CURCULIONINAE Latreille, 1802
This extremely variable group includes some of the most typical and familiar British weevils. Various species can be found in almost all habitats.
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POLYPHAGA Emery, 1886
CURCULIONOIDEA Latreille, 1802
12
29
111
1.2-8mm
Introduction
This huge group is the largest of the weevil subfamilies; it includes about 24000 described species in more than 2200 genera and about 30 tribes, the limits of the group remain rather vague and because of the very wide radiation within many of the genera and tribes no straightforward series of characters will suffice to define it. In some cases the boundaries are vague and various classification systems will be found in the literature, similarly while various groups are recognized as distinct their placement or ranking may vary e.g. Cryptorhynchinae Schoenherr, 1825 have sometimes been included as tribes of the Curculioninae. As a consequence the group is usually described in detail and placed at various points in artificial keys according to the accompanying fauna, this is generally straightforward and easy to deal with where the fauna is limited, but becomes much more difficult in e.g. the Neotropical region where the weevil fauna exceeds 10000 species and all subfamilies vary enormously. This may seem a remote complication for UK workers but such large faunas blur the limits of the various groups and our small fauna must be classified accordingly, hence the need for artificial keys. A particular nuisance is the overlap in morphology between the present group and various Brachycerinae Billberg, 1820, particularly the tribe Erirhinini Schoenherr, 1825, where the superficial resemblance is often remarkable, but the groups are readily separated by fundamental differences in the structure of the genitalia. And so while the relationships of the various groups are still being researched we must accept that the most efficient way to describe the group is by a series of combinations of characters, each of which sits rather awkwardly within a key to the higher groupings of weevils within our fauna. Any attempt to characterize the group morphologically is likely to be futile without an extensive list of characters, clauses and exceptions e.g. the habitus is about as variable as it can be and any generalization will include most of the other weevil groups, but a rather superficial description, and it must be stressed that exceptions will be found for most of the characters, of the group is as follows. Head small and sub spherical, always distinct though variously inserted into the thorax, without a pregular sclerite and with a prementum exposed and visible in ventral view, eyes well-developed and usually large, circular or longitudinally-oval. antennae geniculate with a 5-7 segmented funiculus and a compact and pubescent
club displaying distinct segments and sutures, rostrum long and curved with distinct lateral scrobes. Pronotum quadrate to transverse, prosternum variable; usually without a rostral channel and often lacking antero-lateral lobes. Mesepimeron not ascending and so not visible from above. Elytra with distinct punctured striae and epipleura, scales very variable but never bifid. Femora often toothed ventrally, otherwise smooth, toothed or serrate. Tibiae simple apically, mucronate or with an uncus on the front and middle tibiae but absent or much reduced on the hind tibiae, where present the apical comb of setae are inserted transverse to the tibial axis, tibial spurs absent. Tarsi pseudotetramerous; usually with the third segment strongly bilobed and partly or wholly concealing a tiny fourth segment. Sexual dimorphism is general among the subfamily and is typically and most obviously displayed in the proportions of the pronotum and/or elytra, the length of the rostrum and the placement of the antennae. All tribes are defined by particular combinations of characters which, at least in our limited fauna, makes them very distinctive e.g. in Smicronychini the eyes are placed latero-ventrally and appear close together when viewed from below, the prosternum has a well-formed rostral channel and the claws are connate at the base, and such combinations are mentioned in the following brief overview of the tribes represented in the UK. Fortunately many of our tribes include very distinctive species which will soon become familiar, at least at the generic level, and there are a few very good keys covering the whole family.
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The biology of the group is similarly varied, all are phytophagous and most are groups are restricted to various plant families, most species are oligophagous and the subfamily includes many genera and species associated with trees and woody shrubs although here they feed on foliage or reproductive parts rather than in roots or dead wood. Many are associated with wetland plants but our UK fauna does not include aquatic species. Larvae feed on all parts of plants including seeds, flower buds and catkins, some mine leaves and many either induce galls or develop within galls induced by various wasps. A diverse fauna will be found in all lowland biotopes, rather less so in upland situations, and all are worth working extensively, woodland and grassland, especially on calcareous soils will soon repay the effort; salt marsh margins, heath land, reed beds and waste ground generally will also be found rewarding, and adults of most species are strong fliers and so long-term studies can yield good lists. All UK species are thought to be univoltine and most are active from early in the year, many become inactive during the warmer months and in many species new-generation adults appear after June or July and so the best times to sample are spring/early summer and again in late summer/autumn, and many overwinter as adults and so winter sampling can be productive. As a whole the subfamily includes many serious pest species but in the UK they are rarely a problem, on the other hand very large populations of various species will sometimes be found, these often present serious problems to commercial growers on the continent but rarely so in the UK. The greatest diversity is in the south of the UK and gradually diminishes with latitude but many species occur only, or more frequently, in the north and so travelling to sample new sites can be very rewarding. Life histories and distributions are mentioned in the species accounts and these will give a good idea of how to go about finding and studying the various species, but a varied list of species will soon accrue by simply sweeping and beating a range of plants, many are active nocturnally and will come to light or appear in flight-interception traps, especially on wooded or wetland margins. It cannot be stressed enough that to target species a good knowledge of the host associations and life cycle are essential e.g. species of Cionus Clairville, 1798 will appear sooner or later by generally thrashing about with a sweep net, but a familiarity with figworts and mulleins will allow a series of species to be sampled. The following brief guide to our subfamilies should serve to introduce this concept.
UK Tribes
ACALYPTINI Thomson, C.G., 1859
This small Old-World tribe formerly included only 4 or 5 genera but several more have been transferred from the Derelomini, a tribe represented in Europe by 3 species of 2 genera but not in the UK, and now about 50 species of 12 genera are included, only a single species, Acalyptus carpini (Fabricius, 1792) occurs in North America and this was introduced from the Palaearctic region. No species are known from Africa and the greatest diversity is in the Oriental and Australasian regions although none occur in New Zealand. The Palaearctic genus Acalyptus Schoenherr, 1833 includes 4 species, 2 occur in Europe of which one, A. carpini, extends to the UK. Acalyptus is the only widespread genus, the other genera and species are endemic to certain Islands e.g. Sri Lanka, New Guinea, Java or Luzon etc, or restricted to certain areas of Australia and the southern and eastern Palaearctic region including India and Japan. The European fauna includes only two species of the single genus Acalyptus, both of which are widespread and extend north into Fennoscandia, but only A. carpini occurs in the UK.
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Members of this tribe are sometimes known as flower weevils as the adults generally occur in the flowers of their hosts and it is known that at least some species are involved with pollination; several tropical species are associated with various palms and coconut in particular, one species from Malaysia and Singapore, Derelomorphus eburneus Marshall, 1934, is restricted to coconut flowers and may be an important pollinator. More generally they feed within the flowers of a wide range of Malvaceae, Meliaceae, Arecaceae and Salicaceae, adults feed and mate within the flowers and eggs are laid within flowers or into the stems, ovaries or stamen structures. Larvae generally feed within various flower structures and end up feeding within the ovary, when mature they fall to the ground and pupate in the soil, the few species occurring in temperate regions are univoltine. In warmer areas of Australia, New Guinea, Indonesia and India several species have become pests of cultivated cotton, and several sometimes form large and destructive populations on various Malvaceae.
