TACHYPORINAE MacLeay, 1825
This easily recognizable group includes some of the most abundant and widespread rove beetles in Britain. Species such as Tachyporus hypnorum occur in huge numbers all year round, in a wide range of habitats.
By staphylinid terms this is a rather small subfamily although many more species are likely to be added, especially from warmer regions of the world; at present there are about 1500 described species in 40 genera and 5 tribes, the group has a worldwide distribution and is well-represented in northern temperate zones. Species occur in almost all ecosystems and are often among the most frequently recorded members of the family, the majority are associated with decaying vegetation such as leaf-litter and compost but many occur in decaying fungi and dung and large populations may occur in agricultural biotopes, the majority are facultative predators and considered to be beneficial because among the commonest prey items are aphids.
The genus Derops Sharp, 1889 includes several eastern Palaearctic and Oriental species; there may also be a Nearctic species but this may prove to be a distinct genus. Originally included within the Phloecharinae, Derops is now transferred to the present subfamily as the only genus of this new tribe. Megarthropsiini Cameron, 1919 is also a small Palaearctic group of about 20 species included in 4 genera. Vatesini Seevers, 1958 is a Neotropical group including two genera of myrmecophilous species. The remaining two tribes include the majority of species and are the only representatives across much of the western Palaearctic and Nearctic regions; Tachyporini Macleay, 1825 is most diverse with about 24 genera while Mycetoporini Thomson, C.G., 1859 includes 11 genera, both are almost cosmopolitan in distribution.
Members of this subfamily may be recognized by their fusiform habitus but many other species also have this form and so, until a familiarity of the group is gained, the antennal insertions must be examined as these are crucial in defining the group. The following general description will serve to identify them. Body almost always fusiform, the head narrower than the pronotum and the abdomen tapering from base to apex, most are shiny and glabrous (Sepedophilus Gistel, 1856 is a notable exception) and have various long sensory setae to the pronotum, elytra and abdomen, and many are brightly coloured. Head usually with small and weakly convex eyes, often retracted into the pronotum so that the temples are not visible (Lordithon Thomson, C.G., 1859 and a few other genera are exceptions), antennae slender and weakly broadened towards the apex, without the sensory setae seen in Trichophya and Habrocerus, inserted laterally or towards the front of the head but always outside the base of the mandibles, palps usually short but the terminal segment is very variable. Many Aleocharinae are superficially similar but here the antennae are inserted on the dorsal surface of the head, usually near the anterior margin of the eyes. Pronotum usually broadest near the base and narrowed to rounded anterior angles, and generally smoothly convex and without sculpture. Scutellum usually visible. Elytra quadrate to elongate, with distinct shoulders, more or less parallel-sided and truncate or separately rounded apically. Here the two tribes may be distinguished by the form of the suture; in Mycetoporini they are raised into convex border while in Tachyporini they are flat and form a smooth joint. The surface tends to be smooth and only finely punctured in Tachyporini while in many Mycetoporini there are series of larger punctures, sometimes forming distinct striae; typically a row close to the suture and a row close to the lateral margin as well as others on the disc. The abdomen is typically strongly tapering from the base to the apex, finely punctured and not, or only weakly raised laterally e.g. in Lordithon Thomson, C.G., 1859. The terminal segment(s) are sometimes modified and differ between the sexes and these are often a valuable aid to identification e.g. in some Tachinus Gravenhorst, 1802. The legs are long and slender and some species e.g. Sepedophilus Gistel, 1856 are capable of running very fast when disturbed, in most the fore femora are short and not visible in normal setting while the middle and hind femora are longer and plainly visible. The tibiae are slender and near parallel-sided, with various lateral setae and a pair of spines at the inner apical angle; these tend to be short in many Tachyporini (Tachinus is an exception) and longer in Mycetoporini. Tarsi 4- or 5-segmented, in many Tachyporini they are dimorphic, being dilated in the males, in Mycetoporini the difference is weaker and sometimes very slight. In general species of Tachyporini are much more widespread and common and at least some will occur in just about any habitat, those of Mycetoporini are best looked for among decaying fungal bodies. Generic identification is straightforward and here Joy’s key still works but specific identification will require a series of more modern works, Mike Hackston provides a key to genera and a valuable key to our species of Tachyporus Gravenhorst, 1802, which are based on more extensive keys to the central European genera and species by Dr Arved Lompe. A refined version of Joy’s keys can be found on Mark Telfer’s website and this should be consulted for a general common sense approach to the group. Two papers should also be obtained; Peter Hammond’s 1973 key includes all our species of Sepedophilus and a great deal of interesting discussion of the genus and can be found in the Entomologists monthly magazine Vol. 108: 130-165, while our species of Tachyporus are keyed out by Roger Booth HERE . two versions of this key are available, one of which includes more general morphology, and both use the arrangement of tiny pores and setae on the elytra, they will require a bit of practice with high magnification and low-angle lighting but are worth the effort as even teneral specimens will be confidently identified.
