Peltonotus Burmeister, 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 : 57-58

Peltonotus Burmeister, 1847

Type species.

Peltonotus morio Burmeister, 1847: 75, by monotypy.

Valid taxa.

25 species.

Peltonotus species are distributed throughout Southeast Asia, southern China, and the eastern portion of the Indian Subcontinent (Fig. 61). Peltonotus is currently considered the sole Asian lineage of Cyclocephalini , though its subfamilial classification has been unstable. The genus is remarkable for its confounding combination of morphological and behavioral traits that blurred the lines between historical concepts of the subfamilies Dynastinae and Rutelinae. For example, the sexual dimorphism of the protarsi in Peltonotus species has long been compared to that found in Cyclocephala (e.g., see Burmeister 1847). In contrast, the labral morphology of Peltonotus species matches that found in Asian parastasiine and fruhstoferiine ( Rutelinae) scarabs ( Arrow 1908, 1910). The floral feeding behavior of Peltonotus species on Araceae is also shared between cyclocephalines and Asian parastasiines, adding a further layer of intrigue to unresolved evolutionary relationships between the groups at the subfamilial- and tribal-level (e.g., see Moore and Jameson 2013, Kumano-Nomura and Yamaoka 2006, Kumano-Nomura and Yamaoka 2009, Tung et al. 2010, Hoe et al. 2011, 2016).

Peltonotus was described by Burmeister (1847), and he included it within the Chalepidae division of Cyclocephalidae . The classification of Peltonotus was stable until Arrow (1908, 1910) transferred the genus to Rutelinae based upon the exposed (in dorsal view, produced apically beyond the clypeus) and chitinized labrum. Arrow (1917) later erected the “division” Peltonotini for Peltonotus within his classification of Rutelinae. Ohaus (1918, 1934b) and Machatschke (1972) rejected Peltonotini and included Peltonotus in Pelidnotina ( Rutelini ) in their catalogs of Rutelinae. Morphological phylogenetic analysis of Rutelina ( Rutelinae: Rutelini ) suggested that Peltonotus were more closely related to Cyclocephalini than Rutelini ( Jameson 1998). Subsequent works on the genus have treated Peltonotus as a member of Cyclocephalini ( Jameson and Wada 2004, 2009, Jameson and Jákl 2010, Jameson and Drumont 2013).

Little is known about the biology and natural history of Peltonotus species. The immatures are undescribed. Adults are attracted to lights at night ( Jameson and Wada 2004). Peltonotus malayensis Arrow was collected from the spathes of Epipremnum falcifolium Engl. ( Araceae ), where males and females were observed mating and feeding ( Jameson and Wada 2004). In Thailand, P. nasutus visit the large inflorescences of the terrestrial aroid Amorphophallus paeoniifolius (Dennst.) Nicolson, where adult beetles feed and mate ( Grimm 2009). Peltonotus nasutus can be attracted to the inflorescences in high numbers (over 70 individuals) ( Danell 2010).

Peltonotus species can be recognized by the following combination of characters: 1) dorsal coloration brown to black with variable presence of maculae; 2) body convex, not dorsoventrally flattened; 3) clypeal apex rounded to straight in dorsal view; 4) frontoclypeal suture incomplete medially; 5) apical margin of mentum variably shaped with weak emargination; 6) anterolateral margin of mandible lacking tooth; 7) mandibular molar area with rows of circular micropunctures; 8) galea of maxilla not strongly dorsoventrally flattened; 9) galea of the maxilla on inner surface with 3 fused basal teeth, a free median tooth, and 2 fused apical teeth (3-1-2 arrangement); 10) galea with articulated medial tooth; 11) labrum extending apically beyond clypeal apex (obvious in dorsal view); 12) apical and basal margins of pronotum with beaded margin complete or incomplete at middle; 13) protibia of males with 2 or 3 teeth, females with 3 teeth; 14) protibial spur straight to weakly reflexed; 15) males with inner protarsal claw thickened and not cleft at apex (nib variably present or absent); 16) mesocoxae not widely separated, nearly touching; 17) metacoxae with lateral edge perpendicular to ventral surface; 18) anterior edge of hindwing distal to apical hinge lacking membranous border; 19) anterior edge of hindwing distal to apical hinge with row of long setae extending from apical hinge along length of the costal vein; 20) vein RA with single row of pegs proximal to apical hinge.