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Species are small and relatively soft-bodied weevils with a distinctive elongate-oval appearance and long narrow rostrum. The head is small with symmetrically-convex eyes that often contact the anterior pronotal margin, the antennae are geniculate with 7 funicular segments and placed laterally about the middle of the rostrum which is oriented down and forward. The prothorax is not, or only very finely, bordered laterally, widest about the base and narrowed to a rounded or straight anterior margin. The prosternum is long in front of closely approximated and round or elliptical coxae which are separated by a narrow process but there is no rostral channel, the anterior margin is simple and not extended into post-ocular lobes. Mesosternum short with round or elliptical and well-separated coxae. Metasternum with a well-developed median longitudinal impression and transverse coxal cavities. Elytra elongate, smoothly rounded laterally and truncate to almost continuously rounded apically, with complete punctured striae and densely scaled but without erect sensory setae. Femora not toothed, fore tibiae not toothed, middle and hind tibiae gradually broadened to sharp apical angles but not toothed. Tarsi pseudotetramerous, claws separated to the base and simple, without a basal tooth. Many species show sexual dimorphism in body size, the length and form of the rostrum or the shale of the prothorax.
ANOPLINI Bedel, 1884
Variously classified as a distinct subfamily of the Curculionidae, this small tribe includes only two genera, Anoplus Germar, 1820 with 3 Palaearctic species, and Paranoplus Hustache, 1920 with 4 species from Madagascar. Two species of Anoplus are widespread and generally common across the Palaearctic region and extend north to the UK while a third, A. setulosus Cherry, 1870, is a rare species of southern and central Europe. They are all small beetles, <3mm, elongate and entirely black but for pale antennal scapes, they have a small head with a relatively broad and short rostrum, transverse pronotum and large elytra bearing strongly punctured striae, they are otherwise rather nondescript but immediately distinguished among our fauna by their 3-segmented tarsi which terminate in a widely lobed third segment and lack claws. Our two species are widespread in England, Wales and Scotland, A. plantaris (Naezén, 1794) is locally common, mostly on birch, while A. roboris Suffrian, 1840 is much more local and rare, mostly on alder. Eggs are laid in the spring on host foliage which the larvae will mine, fully-grown larvae cut their way out of the mine and fall to the ground where they will pupate. Adults occur on host foliage from April until late in the year and have been recorded in the winter from litter around the base of host trees.
ANTHONOMINI Thomson, C.G., 1859
This large tribe includes about 830 species in 43 genera, it is most diverse in the New World and, with the exception of the Palaearctic fauna which includes about 90 species of 9 genera (5 of which are monotypic and one including only 2 species), most regions are poor in species; the Afrotropical fauna includes 34 species of 13 genera, 21 species of 5 genera are Oriental and only 2 species are recorded from the Pacific region but none extend to Australia. By contrast the Neotropical fauna includes about 560 species of 19 genera and 165 species of 18 genera occur in North America. With about 560 species Anthonomus Germar, 1817 is by far the largest genus; it occurs in all regions except Australia and includes the only Holarctic member of the tribe, A. pomorum (Linnaeus, 1758). The Palaearctic fauna includes 58 species of 8 genera, of which about 25 species of 6 genera occur in Europe (although the monotypic Macrobrachonyx Pic, 1902 is endemic to the Canary Islands, and the monotypic Sphincticraerus Marseul, 1871 is restricted to Northwest Africa and Spain) and 12 of these extend to the UK. All other Palaearctic genera are either monotypic or include very few species, the exception is the wholly Palaearctic Bradybatus Germar, 1824 with 20 species, 7 are European and one, B. fallax Gerstaecker, 1860, extends to the UK. Furcipus Desbrochers des Loges, 1868 and Brachonyx Schönherr, 1825 both include single Western Palaearctic species that are widespread in Europe and extend to the UK. Many of the genera and species have formerly been included in Anthonomus and so are likely to be missing from older literature.
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Members of the tribe are mostly oligophagous and a very wide range of herbaceous and woody plants have been recorded as hosts; worldwide host plant families include Asteraceae, Solanaceae and Vitaceae among others. A few species have become serious agricultural pests e.g. Anthonomus aeneotinctus Champion, 1903 is an important economic pest of various peppers (species of Capsicum L, Solonaceae) in Central America and the southern states of North America, and A. grandis Boheman, 1843 is a serious pest of cultivated cotton in the United States and Mexico. The larvae of most species develop within galls or plant reproductive structures. Our UK species are mostly associated with woody shrubs and trees, the only exceptions being Anthonomus brunnipennis Curtis, 1840 which occurs on Tormentil (Potentilla erecta (L.), and A. rubi which occurs on a range of rosaceous shrubs and trees. Anthomonus phyllocola (Herbst, 1795) is associated with Scot’s Pine in Central Scotland, the larvae developing within male cones. Brachonyx pineti (Paykull, 1792) is also associated with Scot’s Pine, it occurs in Central Scotland but also very locally in East Anglia, here the larvae develop and pupate at the base of the leaves. Bradybatus fallax is a recent addition to our list and at the moment is very local in the south east, larvae develop in the seeds of various maples and adults overwinter, appearing on host flowers in the spring. Our species are mostly very local and rare but A. rubi (Herbst, 1795) is generally abundant throughout England and Wales, and A. pedicularius (Linnaeus, 1758), which is associated with hawthorn, is common and widespread in the south but rare north of The Wash and mostly absent from The West Country. Adults of most occur over a long season from spring to autumn but many are also active in the winter as they attack unopened buds; A. bituberculatus Thomson, C.G., 1868 though widespread across England and Wales is infrequently recorded but may be found through the winter by beating hawthorn branches. None of our species are economic pests but A. pomorum (Linnaeus, 1758) can be a nuisance in gardens as the larvae feed within apple blossom-buds causing them to turn brown and stop developing, but in certain areas of Europe and Asia however it is frequently a serious economic pest of apples and occasionally other fruits.
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Morphologically defining characters of this tribe are very difficult to list because many other groups both within the subfamily and elsewhere among the weevils share many of their features, hence they are usually keyed out as genera rather than as a tribe but the following general description applies to the majority of species. Small to medium sized species, in the UK from 1.5-4.9mm, elongate and rather parallel-sided with the elytral base wider than the pronotum, usually drab brown to black but many have characteristic patterns of contrasting scales to the pronotum and elytra. Head small with asymmetric and often protruding eyes; these can be unusually flattened and prominent in some species, rostrum long and cylindrical; usually distinctly curved but sometimes (Furcipus) almost straight. Antennae long and slender; the scape not reaching the anterior margin of the eyes, funiculus 6 or 7-segmented and the club long and slender. Pronotum transverse to weakly elongate; broadest about the middle and usually narrowed to a more-or-less straight basal margin, anteriorly often constricted before the apical margin which is narrower than the base, surface without distinct structure. Prosternum usually lacking a rostral channel and without post ocular lobes; the coxae usually equidistant between the apical and basal margins. Mesepimera not ascending and not visible from above. Elytra with prominent shoulders and continuously curved apically, completely covering the abdomen, with complete, well-impressed and punctured striae. Legs long and slender with all femora of similar width and variously toothed internally; the front femora usually with a distinct single or (rarely) doubled tooth. Tibiae often sinuate internally and usually produced apically into a moderate internal tooth. Tarsomere three distinctly bilobed. Claws free and expanded at the base, appendiculate, toothed or split longitudinally.
