Genus Chaetonyx (Scarabaeidae, Orphninae)

Orphninae, Chaetonyx robustus

Genus Chaetonyx Schaum, 1862


Type species: Chaetonyx robustus Schaum, by monotypy.


Small-sized beetles (length 4.5–6.0 mm), with strongly convex, shiny body. Color yellowish brown to dark brown. Clypeus rounded anteriorly, surface smooth, without horns or tubercles. Disc of pronotum without ridges and excavations. Eyes vestigial, almost invisible. Scutellum minute, poorly visible from above. Elytra very convex, fused, without humeral umbones. Elytral striae feebly marked, intervals sparsely punctate. Wings absent. Anterior tibiae with 3 outer teeth, in males there is a smaller variably developed inner tooth. Lateral margin basad of outer teeth not crenulated. Middle and posterior legs similar in shape; posterior femora and tibiae about 1/8 longer than middle ones. Tarsi short. Phallobase with membranous ventral side. Females are similar to males and differs in having anterior tibia with a spur and without inner tooth.

Species composition. Three species are described with one having three subspecies.

Distribution. The genus is distributed in southern Europe, mostly in Balkans and Apennine Peninsula.

Biology. Geophilous species, Ch. robustus is locally abundant in riverine forests in Bulgaria (Gradinarov & Petrova, 2012; Gradinarov et al., 2015).


Barbero, E. & Palestrini, C. (1993) Chaetonyx robustus ssp. liguricus Mariani, 1946: Descrizione del terzo stadio larvale e note sulla morfologia preimmaginale della famiglia (Coleoptera Scarabaeoidea Orphnidae). Bollettino della Società entomologica italiana, 125, 143–149.

Gradinarov, D., Petrova, Y., Tasheva-Terzieva, E. & Frolov, A.V. (2015) Biology of the blind geobiont scarab beetle genus Chaetonyx Schaum (Scarabaeidae: Orphninae) with new distribution records of Ch. robustus Schaum from Bulgaria. ZooNotes, 81, 1-14.

Gradinarov, D. & Petrova, Y. (2012) Development of Steinernema feltiae (Rhabditida: Steinernematidae) in larvae of Chaetonyx robustus (Coleoptera: Orphnidae). ZooNotes, 36.

Mariani, G. (1946) Contributo alla conoscenza degli Scarabeidi paleartici, studio sul genere Chaetonyx Schaum. Mem. Soc. Ent. It., 25, 75-83.

Schaum, H. (1862) Kraatz G.: Beiträge zur europäischen Käfer-fauna. Berliner Entomologische Zeitschrift, 6, 265-266.