrowly and deeply emarginated; 9) galea of maxilla reduced to a roughly quadrate process; 10) galea of the maxilla on inner surface lacking well-developed teeth, teeth when present and visible greatly reduced into spine-like projec tions; 11) males and females with 3 protibial teeth, basal tooth slightly removed from the more apical 2 teeth, and oriented laterally; 12) protibial spur straight to weakly deflexed; 13) males with inner protarsal claw enlarged and narrowly cleft at apex; 14) mesocoxae narrowly separated and touching; 15) meso- and metatibiae with distal, transverse carinae; 16) metacoxae with lateral edge perpendicular to ventral surface; 17) anterior edge of hindwing distal to apical hinge lacking setae and with produced, membranous border; 18) vein RA with single row of pegs extending distally nearly to margin of apical hinge; 19) elytral margin membranous.

The relationship of Ancognatha species to other cyclocephaline genera has not been evaluated. Acrobolbia may be related to Ancognatha based on characters of the clypeus, mentum, pronotum, prosternal process, protarsus, and mandibles ( Jameson 1998, Jameson et al. 2002). Surutu also shares some intriguing characters with Ancognatha , which may be indicative of a close relationship between these two genera. For example, Ancognatha and Surutu species all have a rounded to parabolic clypeal apex and a narrowly, but deeply, emarginated apex of the mentum. Surutu species have a anteriorly projecting tooth at the apex of the labrum, and this is also shared in some Ancognatha species.