Anthonomus
12 species
Brachonyx
1 species
Bradybatus
1 species
CIONINI Schönherr, 1825
Furcipus
1 species
This is a small tribe of about 200 species in 7 genera, it is most diverse in the Palaearctic region with only a relatively few species extending south into India, Southeast Asia and Africa, it is absent from the New World although a single species, Cionus scrophulariae Linnaeus, 1758 has become established in the United States. The majority of species, about 180, are included in Cionus Clairville, 1798, which occurs throughout the Palaearctic region and is also diverse in India, Mediterranean and southern Africa, including Madagascar, and Southeast Asia; the Palaearctic region includes more than 60 species of which 29 occur in Europe. Southern Europe is most diverse in Cionus where several are restricted to alpine habitats but 17 species occur in central and northern areas and of these 6 very widespread species extend to the UK. Cionellus Reitter, 1904 includes the single species C. gibbifrons (Kiesenwetter, 1851) which is widespread in southern Europe and northwest Africa and also known from Turkey. Cleopus Dejean, 1821 includes 2 very widespread European species of which one, C. pulchellus (Herbst, 1795) extends to the UK, a third species, C. japonicus Wingelmüller, 1914 occurs in China and Japan. Formerly classified within the Nanophyinae but recently transferred to the present tribe, Nanomicrophyes Pic, 1908 includes a single species from the Caucasus and 4 recently discovered species from China. Patialus Pajni, Kumar & Rose, 1991 includes a single species from India. Stereonychidius Morimoto, 1962 includes a single species from eastern Siberia and Japan. Stereonychus Suffrian, 1854 includes about 10 species distributed throughout the Palaearctic region and extending south into the Philippines; of the 4 species occurring in Europe only 2 are widespread but none extend to the UK.
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The 2 UK genera, Cionus and Cleopus, include very distinctive weevils that should not be mistaken for any others although specific identification of Cionus species can be difficult without reference material. All are small to medium sized weevils, 2.2-5.0mm with very broad and slightly elongate elytra, narrow pronotum and a small head, the group may be distinguished among the UK fauna by the 5-segmented funiculus, concealed pygidium and abdominal sternites 2-4 curved backwards towards the lateral margins. All species have dense elongate scales which often obscure the underlying cuticle, these usually form distinct dorsal patterns; in most these are substantially pale with areas of darker scales arranged into symmetrical patterns or tessellations along the elytral interstices, and a common feature seen in many are one or two near-circular large and dark maculae on the elytral suture. In most the scales are simply recumbent but in some e.g. C. olens (Fabricius, 1792) they are ‘doubled’, with dense recumbent scales and also erect scales to the elytra. The ventral surface is usually clothed with scales but less densely so. The head is narrower than the pronotal fore-margin and visible mostly as a pair of large and convex eyes, the interocular distance being less than or equal to the width of the rostrum. The rostrum is long, narrow and variously curved or angled about the middle, the lateral scrobes being concealed from above, the antennae are geniculate with a long scape that broadens towards the apex, the first two funicular segments are usually longer than the others and the 3-segmented club is usually long and pointed. The pronotum is broadest across the base and strongly narrowed to a straight or slightly curved anterior margin, the posterior angles are acute and the basal margin is sinuate either side of the middle, the surface is usually strongly punctured and there is a variable subapical constriction it is otherwise devoid of structure. Legs long and robust with projecting coxae and small trocanters obliquely joined to the femora, the fore-coxae are separate (in UK species) but there is no rostral channel between. Femora sinuate at the base and broadened to a variously-developed ventral tooth, the distal part narrowed, tibiae long and narrow, usually sinuate at the base and obliquely truncate or simply curved apically, in most without any obvious apical spines. Tarsi pseudotetramerous with the third segment widely bilobed and the terminal segment much longer than the others, claws connate and simple or with only a small tooth towards the base, in many Cionus the claws on the front tarsi are unequal in the male, usually with the inner claw shorter than the outer. (Species of Patialus and Stereonychidius have only single claws.) Elytra slightly elongate with a more-or-less straight basal margin and rounded shoulders, the base much broader than the base of the pronotum, weakly rounded or parallel-sided laterally and continuously curved around the apex, well-impressed and narrow punctured striae are present to the apex but usually obscured by the dense scales.
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Cleopus pulcellus is local and sometimes common throughout England and Wales and occurs sporadically and rarely further north to the Scottish Highlands. Three of our Cionus species are common, C. scrophulariae (Linnaeus, 1758) throughout the mainland though rarer in Scotland, C. tuberculosus (Scopoli, 1763) which occurs across southern England and the midlands but is largely absent from Wales, and C. alauda (Herbst, 1784) which is common across Wales and England north to Nottingham. C. hortulanus (Fourcroy, 1785) has a similar southern distribution but is much less frequently recorded, and C. nigritarsis (Reitter, 1904) is widespread in southern England and the midlands though absent from the West Country but very local and rare and records are widely scattered. C. longicollis Brisout de Barneville, 1863 is confined to the brecklands of Norfolk and Suffolk although there are old records from Hampshire.
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In the UK there are one or two generations each year; adults appear in the spring and are present until late in the summer or into the autumn, they generally occur in numbers where found and are easily sampled by sweeping or beating suitable foliage. Host plants include various species of Verbascum L. (mulleins) and Scrophulularia L. (figworts) (Scrophulariaceae) and adults have been observed feeding on Buddleja and various introduced Scrophulariaceae. Mating occurs from early in the season and eggs are laid on host foliage, larvae have been recorded from April until September, they feed on flowers and leaves in the open and are covered with a secretion which protects them from parasites and gives them the appearance of a shiny grey or yellow blob, they develop quickly and pupation occurs from Late June or July in a spherical cocoon attached to the underside of a leaf or among flower-heads where it resembles an unopened bud. New-generation adults are active through the summer and autumn and overwinter in the soil. In warmer climates there may be several generations each year e.g. in India Cionus hortulanus, which is a major pest of Verbascum Thapsus L. grown commercially for medicinal purposes, produces at least two generations between June and October.
