Erotylidae, or the pleasing fungus beetles, is a family of small beetles. At most some 2 cm (less than 1 inch) long, some species of Erotylidae are as small as 2 mm. They belong to superfamily Cucujoidea and contain hundreds of genera, with much more than 3.000 described species, and new ones being discovered even today. The family name, like the common name referring to their often colorful, shiny and rounded "cute" appearance, means "darling" or "beloved" (from Ancient Greek ἐρωτύλος); they were historically popular with insect collectors.
In the present circumscription, the family contains up to 10 subfamilies (Cryptophilinae, Dacninae, Encaustinae, Erotylinae, Languriinae, Loberinae, Megalodacninae, Pharaxonothinae, Tritominae, and Xenoscelinae, but see below). In other words, the narrowly circumscribed Erotylidae correspond to the subfamily Erotylinae in the former definition sensu lato; other subfamilies of the old loosely-defined Erotylidae have nowadays been restored to independent family status within the Cucujoidea.
Pleasing fungus beetles are an ancient lineage, probably originating considerably more than 100 million years ago. The oldest fossil assigned to this group is an undescribed species known from Early Cretaceous (Barremian) Lebanese amber.
Description and ecology
These beetles are typically smallish (less than 1 cm long) as adults, and have a more or less oval "pill-shaped" form; some genera are elongated, some are more rounded. Their antennae are rather large compared to their overall size, and usually prominently expanded at the tip. The usual coloration of pleasing fungus beetles is either black (often with a few jagged bands across or large spots on the elytra in a contrasting reddish-ochre to yellowish color), tan to chestnut brown (often with numerous small black dots on the upperside), or part black part brown without pattern. While most genera have a shiny surface, occasionally with metallic iridescence, some are hairy.
The members of this family have a characteristic combination of synapomorphies which distinguishes them from their relatives: gland ducts below and an impressed line above the compound eyes, the keel on the pronotum sides is simple, the coxal cavities of the forelegs are laterally extended, a trochantinal notch is present, the sides of the midleg cavities are closed by a forward expansion of the metasternum, and the aedeagus of the male genitalia has fairly long struts on the penis and is laterally compressed.McHugh, Joseph V. & Chaboo, Caroline S. (2015): Beetles (Coleoptera) of Peru: A Survey of the Families. Erotylidae Latreille, 1802. J.Kans.Entomol.Soc. 88(2): 274-282.
Erotylidae feed on plant and fungal matter; some are important pollinators (e.g. of the ancient cycads), while a few have gained notoriety as pests of some significance. Sometimes, useful and harmful species are found in one genus, e.g. Pharaxonotha. Most pleasing fungus beetles, however, are inoffensive animals of little significance to humans.
It is sometimes assertedDelkeskamp, Kurt (1943): Aus Afrikas Erotyliden-Fauna (Col.) 9. Beitrag zur Kenntnis der Erotyliden. ["From the erotylid fauna of Africa. 9th contribution to the knowledge of erotylids." Article in German.] Dt. entomol. Z. 1943: 28-55. PDF fulltext. that the contrasting coloration of many Erotylidae signals a revolting taste or even toxicity. However, actual data are almost non-existent beyond the recognition of apparent mimicry complexes, e.g. involving Megalodacne and the sap beetles of genus Glischrochilus, Cypherotylus and the darkling beetles of genus Cuphotes, or various genera of pleasing fungus beetles and carrion beetles or handsome fungus beetles or the darkling beetles of genus Diaperis. Also, there are anecdotal observations, such as an American five-lined skink (Plestiodon fasciatus) – usually a voracious hunter of small beetles – which ignored individuals of I.quadripunctatus even when the beetles came as close as to touch the predator. But it is not clear which species mimics which, or if they are actually all repulsive to predators (making the mimicry Müllerian).
