Description

Both the present family and Orsodacnidae were previously classed as subfamilies of the Chrysomelidae but recent studies on both adult and larval morphology as well as phylogenetic analysis have shown both to be independent groups of family rank. Megalopodidae share many characters with both chrysomelids and cerambycids but are distinct in the structure of the genitalia, morphologically they are distinct from cerambycids in having the antennae mounted above the mandibles rather than on pre-ocular tubercles, and from Chrysomelids they may be recognized, at least among the limited UK fauna, by the form of the pronotum coupled with randomly punctured elytra and the general habitus; and with only 3 species of Zeugophora on our list this is a straightforward way of identifying them. All are small and rather flattened beetles, elongate in form; between 2 and 3 times longer than wide and, in Zeugophora <5mm, but some tropical species of the Megalopodinae may reach 7.5mm. Species of Zeugophora are rather uniform in appearance and members of other genera tend to be similar in terms of morphology but many differ most noticeably in the form of the hind legs which may be greatly developed, with enlarged and ventrally-toothed femora and strongly curved tibiae e.g. species of the North African genus Clythraxeloma Kraatz, 1879 or, where these features are perhaps best developed, species of the large, old world genus Temnaspis Lacordaire, 1845, the hence the vernacular name for the group. Some species of Temnaspis also have moderately thickened antennae but overall, in a superficially morphological sense, most species will be recognized as members of the family with a little experience. In tropical regions there are some strikingly coloured and metallic species but this is also true of many Holarctic Zeugophora e.g. Z. annulata (Baly, 1873) from Japan, conversely many tropical species are rather drab coloured e.g. many Neotropical Megalopus Fabricius, 1801. The following description refers to Zeugophora as this is the European representative of the family. Most are, at least to some extent and usually extensively, brightly coloured; red, yellow or blue, often metallic and with darker markings to the body that form distinct patterns or simply bicoloured. Most are have fine recumbent pubescence to the dorsal surface although this is not always obvious, while some have dense erect pubescence which is obvious to the naked eye e.g. the Nearctic Z. atra Fall, 1926. Head hypognathous; transverse from above with prominent eyes and short temples which are contracted towards the base, frons smoothly convex and without sculpture or impressions but usually strongly punctured , frontoclypeal suture distinct but otherwise without ridges or impressions on the frons, labrum transverse and rounded, truncate or emarginate anteriorly. Eyes variously convex and at least to some extent emarginate anteriorly. Antennae 11-segmented and filiform or weakly thickened or serrate towards the apex, inserted behind the mandibles, the insertions visible from above. Mandibles curved and relatively long; with small internal teeth towards the apex and bidentate apically, terminal segment of maxillary and labial palpi cylindrical to fusiform. Pronotum very characteristic; as wide as the head, quadrate or weakly transverse and with a large and distinctive lateral tooth, evenly convex and lacking lateral borders or explanate margins, surface usually strongly and randomly punctured. Anterior and posterior angles distinct, anterior margin simply curved, posterior margin sinuate or bisinuate. Scutellum small but usually obvious.  Elytra broadly elongate and parallel-sided to distinctly narrowed in the anterior third, with broad rounded shoulders and continually rounded apices, epipleura incomplete; usually narrowly developed in the basal half and delimited by a fine ridge. Surface evenly convex and randomly punctured, at least as strongly as the pronotum but sometimes becoming weaker towards the apex. Hind wings well-developed.  Legs relatively long and robust, pro- and meso-coxae strongly projecting and variously transverse, usually only weakly so, metacoxae flat and more strongly transverse, femora only weakly expanded and lacking ventral teeth, separated from the coxae by distinct trocanters; trocanter-femur joint strongly transverse. Tibiae more or less straight, without teeth or lateral spines and gradually broadened from base to apex, each with two short spurs on the inner apical angle; those on the pro-tibiae may be very small and hidden among a fringe of apical setae and so difficult to see. Tarsi 5-5-5 but may appear 4-4-4 as the small fourth segment may be hidden within the lobes of the third, segments 1 and 2 simply broadened or variously lobed, 1-3 densely setose ventrally. Claws strongly curved and with a basal tooth or lobe which may be very wide. Larvae are distinctive; pale and soft with a darker and well-sclerotized head, broadly elongate and strongly flattened, without legs and with each abdominal segment laterally produced and setose, they lack urogomphi and have lobed setae along the anterior margin of the labrum.