Telmatophilus Heer, 1841
POLYPHAGA Emery, 1886
CUCUJOIDEA Latreille, 1802
CRYPTOPHAGINAE Kirby, 1826
CRYPTOPHAGINI Kirby, 1826
T. brevicollis Aubé, 1862
T. caricis (Olivier, 1790)
T. typhae (Fallén, 1802)
This small genus includes 3 widespread Western Palaearctic species of small cryptophagid beetles (Cryptophaginae, Cryptophagini), all of which extend to the UK and some of which should soon be found when working marginal habitats and reed beds etc. Historically 5 species have been recognized and as these were keyed out in Joy’s handbook many UK collections are laid out accordingly, and so far as most UK collectors are concerned this situation endured until 2018 when the latest checklist reflected the 2012 revision by Otero. T. brevicollis Aubé, 1862 remains a distinct species and is readily identified by the proportions of the pronotum. T. sparganii (Ahrens, 1812) is synonymised with T. caricis (Olivier, 1790); these were formerly separated on colouration and size, sparganii being smaller and paler. T. schonherrii (Gyllenhal, 1808) is synonymised with T. typhae (Fallén, 1802), the separation was based on subtle differences in the shape of the pronotum and the colour of the femora. The situation is now straightforward and the species are readily identified as follows (based on Joy’s key):
-Pronotum quadrate or very nearly so, punctation fine and dense; the pronotum and elytra about equally punctured. Colour very variable, from entirely reddish-yellow to entirely dark or with yellow marks to the elytra. 2.0-3.0mm.
-Pronotum distinctly transverse and much more strongly punctured than the elytra.
-Pronotum densely and more strongly punctured, sides very slightly sinuate. 2.4-2.7mm.
-Pronotum not densely and less strongly punctured, lateral margins vary from evenly rounded with obtuse posterior angles (formerly identified as typhae) to slightly sinuate before perpendicular posterior angles (formerly schonherrii).
Among the UK fauna the genus is distinguished by the following combination of characters: Body elongate and discontinuous with the pronotum only a little narrower than the elytra. Head transverse and produced anterior to proportionally large, very convex asymmetrical eyes that are broadest behind the middle, and short temples. The vertex and frons are simply convex, without ridges, furrows or tubercles, and finely punctured and pubescent. Antennae inserted on the antero-lateral margin and separated by more than the length of the first segment; basal segment short and broad, 2-8 variously elongate and 9-11 broadened, forming a distinct club. Pronotum quadrate to transverse (up to 2X broader than long), lateral margins rounded and sinuate (sometimes hardly so) before distinct posterior angles, and variously denticulate, basal margin strongly sinuate. Surface simply convex or explanate laterally, sometimes with a fine transverse impression and small fovea near the base, and finely punctured and pubescent. Elytra elongate with distinct shoulders, weakly curved lateral margins and continuously curved around the apex, completely covering the abdomen; without striae although there may be a fine and partial sutural groove, punctation diffuse and fine, pubescence fine and recumbent. Legs long and slender, entirely pale or with the femora darker. Femora simple, without teeth, tibiae simply broadened towards the apex; sometimes more strongly so in the female, basal tarsal segments broad and lobed, the second and third often strongly so and concealing the tiny fourth segment, terminal segment long and slender. Claws smooth and without a distinct basal tooth. The saproxylic species Paramecosoma melanocephalum (Herbst, 1793) is superficially similar but smaller; 1.8-2.2mm, lacks lobed tarsomeres and has a fine keel at the base of the pronotum. Our 2 species of Henoticus Thomson, C.G., 1868, which occur among fungi or are occasionally found in stored products, might also be mistaken for the present genus but they have a deep transverse groove at the base of the pronotum and lack the lobed tarsal segments of Telmatophilus.
Telmatophilus brevicollis Aubé, 1862
T. brevicollis occurs throughout Central and Southern Europe but is rare and local in the UK; it is widespread in East Anglia but otherwise confined to the Kent coast, South Hampshire and the area around the Severn estuary. Adults occur on branched bur-reed, Sparganium erectum L. and larvae develop among the flowers.
2.3-2.6mm. Body dark brown, contrasting with pale the legs and rather dense pale pubescence. Distinguished by the transverse (about 2X wider than long) and very convex pronotum which is broadest about the middle, strongly sinuate in the posterior half and very finely crenulate laterally. Compared with our other species the pronotum is flatter and distinctly explanate towards the lateral margins. The surface is finely and moderately densely punctured and transversely impressed before the base, this terminating in a small fovea either side although this may be obscured by pubescence.
Telmatophilus caricis (Olivier, 1790)
T. caricis is widespread and locally common across England and Wales although generally absent from the west country and more scattered further north to the Scottish border, the pale form, formerly known as sparganii, is known from only a few southern records. Adults are associated with bulrush, Typha sp. and bur-reed, Sparganium sp. and larvae develop within the seed heads.
2.4-2.8mm. Forebody black, elytra variously brown although sometimes they are very pale with darker sutural and lateral margins, appendages pale; entire dorsal surface with fine pale and recumbent pubescence. Body distinctly more convex compared with our other species. Pronotum near-quadrate and widest slightly in front of the middle, variously sinuate towards the base, sometimes very weakly so, evenly convex and without impressions or other sculpture, crenulations to lateral margins very fine. Pronotal and elytral punctures about equal in size and density. Elytra with a fine and shallow but distinct groove beside the suture.
Telmatophilus typhae (Fallén, 1802)
T. typhae has a rather disjuct English distribution; it is locally common in the southeast; Kent and East Sussex, and across Wales and central England but absent from much of the West Country and southern central England, further north it is generally local and scarce to the Scottish border. The form formerly called schonherrii occurs throughout this range but is very scattered and infrequent. Adults occur on a range of marginal plants but are mostly associated with common bulrush, Typha latifolia L., upon which the larvae develop.
2.0-2.5mm. Body entirely black or with the elytra a little paler, the pubescence fine and recumbent. Pronotum slightly but distinctly transverse, strongly rounded laterally and usually sinuate before the posterior angles, crenulations fine but obvious. Base with a transverse impression linking two small fovea. Pronotal punctures stronger and denser than those on the elytra. Elytra often with an oblique shallow impression from below the shoulders extending almost to the middle.