MYCTERIDAE Oken, 1843

Palm Beetles

This species is included on the British list on the basis of a few historical records. In Europe adults occur on flowers in sunny grassland areas.

POLYPHAGA Emery, 1886

TENEBRIONOIDAE Latreille, 1802

Mycterinae Blanchard, 1845

Mycterus Clairville, 1798 

M. curculioides (Fabricius, 1781)

5-10mm

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Around the World

This small family of morphologically very diverse beetles includes more than 160 species in about 60 genera and 3 subfamilies, the distribution is worldwide but the majority of species occur in tropical regions; the Neotropical zone is most diverse with 11 genera and about 65 species, 30 species of 13 genera occur in Africa and about 20 in Australia. Northern temperate regions are generally poor in diversity; 12 species occur in the United States and 4 in Canada while 7 species of 4 genera have been recorded from Europe including Batobius bicolour (Fairmaire & Germain, 1863), a Chilean endemic recorded from France. Historically the species have been included in various families e.g. Pythidae and Salpingidae and the present 3 subfamily system has only been generally accepted since 1995, but specimens remain undescribed in collections throughout the world and so further revisions may occur. Hemipeplinae Lacordaire, 1854 includes 2 genera; the monotypic Holopeplus Arrow, 1930 occurs in the Caribbean while Hemipeplus includes more than 20 species and is pantropical. Eurypinae Thomson, C.G., 1860 is the most diverse group with an almost worldwide distribution. Of the Neotropical fauna several genera are endemic e.g. the widespread monotypic Cleodaeus Champion, 1889, 12 species of Conomorphus Champion, 1889, the monotypic Conomorphinus Champion, 1889 from Bolivia and Peru, the widespread Physcius with 23 species and Physiomorphus Pic, 1917 with 8 species, 5 species of Thisias Champion, 1889 which extends north to Mexico, the monotypic Thisiomorphus Pic, 1931 from Brazil and 2 species of Brasilaccoderus Pollock. Four genera are endemic to Madagascar; Mastilius Fairmaire, 1901 (4 spp.), Phaeogala Fairmaire, 1896 (5 spp.) and the monotypic Abulia Fairmaire, 1896 and Mimophyscius Pic, 1935, and 3 genera are endemic to Africa; Lacconotopedilus Pic, 1935 with 2 species and the monotypic Abulia Fairmaire, 1896 and Falsopedilus Pic, 1924. Two genera are endemic to the Seychelles; Stictodrya Champion, 1917 and Mycteromimus Champion, 1917, both of which are monotypic. The Australian fauna includes 14 species of Trichosalpingus Blackburn, 1891, which is endemic, and Loboglossa Solier, 1851 which includes 5 species and also occurs in South America. The monotypic Grammatodera Champion, 1916 is endemic to Sri Lanka and the 5 species of Omineus Lewis, 1895 are Oriental and Southeast Asian. Three genera have been recorded from Europe; Bertotinus Kirejtshuk & Nel, 2009, Neopolypria Abdullah, 1964 and Batobius.

So far as is known species of Hemipeplinae are associated with various monocotyledons. The flattened larvae of some Hemipeplus occur among unopened coconut palm fronds and are thought to feed on fungal hyphae. The life histories and ecology of members of the Europinae are generally poorly understood but the larvae of many genera e.g. Phaeogala Fairmaire, 1896, Physcius Champion, 1889 and Physiomorphus Pic, 1917 develop under bark and pupal cells of some have also been found there. Several species are associated with palm trees; larvae of Eurypus muelleri (Seidlitz, 1917) occur among dead leaves while those of E. rubens (Kirby, 1818) live in coconut palm leaf axils.

