ATTELABIDAE Billberg, 1820

Leaf-Rolling Weevils

Attelabinae includes two widespread though local species; Attelabus oak, and Apoderus on hazel. Both species are very distinctive among the UK fauna. The rest of the family is covered here.

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Superfamily:

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Size:    

POLYPHAGA Emery, 1886

CURCULIONOIDEA Latreille, 1802

2

11

1.8 - 9mm

Introduction

The limits of this group have varied widely over the years, more particularly as to whether the rhynchitids should be included as a subfamily or whether they constitute a distinct family group, but the modern interpretation includes Rhynchitinae Gistel, 1848 and Attelabinae Billberg, 1820 as equal divisions of the Attelabidae, and this is the system we have adopted for this site. These groups are morphologically diverse but distinct and, intuitively, closely related, and both are well represented in the Palaearctic region, although only very poorly so in Europe. For historical reasons i.e. that the rhynchitids were included as a separate family in our latest UK checklist (etc.), they are described separately here. The common name refers to the habit of most species of producing leaf-rolls into which eggs are laid. The group is almost cosmopolitan in distribution, being absent from most Pacific islands, and includes about 3000 species in 2 subfamilies although some other groups e.g. the Pterocolinae Lacordaire, 1865, the New World ‘Thief-Weevils’, are sometimes included as a distinct subfamily. By far the greatest diversity is in tropical and subtropical regions, and temperate areas, Europe and North America in particular, are very poorly represented with 6 species in each case. The Palaearctic fauna includes 6 tribes of Attelabinae and these are representative, with a few notable exceptions, of the wider world fauna.  Non-Palaearctic groups include the Trachelophorini Voss, 1926, a tribe of 9 genera and about 50 African and Indian Ocean island species, these are the most morphologically developed members of the family and include the famous Giraffe Weevils of Madagascar (Trachelophorus Jekel, 1860); about 15 species are known and all exhibit pronounced sexual dimorphism with the males having an extremely elongated head and pronotum, some measure up to 2.5cm, which is the longest of any attelabid, these adaptations are used to fight off rival males while the female is making leaf-rolls. Beyond this extreme sexual dimorphism members of the tribe are ecologically and morphologically typical of the group as a whole. Pilolabini Voss, 1925 includes 2 genera and about 15 species and is almost exclusively Mexican with a single species from Costa Rica. Lagenoderini Voss, 1925 includes 9 genera from Africa and Madagascar. Hybolabini Voss, 1925, in the widest sense, and Euscelini Voss, 1925 are huge New World tribes with the vast majority of species from tropical areas.

Description

The Palaearctic fauna, while diverse, are mostly recognizable from a familiarity of our 2 UK species although some Oriental species of e.g. Clitostylina Voss, 1926 display the extreme sexual dimorphism seen in the Madagascan Giraffe Weevils. Apoderini Jekel, 1860 includes 3 subtribes; Clitostylina with 6 Asian and oriental genera, the familiar Apoderina Jekel, 1860 with 13 genera of which 2 occur in Europe and one, Apoderus Olivier, 1817, extends to the UK and Hoplapoderina Voss, 1926 with 6 Asian and Oriental genera. Attelabini Billberg, 1820 includes 3 genera, 2 are Asian while Attelabus Linnaeus, 1758 includes 3 European species of which one extends to the UK. Euopini Voss, 1925 is represented by 57 Asian and Oriental species of the single genus Euops Schöenherr, 1839. Euscelophilini Voss, 1925 includes 3 genera and 23 Asian and Oriental species. Lamprolabini Voss, 1925 includes 5 genera and 33 Asian and Oriental species. Paramecolabini Legalov, 2003 includes 2 genera and 10 Asian and Oriental species. While this fauna may appear diverse it is only a fragment of a much larger and more southern fauna e.g. Apoderus includes about 370 species and occurs throughout the New World, Africa Eurasia and southeast Asia, and Attelabus includes about 350 species and is almost cosmopolitan.

The European fauna consists of the following species:

  • Apoderus coryli Linnaeus, 1758, is a very widespread Eurasian species extending north to the UK.

  • Apoderus ludyi Reitter, 1890, an Italian endemic.

  • Compsapoderus erythropterus Gmelin, 1790, formerly included in Apoderus, is a very widespread species extending east to China and Japan.

  • Attelabus nitens Scopoli, 1763 occurs throughout Europe and much of Asia and extends to the UK.

  • Attelabus sulcifrons Argod-Vallon, 1895 is a local species of south-eastern Europe and eastern North Africa.

  • Attelabus variolosus Fabricius, 1801 is restricted to Spain, Morocco and Algeria.

