Cartodere Thomson, C.G., 1859
POLYPHAGA Emery, 1886
CUCUJOIDEA Latreille, 1802
LATRIDIINAE Erichson, 1842
According to Rücker (2010) this genus of small scavenger beetles includes 39 species in two subgenera, but because various species have been included in closely similar genera, other estimates will be found online and in the literature. The greatest diversity is in the Palaearctic region but this is likely because many regions remain under-explored e.g. C. barclayi Rücker, 2012 was recently described from New Guinea. The first fossil species, C. succinobaltica was described from Baltic amber in 2012 (Bukejs, 2012). So far as is known the species are mould feeders which, at least in the wild, are mostly associated with decaying vegetation and seeds etc, but some may be found among mould in almost any situation e.g. on dung and rotting fruit. Larvae are often common among decaying vegetation or under bark, and they were formerly frequently recorded from damp basements etc. where they developed among spores and moulds. They are thus ideally suited to infesting stored grains and fruits etc and in this way several Palaearctic species have become more or less cosmopolitan through international trade in foodstuffs. Although they are sometimes common among stored foods they do not cause direct damage as they feed on spores and hyphae, rather they are an indication of damp conditions and suitable drying techniques will usually destroy an infestation. Adults will occur regularly among extraction samples etc, but they are generally nocturnal and a very good way of sampling them is to examine dead wood that has started to develop fungus or slime moulds; freshly cut stumps and branches may also attract large numbers of specimens, especially where sap is oozing from the xylem.
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They are small beetles, 1.25-2.5 mm, readily identified among our UK fauna by the habitus, which is typical of many latrid genera, the lack of angled keels to the head (cf. Lithostygnus), the broadly-oval and free (not fused) elytra, and the form of the pronotum which has two well developed longitudinal keels and strongly indented lateral margins which may include translucent membranes in fresh specimens. The subgenera are readily identified by the form of the antennae; in Cartodere s.str. the club is two-segmented while in Aridius Motschulsky, 1866 it consists of three segments. The European fauna includes two species of Cartodere s.str. and four species of C. subg, Aridius although other species have been recorded e.g. C. (C.) approximata (Wollaston, 1877), which is native to St. Helena, C. (C.) australica (Belon, 1887) which is known from Adelaide and only doubtfully recorded from Europe, or C. (C.) norvegica Beach, 1940 which was recorded from mouldy poplar bark near Cologne and is probably the introduced Australian species C. (C.) satelles (Blackburn, 1888). Of our four UK species, C. nodifer (Westwood, 1839) and C. bifasciata (Reitter, 1877) are widespread and generally common throughout the UK, both occur throughout Europe and both extend to northern latitudes of Fennoscandia, while the remaining species are much more restricted.