Colydiidae
Includes 12 British species contained within 9 genera and 2 subfamilies. Small to medium sized beetles (2.5-7.0mm), mostly elongate and either convex or flattened. Larvae and adults are associated with fungi on a range of broadleaved trees, under bark or within galleries of wood boring beetles or among decaying vegetable matter. None of our species are common although several e.g. Bitoma may be locally so and many have a restricted distribution.

Antennae usually clubbed, although Orthocerus is an interesting exception, 10 or 11 segmented, rarely 8 or 9 and inserted in front of eyes, basal segment either exposed or concealed beneath the anterior clypeal margin. Pronotum quadrate or elongate and usually with front angles produced. Elytra entirely covering abdomen, usually striate and often carinate. Tarsi simple ie without bilobed segments, 4 segmented except in Langelandia in which there are 3.

Our only member of Pycnomerinae, Pycnomerus fuliginosus Er., was only recently added to our list by Welch (1964) from specimens found in tidal refuse at Slapton, Devon. This Australian import has now become naturalised and is found under the bark of various broad leaved trees. It occurs around the Hants/Surry/Sussex borders, Devon and Epping forest and now in Herts. (Alexander). A small (4mm or so) and very distinctive species; antennae with a weak 2 segmented club and all other segments transverse. Head and pronotum strongly punctured, pronotum widest before front angles and with a longitudinal furrow either side of centreline. Elytra elongate and gradually contracted to apex, interstices barely wider than striae; flat with short and stout golden setae. An excellent habitus drawing is included in Welch's paper. A second species P.terebrans (Olivier), known only from bronze age fossils from Shropshire, Somerset and London (Alexander) is not now included in the British list.

Our other species are included within three tribes of the Colydiinae. Orthocerini includes a single British species, Orthocerus clavicornis (L.), keyed out in Joys Orthoceridae within his Teredilia and quoted simply as local. Medium sized, 4-5mm, and very distinctive; elongate and almost parallel with the head strongly and broadly produced in front of the eyes, dull black with lighter scales and curved setae which are especially noticeable along the sides and on the legs. Head and pronotum irregularly raised, alternate elytral interstices raised. Antennae are unique among British beetles. Generally around roots of grass tussocks in sandy places.

Synchitini includes the genera Synchita Hellwig, Cicones Curtis, Bitoma Herbst, Endophloeus Dejean and Langelandia Aube in the UK. Synchita includes two species, S.humeralis (Fab.) and a recent addition to our list, S.separanda (Reitter), added by Allen (1964). The genus is keyed to the Nitidulid subfamily Erotylinae in Joy purely for practical reasons and without any phyllogenetic justification.. Both species are described and compared in detail in Allens paper with good line drawings of the whole insects (minus appendages) as well as male genitalia and a discussion of the historic occurrence of each species is given. These are small, 2.5-5mm, elongate and drab species occurring in fungi on broadleaved trees during the summer. They are uncommon and have a mostly southeastern distribution.
Two species of Cicones occur in Britain of which one, C.undatus (Guerin-Meneville), has only recently been added to our list by Mendel and Owen (1987) from specimens found under sycamore bark during 1984 at Windsor Great park. A key is given separating this from our other species, C.variegatus (Hellwig), and line drawings of both are provided. Since this original discovery the species has been found regularly throughout the year at the Windsor site. Our other species is a rare insect of southeast England. Both are small, 2.5-3.5mm, elongate and drab species associated with broadleaved trees. Both will key to Cicones (Nitidulidae, erotylinae) in Joy.
Bitoma Herbst is featured.
The last known record of Endophloeus markovichianus (Piller and Mitterpacker) was from south Hampshire in 1927 and the species may now be extinct in the UK.
Langelandia anophthalma Aube is a small, 2.5-3.5mm, rather parallel-sided species with a distinctive pronotum; sides finely crenulate and broadest in front of middle, front angles produced and surface with three longitudinal raised lines. Color varies from pitchy to reddish or testaceous sometimes with the head and pronotum darker. It is a rare species of southeast England (Joy quotes Kent only) generally occurring underground in decaying potatoes (Joy quotes August).

Colydiinae includes two genera, Colydium and Aulonium Er. both of which are featured.

See ID Aids for a key to the genera

References
Allen, A.A., 1964. The genus Synchita in Britain; with an addition to the fauna and a new Synonym. Ent.Mon.Mag 100: 36-42
Mendel, H. and Owen, J.A., 1987 Cicones undata new to Britain. Ent.Rec 99:93-95
Welch, R.C. 1964. Pycnomerus fuliginosus new to Britain. Ent.Mon.Mag. 100:57-60


Aulonium
trisulcus

Aulonium
trisulcus

Aulonium
trisulcus

Bitoma
crenata

Bitoma
crenata

Bitoma
crenata

Bitoma
crenata

Colydium
elongatum

Pycnomerus
fuliginosus

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