Canadian Journal of Arthropod Identification

The Cryptophagidae of Canada and the northern United States of America

CJAI 40 -- December 20, 2019

Georges Pelletier & Christian Hébert

An Editorial Corrigendum has been published for this paper doi:10.3752/cjai.2019.40ed.

| Abstract | Introduction | Materials & Methods | Checklist | DNA Barcoding | Taxonomy | Key to Species | Acknowledgments | References | PDF | Cite |
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Cryptophagidae, also known as hairy fungus beetles, are common beetles often found as adults in the leaf litter, under the bark of trees, logs and stumps. They are easily distinguished by their small size (usually less than 3.5 mm), oval or elongate-oval body, often reddish to yellowish brown, sometimes dark brown to black, usually covered with silky hairs, antennae with a loose 3-segmented club and basal insertions visible from a dorsal view (White 1983), pronotum usually with well-developed lateral carinae, abdominal ventrite 1 longer than the each of the other ventrites, epipleuron distinct in its basal half, and elytra with confused punctation (Leschen and Skelley 2002). They are very secretive beetles, hence the name “Cryptophagidae”, which loosely translated means “feeding in hidden places”. About 165 species belonging to 16 genera have been recorded so far in North America. All genera are included in this publication except Sternodea, which is found in Florida and does not have any described Nearctic species, and Amydropa,with only one described species from Baja California (Leschen and Skelley 2002). Bousquet et al. (2013) listed 73 species in Canada, including 18 Holarctic and 10 introduced species.

The taxonomy of Cryptophagidae is moderately known in Canada and the northern United States of America. Cryptophagus, the nominal genus, was described by Herbst in 1792 with C. scanicus (Linnaeus)as the type species. Cryptophagus cellaris and C. lycoperdi, both described by Scopoli in 1763 andintroduced into North America, were among the first species of the family to be named. During the 19th century, most studies of Cryptophagidae were carried out in Europe, mainly by Erichson in 1846 and Mäklin in 1852-1853. In North America, very few species were described prior to 1900 (LeConte 1869). Casey (1900) made a major contribution to the family; however, the majority of species that he described in his later revision (Casey 1924) have been synonymized. Although he described 114 species in his publications, 66 species fell into synonymy, including 24 species of Cryptophagus Herbst and 21 species of Atomaria Stephan.

No major revision was published on Nearctic species until Woodroffe and Coombs (1961) on Cryptophagus. This excellent and well-illustrated publication has been helpful to link the Palearctic and Nearctic fauna and to separate distinct species based on their geographic variation, which can be significant in that genus. Four of Casey’s species were synonymized in the highly variable C. croceus Zimmermann. Ten introduced species and two Holarctic species were recorded for the first time in North America. They described five new Nearctic species, including the common C. varus Woodroffe & Coombs.

Hatch (1962) revised the family in the Pacific Northwest, stabilizing the names of many species in that region. Bousquet (1989) reviewed the North American genera of Cryptophaginae. Myrmedophila Bousquet was extracted from Cryptophagus as a newly described genus.Poole and Gentili (1996) list all known Nearctic Cryptophagidae. Leschen (1996) revised the genera of the entire family with cladistic phylogenetic analysis. Anchicera Thomson was definitively united with Atomaria as a subgenus, and Glyptophorus Parkwas united with Henoticus Thomson. Downie and Arnett (1996) provided identification keys and diagnoses of all species known in northeastern North America. Among the 56 species of Cryptophagidae recorded, 36 species are still valid, mostly in the Cryptophaginae. Lyubarsky (2012) described three species of Atomaria from the eastern Palaearctic but none of these species fit the description of any Nearctic species.

Cryptophagidae are distributed worldwide. Cryptophagus, Henoticus, Caenoscelis Thomson and Atomaria are widely distributed in North America. Antherophagus Dejean, Henotiderus Reitter, Myrmedophila and Telmatophilus Heer have a northern and a western distribution. Salebius Casey and Hypocoprus Motschulski have been collected so far only in western North America. Pteryngium Reitter appears to be Holarctic. Curelius and Ephistemus have been introduced from Europe or Asia.

Cryptophagidae are found in a wide variety of habitats. Cryptophagus, Henoticus and Atomaria are mostly forest dwellers and are often collected in soil litter and under bark. Henotiderus prefers trees, under the bark, whereas Myrmedophila and Hypocoprus prefer ant nests (Leschen & Skelley, 2002). Many specialized species of Atomaria live in animal burrows, beaver lodges, or in ant and bird nests. Antherophagus adults are found on flowers, feeding on pollen, whereas the larvae of some species live inside bumblebee nests and beehives where they feed on honey. Telmatophilus are common in aquatic habitats, where they feed on Spargania and Typha (Leschen & Skelley, 2002). Many species of Cryptophagus and Atomaria (Anchicera) are found indoors where they feed on stored food products (Bousquet, 1990), or on fungi and mold found within the walls or in basements where humidity is high. Any water problems, often caused by leaking pipes, will usually attract fungi and mold that will attack wood structures and that will in turn attract many silky fungus beetles, mostly in remote areas. Because of their small size and their secretive behavior, they usually remain undetected.

Species in the genera Telmatophilus, Hypocoprus and Tisactia Casey seem to be more active in spring, from April to June, but most species of other genera are most active from June to mid-August. Many species have an extented period of activity that can include fall and winter, remaining active under the snow cover and at the base of tree trunks. Indoors, most species are active year round. Many species that are mostly collected in late spring and summer in Canada are mostly active during winter in the southeastern United States of America.