All are small to medium sized beetles with the majority from 2-12mm, they have a characteristic form that is distinct from the rhynchitids and will soon become familiar; elongate with the head long, broadest across the eyes and often with long and curved temples, a near-quadrate pronotum which is curved laterally and narrowed toward the anterior margin, and rather square-looking elytra which are much broader across the shoulders than the pronotal base and usually have strongly punctured striae. They are convex, often strongly so, although the elytra are often flattened across the disc, most are glabrous or only finely pubescent although there are exceptions e.g. the rather densely pubescent nearctic species Himatolabus pubescens (Say, 1826), and many are brightly coloured, often a combination of red, yellow and black and many are bicoloured with the forebody contrasting against the elytra while some e.g. the Nearctic Synolabus bipustulatus Fabricius, 1776 or the southeast Asian genus Paroplapoderus Voss, 1926,have distinctive patterns, and many genera e.g.the Chinese Tomapoderus Voss, 1926 or the widespread Euops include  partly or wholly metallic species. The head is often long behind the eyes, in males of some sexually-dimorphic species extremely so, and usually smoothly convex, they eyes are generally well-developed and convex, in some e.g. species of Euops, they are massive and united across the vertex, and the rostrum tends to be short and broad, in many there are distinct longitudinal ridges between the eyes which generally extend onto the rostrum. The labrum is usually fused to the clypeus, the maxillary palpi are short and 4-segmented, without expanded segments, and the mandibles lack the external teeth seen in Rhynchitinae. Labial palpi inserted ventrally on the mentum, 3-segmented but sometimes greatly reduced. Antennae 11 or 12-segmented and without the distinct scape seen in the Curculionidae, usually with 3-segmented and usually narrow and pointed club, inserted laterally or dorsally on the rostrum. Pronotum quadrate to transverse but sometimes sexually dimorphic and greatly elongate anteriorly in males, usually curved laterally, unbordered and narrowed to the anterior margin, surface generally without sculpture but commonly with a transverse furrow  towards the base and sometimes with various impressions or tubercles e.g. in some Leptapoderus Jekel, 1860, anteriorly rounded or angled, posteriorly with distinct, usually obtuse, angles. Scutellum usually conspicuous; sometimes prominent above the elytra and triangular or rounded apically. In most species the elytra are convex and rather flattened, with well-developed shoulders and at least 6 variously punctured but distinct striae, sometimes an abbreviated scutellary stria, and smooth or only finely punctured interstices. In many exotic species the elytra have prominent tubercles; in some they are numerous and small but in e.g. some Hoplapoderus Jekel, 1860 there are 3 discrete and sharp tubercles to each elytron, and in the amazing Lamprolabus bispinosus (Gyllenhal, 1833), from Sumatra etc., there is a single large thorn-like projection toward the lateral margin. In most the apical declivity is rather steep, the elytra are to some extent truncate and the pygidium is exposed, in some tropical species the elytral apex is produced backwards or has prominent ridges. Wings usually well-developed although lacking an anal lobe or medial fleck, and most are strong fliers. Abdomen with 5 visible sternites, the first 4 to some extent fused. Legs long and robust; pro- and mesocoxae round and to some extent projecting, metacoxae transverse and flat, trocanters small and triangular, femora generally broadened about the middle and usually smooth although in many exotic species variously developed with prominent teeth or outgrowths, sometimes sexually dimorphic, probably most developed in Neoeuscelus longimanus (Olivier, 1789) (which must be seen to be believed!), tibiae long, slender and often produced to a sharp tooth at the inner apical angle, sometimes extremely developed, usually with fine teeth along the inner margin and with 1 or 2 apical spurs. Tarsi 5-segmented with the third strongly bilobed and often concealing the fourth, claws fused towards the base. Adult are readily distinguished from rhynchitids by the fused and simple claws i.e. not dentate or bifid, the toothed inner margin of the pro-tibiae and the smooth external margin of the mandibles.

Ecology

Many species are monophagous or oligophagous on various deciduous trees and shrubs and all so far as is known all are leaf-rollers. After mating the female selects a suitable leaf and makes various incisions across the surface to facilitate rolling, typically the main vein is partially severed and several transverse cuts are made across the leaf before it is folded several times and then rolled, at some stage during this rolling process she will insert an egg, or rarely more than one, and then complete the roll. This video shows the process. Each species or genus will produce a characteristic roll, or ‘nidus’ which, within limited faunas, can be used for determination. During this process the male guards the female from the attentions of other males, constantly patrolling the leaf and making occasional short flights, and during this time fights between males are common. The roll will usually turn brown and either remains on the tree for a while, even into the autumn, or quickly fall to the ground, larvae develop and overwinter within the roll, pupate within the roll rather than in the soil during the following spring and the resulting adults appear in the spring or early summer. Attelabid larvae are short, broad, usually strongly curved or angled and tapered at both ends. The head is retracted into the prothorax, either lacking ocelli or with one either side, and has 2-segmented antennae hidden under the anterior angles of the frons, the mandibles are bifid and toothed internally, maxillary palps 2- or 3-segmented and the labial palps are 2-segmented. The thorax lacks legs and possesses round, intersegmental spiracles. Abdomen with 10 visible segments with strong dorso-lateral folds which often form roughly triangular extensions, each segment with various transverse grooves which separate them into several convex parts and with a pair of circular spiracles. Eighth segment without an armature, anus with 3 small ventral lobes and a large and prominent dorsal lobe. Larvae are readily distinguished from those of rhynchitids by the labium being fused to the postlabium, 2-segmented maxillary palps and, where this is available, the form of the nidus.  Towards the end of summer larvae can be found within leaf-rolls, by this time they are large, fat and yellow with a dark, sclerotized head and will have eaten a substantial central cavity into the roll.

UK Species

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