Silvanidae · aruodvabaliai

• Grain Beetles, Silvan Flat Bark Beetles
• Raubplattkäfer
• kaitahäröt
• aruodvabaliai
• šaurvaboļu dzimta
• spitshalskevers
• spichrzelowate
• smalplattbaggar

• archive.org: ukbeetles.co.uk/silvanidae
• en.wikipedia.org/wiki/Silvanidae
• gbif.org/species/7850

Silvanids generally are small, brownish, flattened, pubescent and densely punctured beetles ranging from 1.2-15 mm in length, and mostly with a 5-5-5 tarsal formula. They have short, strongly clubbed, to very elongate antennae, and frequently grooves or carinae on the head and/or pronotum. Many genera have the lateral margins of the pronotum dentate or denticulate.

The majority of species of the Silvanidae are thought to be fungivores and most are saproxylic, occurring beneath the bark of damaged or fallen trees and logs etc. Most temperate species occur under the bark of deciduous trees especially oak, beech and hornbeam but a few occur under conifer bark and some have a wide host range.

Minta grybais, augalinės kilmės maistu. Yra sinantropų, mintančių grūdais, miltais, duonos produktais.

Most of the text below is from now defunct site www.ukbeetles.co.uk, where it was published under a CC BY 4.0 License.

Introduction

This cosmopolitan family includes about 500 described species in about 60 genera and 2 subfamilies although the arrangement has varied widely with up to 4 subfamilies being recognized; major groups such as Psammoecinae and Cryptomorphinae are now treated as tribes of the Sylvaninae (Kirby, 1837). Although many variations will be found the Brontinae (Erichson, 1845/Blanchard, 1845) now includes 10 genera and about 40 species and is not divided into tribes; former tribes include Hyliotini (Reitter, 1879) and Uleiotini (Gistel, 1856). At one time the Brontinae included the Telephanini (LeConte, 1861) to accommodate the genus Telephanes (Erichson, 1845), a large pantropical group of about 110 species, the distinction being the form of the anterior coxal cavities; open in Brontini and closed in Telephanini, but the group is now included in the Silvaninae. Species of the Brontinae are distributed throughout the Holarctic, Oriental and Australasian regions and several occur in Madagascar but only a single species, Parahyliota africanus (Grouvelle, 1889), occurs in Africa, and two are Neotropical, a single species of Australohyliota (Thomas, 2004), the other member of the genus occurring in Australia, and the only member of the genus Microhyliota (Thomas, 2004); M. Integricollis (Fairmaire, 1860). Silvaninae is a cosmopolitan group of about 50 genera included in 3 tribes. Cryptamorphini (Casey, 1884) includes about 30 species of Cryptamorphus (Wollaston, 1854), 17 of which occur in Australia and/or New Zealand and the remainder in southern Asia or Indonesia. C. redtenbacheri (Reitter, 1876) is doubtfully recorded from Chile and C. desjardinsi (Guérin-Méneville, 1844) is cosmopolitan. Psammoecini (Reitter, 1829) includes 5 genera, 2 of which are large; Psammoecus (Latreille, 1829) with more than 80 species is a widely distributed old world genus with the greatest diversity in southeast Asia and Australia, and Telephanus (Erichson, 1845), with more than 100 mostly new world species with the greatest diversity in the Neotropical region where many are localized or Island endemics e.g. T. dentatus (Nevermann, 1937) from Haiti and the Dominican Republic, and T. darlingtoni (Nevermann, 1937) from Jamaica. With one exception the remaining genera are monotypic; Pseudochrodes suturalis (Reitter, 1876) is Neotropical, Indophanus dakshinus (Pal, 1982) is Indian, Psammaeochidius spinicollis (Fairmaire, 1869) is Madagascan, and Megapsammoecus (Karner, 1995) includes a species from China and one from India. The cosmopolitan tribe Silvanini (Kirby, 1837) includes the majority of the genera, some of which are localized or Island endemics e.g. Acathartus insignus (Grouvelle, 1895) from Sumatra, Metacorimus mroczkowskii (Halstead, 1997) from Cameroon or Astilpnus reflexicollis (Motschulsky, 1868) from Egypt. Cathartosilvanus tropicalis (Van Dyke, 1953) occurs on the Galapagos Islands. Some larger genera have interesting distributions e.g. Austronausibus (Halstead, 1980) includes 6 Australian species while Eunausibius (Grouvelle, 1912) includes 5 Neotropical species, and Airaphilus (Redtenbacher, 1858), with about 36 species is mostly Palaearctic but with a single species from India, 3 from South Africa and one from Ethiopia, there are also several Island endemics e.g. A. nubigena (Wollaston, 1863) from Tenerife and A. vaulogeri (Grouvelle, 1912) from Tunisia. Many species have become dispersed through trade etc. e.g. Eurausibius salutaris (Parsons, 1974), native to Brazil and Guyana, is now established in the United States, and Silvanus lateritius (Broun, 1880) is native to Australia but also occurs in South Africa, Hawaii and Madeira.

The central European Silvanid fauna includes 17 species of 12 genera of which 8 are synanthropic while the Nearctic fauna includes 32 species in 14 genera. Among the U.K. fauna the family is most closely related to the Cucujidae although more generally there is a closer phylogenetic relationship with the Passandridae Erichson, 1845.

