BRACHYCERINAE Billberg, 1820
Our UK representatives of this otherwise extensive and diverse group are mostly restricted to wetland habitats, the exception being the subterranean Ferreria marqueti.
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Introduction
The limits of this subfamily have been rather dynamic over the years and several genera remain of uncertain placement but a modern definition includes a few groups formerly classified as distinct families or as subfamilies of the Curculionidae Latreille, 1802 i.e. Erirhinini Schoenherr, 1825, Raymondionymini Reitter, 1913 and Tanysphyrini Gistel, 1848. The genus Bagous Germar, 1817 is also suspected of belonging within this subfamily but for now remains within the curculionid subfamily Bagoinae Thomson, 1859, it includes more than 300 species and occurs throughout the world with the exception of Central and South America. Discounting Bagous and considering the group in this wider sense there are about 1100 species of 100 genera in 7 tribes. Tanysphyrini Gistel, 1848 includes about 150 species in more than 30 genera, is cosmopolitan and most diverse in the Neotropical region; 9 species of 5 genera have been recorded from Europe. Erirhinini Schöenherr, 1825 is also cosmopolitan but is most diverse in the central Palaearctic and Afrotropical regions. Raymondionymini Reitter, 1913 is most diverse around the Mediterraneam but also extends to the Central and North America, it includes about 90 species in 16 genera, other groups from e.g. Madagascar and New Zealand are usually included but their placement remains uncertain. These three tribes constitute the entire fauna of many northern temperate regions including the United States, Canada and most of Europe. Cryptolaryngini Schalwyk, 1966 includes the Asian genus Perieges Schöenherr, 1842 with 3 species of which one extends west to European Russia, and the Southern African genus Cryptolarynx Schalkwyk, 1966 also with 3 species. Himasthlophallini Zherikhin, 1991 includes a single species, Himasthlophallus flagellifer Egorov & Zherikhin, 1991, native to the eastern Palaearctic. Myrtonymini Kuschel, 1990 is a small group of 2 genera and 6 species occurring in the Australasian and Pacific regions. Brachycerini Billberg, 1820 includes about 500 species in 11 genera and is restricted to the African and southern Palaearctic regions; Brachycerus Olivier, 1789 includes about 400 species of which 51 are Palaearctic and 22 occur in southern Europe.
Ecology
Tanysphyrini and many Erirhinini are associated with wetlands, the latter in marginal environments and the former often leading a semi-aquatic life, while species of Raymondionymini and Myrtonymini are mostly endogean, occurring in soil or among decaying vegetation. Some wetland Tanysphyrini and Erirhinini have become pests of cultivated rice in their native countries as well as further afield, and some Tanysphyrini have been used with great success around the world as biocontrol agents of invasive aquatic monocotyledons. The species are otherwise generally associated with xeric and arid regions, especially in Africa, and this includes many Erirhinini. They are mostly associated with grasses but a wide range of host plants have been recorded; Tanysphyrini develop in aquatic Araceae, Hydrocharitaceae and Alismataceae etc. but in southern hemisphere regions they also develop in various mosses and ferns. Brachycerus is the largest genus within the subfamily and while it is well-represented in southern Palaearctic regions the biology of only a few are understood; they are generally associated with geophytes of the families Liliaceae, Amaryllidaceae, Araceae and Orchidaceae, the larvae are mostly endophytic, boring into leaves, stems, roots or underground tubers, bulbs or corms etc. Adults are generally nocturnal and disperse by flight, remaining in the soil or among tussocks etc. by day and some regularly produce very large populations.
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Description
Adults vary widely in size, from less than 1mm to about 60mm in some Brachycerus. Our UK groups are discussed elsewhere but the Brachycerini are very distinct; usually robust and elongate to sub-globular and very convex, glabrous to sparsely or densely setose or squamose and uniformly dark or with spots or bands of colour but never metallic. Head transverse and proportionally small with weakly convex and oval eyes and a broad rostrum which may be as long as the pronotum, in repose deflexed between the procoxae, antennae short and often pseudorthocerous with an expanded basal segment, 7-segmented funiculus and gradually widened apically or with a compact 3 or 4 segmented club. Mouthparts well-developed with robust tridentate mandibles and large, 3-segmented palpi. Pronotum quadrate to transverse, laterally rounded and often constricted anteriorly or posteriorly, smooth or with various teeth or spined, surface sparsely to densely and strongly punctured and often strongly sculptured with tubercles or longitudinal ridges or furrows. Elytra elongate to broadly rounded, usually without prominent shoulders, continuously rounded and steeply declined laterally and apically and completely covering the abdomen. Each elytron with up to 10 punctured striae but very variable, from smooth and glabrous e.g. in the South African Brachycerus apterous (Linnaeus, 1758), among the largest of the species, to strongly and regularly tuberculate as in the African B. conquestus or strongly and irregularly sculptured with ridges and tubercles. Legs long and robust; procoxae elongate and protruding, only rarely separated by a rostral channel, mesocoxae subglobular and narrowly separate, metacoxae transverse and often reaching the elytral margin, trocanters small and transverse, femora unarmed but often, and sometimes strongly, tuberculate, tibiae long and sub-cylindrical, often denticulate internally and only weakly expanded towards the apex; obliquely truncate and usually developed into a strong uncus-like mucro. Tarsi 4 or 5-segmented with 1-4 variously lobed but (Brachycerus) without the contrasting bilobed third tarsomere seen in many groups, apical margin of onychium curved up between the claws; claws large and smooth, often with a strong basal seta.
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For a key to the UK species click HERE.
UK Tribes
