Dacne

Dacne
Dacne picta, adult from above
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Clade:	Pancrustacea
Class:	Insecta
Order:	Coleoptera
Suborder:	Polyphaga
Infraorder:	Cucujiformia
Family:	Erotylidae
Subfamily:	Erotylinae
Tribe:	Dacnini
Genus:	Dacne Latreille, 1797
Type species
Dermestes bipustulatus Thunberg, 1781
Synonyms
Cnesophages Reitter, 1875 Engis Paykull, 1800

Dacne is a genus of pleasing fungus beetles (family Erotylidae). In its family, it is placed in tribe Dacnini of subfamily Erotylinae, or in a distinct subfamily Dacninae. The "trans-Beringian", Neotropical and African members of the genus have been separated in distinct subgenera, which have recently been proposed for full genus status.¹

The remaining Dacne sensu stricto – the former subgenus Dacne (Dacne) – is not so diverse by Erotylidae standards, but its 17 species occur widely across the Holarctic, mainly in the cooler regions; few range into the tropics. One species, D.picta from northeastern Asia, has proven ecologically adaptable and adept at infesting stored goods, and consequently became established at transport and trade hubs in such far-flung locations as Australia, Eastern Europe, the continental USA, and the Hawaiian Islands.²¹

Like most of their close relatives, Dacne adults are small pill-shaped beetles with antennae that end in distinct clubs. The forepart of their bodies is black and/or reddish-brown; the elytra are typically black, with one reddish blotch or band near the fore ("shoulder") end of each elytron, and in some species a similar but smaller mark near the elytra tips. The elytra spots may be as large as to form continuous bands when the wings are closed.³

These beetles can be distinguished from their relatives by the synapomorphic combination of strongly swollen antenna "clubs" (typically asymmetrical or with semicircular shape), and a pronotum whose forward margin is convec and swollen, forming a "hood" which covers the base of the head.¹

Less unequivocal characters, which still denote many members of this genus but few other pleasing fungus beetles, are the evenly-scattered punctures on the pronotum, whose sides each feature a thin bead, a short-lined prosternum with an inconspicuous central plate, widely separated middle leg attachment points, and a straight border between meso- and metasternum. The female genitalia of Dacne sensu stricto typically lack gonostyli, have a gonocoxite notably sclerotized to form a chisel-like structure, and rows of tooth-like lamellae on segment 9; these traits are also shared with few other Erotylidae.¹

The following species, forming the former subgenus Dacne (Dacne), are retained in the reduced genus Dacne. They occur in Eurasia, from Europe eastwards north of the Alpides chain, to Japan and Taiwan, and from there around the eastern Himalaya to Southeast Asia, India and Sri Lanka; some occur in North America and the genus barely extends into Central America:¹⁴

• Dacne akitai Narukawa, 1992¹
• Dacne bipustulata (Thunberg, 1781) (= D.humeralis, D.jekeli, D.scanicus)⁴
• Dacne californica (Horn, 1870)
• Dacne fungorum Lewis, 1887⁴ (= D.nigrocephala)
• Dacne indica (Crotch, 1876)⁴
• Dacne japonica Crotch, 1873⁴
• Dacne kidoi Nakane, 1981⁴
• Dacne minima Nikitsky and Kompantzev, 1995¹
• Dacne notata (Gmelin, 1790)⁴ (= D.bipustulata (Fabricius, 1787) non Thunberg, 1781)
• Dacne optabilis Gorham, 1896⁴
• Dacne osawai Ashida and Kim, 1999¹
• Dacne picta Crotch, 1873⁴
• Dacne pontica (Bedel, 1868)⁴
• Dacne pulchella Arrow, 1925⁴
• Dacne quadrimaculata (Say, 1835)
• Dacne rufifrons (Fabricius, 1775)⁴ (= D.angustata, D.binaeva, D.flava)
• Dacne semirufula (Reitter, 1897)⁴

In addition to the described species, an unidentified population is known from southern France, where specimens were collected and their DNA barcode sampled.⁵

African species:¹

• Dacne aequinoctialis (Thomson, 1858)¹
• Dacne clavata Delkeskamp, 1954¹
• Dacne nigropicta Delkeskamp, 1954¹
• Dacne rufa Delkeskamp, 1954¹

A single extant Brazilian species is placed here as of 2023, but undescribed species may conceivably exist in the Neotropics:⁶

• Dacne ducke Skelley, 2004¹

In addition to the living member, the fossil Dacne brodzinskyi from Miocene Dominican amber was assigned to this (sub)genus by Skelley in 1997. Both species share some peculiar traits that suggest they might not even be particularly close to Dacne, but instead belong to a different subfamily of Erotylidae.⁶

Found in northern East Asia and in northwestern North America west of the Rocky Mountains, indicating dispersal across the Bering Strait:¹

• Dacne cyclochilus Boyle, 1954¹
• Dacne hujiayaoi Dai & Zhao, 2013¹
• Dacne maculata Chûjô, 1940⁴ (formerly in Dacne (Dacne))
• Dacne picea LeConte, 1875⁴ (= D.vittata Casey, 1916)
• Dacne pubescens Boyle, 1956¹
• Dacne tangliangi Dai & Zhao, 2013¹
• Dacne zonaria Lewis, 1887⁴ (= D.jureceki; formerly in Dacne (Dacne))