Tachyporini MacLeay, 1825
Our UK Tachyporini fauna includes 40 species of 6 genera. Sepedophilus are distinct among the subfamily in being finely and densely pubescent and lacking, or almost lacking, raised abdominal borders. They are associated with decaying vegetation in damp situations and some of the most common will also be found under bark or associated with decaying fungi on stumps and fallen timber, they are generally nocturnal but may be seen running on timber in hot sunshine, adults occur year round and will soon appear among suitable extraction samples. The south of England is most diverse in species and some e.g. S. bipunctatus (Gravenhorst, 1802) are more or less restricted to that region, but it is probably true to say that the group as a whole is under-recorded e.g. S. constans (Fowler, 1888) is common across South Hertfordshire but the NBN would suggest otherwise. Tachyporus includes small, red and dark bicoloured species that are distinguished by the presence of outstanding setae to the pronotum and elytra and a reduced terminal maxillary palpomere. Lamprinodes saginatus (Gravenhorst, 1806) shares these characters but here the distal antennal segments are strongly transverse, in Tachyporus they are elongate to quadrate and only rarely slightly transverse. Lamprinodes is a widespread but very local insect of England and Wales with occasional records from Scotland, Man, Lundy and Anglesey. Coproporus immigrans Schülke, 2007 is a small, 2.2-2.8mm, but very distinctive species; it has fully-developed apical maxillary palpomeres, antennomeres 9 and 10 strongly transverse and relatively massive and convex forebody and elytra. It is thought to be of Asian or Australian origin and has been spreading in northern Europe in recent decades, there are scattered records across the south of England and it seems likely to become more widespread and common. The species generally occurs among decaying wood and may be associated with ants. Tachyporus includes our most widespread and abundant species though most become much more local in the north. They occur in a wide range of habitats and will soon appear from general sweeping in the warmer months or by sampling tussocks etc. during the winter. T. hypnorum (Fabricius, 1775) is not only very common but also easily identified, even in the field, and will provide a good introduction to the genus. Cilea silphoides (Linnaeus, 1767) is locally common in decaying fungi and plant remains across the south, it is very distinctively coloured and, though small, easily recognized in the field. Fourteen of the thirty or so European species of Tachinus Gravenhorst, 1802 occur in the UK and many are widespread and common, they are broader and more robust than other members of the subfamily and as such are distinctive, they probably occur in a wider range of habitats than other members of the subfamily as they will often be found among carrion, dry dung or at sap as well as the usual decaying plant matter. Species are always more than 3mm long, they lack setae on the lateral margins of the pronotum and elytra but (except in T. lignorum (Linnaeus, 1758)) have a few long setae on the distal abdominal segments, the terminal maxillary palpomere is about as long as the penultimate. Joy’s key remains useful but the recent addition to our list of T. flavolimbatus Pandellé, 1869-which will key to T. marginellus (Fabricius, 1781) or T. laticollis Gravenhorst, 1802-make these couplets redundant. The key by Dr Arved Lompe covers all the UK species although our very common and widespread species T. rufipes (Linnaeus, 1758) is given by more recent name of T. signatus Gravenhorst, 1802.
Mycetoporini Thomson, C.G., 1859
Our UK Mycetoporini fauna includes 28 species of 7 genera. They tend to be less widespread and common compared with members of the previous tribe and, at least in our experience, almost always associated with decaying fungi, and when found they tend to occur in small numbers. More than half our species are included in the genus Mycetoporus Mannerheim, 1830, and our two species of Ischnosoma Stephens, 1829 were formerly included as well, but at least six of these have been added to our list since Joy’s key was written and so this is now not useful. Species of both genera are recognised by the very narrow terminal maxillary palpomere, and Ischnosoma have longer antennae but in any case are distinctively coloured. They are colourful, shiny and glabrous species with flat eyes, long lateral setae and pubescent abdominal segments, the elytra always have a sutural and lateral row of strong punctures and there are often extra rows on the disc. Several species are widespread but none is particularly common, they occur in decaying vegetation, fungi and moss and specimens may sometimes be found on damp dead wood at night. All our UK species are keyed HERE. Bolitobius Leach in Samouelle, 1819 and Parabolitobius Zhao & Sakai, 2000 may be identified by the third antennomere which is about twice as long as the second, our three species are widespread and our two Bolitobius may be locally common. In the remaining species the third antennomere is, if at all, only slightly longer than the second. Our five species of Lordithon Thomson, C.G., 1859 have a distinctive appearance with the strongly tapering abdomen and elytra widened towards the apex, more subtly the base of the terminal maxillary palpomere is as wide as the apex of the penultimate segment. They are shiny and glabrous, rather flattened species with long setae and spurs to the middle and hind tibiae, in all cases the head is black and the appendages pale, the body otherwise varies in colour. All species are associated with saproxylic fungi and several e.g. L. lunulatus (Linnaeus, 1760) or L. trinotatus (Erichson, 1839) are widespread and locally common. Bryoporus cernuus (Gravenhorst, 1806) is distinguished by a strong setiferous puncture on the inner margin of each eye and by having the terminal maxillary palpomere distinctly narrower than the penultimate segment, it is in any case of a distinctive shape and colour and, at 4.5-5.5mm, not likely to be confused with any other species. It is very rare in the south (East Anglia) and known from only a few records. Two species of Bryophacis Reitter, 1909 occur in the UK, both of which are very local and rare; B. maklini (Sahlberg, J., 1871 is known from a few specimens collected in the Lake District and the Scottish Highlands while B. crassicornis (Mäklin, 1847) is known from the Norfolk coast and northeast of England. The genus may be recognized by the incised basal margin of the scutellum and the short and transverse penultimate maxillary palpomere.
Tachyporini MacLeay, 1825
Mycetoporini Thomson, C.G., 1859