CURCULIONINI Latreille, 1802
This small tribe has traditionally included 3 subtribes but it has recently been revised ( Pelsue, F.W. & O’Brien, C.W. 2011) and now includes 16 genera divided into 6 subtribes, the majority of species, about 350 (although quotes of up to 500 will be found in the literature), are included in the Holarctic genus Curculio Linnaeus, 1758 and the greatest diversity is in the eastern Palaearctic and Oriental regions. The Nearctic fauna is represented by about 30 species of Curculio and also includes the adventive Palaearctic species Archarius salicivorus (Paykull, 1792). Briefly the subtribes may be outlined as follows but further changes are likely and there are other genera, mostly from Southeast Asia and Madagascar, of doubtful placement. The monogeneric Erganiina Pelsue & O’Brien, 2011 occurs in China. Labaninina Pelsue & O’Brien, 2011 includes 3 genera and about 20 species from China, Japan and Southeast Asia. Pseudobalaninina Heller, 1925 includes Carponinus Heller, 1924 from the eastern Palaearctic and southeast Asia, and Aviranus Fairmaire, 1902 and Pseudobalaninus Faust, 1889 from Madagascar. Archariina Pelsue & O’Brien, 2011 includes about 30 species of the widespread Palaearctic genus Archarius Gistel, 1856, 3 species of Koreoculio Kwon & Lee, 1990 from Japan and Korea, and the monotypic Pagumia Kwon & Lee, 1990 from China. The European fauna includes 6 species of Archarius, of these 3 are widespread and extend into Asia but 3 are very restricted; A. troglodytes (Jekel, 1861) and A. vicetinus (Cussigh, 1989) are endemic to Italy while A. ochreatus (Fahraeus, 1843) occurs in Spain and France (2 ssp.). Timolina Heer, 1925 includes the single African genus Timola Pascoe, 1886. Curculionina Latreille, 1802 includes several small Old-World genera e.g. Indocurculio Pajni, Singh & Gandhi, 1994, which originally included 2 species from India but now includes several more from Southeast Asia, and the monotypic Pimelata Pascoe, 1888 from India, but is dominated by the large genus Curculio which occurs worldwide except for much of South America. The Palaearctic fauna includes about 155 species of Curculio, they are by far most diverse in the east, especially in China and Japan, and this continues a very diverse Southeast Asian fauna, but only 10 occur in Europe. Of the European fauna most are widespread Eurasian species that also occur in Mediterranean North Africa, this applies to 6 species that extend to the UK, and only C. propinquus Desbrochers, 1868 is confined to Europe, being widespread in the south and southeast, the local C. reichei Desbrochers, 1868 occurs in Italy and Crete but also in Turkey.
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Most species may be recognized by the long, curved rostrum and compact body form but more precisely members of this tribe are distinguished from other weevils by their vertically opposed mandibles and ascending mesepimera which, unlike in some groups such as Ceutorhynchinae, are not visible from above between the base of the pronotum and elytra, the only exceptions to this are certain exotic members of the huge subfamily Baridinae which is only poorly represented in the UK. The following general description will separate the tribe from other groups of weevils. Colour usually drab brown to grey, often with patterns of contrasting lighter or darker scales, entire dorsal surface with dense tomentose or squamose scales and sometimes with erect seta-like scales, in some with erect series of scales in the sutural interval towards the apex. Head transverse with weakly convex eyes that occupy most of the margin, rostrum long, curved and tubular with long lateral scrobes not visible from above, usually glabrous beyond the antennal insertions but some with subapical tufts of long setae, in some the rostrum is very long and here the pre-rostrum is often straight, vertex substantially retracted into the prothorax, interocular distance usually small. Antennae 11-segmented, geniculate, the scape usually long and slender, funiculus 7-segmented, the club, which may be very slender, 3-segmented though often appearing 4-segmented due to a constricted apical segment. In many the rostrum is longer in the female. Prothorax not bordered laterally, usually sinuate across the base, broadest in the basal half and narrowed to a more-or-less straight anterior margin, post ocular lobes absent or at most only very weakly developed, coxae closed behind and placed towards the base of the prosternum, closely approximated. Mesosternum short and produced between the coxae to meet the metasternum, the coxae round or weakly transverse and separated by at most the diameter of a coxa, mesepimera ascending but not visible from above. Scutellum varying in shape and sculpture but always visible. Elytra with 11 well-impressed and usually punctured striae, the interstices punctured and sometimes cross-rugose, but otherwise without sculpture. Pygidium usually exposed in males. Legs long and robust with clavate femora which may have a ventral tooth, pro- and mesotibiae usually uncinate, metatibiae uncinate, mucronate or with an apical tooth or appendage internally in males but lacking in females. Claws free and toothed at the base, in some species apically bifid.
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The common name of acorn weevils or nut weevils refers to the association of many species with the fruits of various trees; many are associated with Fagaceae (oaks), Betulaceae (hazel) and Juglandaceae (hickory) where the larvae feed within developing fruits. Most species are oligophagous and in mixed woodland there will usually be a preferred host. The female uses her long rostrum to bore into acorns etc. prior to ovipositing, generally only a single egg is inserted into each nut and the larva will develop rapidly within, the fully grown larva will leave the fallen nut and pupate in the soil, adults emerge the following year and so the life-cycle is univoltine but larvae are able to diapause within the host for up to three years, producing abundant adult populations in certain years. Some species may occur in very large populations and become pests of commercial forestry e.g. Curculio occidentis Linnaeus, 1758, the filbert weevil, is an occasionally serious pest of several species of oak in North America, C. caryae Horn, G.H., 1873 is an economically important pest of pecan and walnuts, and C. sayi (Gyllenhal, 1836) the lesser chestnut weevil, together with the less prevalent C. caryatrypes (Boheman, 1843), large chestnut weevil, is a widespread pest of commercially grown chestnuts in the United States, in Europe this role is taken by C. elephas (Gyllenhal, 1836), the chestnut weevil, here it is a more serious pest and bad infestations can infect 90% of chestnuts, control of this species is also more difficult because while the American species are confined to chestnuts, C. elephas also develops in acorns of Quercus ilex L., holm oak. The ‘classic’ nut weevil is Curculio nucum Linnaeus, 1758, a widespread Palaearctic species which attacks hazel nuts, in northern areas it generally occurs in small ‘wild’ populations but in countries such as France, Spain, Italy and Turkey where hazel nuts are grown as commercial crops it remains a serious pest. Other feeding strategies are also seen in the group where larvae develop commensally within galls produced by various wasps or within male catkins of various trees.
ELLESCINI Thomson, C.G., 1859
The classification of this group has varied over the years and it has sometimes been considered as a distinct subfamily of the Curculionidae, it is now generally divided into 2 subtribes but the limits and generic placement remain unsettled. Ellescina Thomson, C.G, 1859 includes 7 genera but will almost certainly be revised; Ellescus Dejean, 1821 includes 15 species and is Holarctic in distribution, 4 occur in North America and 5 in Europe of which the very widespread E. bipunctatus (Linnaeus, 1758) extends to the UK. The other genera are restricted in distribution and some are only doubtfully included in the group; the Australian Sellechus Lea, 1908 will probably be assigned to Storeini, Bathrorygma Marshall, 1926 (Java) and Minyrophilus Voss, 1957 (Sri Lanka) are doubtfully placed, and Minyrus Schönherr, 1835 and Ontoctetorus Faust, 1895, both from Southeast Asia and the Oriental regions, are now more usually includes in Anthonomini. The 2 species of Proctorus LeConte, 1876 occur in the Nearctic region. Dorytomina Bedel, 1886 includes 3 genera and is Holarctic in distribution; with about 80 species Dorytomus Germar, 1817 is by far the most diverse genus, 21 species occur in the Nearctic region and the rest are Palaearctic; 26 species occur in Europe and 14 of these extend to the UK. The 3 species of Adorytomus Voss, 1953 occur in China, Japan and Southeast Asia, and the monotypic Rodotymus Zumpt, 1932 in Central Asia.
