Teredus cylindricus (Olivier, 1790)

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POLYPHAGA Emery, 1886

CUCUJOIDEA Latreille, 1802

BOTHRIDERIDAE Erichson, 1845

TEREDINAE Seidlitz, 1888

Teredus Dejean, 1835

Unusual among our members of the family in being saproxylic, the others being largely subterranean, this species has historically been considered very rare and endangered in the UK with only a few scattered records from old established deciduous woodland in Berkshire, Surrey and Nottinghamshire but there have been a few more recent records from the southeast and, at least from our local experience, there seems to have been a recent increase in distribution and abundance. More widely it occurs throughout Europe extending north to Öland and east into western Russia Asia Minor, it is also recorded from Algeria and Tunisia but it is nowhere common and in most parts of northern Europe it is very local and rare. Adults probably occur year-round; we have recorded them from April to October and there are other records from January, we have also observed them mating from May until July and so it seems likely they breed in spring and early summer with larvae developing through the summer and new-generation adults appearing in late summer and autumn, peak populations occur from May until July. Adults occur in woodland and wooded parkland etc., they are nocturnal and occur more or less exclusively on areas of dry denuded and often extensively cracked xylem of oak, beech and horse chestnut although we also found them in large numbers on Prunus avium, they usually occur in numbers and often in abundance. They often occur alongside the ant Lasius brunneus (Lat.), which nests in trees and is active on the surface of trunks etc. at night but a specific association is unlikely as locally (South Hertfordshire), where the beetle abundant in our local park and woodland, while it often occurs with the ant it is more often present in its absence. Larvae develop within galleries of other wood-boring beetles and are known to predate Ptilinus pectinicornis (L.), Anobium spp, Dryocoetes villosus (Fab.) and Xestobium rufovillosum (Deg.).

Teredus cylindricus 1

Teredus cylindricus 1

Teredus cylindricus 2

Teredus cylindricus 2

Teredus cylindricus 3

Teredus cylindricus 3

Adults are likely to be confused with Rhizophagus in the field but may be distinguished by the form of the antennae and pronotum.  3.5-4.5mm. Elongate, sub-parallel and convex with the pronotum almost half the elytral length, entirely black or with the elytra dark reddish-brown, appendages lighter brown. Head transverse with weakly convex eyes and evenly convex vertex and frons, frontoclypeal suture deeply impressed and clypeus evenly rounded anteriorly, punctation fine and diffuse; each puncture well-separated from its neighbours. Antennae inserted laterally in front of the eyes, 11-segmented with a well-defined 2-segmented club. Pronotum elongate, about 4:3, broadest behind a smoothly curved apical margin and narrowed to sharp posterior angles, laterally narrower and slightly sinuate in the basal third or half so appearing distinctly broader in the apical half (which gives the species a very distinctive appearance). Surface smoothly convex, diffusely and quite strongly punctured and extremely finely microsculptured. Scutellum transverse with curved lateral margins. Elytra parallel-sided and continuously curved apically, with distinctive forwardly-produced shoulders and regularly punctured striae which mostly fade just before the apex, interstices very finely and sparsely punctured. Legs robust and moderately long, with broad, ventrally excavate femora substantially visible with normal setting. Tibiae curved and broadened from base to apex, the external apical angle produced sharp and slightly produced, the middle and hind tibiae with several short and stiff apical setae, the front tibia with a short but distinct apical spur. Tarsi 4-segmented; segments 1-3 short and lobed below, the terminal segment curved and proportionally very long. Claws smooth and curved with a blunt tooth in the basal half.