Form elongate oval. Labrum and mandibles prominent, produced beyond apex of clypeus, clypeus with or without horn. Antenna with 10 segments, antennal club with 3 tomentose segments. Anterior coxae transverse. Pronotum with or without horn-like lateral or anterior projections. Scutellum exposed. Metasternum longer than abdominal sternites. Metatibia with apical spines separated by basal metatarsal segment. Tarsal claws on all legs not independently movable, claws equal in length or size. Onychium cylindrical with 2 setae. Pygidium exposed weakly beyond apices of elytra.
The name Orphninae was erected by Erichson (1847). Paulian (1984) elevated the Orphninae to family-level status and created a new subfamily, the Aegidiinae for the New World taxa. We follow Lawrence & Newton (1995) and treat the group as a subfamily of the family Scarabaeidae. The Orphninae resemble members of the Hybosorinae based on the prominent mandibles and labrum, and Arrow (1911) commented that the Orphninae share a pectinate tibial spur (which we have not observed in New World taxa) with the Ochodaeidae. Scholtz &Chown (1995) hypothesized that the Orphninae is a member of the Scarabaeidae and is basal to the clade that includes the subfamilies Melolonthinae, Dynastinae, Rutelinae, Cetoniinae, Trichiinae, and Valginae. Based on larval characters, Paulian & Lumaret (1982) hypothesized that the Orphninae are intermediate between the "laparostict" and "pleurostict" scarabs and show some convergences with certain tribes of Melolonthinae. In a more recent phylogentic analysis based on larval characters Grebennikov & Scholtz (2004) were not be able to establish the phylogenetic relationships of the Orphninae. In their phylogeny, Orphninae is part of a politomy that includes other Scarabaeidae subfamilies, Lucanidae, Hybosoridae, Bolboceratids (considered as family), and Geotrupidae. Preliminary phylogenetic analyses based on molecular data suggest that the Orphninae are sister taxa to the Allidiostomatinae (Scarbaeidae) (Ocampo et al. in prep.).
The subfamily includes about 80 species worldwide (Arrow 1912, Paulian 1984). The subfamily is divided into two tribes: the Aegidiini and the Orphnini. The tribe Aegidiini is distributed in the New World and includes four genera. The tribe Orphnini is distributed in the Old World and includes 10 genera (Arrow 1912).
New World Genera (click on species names for more information)
Aegidium Westwood 1846
Includes 12 species (Paulian 1984) that occur from southern Mexico to Chile and to the West Indies. Adults have been found feeding on decaying banana stems in coffee-cacao plantations (Morón 1991). Adults have been collected in flight intercept traps. The larva of one species, A. cribratum Bates, was found under rotten logs and was described by Morón (1991). Keys to species: Paulian 1984.
Aegidiellus Paulian 1984
A monotypic genus that includes A. alatus (Castelnau) from Rio de Janiero in Brazil. Reference: Paulian 1984.
Aegidinus Arrow 1904
Includes three species from Colombia, Guyana, and Brazil. Key to species: Paulian 1984.
Paraegidium Vulcano, Pereira & Martinez 1966
A monotypic genus, including only P. costalimai Vulcano, Pereira & Martinez, from eastern Brazil. Reference: Paulian 1984.
Little is know of the ecology and biology of this small group of scarabs. In the New World, adults are collected at low- to mid-elevations. They have been observed on banana and cacao plantations on banana stems and have been collected in flight intercept traps.
Morón (1991) described the larva of Aegidium cribratum. It was found under rotting logs.
ARROW, G.J. 1911. XLVIII. On lamellicorn beetles belonging to the subfamies Ochodaeinae, Orphninae, Hybosorinae, and Troginae. Annals and Magazine of Natural History (series 8) 7: 390-397.
ARROW, G.J. 1912.
Scarabaeidae: Pachypodinae, Pleocominae, Aclopinae, Glaphyrinae, Ochodaeinae,
Orphninae, Idiostominae, Hybosorinae, Dynamopinae, Acanthocerinae, Troginae.
Coleopterorum Catalogus pars 43, W. Junk, Berlin. 66 pp.
ERICHSON, W. F. 1845-1847. Natureschichte der Insecten Deutschlands. Erste Abtheilung, Coleoptera, Vol. 3: 1-800. Verlag der Nicolaischen Buchhandlung, Berlin.
LAWRENCE, J. F. AND A. F. NEWTON, JR. 1995. Families and subfamilies of Coleoptera (with selected genera, notes, and references and data on family-group names), pp. 779-1006. In J. Pakaluk and S. A. Slipinski (eds.), Biology, Phylogeny, and Classification of Coleoptera. Papers Celebrating the 80th Birthday of Roy A. Crowson. Muzeum i Instytut Zoologii PAN, Warszawa, Poland.
MORON, M. A. 1991. Larva and pupa of Aegidium cribratum Bates (Coleoptera: Scarabaeidae: Orphninae). Coleopterists Bulletin 45(4): 360-367.
PAULIAN, R. 1984. Les Orphnidae Americains (Coleopteres, Scarabaeoidea). Annals Société Entomologique de France (N.S.) 20(1): 65-92.
PAULIAN, R. and J.-P. LUMARET. 1982. La larve des Orphnidae. Bulletin de la Société Entomologique de France 87: 263-272.
SCHOLTZ, C. H. and S. L. CHOWN. 1995. The evolution of habitat use and diet in the Scarabaeoidea: a phylogenetic approach, pp. 355-374. In J. Pakaluk and S. A. Slipinski (eds.), Biology, Phylogeny, and Classification of Coleoptera. Papers Celebrating the 80th Birthday of Roy A. Crowson. Muzeum i Instytut Zoologii PAN, Warszawa, Poland.