Triplax russica (Linnaeus, 1758)

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POLYPHAGA Emery, 1886

CUCUJOIDEA Latreille, 1802

EROTYLIDAE Latreille, 1802

EROTYLINAE Latreille, 1802

TRITOMINI Curtis, 1834

Triplax Herbst, 1793

This species is locally common across Europe from The Pyrenees to Northern Italy, the Balkans and parts of European Russia, it extends north to the UK and the far north of Fennoscandia and is known from the Caucasus and north west Africa, in central Europe it is often the most common member of the genus but in the south it is local and often confined to mountain areas, to the north it is sporadic and very local in the southern Baltic countries but generally common across Scandinavia. In the UK it is locally common across south and central England but rare in the west; it is generally absent from the north but is widespread though local in the northern Scottish Highlands. Adults are present year-round; they overwinter among decaying wood and fungi or under bark and become active early in the year, peaking in abundance from May until August. Typical habitats are deciduous woodland and parkland with plenty of mature trees in various stages of decay, they occur on a wide range of trees but more often on ash, birch, beech and oak, and on the continent sometimes on pines and other conifers. Mating occurs through the spring and females oviposit either directly into various sporocarps or among crevices beneath, the most common hosts are tinder fungus (Fomes fomentarius (L.) Fr. 1849), Dryad’s Saddle fungus (Cerioporus squamosus (Huds.) Quélet (1866)) and various species of Inonotus P. Karst (1879) but adults are sometimes common in Chicken –of-the-woods (Laetiporus sulphureus (Bull.) Murrill (1920)) and Oyster mushrooms (Pleurotus (Fr.) P. Kumm. 1871) among others. Fully-grown larvae pupate among host material or in crevices from early June and new-generation adults appear from July. Adults are nocturnal and both adults and larvae are mycophagous, they disperse on warm spring and summer evenings and are sometimes active at night on trunks and stumps but otherwise remain among host material and are rarely seen, they usually occur in numbers and usually among numbers of other mycophagous beetles, including the superficially similar T. aenea (Schaller, 1783). Nocturnal searching among bracket fungi and bark is the best way to find adults but they sometimes appear in numbers by tapping older brackets over a sheet, and they may occur in suitable extraction samples at any time of the year.

Triplax russica 1

Triplax russica 1

Triplax russica 2

Triplax russica 2

Triplax russica 3

Triplax russica 3

Triplax russica 4

Triplax russica 4

Triplax russica 5

Triplax russica 5

5.0-6.5 mm. Elongate-oval, flattened and discontinuous in outline, forebody and legs orange, elytra, scutellum and antennae black, underside extensively orange with meso- and metasternum, coxae and trocanters black. Head transverse with convex and prominent eyes and smoothly convex and sparsely punctured vertex and frons, terminal maxillary palpomere strongly securiform and antennae with an abrupt and loose three-segmented club. Pronotum transverse, broadest towards slightly acute posterior angles and evenly narrowed to projecting anterior angles, apical margin curved and basal margin widely sinuate, surface convex but variably impressed medially in front of the base, punctures large, shallow and widely separated, basal margin finely bordered and with a series of larger, mostly elongate punctures. Elytra smoothly narrowed from finely-toothed humeral angles to a continuous apical margin, basal margin with a transverse series of larger and sometimes confluent punctures, surface variably impressed inside the shoulders but otherwise rather flattened, striae consist of rows of punctures which may be faint or even absent in places, interstices finely punctured throughout. All coxae widely separated, femora flat and broad, tibiae gradually widened from the base to obliquely-truncate apices and without terminal spurs. Tarsi 5-segmented but appearing 4-segmented as the small fourth segment is partially hidden within the broadly-lobed third segment, terminal segment curved and almost as long as the others combined. Claws smooth and without a basal tooth.

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