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All UK species are associated with willows (Salix L.) and/or poplars (Populus L.); larvae develop in catkins or developing shoots although some foreign species develop in sawfly galls on willow stems, and pupation occurs in situ. Adults of most species occur year-round and are active over a long season; they overwinter under bark or among dead wood and often become active during mild spells when they can be found on fencepost etc. through the night. Many of our UK species are widespread and common and may be sampled by beating or sweeping host material but nocturnal searching is by far the easiest way to find them in numbers. Perhaps the most common UK species is D. taeniatus (Fabricius, 1781), which occurs on willows in most habitats and should soon be found by beating foliage, but another willow-feeding species D. melanophthalmus (Paykull, 1792)is also common and widespread. Common species associated with poplars include D. tortrix (Linnaeus, 1760) and D. dejeani Faust, 1863. D. longimannus (Forster, 1771), readily identified by its very long front legs, is associated with black poplar and is locally common throughout England and Wales. Ellescus bipunctatus (Linnaeus, 1758) is a widespread and locally common species associated with willows in damp habitats; adults overwinter among grass tussocks and occasionally occur in extraction samples. Mating pairs of most species may be found in spring and early summer and larval development occurs accordingly but other strategies occur; in Germany Dorytomus melanophthalmus oviposits in the autumn and the eggs overwinter to produce spring larvae which develop in catkins, the biology may be similar in the UK where adults occur from early March until December.
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Members of the tribe are small to medium-sized and elongate weevils similar in appearance to Anthonomus etc., many are characteristically patterned or coloured but identification within the group can be difficult. Dorytomus are distinguished from other genera within the subfamily by the combination of simple claws and a well-developed tooth beneath the front femora, Ellescus has toothed claws and lacks the femoral tooth but can be distinguished by the overall appearance and by having small and sharp tooth at the internal apical angle of all tibiae. The funiculus is 7-segmented in both genera. While some species of Dorytomus are characteristically coloured and patterned the majority are variable in appearance and host plant associations are of little help, beyond this the characters used in their identification are often subtle and the ventral surface will usually need to be examined, fortunately we have several very good keys to the UK fauna and with a little experience and access to a few reference specimens the majority of specimens can be confidently identified.
Dorytomus
14 species
Ellescus
1 species
MECININI Gistel, 1848
This is a small group of about 240 species in 7 genera, it is mostly Palaearctic in distribution with only a single native species in North America although a further six have been introduced and become established, a single monotypic genus, Colubus Schönherr, 1843 occurs in South Africa and the 4 known species of Rhinumiarus Caldara, 2001 occur in South America (Suriname and Argentina), several Western Palaearctic genera extend into North Africa, several are represented in tropical Africa and some have been transported with trade to other parts of the world. Gymnetron Schönherr, 1825 is the most diverse genus with about 100 species, it is absent from the Nearctic region but otherwise widespread in Eurasia and tropical Africa. Cleopomiarus Pierce, 1919 includes about 40 species, it is widespread in the Palaearctic region and also represented in tropical Africa and North America (possibly introduced); 19 species are Palaearctic and many of these are restricted in distribution e.g. to Syria and Turkey or Algeria and Morocco, or endemic to certain countries e.g. Japan, Afghanistan and France but at least 6 are widespread; 8 occur in Europe and 3 of the most widely-distributed species extend to the UK. Mecinus Germar, 1821 includes about 55 Palaearctic species and subspecies, at least 4 of which have become established in North America, the majority occur in western areas and many have a restricted distribution or are endemic to certain countries, several occur only in North Africa and several more European species extend south into northwest Africa and The Middle East, more than 40 species occur in Europe and western regions are most diverse but about 12 are very widespread and of these 6 extend to the UK. Miarus Schönherr, 1826 includes about 20 Palaearctic species, the greatest diversity is in the west; 13 occur in Europe and 2 are endemic to northwest Africa, only 4 species are widespread and of these only R. campanulae (Linnaeus, 1767) extends to the UK. Rhinusa Stephens 1829, formerly a subgenus of Gymnetron, includes about 40 Old World species, of which 5 are established in North America, 32 are Palaearctic (mostly in western regions) and several more occur in North Africa, at least 12 are very widely distributed and of these 5 extend to the UK.
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All species are small, <5mm, they vary from elongate, flattened and rather parallel-sided to broadly-oval and convex in form, they are drab grey or with various red or brown markings and most are distinctly pubescent and this usually forms rows on the elytra. Useful and almost universal characters for separating the group are 5-segmented funiculus, only partially visible tarsal sockets and connate claws, the ventral margin of the scrobes is rounded and slightly protruding (from above), the prosternum lacks a rostral channel, tergite 7 is to some extent exposed and the posterior margin of the third and fourth ventrites is usually angled laterally. These characters will distinguish all UK genera except for Cleopomiarus and Miarus, here the claws are not connate and the prosternum has a deep channel between the coxal cavities, but they are otherwise distinctive weevils readily assigned to the group by the 5-segmented funiculus and unarmed front femora.
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Palaearctic species of Gymnetron are associated with Plantaginaceae, and more particularly species of Veronica L. while those in tropical Africa are more general and associated with various Scrophulariaceae. Our UK species are all oligophagous on various species of Veronica with larvae inducing galls as they develop in stems or fruits, and with the exception of G. veronicae (Germar, 1821) all are very local and scarce. Species of Miarus are associated with various Campanulaceae, our single UK species, M. campanulae (Linnaeus, 1767) is usually associated with Campanula rotundifolia L. Species of Rhinusa are associated with a range of Scrophulariaceae and Plantaginaceae; our 3 UK species occur on Linaria vulgaris Mill. (Toadflax), the larvae develop in fruits, stems and roots and induce gall formation. R. antirrhini (Paykull, 1800), which is locally common in the south of England, has been used as a biocontrol agent in The United States. Some foreign species are inquilines in galls made by other members of the genus. Larvae of Cleopomiarus develop in various Campanulaceae but adults visit a wide range of flowers where they feed on pollen, 2 of our 3 UK species are widespread and associated with various Campanula L. and Phyteuma L. but the very local and rare C. micros (Germar, 1821) is monophagous on Jasione montana L. (sheep’s bit scabious). Mecinus are associated with Plantagineae; 6 species occur in the UK and several are widespread and generally common; M. janthinus Germar, 1821 is a recent introduction that seems to be spreading rapidly while M. collaris Germar, 1821 is a widespread but very local species of salt marshes.
