ENDOMYCHIDAE Leach, 1815

Handsome Fungus Beetles

Adults and larvae of all UK species feed on fungus. They mostly occur in wooded environments, although some species are synanthropic.

POLYPHAGA Emery, 1886 

CUCUJOIDEA Latreille, 1802

5

5

8

1-6mm

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Introduction

This is a moderately large family of about 1800 species in 130 genera and 12 subfamilies; it is cosmopolitan in distribution with by far the greatest diversity in Southeast Asia, equatorial Africa and tropical South America. About 75 species are recorded from Europe of which 15 extend to central and northern areas and 8 are recorded from the UK. They are closely related to coccinellids and in warmer regions many are large and brilliantly coloured, a condition hinted at in the European Endomychus Panzer, 1795, but more generally endomychids are widely variable in size and morphology but the majority may be recognized by the clubbed antennae, distinct frontoclypeal suture, presence of a pair on basal pronotal sulci, 4-4-4 tarsal formula and the absence of post-coxal lines on the basal abdominal ventrite. As the common name indicates most species feed on fungi, either on decaying wood or among vegetation. The following gives some idea of the distribution of genera within the subfamilies, those represented in the UK are given in italics.

  • ANAMORPHINAE Strohecker, 1953 is a large group of 36 genera; it is predominantly tropical although the genus Symbiotes Redtenbacher, 1849 is the exception with 5 species from the Nearctic and western Palaearctic regions. Most genera are of rather restricted distribution and some are endemic to relatively small areas; the 2 species of Aclemmysia Reitter, 1904 occur in Algeria and Italy while the 2 species of Acritosoma Pakaluk & Ślipińsky, 1995 occur in Mexico and Peru. Coryphus Csiki, 1902 includes 4 species from New Guinea, the 15 species of Erotendomychus Lea, 1922 are Australian. Africa is rich in endemics e.g. Afralexia Strohecker, 1967 (2 spp.) and Baeochelys Strohecker, 1974 (3 spp.) from Congo, and Anagaricophilus Arrow, 1922 (9 spp.) and Cyrtomychus Kolbe, 1910 (2 spp.) from Madagascar and the Seychelles. Others are more widespread although tend to be restricted to either the Old or New Worlds e.g. Asymbius Gorham, 1896 (11 spp.) is widespread through southeast Asia while Bystodes Strohecker, 1953 occurs throughout the Old World tropics, and Bystius Guérin-Méneville, 1857 (18 spp.) occurs throughout Central and South America. The group is represented in the UK by the single species Symbiotes latus Redtenbacher, 1849.

  • DANASCELINAE Tomaszewska, 2000 includes 2 monotypic genera; Danascelis Tomaszewska, 1999 from Pakistan and the Nearctic Hadromychus Bousquet & Leschen, 2002.

  • ENDOMYCHINAE Gerstaecker, 1857 includes 5 genera and is almost exclusively eastern and south-eastern Asian in distribution, the only exceptions being several species of Endomychus Panzer, 1795. Endomychus includes 36 species and is predominantly eastern in distribution; the exceptions are E. limbatus (Horn, 1870) and E. biguttatus Say, 1824 from the Nearctic region, E. coccineus (Linnaeus, 1758) which is a widespread western Palaearctic species and the only UK member of the group, and E. armeniacus Motschulsky, 1835 which occurs in western Russia extending south to Iran.

  • EPIPOCINAE Gorham, 1873 includes 4 rather speciose genera; Anidrytus Gerstaecker, 1858 (~60 spp.), Ephebus Gerstaecker, 1858 (10 spp.), Epipocus Germar, 1843 ((~35 spp.) and Epopterus Chevrolat, 1844(~65 spp.). All occur in the Neotropical region with a few extending into Central and North America.

  • EUPSILOBIINAE Casey, 1895 includes 6 genera and 10 species, most are Neotropical but single species occur in the Seychelles and the United States.