Systematics
Historically, the pleasing fungus beetles with their prominent "clubbed" antenna tips were long affiliated with the "Clavicornia". These were eventually resolved to be a polyphyletic assemblage of more-or-less-closely related Cucujiformia families and replaced by several superfamilies, with the Erotylidae assigned to the "flat-bodied" bark and fungus beetle superfamily Cucujoidea. Their closest relatives are still undetermined, but many have been proposed throughout the years: Some of these, like the Alexiidae/Cerylonidae and the handsome fungus beetles (Endomychidae), or the false skin beetles (Biphyllidae), turned out to be unrelated Cucujiformia which simply look similar (mainly in having "clavicorn" antennae). Other authors proposed the Erotylidae to be part of a clade with silken fungus beetles (Cryptophagidae) and the small cucujiform family Propalticidae, or with the Phloeostichidae (another unusual family of fungus beetles) and the singular Australian genus Lamingtonium. Molecular data tentatively support the enigmatic Propalticidae as closely related to pleasing fungus beetles, but as part of a clade containing lined and the "typical" flat bark beetles (Laemophloeidae and Cucujidae), the shining flower beetles (Phalacridae), but not the silken fungus beetles; a clade uniting the Erotylidae with Monotomidae, Helotidae, and the relict genus Ericmodes was considered about as likely however.Drilling, Kai (2010): Exocrine glands in Erotylidae (Coleoptera, Cucujoidea): chemical ecology, morphology and evolution. Dr.rer.nat thesis, University of Bayreuth. PDF fulltext
The division into subfamilies and tribes is not definitely established. For example, the Cryptophilinae, Loberinae and Pharaxonothinae are sometimes included as tribes in the Xenoscelinae, and similarly the Dacninae, Encaustinae, Megalodacninae and Tritominae in the Erotylinae, resulting in a 3-subfamily arrangement. The lasting doubts on the monophyly of lower ranked taxa within Erotylidae necessitate further phylogenetic studies with better sampling and studies of unexplored character sets, for example the metendosternite and penile flagellum, which are generally lacking detailed morphological studies within the Coleoptera literature.
Selected genera The following genera are a sample of those usually retained in the reduced Erotylidae:
Acropteroxys Aegithus Afrodacne Delkeskamp, 1954Skelley, Paul E. (2023): Subgenera of Dacne Latreille, 1797 (Erotylidae: Erotylinae: Dacnini) given full generic rank. Insecta Mundi 0971: 1–9. Ameridacne Skelley, 2009 Antillengis Skelley, 2009Wikispecies: Erotylidae. Retrieved 2026-06-30. Apetus Delkeskamp, 1935 Apteronesitis Arrow, 1928Chûjô, Michio & Chûjô, Michitaka (1988): A catalog of the Erotylidae (Insecta, Coleoptera) from the old world (excl. the Ethiopian region) I. Esakia 26: 139-185. PDF fulltext. Asmonax Gorham, 1892Chûjô, Michio & Chûjô, Michitaka (1989): A catalog of the Erotylidae (Insecta, Coleoptera) from the old world (excl. the Ethiopian region) II. Esakia 28: 75-96. PDF fulltext. Atomarops Reitter, 1889Leschen, Richard A.B. & Węgrzynowicz, Piotr (1998): Generic catalogue and taxonomic status of Languriidae (Cucujoidea). Ann.Zool. 48(3/4): 221-243. PDF fulltext Aulacocheilus Brachydacne Arrow, 1937Deelder, C.L. (1942): Revision of the Erotylidae (Coleoptera) of the Leiden Museum. Zool. Meded. 