Cleopomiarus
3 species
Gymnetron
5 species
Mecinus
6 species
Miarus
1 species
Rhinusa
3 species
RHAMPHINI Rafinesque, 1815
This relatively small tribe of very distinctive weevils occurs throughout the world with the exception of much of Australia and most of the Neotropics, diversity is greatest in the Old World tropics but the Palaearctic region has a very rich fauna, especially when compared to that of North America. In older works the group was often classified as a distinct subfamily which corresponded broadly with the subtribe Rhamphina, and many of the species were included in only a few genera, especially Orchestes, Rhamphus and Rhynchaenus. In a modern and broader sense the tribe is now usually classified into 4 subtribes, the largest of which is Rhamphina Rafinesque, 1815, it includes all the Nearctic and European species and the vast majority of the Palaearctic fauna, it includes 15 genera, of which 11 are Palaearctic and 6 occur in Europe. In terms of species about 150 are Palaearctic, of these about 50 occur in Europe and 19 extend to the UK. The largest genus is Orchestes Illiger, 1798, a Holarctic group extending south to the Congo and Madagascar, about 70 species are Palaearctic and 18 of these occur in Europe. Two more genera, Isochnus Thomson, 1859 and Tachyerges Schoenherr, 1825 are Holarctic, but beyond this the subtribe is an Old-World group, several genera are widespread e.g. Rhamphus Clairville, 1798 occurs across the Palaearctic region and is also known from Australia, but several are of rather restricted distribution e.g. Indodinorrhopalus Pajni & Sood, 1981 from Nepal, India and Thailand, or Sphaerorchestes Morimoto & Miyakawa, 1996 which occurs from Japan to Nepal and Borneo, and some are endemic to certain areas e.g. Afrosmicronyx Hustache, 1935 from Mali, Rhamphonyx Voss, 1964 from Sudan or Rhynchaenophaenus Voss, 1956 from New Guinea. No genera and only a very few species are endemic to Europe e.g. Rhamphus monzinii Pesarini & Diotti, 2012 and Orchestes longulus Schaufuss, 1862 from Italy, Pseudorchestes angelovi Dieckmann, 1970 from Bulgaria, and P. kostali Dieckmann, 1985 from Hungary, among a few others. Dinorhopalina Voss, 1936 is an Old-World subtribe of two genera; one from Japan and Burma, and one from South Africa. Ixalmina Voss, 1936 includes only Ixalma Pascoe, 1871, a small genus of about 12 species from India, Japan and Southeast Asia. Tachygonina Lacordaire, 1866 includes 4 genera from central and South America although a few species of Tachygonus Guérin-Ménéville, 1833 (which was formerly included in another subfamily) extend north as far as Canada.
Most species may be recognized by the enlarged hind femora, which are adapted to provide a powerful jump, the rostrum reflexed under the body although the front coxae are usually contiguous or nearly so, and the eyes which are generally placed close together. Some other weevil groups e.g. Ceutorhynchinae, include a few species capable of jumping, albeit feebly when compared with the present tribe, but they are otherwise very distinct. Most species are small or very small, 1.0-5.0mm, and of a characteristic elongate-oval shape, either continuous in outline or with the shoulders distinctly broader than the base of the pronotum, and varying from dark and almost glabrous, with only very fine dorsal pubescence, to densely scaled and colourful or distinctly patterned, in some there are long erect setae to the lateral margins of the head, pronotum and the base of the elytra. The head is typically small and, from above, consists mostly of large and convex eyes which are either closely approximated or touching; the vertex is generally short and variously punctured and scaled or pubescent. The rostrum is usually curved, long and slender, generally 3-7X longer than broad, with lateral scrobes not visible from above, its orientation varies widely from almost smoothly continuous with the vertex to steeply declined and almost perpendicular to the vertex. The antennae are usually geniculate with the basal segment much longer than the second segment and there is usually a distinct angle between the two, but in some e.g. species of Rhamphus Clairville, 1798 the basal segment is more or less equal to the second, lacking an angle between the two, and these are best described as ‘orthocerous’. The form of the scape is usually long and distinctly broadened to a rounded apex, the second and third segments are usually longer than 4-8 which vary from weakly transverse to elongate but they are rarely very long and in most the antennae are short or only moderately long, segments 9-11 form a distinct and usually elongate club. The prothorax is usually broadest about the base and narrowed to a straight or weakly curved anterior margin, the basal margin is straight or only weakly produced towards the centre and the lateral margins are not bordered. The surface is variously punctured, often strongly so, and generally lacking structure although in some there is a median longitudinal depression, the prosternum is usually long anterior to the coxae and in repose the rostrum lies either on the prosternum or over the coxae, rather than in a central rostral channel as in e.g. Ceutorhynchinae. The elytra are very variable; mostly elongate-oval with variously developed shoulders and a continuously rounded apical margin, in some they are proportionally very large or very broad and in most they are only moderately convex, the striae are distinct to the apex, finely to moderately punctured and narrower than the interstices although in some e.g. Rhamphus, the punctures may be very strong. The legs are well-developed in all cases; the femora may be simple or toothed or, e.g. in some Orchestes, the hind femora may have a series of stiff spines or setae towards the apex, in most the hind femora are much larger than the middle femora but e.g. Isochnus, only slightly so. Tibiae usually about as long as the femora, only weakly broadened towards the apex and usually with only weakly-developed apical spurs although in soma the hind tibiae are produced into a sharp spur. Tarsi pseudotetramerous, the two basal segments normally developed and the tiny fourth segment hidden within the strongly bilobed third segment. Claws well-developed; usually smooth, curved and with a distinct basal lobe or tooth.
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In temperate regions most species are thought to be univoltine with adults overwintering and reproducing in the spring, larvae developing through the spring and summer and new-generation adults appearing in late summer and autumn. Hosts include a range of deciduous trees and shrubs although many species occur on a rather narrow selection such as elm, oak, alder, birch, poplar and various willows, eggs are laid on leaf surfaces and larvae develop and pupate within leaf-mines. Adults of most species usually occur in small numbers but some may occasionally swarm in the spring or early summer e.g. we found Isochnus sequensi (Stierlin, 1894) in numbers by sweeping grass below poplar trees on a reservoir margin in South Bucks during late May and early June. Some may occasionally produce large populations and become pests of ornamental or commercially-grown trees, most notably Orchestes fagi (Linnaeus, 1758), the beech leaf-mining weevil but also e.g. O. testaceus (Mueller, 1764,) the alder flea weevil or Orchestes alni (Linnaeus, 1758), the elm flea weevil. A much smaller number of species are associated with herbaceous plants, in the UK Pseudorchestes pratensis (Germar, 1821) develops on knapweed while Rhynchaenus xylostei Clairville, 1798 (a widespread European species but known in the UK from only a single 19th century record) is associated with Fly-honeysuckle, Lonicera xylosteum.