  • LEIESTINAE         Thomson, 1863 includes 13 species in 6 genera and is Holarctic in distribution. Leiestes Chevrolat, 1836 includes 3 widespread Palaearctic species while the monotypic Panaleies Tomaszewska, 2000 and Panamonus Gorham, 1873 (4 spp.) occur in Japan. The remaining genera are Nearctic.

  • LYCOPERDINAE Redtenbacher, 1844 includes the majority of the species, about 600, in 40 genera and is pantropical with many species from the Palaearctic region and 6 species of 3 genera from the United States. The greatest diversity is in eastern and south-eastern Asia but the group is also well-represented in warmer African regions and there are many endemic genera and species e.g. Cymones Gorham, 1886 (9 spp.) and Haploscelis Blanchard, 1845 (26 spp.) are endemic to Madagascar, and there are endemic species from other genera from Madagascar (2), South Africa, Kenya, Romania (2), and the Canary Islands (3). Of the widespread Old World genus the Nearctic L. ferruginea LeConte, 1824 is the only New World species. The group will be familiar to UK coleopterists as two widespread western Palaearctic species, L. bovistae (Fabricius, 1792) and L. succincta (Linnaeus, 1767) occur here and are the only members of the subfamily to do so.

  • MEROPHYSIINAE Seidlitz, 1872 is a cosmopolitan group of 110 species in 12 genera, of these Holoparamecus Curtis, 1833 includes 60 species and Merophysia Lucas, 1832 includes 26. The greatest diversity is in the Palaearctic region, and especially Mediterranean areas, and there are many endemics throughout the world. Only a few species occur in the New World; the United states fauna includes 6 species of Holoparamecus while 3 genera are Neotropical; 2 are monotypic while Cholovocerida Belon, 1884 includes 3 species of which 2 are Chilean and Brazilian endemics while C. maderae (Wollaston, 1854) occurs across Central and South America, Galapagos, Hawaii and also Madagascar. The UK fauna includes 3 species of Holoparamecus; the Holarctic H. singularis (Beck, 1817), H. depressus Curtis, 1833 which occurs throughout the New World as well as much of the Palaearctic and parts of Africa (Cameroon, Senegal, Madagascar etc.) and H. caularum (Aubé, 1843) which is almost cosmopolitan. This group was formerly included as two subfamilies, Holoparamecinae and Merophysiinae, of the Merophysiidae by Crowson, 1955.

  • MYCETAEINAE Jacquelin du Val, 1857 includes 2 genera and 7 species. Agaricophilus Motschulsky, 1838 is western Palaearctic with species from Russia and Europe while Mycetaea Stephens, 1829 is more widespread with 2 species from South Africa, 1 from Morocco and 1 from Australia. M. subterranea (Fabricius, 1801) is cosmopolitan and locally common in the UK.

  • PLEGANOPHORINAE Jacquelin du Val, 1858 includes 3 genera and more than 20 species. The monotypic Dadocerus Arrow, 1920 is from Borneo. Plegonomorphus Hampe, 1855 includes 2 European species while Trochoideus Westwood, 1833 is pantropical with endemics from Madagascar, Java and Sumatra, and T. desjardinsi Guérin-Méneville, 1838 which is cosmopolitan but does not occur in the UK.

  • STENOTARSINAE Chapuis, 1876 is a speciose group of 9 genera although some of these, including the large genera Stenotarsus Perty, 1832 and Danae Reiche, 1847 are sometimes includes in the Endomychinae. The group is pantropical and very diverse in Africa and southeast Asia and only few species extend into temperate regions; Stenotarsus is the largest genus of the family with more than 250 species worldwide, about 100 occur in the New World but only a single species occurs in the USA. Despite the great African and eastern Asian diversity the group is not represented in Europe although the monotypic Perrisina Strand, 1921 is endemic to Algeria.

  • XENOMYCETINAE Strohecker, 1962 includes 2 species of the single genus Xenomycetes Horn, 1880, both occur in the United States.