Description

Our familiar European Mycterus is rather atypical of the family as a whole and most species are quite different. They vary from 2 to 12mm, are elongate and usually have the head, pronotum and elytra separately rounded, most are weakly convex although species of Hemipeplus are very flattened, elongate and parallel-sided; so distinctive that they were formerly included in the Cucujidae, they vary from glabrous to densely pubescent and most are rather drab coloured, black to testaceous or bicoloured. The head is usually relatively small but prominent with large convex and protruding eyes and almost all lack a distinct rostrum. Antennae 11-segmented and filiform to serrate, rarely pectinate, inserted laterally in front of the eyes, the insertions visible or hidden from above. Pronotum quadrate to elongate and lacking sculpture although in many with distinct basal fovea, broadest at distinct posterior angles and narrowed anteriorly or evenly rounded laterally and broadest about the middle. Procoxal cavities open behind and often externally also, many species closely resemble Tenebrionidae but here the procoxal cavities are closed behind, in some with a distinct and raised prosternal process, mesocoxae oval and narrowly separated, mesocoxal cavities widely transverse, sometimes reaching the elytral epipleura. Scutellum transverse, oblong to triangular or curved, and usually obvious. Elytra parallel-sided to weakly curved laterally and usually completely covering the abdomen, continuously or separately rounded apically and with well-developed epipleura extending from the base to beyond the middle, often to the apex. Surface variously punctured, often very finely so, and lacking striae. Abdomen with 5 ventrites; 1-3 connate, males often have a patch of dense setae or a tubercle on one or more basal ventrites. Legs generally rather short, thin and lacking teeth or large spurs on the femora and tibiae. Procoxae projecting below the prosternum, with small and concealed trocanters. Tarsi 5-5-4, each with various segments lobed.

Mycterinae Blanchard, 1845 includes about 17 species of the single genus Mycterus Clairville & Schellenberg, 1798. The distribution is mostly Holarctic with 5 species from the Nearctic, 5 from Asia, and 2 occur in central Europe of which one has been recorded from the U.K. Beyond this 2 species are known from South Africa and several more, including some unidentified, from India. Among the family the genus is very distinctive; very reminiscent of weevils but with serrate antennae and 5-5-4 tarsi, or Salpingidae but with the penultimate tarsal segment lobed. All species are small, 5-11mm, elongate-oval with the pronotum narrower than the elytra and the elytra smoothly rounded apically. All have rather dense adpressed pubescence which varies from pale grey to rich yellow-bronze, even within a species. The head is quadrate with large convex eyes, a distinct rostrum and 11-segmented filiform or serrate antennae. The legs are slender and relatively short with at least one segment of each tarsus lobed. Adults occur on flowers and are often, if sporadically, abundant. The Nearctic M. quadricollis Horn, 1874, the ‘yucca beetle’, is often very abundant on various succulent plants etc. in western desert regions of the United States and has become an occasional pest of ornamental plants in gardens, the adults and larvae burrow through the soft leaves and stems and quickly damage plants.

Mycterus curculioides (Fabricius, 1781) 

This is the more widespread of the 2 central European species; it occurs sporadically across North Africa, south and central Europe and east through western Asia and southern Russia. Adults occur on flowers, especially those of Apiaceae in grassland habitats, often on slopes exposed to the sun, and are often abundant in warm weather; they have a long season extending from February to June in southern parts of Europe but are generally active from mid-March to May. Larvae are thought to develop in stems and roots of herbaceous plants and have also been recorded under pine bark. Although retained on the U.K. list the species has not been recorded here since the late nineteenth century when it was found in Oxfordshire.

Adults are very distinctive, they vary widely in size from 5-10mm and are entirely black, the dorsal surface being coloured by dense short, recumbent pubescence from pale grey to rich gold although that on the head is generally pale. Head prognathous and much narrower than the pronotum; at the broadest point, across the eyes, about half the width of the pronotal base, with large convex eyes and curved temples. Vertex flat or slightly concave extending anteriorly to a broad, sub-parallel rostrum which is about twice the length of the head. Rostrum with two narrow dorsal impressions which diverge towards the base and apex and lateral scrobes that are obvious from above. Antennae 11-segmented, long and weakly serrate, without a scape and with all segments elongate, the terminal segment constricted medially and pointed. Pronotum transverse, broadest at distinct posterior angles and narrowed to a rounded anterior margin, the basal margin widely sinuate. Scutellum transverse and heart-shaped. Elytral base as wide as the base of the pronotum, shoulders not prominent or raised, laterally gently curved or almost parallel to a continuously rounded apical margin, epipleura well-developed from the base and reaching the apex. Surface strongly and quite densely punctured but lacking striae. Hind wings well-developed. Abdomen with 5 visible sternites; the fourth connate with the third and fifth. Legs slender and unmodified, without obvious teeth or spurs and finely pubescent throughout. Tarsi 5-5-4, the penultimate segment of each widely lobed.

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