Rhamphus
3 species
Rhynchaenus
1 species
Tachyerges
4 species
SMICRONYCHINI Seidlitz, 1891
This is a small tribe containing about 160 species in at least 7 genera and probably more as there are many named specimens of uncertain placement which probably belong here, it has sometimes been included as a group within the Erirhinini Schönherr, 1825 or as a distinct subfamily of the Curculionidae Latreille, 1802, but is now widely accepted as a tribe of the Curculioninae. Worldwide the group is poorly understood and most genera are in need of revision but the faunas of northern temperate regions are fairly well understood. The greatest diversity is in the Holarctic region and the group is only poorly represented elsewhere; Australia, India, Africa and Central America. Afrosmicronyx Hustache, 1935 includes 10 species and is a largely Afrotropical genus although a single species extends north to Tunisia but none are present in Europe. Topelatus Hustache, 1920 includes 6 species and is endemic to Madagascar. Sharpia Tournier, 1875 is a mostly Palaearctic genus of about 12 species, they occur in semi-arid regions of the Mediterranean, Caucasus and Near East, extending east into the middle of Asia and south to Mediterranean North Africa. Three species occur in Europe but only the Eurasian S. rubida Rosenhauer, 1856 is widespread; it occurs around the Mediterranean and extends into central Europe but has not been recorded from the UK. Promecotarsus Casey, 1892 includes 4 Nearctic species. The monotypic genus Hedychrous Marshall, 1923 occurs in Bangladesh and India. The majority of the species, about 140, are included in the large genus Smicronyx Schönherr, 1843, this is usually divided into five or more subgenera although Afrosmicronyx is variously included and some are variously considered as distinct genera e.g. the European Chalybodontus Desbrochers, 1897. Three subgenera are confined to the Nearctic region and this fauna, along with members of the nominate subgenus, includes about 70 species. The Palaearctic fauna includes about 50 species of 3 subgenera; 6 species of Chalybodontus occur in Europe or adjacent parts of western Asia and northwest Africa, a single species of Pseudomicronyx Dietz, 1894, introduced from North America, occurs in Europe and the remainder, including 17 European species, belong to the nominate subgenus. Several European species are of very restricted distribution but 5 are very widespread and of these 3 extend to the UK. The genus is otherwise widespread, occurring in the Oriental region, Southeast Asia and extending into northern Australia, and in the New World south to Nicaragua.
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Members of this tribe are small to medium sized weevils, from about 1.5 to 8.0mm, elongate and discontinuous in outline, with a small head and quadrate to transverse pronotum which is broadest about the base and narrowed to a straight anterior margin, the base of the elytra is broader than the base of the pronotum and usually has distinct shoulders. In most the dorsal surface is clothed with broad recumbent scales and fine setae, the pronotum is extensively punctured or finely tuberculate and the elytra have distinct and well-impressed striae from the base to the apex. Variation in size, shape and vestiture is fairly wide and while the colouration is mostly drab grey to brown with various patterns in some species, there are no obvious features distinguishing the group. However, among the UK fauna they may be distinguished by the small size, 1.8-2.5mm, 8-segmented funiculus and basally connate tarsal claws; no other UK weevil group displays this combination of features.
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Most species are monophagous or oligophagous but a wide range of plant families have been recorded as hosts e.g. Fabaceae, Malvaceae, Asteraceae, and Convolvulaceae. Larvae develop within stems or seeds, sometimes inducing gall formation, and pupation occurs either within infested plant tissue or in a subterranean cell beneath the host. Adults feed on plant tissues although one species, the New World Smicronyx squalidus Casey, 1892 is known to feed on nectar. In warmer areas of Mexico, Africa and Australia several species have been trialled as biocontrol agents of various parasitic plants but with only limited success. In temperate regions adults are active over a long season from early spring into the winter. Our 3 UK species are associated with Cuscuta L. (dodder, parasitic Convolvulaceae) or various species of Gentianaceae. All are rare or very rare (in the UK) and of restricted distribution; S. jungermanniae (Reich, 1797) is very local along the south coast of England with a few more inland records from Norfolk and Surrey, S. coecus (Reich, 1797) is known from a very few, mostly coastal, records from southeast England, and S. reichi (Gyllenhal, 1836), the most widespread of our species, is very local in southeast England with a few scattered records from the West Country and the midlands.
Smicronyx
3 species
STOREINI Lacordaire, 1863
This is a large tribe of about 40 genera, it is a mostly southern hemisphere group with by far the greatest diversity in the Australasian region; 24 genera are endemic to Australia and a further 3 occur in Australia and a few surrounding islands, a single genus is endemic to New Zealand and one is widespread in the Neotropical region, 2 occur in tropical Africa of which one is endemic to Madagascar. The Palaearctic fauna includes 3 genera; Imathia Pascoe, 1885 includes single species from Thailand and Japan, Aubeonymus Jaquelin du Val, 1885 includes 8 species from Europe, and Pachytychius Jekel, 1861 includes 50 species distributed throughout the region; 18 occur in Europe and of these the widespread western European P. haematocephalus (Gyllenhal, 1835) is known from a single locality on the south coast of England, this species is also the only representative of the tribe to occur in North America, having been introduced from Europe.
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Our species has been named the Gilkicker weevil after its UK location, a small stretch of coast between Gilkicker Point and Browndown in Hampshire. The weevil occurs on various species of Lotus L. (bird’s-foot-trefoils) on sparsely vegetated shingle and its restricted distribution may be due to an intolerance of cold conditions. Larvae develop within ripening seed pods and pupate in the soil below; adults are active in spring and late summer and overwinter in the soil.
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This tribe was formerly included within the Erirhininae (in the older and wider sense) but is distinguished from that group by the structure of the aedeagus and may be identified by a combination of morphological characters. Our single species is small, 3.0-3.9mm and resembles Tychius but has simple claws and lacks the reflexed suture between the second and third abdominal sternites. It is entirely dark reddish-brown with dense but uneven elongate pale scales which do not obscure the cuticle, the foreparts are densely and moderately strongly punctured and the elytral interstices more finely so. The head is transverse with large and convex but not protruding eyes separated by about the width of the rostral base, the rostrum is long, parallel-sided and curved downwards and the antennae are long and slender with the funiculus 7-segmented. The pronotum is transverse and strongly rounded laterally, without sub-basal or sub-apical constrictions and simply convex. The prosternum is long in front of closely approximated coxae, the antero-lateral margins are produced into weak post-ocular lobes and there is no rostral channel. The elytra are long, subparallel in the basal half and continuously rounded apically to completely cover the pygidium, the striae are punctured and well-impressed to the apex and the interstices more-or-less flat. Front and middle femora smooth, hind femora strongly toothed ventrally. All tibiae with a small sharp tooth at the internal apical angle.
Pachytychius
1 species
STYPHLINI Jekel, 1861
This is a small and mostly western Palaearctic tribe of 10 genera, some of which were formerly included within the Erirhinini Schönherr, 1825; genera from other areas may occasionally be included e.g. the Madagascan Madecastyphlus Richard, 1979, but these are now thought to belong in other tribes within the subfamily. Geranorhinus Chevrolat, 1860 includes 2 species from southwest Europe. Orthochaetes Germar, 1824 is a western Palaearctic genus of 17 species, 2 of which extend to the UK. The monotypic Paraphilernus Desbrochers, 1892 is endemic to Kazakhstan and the monotypic Paroryx Reitter, 1913 occurs in Algeria and Sicily. Philernus Schönherr, 1835 includes 4 species and is widespread in the Western Palaearctic including North Africa. Pseudostyphlus Tournier, 1874, also with 4 species, is widespread in Central Europe and extends east into Kazakhstan; the most widespread species, P. pillumus (Gyllenhal, 1835) extending north into the UK and Scandinavia. Styphlidius Penecke, 1936 includes 5 species from Mediterranean areas of Europe. Styphlus Schönherr, 1826 includes 17 species and is widespread across Europe and the Middle East. The 3 species of Trachystyphlus Alonso-Zarazaga & Lyal, 1999 are endemic to Austria. The monotypic Turanostyphlus Davidian & Savitsky, 2000 is widespread in southern Asia.