24(3): 49-115. Fulltext Brachypterosa Zablotny & Leschen, 1996 Cardiodacne Philipp, 1965 Cathartocryptus (= Xenoscelinus) Chinophagus Ljubarsky, 1997 Cnecosa Pascoe, 1866 Combocerus Coptengis Crotch, 1876 Crowsonguptus Leschen & Węgrzynowicz, 1998 (= Coelocryptus Sharp, 1900 nec Thomson, 1873: preoccupied) Cryptodacne Cryptophagops Grouvelle, 1919 Cryptophilus Cycadophila Xu, Tang & Skelley, 2015 Cypherotylus (= Gibbifer) Cyrtengis Reitter, 1900 Cyrtomorphus Dacne (= Cnesophages, Engis) Dasydactylus Dromodacne Arrow, 1925 Echinothallis Skelley, Leschen & Liu 2021 Empocryptus Sharp, 1900Sen Gupta, T. (1968): Review of the genera of the tribe Loberini (Coleoptera: Languriidae). Breviora 303: 1-27. Fulltext (= Pseudhenoticus) Encaustes Lacordaire, 1842 Endytus Bedel, 1882 Episcapha Episcaphula Crotch, 1876 (= Cadne, Cedna, Decna, Lanugodacne; sometimes in Megalodacne) Epytus (= Oocyanus) Erotylus Euzostria Gorham, 1888 Fitoa Dajoz, 1973 Haematochiton (may belong into Mycotretus) Hapalips Henoticonus Reitter, 1878 Hirsutotriplax (= Hirsotriplax) Hoplepiscapha Lea, 1922 Hornerotylus Chûjô, 1941 (formerly in Aulacocheilus) Hybosoma Gorham, 1883 Idiodacne Arrow, 1925 Iphiclus (= Brachysphoenus) Ischyrus Lacordaire, 1842 (= Micrischyrus) Kuschelengis Skelley & Leschen, 2007 Languria (= Janessa) Languriomorpha Langurites Laurenticola Philipp, 1965Skelley, Paul E. (1998): A Catalogue of the Crotch Collection of Erotylidae (Coleoptera). Ann. Zool. 48(1/2): 1-44. PDF fulltext Lepidotoramus Linodesmus Bedel, 1882 Loberogosmus Reitter, 1876 Loberolus Grouvelle, 1919 Loberopsyllus Martinez & Barrera, 1966 Loberoschema Reitter, 1896 Loberus Lobosternum Macrodacne Heller, 1918 (1920) (sometimes in Megalodacne) Madadacne Philipp, 1965 Masahiria Wegrzynowicz, 2005 Megalodacne (= Psephodacne, Romodacne) Megischyrus (= Ischyrus Dejean, 1836 ("1837"; unavailable)) Metallencaustes Heller, 1918 (1920) Micrencaustes Crotch, 1875 (= Mimencaustes) Microdacne Skelley, Leschen & Liu 2021 Microsternus Mimodacne (sometimes in Megalodacne) Mycolybas Mycomystes Mycotretus Neoblytus Bedel, 1882 Neocoptengis Heller, 1900 Neodacne Chûjô, 1976 (sometimes in Megalodacne) Neopriotelus Neosternus Dai & Zhao, 2013 (formerly in Microsternus) Neothallis Fauvel, 1891 (= Monothallis) Nesitis Bedel, 1882 Oretylus Heller, 1920 (sometimes in Megalodacne) Paphezia Zablotny & Leschen, 1996 Paracoptengis Heller, 1918 (1920) Pharaxonotha Phonodacne Arrow, 1925 Plagiopisthen Thomson, 1856 Pseudischyrus (may belong into Tritoma) Satelia Lewis, 1887 Scaphidomorphus Scaphodacne Heller, 1918 (formerly in Megalodacne) Setariola Jakobson, 1915 Simocoptengis Heller, 1918 (1920) Stengita Reitter, 1875 Stenodina Fairmaire, 1898 Subana Heller, 1918 (1920) Tamboria Heller, 1918 (1920) Telmatoscius Sharp, 1900 Tetrathallis Crotch, 1876 Thallis Erichson, 1842 Thaumastodacne Deelder, 1942 Tomarops Grouvelle, 1903 Toramus (= Itomarus) Trichulus Bedel, 1882 Triplatoma Westwood, 1832 (= Pantheropterus) Triplax (= Paratritoma, Tritomapara) Tritoma (= Cyrtotriplax) Xenodacne Boyle, 1956 Zavaljus
Earlier authors did not include the lizard beetles and relatives in the Erotylidae; instead, genera such as Pseudodacne (and sometimes its entire family Euxestidae) or Eidoreus (today family Eupsilobiidae) were assigned to the pleasing fungus beetle family.
References
Further reading
External links
Key to the British species of family Erotylidae