Pocadius ferrugineus (Fabricius, 1775) and P.adustus Reitter, 1888

P.ferrugineus
Two species of Pocadius Erichson are recognised as British: P.adustus (lanuginosus Franz), which has been added since the publication of Joy's handbook, and P.ferrugineus. These are superficially very similar and both will key to P.ferrugineus in Joy although a little awkwardly as the head colour will be assumed to be variable.

Pocadius are distinctive and instantly recognisable, even in the field; 3-4.5mm, elongate oval, convex and rather shiny pale brown to the naked eye and generally found around fungi but they will need to be examined closely for a specific determination. Our species are easily separated (Johnson, 1976):

Head colour
In P.ferrugineus this is either entirely dark; black to dark brown, or the vertex is slightly and obscurely (visible at X20) lighter brown, contrasting with the pale pronotum. In P.adustus the head is entirely reddish brown, like the elytra and pronotum, or slightly darker or, rarely, darker around the eyes.

Apical margin of front tibiae from the external tooth to the apical spur
In P.adustus this is either straight or convex ie curved outwards. In P.ferrugineus it is concave (this is a character we have had trouble appreciating in some specimens).

Pubescence
In both species the entire upper surface is clothed with curved, backwardly directed yellow or golden pubescence, on the elytra this is arranged in longitudinal rows along the interstices. In P.adustus this is longer and more erect, most readily appreciated along the elytral margins where its length is about twice the width of the explanate margin. In P.ferrugineus it is much shorter and more recumbent; about the width of the explanate margin and more obliquely inclined.

It also seems obvious that P.adustus is broader with the elytral margins more parallel sided, in P.ferrugineus the elytra taper from the basal third to the apex.

These are morphologically very similar and very distinctive beetles which, once familiar, cannot be mistaken for any other. They are relatively large, 3.5-4.5mm, and , with the above differences in mind, the following description will serve both species. Overall colour orange brown with areas of the pronotum and/or elytra obscurely darker, entire body with pale or golden pubescence, rather sparse on head and pronotum. Head broadest at strongly protruding eyes, temples abruptly narrowed, clypeus produced and with a deep transverse furrow at base. Antennae 11 segmented, basal segment dilated on inner side, 9-11 strongly transverse and forming a broad and slightly elongate club, 9 and 10 dark, 11 brown. Head and pronotum with wide and shallow puncturation, cuticle more shining in P.ferrugineus. Pronotum convex, broadest in front of slightly obtuse hind angles, curved to projecting front angles. Anterior margin without border, posterior margin bordered and strongly sinuate. Margins of pronotum and elytra bordered, more widely explanate in adustus. Scutellum large and triangular, punctured and pubescent as pronotum. Each elytron with ten striae containing wide and shallow punctures, in adustus these are slightly deeper and the cuticle appears transversely wrinkled around them. Apices separately rounded in ferrugineus, broader and appearing somewhat truncate from above in adustus. Pygidium punctate and pubescent, more finely so in ferrugineus. Legs entirely pale brown. Middle and hind tibiae with rows of curved setae, as on elytra. Outer edge of all tibiae curved and produced at apex, anterior edge with a strong spine on inside. Tarsi 5-5-5, without lobed segments, last segment elongate. Claws narrow and curved, without tooth at base.

Both species are widespread across England and Wales (NBN as well as confirmed records given by Johnson) but apparently absent from the west country. Both appear to be local but there are many more recent records for ferrugineus and this species appears to occur further north. Johnson states that the Manchester museum collection contained 51 adustus (as lanuginosus) and 94 ferrugineus and the data suggested that the two do not appear to occur together.

In the literature P.ferrugineus has long been associated with puffball fungi (Lycoperdon spp.) eg Joy and Fowler but now the situation is not clear cut; Hurka also quotes the species from old puffballs but adds also in dry fungi of other genera. Our own few records are interesting in this respect, we have found P.ferrugineus in Whippendell wood among a large colony of puffball fungi (old and brittle fruiting bodies of Lycoperdon germaluce growing on the roots of an old dead Oak (03/04/09).

Two specimens of P.adustus were extracted from a sample of well rotten Laetiporus sulphureus taken from a fallen and decaying trunk of Prunus avium, the site was in deep shade and many other beetles were present.

P.ferrugineus pubescence

P.adustus pubescence

P.ferrugineus

P.adustus

P.ferrugineus

P.adustus

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