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They are small weevils, <5mm, elongate and discontinuous in outline but otherwise very diverse in form; they are mostly characterized by a stout and moderately long rostrum with the scrobes oriented towards the front margin of the eyes and the antennae inserted near the apex. The head is transverse with small convex eyes, the prosternum lacks a rostral channel, the elytral interstices are either all convex or alternately convex and the legs are robust with relatively short tarsi. Beyond this basic description the morphology is very variable, especially the shape of the pronotum and elytra, as the following brief description, laid out as a key, of our 2 UK genera will show. Both genera have the claws simple and separate at the base, alternate elytral interstices raised and bearing long semi-erect setae.
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The biology of most species is only poorly understood but adults are usually found under stones or logs etc. or by sieving litter or moss in a wide range of habitats, often on bare soil along wooded margins or on disturbed waste ground, some are associated with particular biotopes such as chalk grassland or thinly-vegetated sandy soil on dunes and on the continent some occur at high mountain altitudes. Species of Orthochaetes are associated with a very wide range of plant families but are most often recorded, along with Pseudostyphlus, from various Asteraceae. Species of Trachystyphlus are associated with various Caryophyllaceae. Larvae of Orthochaetes mine leaves while those of Pseudostyphlus develop in flower heads, seeds or roots, and so far as is known all pupate in the soil. The parthenogenetic state of our two species of Orthochaetes seems to be unique among the subfamily.
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Of our three UK species, Orthochaetes setiger (Beck, 1817) is the most widespread, occurring throughout England and Wales and occasionally in Scotland, it is associated with a variety of Asteraceae on open grassland, often in chalky districts. O. insignis (Aubé, 1863) is a very local and almost exclusively coastal species of Wales and southern England north to The Wash; it is associated with a wide variety of plants and often found on disturbed grassland. Pseudostyphlus pillumus (Gyllenhal, 1836) is a very rare species of southeast England; it is associated with various Asteraceae on open waste ground and field margins.
Orthochaetes
2 species
Pseudostyphylus
1 species
TYCHIINI Gistel, 1848
This large and speciose tribe is distributed throughout the world with the exception of Australia and New Zealand, it is by far most diverse in the tropics but northern temperate regions are also diverse in species if not in genera. The group is classified into 4 subtribes, 3 of which occur in the Palaearctic region, including Europe; the most diverse subtribe, at least in generic terms, is Ochyromerina Voss, 1935 with 28 genera (and including many more of uncertain placement) distributed throughout tropical and subtropical regions of the Old World with the exception of Australia and New Zealand. Demimaeina Voss, 1937 includes 2 Old World genera but only one of these is represented in the Palaearctic region with many species endemic to Japan. Lignyodina Bedel, 1884 includes 2 genera and is widespread throughout the New World; 5 species of Lignyodes Dejean, 1835 are known from the Palaearctic region; 3 from Europe, and one each from Turkey and Japan but none extend to the UK. Tychiini Thomson, C.G., 1859 includes 3 genera; Sibiniella Voss, 1956 is endemic to New Guinea but the others are large and very widespread genera. Sibinia Germar, 1817 is Holarctic and extends south into Central and South America, where it is very speciose, and Africa, it includes about 150 species in the New World and more than 100 in the Old World; 69 are recorded from the Palaearctic region and 35 from Europe of which 4 extend to the UK. Tychius Germar, 1817 includes at least 630 species and there are many more in collections waiting to be described, it is an Holarctic group extending south into Africa and which is very diverse in northern temperate regions; 225 species are recorded from the Palaearctic region and this includes 120 species from Europe of which 14 are recorded from the UK. By contrast the Nearctic fauna includes 16 species, of which 4 are adventive.
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All are of a characteristic elongate-oval appearance, usually discontinuous in outline with more-or-less distinct shoulders and rounded pronotal margins, they are densely scaled and often characteristically patterned, often with longitudinal strips of pale and darker scales to the pronotum and elytra, and all are small beetles, 1.4-3.0mm. Ventral surface usually densely scaled throughout. Among the subfamily they are distinguished by the combination of toothed claws and the form of the abdomen where the suture between the second and third sternites is angled and reflexed posteriorly towards the lateral margins. The head is moderately large with flat to weakly convex eyes separated by about the width of the base of the rostrum, the vertex and frons are flattened to slightly convex and lack sculpture and the rostrum is long and robust, often narrowed from the base to the apex but never expanded apically, and the mandibles move horizontally. The antennae are inserted about the middle of the rostrum, the scape thickened distally and the funiculus 6 or 7 segmented. Pronotum transverse to quadrate and lacking a lateral border; usually widest about the middle, often distinctly constricted before the base and apex and simply convex. Prosternum usually long in front of closely approximated coxae and lacking a rostral channel or post-ocular lobes. Mesepimera not visible from above. Scutellum visible; usually small and triangular. Elytra with impressed and punctured striae complete to the apex, apical margins continuous or separately rounded and covering (in Tychius) or leaving the pygidium substantially exposed (Sibinia). Identification can be difficult, especially with species of Tychius, but at least some species are characteristically coloured or patterned and several very good keys are available for the UK fauna.
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Our species of Sibinia are monophagous or oligophagous on various Caryophyllaceae and Plambaginaceae; adults occur over a long season from early spring and larvae feed among developing host reproductive organs. All are very local and generally uncommon; S. pyrrhodactyla (Marsham, 1802) is a very rare heathland species known from only a few sites in the south, S. arenariae Stephens, 1831 is a coastal species found on grassland and salt marsh margins in the south of England and Wales, S. primita (Herbst, 1795) is a grassland species occurring across southern England and around the Welsh coast, and S. sodalis Germar, 1824 is a coastal species recorded mostly from South Wales although there are scattered records from the south of England and Anglesey. Species of Tychius are associated with various Fabaceae, larvae develop among seeds or induce galls and adults may be swept from host foliage. Many are local and restricted to the south and some are very local and rare e.g. T. breviusculus Desbrochers, 1873 is known from the Coasts of Dorset and Essex, and T. crassirostris Kirsch, 1871 occurs on cliffs at a single Dorset locality, but the genus also includes a few common and widespread species that should soon appear by general sweeping. Among the most widespread and common are T. picirostris (Fabricius, 1787) which occurs throughout England and Wales, T. junceus (Reich, 1797), T. pusillus Germar, 1842 and T. meliloti Stephens, 1831 which are widespread in the south, and T. schneideri (Herbst, 1795) which is local around the south coasts of Wales and England.
Sibinia
4 species
Tychius
14 species