Aegidinus Arrow, 1904

Frolov, Andrey V., Akhmetova, Lilia A. & Vaz-de-Mello, Fernando Z., 2019, Contribution to the knowledge of Aegidinus Arrow (Coleoptera: Scarabaeidae: Orphninae): new species and comments on the classification and nomenclature, Journal of Natural History 53 (11), pp. 725-747 : 726-727

publication ID 10.1080/00222933.2019.1606953

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Aegidinus Arrow, 1904


Genus Aegidinus Arrow, 1904

Type species

Aegidium guianensis Westwood, designated by Paulian (1984).


Body small to mid-sized (length 6 to 12 mm), reddish brown to dark brown. Mandibles subsymmetrical, with long processes on the outer sides. Clypeus with tubercle or horn on anterior margin medially in males, without horn in females. Pronotum variably excavated medially in males, convex to depressed medially in females; anterior margin of pronotum in males with a tubercle or horn medially. Propleura with carinae separating anterolateral areas from basal area. Scutellum narrowly rounded apically, about 1/15 length of elytra. Elytra convex, with marked humeral umbones and striae marked with elongated punctures. Wings fully developed. Metepisternon triangular, its posterior angle rounded to triangular and situated in distinct concavity of epipleuron. Protibiae with three strong outer teeth in both sexes and with a smaller medial tooth in majority of males. Each procoxa with two cavities. Phallobase tube shaped with strongly sclerotised ventral side but without differentiation of ventral and dorsal sclerites. Parameres relatively short, with complex shape, apices without setae. Gonocoxites separated into two more or less distinct parts.

Aegidinus is distinct among the orphnines in having the following unique characters: mandibles with processes on the outer sides; shape of the gonocoxites is diverse and species specific at least in majority of species; procoxae with two cavities each; parameres are asymmetric in two species; phallobase with protruding ventroapical plate in some species. From other Aegidiini, Aegidinus also differs in the absence of a hole connecting mesocoxal cavities, and in having more or less distinct transverse carina on metatibiae.

Diagnostic characters of species

Most Aegidinus species are similar externally and, despite some interspecific variation of the body sculpture and head and protoracic armature in some species, reliable identification is only possible by examining the shape of the male genitalia. External female genitalia (gonocoxites) are also highly specific, although their usefulness in distinguishing closely related species requires further evaluation (see Discussion below).

Species composition and distribution

Aegidinus comprises 14 species including two newly described in this work. Members of the genus occur in South America, mostly in the Amazon and Guianan moist forest regions to Yungas in the west, and on the island of Trinidad ( Figure 7 View Figure 7 ).