UK Species

Ecology

So far as is known all species are fungivores; some are associated with mammal, bird or social insect nests and many occur among leaf-litter in forest environments but in all cases they are known to consume various fungi and any association is due to the presence of fungi rather than the animal hosts. Myrmecophilic and termitophilic species very probably develop on fungi cultivated by the hosts but they may scavenge and develop on incidental fungi growing among nest detritus. Some species are generally associated with ants etc. in the wild e.g. Pleganophorus bispinosus Hampe, 1855 occurs under bark and among moss on various broadleaf trees, usually in association with Lasius brunneus. Insect host associations have been published for about 24 endomychids from 14 genera and 6 subfamilies. Several species have been observed feeding upon leaves and other plant material but in all cases they are otherwise known to be fungus feeders. Associations with various trees and other plants are often found in the literature but these more likely reflect associations between the host fungi and the plants on which the beetles occur. Both adults and larvae may feed upon large fruiting bodies, graze smaller ones or consume mycelia, some feed on spores and some have been observed feeding upon lichens. Very obviously a large number of species will be found by searching around the bark etc. of decaying wood, especially where fungi are obvious, or by sieving litter in wooded environments etc. and many species regularly occur in extraction samples from such situations. Adults of many species are gregarious and may be found by searching nocturnally, sometimes in unexpected situations; Mycetaea subterranea (Fabricius, 1801) occurs in the wild in tree hollows and old bird nests etc. but is also synanthropic occurring in damp cellars and stables etc. where they develop on fungi growing on walls or exposed structural timbers and may develop very large populations. Bird nests are always worth examining as several endomychids e.g. species of Symbiotes and Holoparamecus, are regularly present. More generally a few species are associated with stored products and may become pests as large populations develop, these include species of Holoparamecus, Mycetaea subterranea and Merophysia letourneuxi, and a wide range of products have been recorded including flour, grains, bones, nuts, chocolate, bamboo, wine corks and paper products etc. Trochoiderus desjardinsi has been recorded developing among kapok seeds and coconut husks. Many specific fungal-host associations will be found in the literature and while a few endomychids appear to be restricted to one host e.g. Symbiotes duryi Walton, 1910 or S. impressus Dury, 1912 with Pleurotus ostreatus, or Leiestes seminiger, Gyllenhal, 1808 with Piptoporus betulinus, the majority are polyphagous or oligophagous and some genera are associated with one type of fungus e.g. Lycoperdina with puffballs.

Description

Endomychids are small to medium sized beetles, 1.0-10.0mm, the majority being 2-7mm, and elongate-oval to almost circular and continuous or discontinuous in outline, moderately convex to flattened and widely explanate. The colour varies widely; smaller species are drab, otherwise black or brown to vividly red or yellow or with coloured patterns or spots, and many are variously metallic. Many are glabrous; when present the pubescence is fine and moderately dense, recumbent to erect and sometimes doubled. Head obvious from above, weakly declined and prognathous, the vertex smooth and variously punctured, rarely with major impressions etc. Frontoclypeal suture present, the clypeus generally quadrate to trapezoidal and narrow, labrum small, quadrate and curved anteriorly, mandibles small, curved and sharp or dentate. Eyes proportionally large and moderately convex, temples generally hidden within the pronotum, antennae 8-11 segmented although sometimes 4 or 5 segmented and modified, usually 11-segmented with a distinct 1-3 segmented club and inserted laterally in front of the eyes, in a few species the number of segments or the form of the club is sexually dimorphic. Labial palps 3-segmented with the terminal segment cylindrical to narrowly triangular, maxillary palps 4-segmented with the apical segment developed; oval to triangular or securiform. Pronotum broader than the head, transverse to weakly elongate and variously explanate, sometimes only in the basal half, and distinctly bordered laterally. Lateral margins very variable, posterior angles distinct and well-defined, anterior angles simple to strongly produced forward, sometimes substantially concealing the head. Surface variously punctured and microsculptured, usually with a pair of elongate basal impressions which may extend forward to the disc or to the anterior margin, or with sub-lateral grooves, in some exotic species with greatly developed structures; tubercles, ridges or spines. Prosternum variable, often long anterior to round, open posteriorly and closed internally, coxal cavities, the process usually long and reaching the mesosternal margin. Mesosternum short with coxal cavities open or closed by the metasternum. Metasternum broad and long anterior to transverse and widely separated coxal cavities, in many with distinct sub-coxal fovea and a median longitudinal impression, basal margin often arcuate either side of the middle and extending between the meso-coxae. Scutellum small to medium sized and generally distinct from above; triangular to truncate or apically rounded. Abdomen with 5 or 6 ventrites; the basal ventrite usually longest and lacking post-coxal lines. Elytra entire and completely covering the abdomen, usually continuously rounded apically and with well-developed and complete epipleura. The surface varies from finely and randomly punctured to strongly punctured and/or striate, in some exotic forms with greatly developed sculpture or very widely explanate, in outline generally broadest about or in front of the middle, curved laterally and tapering to the apex. Legs generally long and slender with concealed trocantins. Pro-coxae convex and circular to slightly transverse, not prominent and usually widely separated. Meso-coxae usually convex, round and widely separated. Metacoxae transverse and widely separated. Trocanters small, femora unarmed although in some exotic species with long and slender spines, tibiae slender with small and obscure spines on the inner apical angle. Tarsi 4-4-4 or 3-3-3, 1-3 variously lobed, in many the third is small and obscured by the lobes of the second. Claws simple and well-developed.

In temperate regions most species are quite typical although they vary widely e.g. the tiny Symbiotes and Mycetaea are very different from the much larger Endomychus or Lycoperdina and while some larger species e.g. Endomychus coccineus (Linnaeus, 1758) are strikingly coloured, the majority are quite drab and even within a genus the colour can vary widely e.g. Endomychus jureceki Mader, 1936 is entirely metallic blue. The small species of Pleganophorus are unusual in having 4-segmented antennae with the terminal segment greatly enlarged, and generally the rather atypical species of Holoparamecus are distinctive due to their elongate form and strongly constricted pronotum. Tropical species on the other hand can be very different and difficult to appreciate from a familiarity with temperate forms e.g. Neotropical species of Corynomalus Chevrolat, 1836 and southeast Asian species of Cyclotoma Mulsant, 1851 are very convex and rounded, often have long legs are often strikingly coloured and/or metallic. Some Southeast Asian species of Eumorphus Weber, 1801 have very widely explanate elytra and are quite unlike any temperate forms, this is most developed in E. marginatus Fabricius, 1801 and E. halaeus Arrow, 1920. But some of the most strikingly developed species have various pronotal and elytral modifications; some species of the Southeast Asian genus Amphisternus Germar, 1843 e.g. A. vomeratus (Gorham, 1901), have very large and curved horn-like elytral growths in both sexes. Among the most developed are some species of the Neotropical genus Cacodaemon Thomson, 1857; C. hamatus (Guérin-Méneville, 1837) has 3 large and blunt tubercles on each elytron, the entirely black C. satanas (Thomson, 1856) has long, thin legs and long thorn-like projections to the pronotum and elytra and the bizarre C. spinosus (Gorham, 1901) is similarly spined but has a red marking towards the base of each elytron. Similarly the larvae of some tropical species are strikingly developed with long multi-spined and brightly coloured defensive outgrowths.

Endomychid larvae vary widely in overall morphology, from simply elongate to fusiform or depressed and rounded, often pubescent and many have dorsal or lateral tubercles or well-developed and setose spines or other protuberances, and some have stiff and sharp or fan-like dorsal setae. Most are rather drab but some, especially in tropical areas, are brightly coloured or drab with brightly coloured markings.

Endomychus coccineus (Linnaeus, 1758) larva

A key to the British species is available HERE.

Symbiotes latus

L. succincta

Mycetaea subterranea

Holoparamecus caularum

H. depressus

H. singularis

Lycoperdina bovistae

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