Adults of some species of the Brontinae can reach 15 mm but the majority of Silvanids are less than 10 mm in length. The habitus is generally elongate and near parallel-sided and most species are to some extent flattened, often strongly so, and some e.g. species of Dendrophagus or Uleiota superficially resemble cerambycids while others e.g. species of Telephanus or Psammoecus resemble carabids but most will be recognized, with a little experience, from the overall form. Most are drab coloured, black to pale brown although several genera include maculate or patterned species e.g. Psammoecus or Monanus and the Nearctic Telephanus atricapillus (Erichson, 1846) is among the most attractive. In general the Brontinae are larger, less compact and have longer antennae and in some species the mandibles of the male are modified. Members of Brontinae and the Silvaninae genus Telephanus have inverted male genitalia, open procoxal cavities and mandibular mycangia; structures adapted for the transportation of symbiotic fungi. The remaining genera of the Silvaninae lack these characters.

Description

The head is very variable; prognathous with the labrum usually visible and well-sclerotized. The mandibles are visible from above, with bidentate or bilobed apices and the inner edge simple or with a single tooth. The apical segment of the labial and maxillary palpi is usually cylindrical, never securiform. The eyes vary from large and convex e.g. Ahasverus to small and relatively flat e.g. Oryzaephilus, the size of the facets is also variable and in some species the eyes are finely pubescent. The antennae are vary widely; from distinctly clubbed e.g. in Silvanoprus (Reitter, 1911) to filiform e.g. in Psammoecus and they are sometimes very long as in most Brontinae but the longest, proportional to the body, are probably seen in the Neotropical species Australohyliota chilensis (Blanchard, 1851). The insertions are sometimes visible from above. The vertex is variously punctured and to some extent convex although often depressed behind the labrum and sometimes sculptured e.g. the Australian Nepharinus goudiei (Lea, 1904) has a very elongate head with short and thick filiform antennae and raised ridges to the head, pronotum and elytra. The temples may be short and constricted towards the base as in Psammoecus or variously expanded and even toothed e.g. in Silvanus. In many species the width of the head, measured across the eyes, is equal to or a little narrower than the anterior margin of the pronotum. The form of the pronotum is very variable, generally quadrate to elongate and from convex e.g. in Ahasverus to flat as in Uleiota, the surface is variably punctured and sometimes has raised sculpture or depressions. The lateral margins may be smooth and almost parallel-sided e.g.in Ahasverus longulus (Blatchley, 1910) or sinuate e.g. in species of Dendrophagus but in general they are dentate and this is a good indicator of the family; common among members are laterally or anteriorly produced anterior angles which vary from smoothly rounded to sharply acute and lateral margins varying from being finely denticulate to having unequally spaced larger teeth e.g. in Oryzaephilus surinamensis (Linnaeus, 1758); sometimes the entire margin is toothed e.g. in Austronausibius aemulus (Halstead, 1980) with 4 or 5 large teeth, and sometimes there are various irregular lateral projections and teeth e.g. in species of the New Zealand genus Brontipriscus (Sharp, 1886), Megahyliota feae (Grouvelle, 1892) from Thailand or species of Macrohyliota (Thomas, 2004) from southeast Asia and Australia but perhaps most developed in species of Brontoliota (Thomas, 2004) from Queensland. The scutellum is usually obvious. The elytra tend to be subparallel or weakly rounded laterally and evenly rounded apically to cover the entire abdomen although in some tropical species they vary from obliquely truncate to separately produced. In some the surface is smooth or weakly carinate, especially in temperate Brontinae, but most species have between 6 and 10 well-formed and punctured striae and in some there is also a scutellary striole. The interstices are variously punctured and sculptured and in some there are longitudinal carinae, in many, or even most, they are finely pubescent. The legs are usually robust and relatively long with the femora much wider than the tibiae. The pro- and mesocoxae lie in depressions; the pro coxae are circular with the cavities open or closed, and well separated, the mesocoxal cavities are open laterally and the metacoxae only weakly transverse, if at all. The tarsi are usually 5,5,5 although sometimes appear to be 4,4,4 due to the tiny basal segment, with the segments variously lobed beneath, in some Telephanus strongly so, and the last segment elongate. The claws are generally smooth and lack appendages.

As with most groups of beetles the various characters can become exaggerated in tropical or subtropical species and in the present family some examples of this can be seen in Telephanus gomyi (Thomas, 1992) or T. allaudi (Grouvelle, 1899) in which there are long erect setae to the pronotum and elytra, or perhaps most spectacularly in the Madagascan T. spinosus (Grouvelle, 1890) with huge mandibles, massively developed hind femora which are toothed on the inner margin, very long metatibiae which bear a large internal tooth, and widely bilobed tarsal segments.

Ecology

The majority of species of the Silvanidae are thought to be fungivores and most are saproxylic, occurring beneath the bark of damaged or fallen trees and logs etc. Most temperate species occur under the bark of deciduous trees especially oak, beech and hornbeam but a few occur under conifer bark and some have a wide host range e.g. Silvanus muticus (Sharp, 1899), a native Nearctic and Neotropical species recently imported into Europe, occurs beneath both deciduous and coniferous bark. In tropical regions they occur under the bark of a wide range of species e.g. Ficus and in the case of S. lateritius (Broun, 1880), Eucalyptus. Species of Cryptamorpha (Wollaston, 1854) have been recorded on Corynocarpus (New Zealand Laurel), Dracophylum (Australian ‘Grass Trees’) and the monocotyledon Cordyline. Some species are known to be predacious e.g. Cathartus quadricollis (Guérin-Méneville, 1844), The Square-necked Grain Beetle, has been found inside coffee beans feeding upon larvae of the coffee bean borer weevil, Hypothenemus hampei (Ferrari, 1867) (Scolytinae) and in macadamia nuts feeding upon the tropical nut borer weevil H. obscurus (Fabricius, 1801) in Hawaii. Species of Brontoliota (Thomas, 2004) occur on the outside of fallen branches etc. in wet forest areas of Queensland, and Protodendrophagus antipodes (Thomas, 2004) occurs under rocks in alpine areas of New Zealand. Adults of many species of the very diverse Neotropical genus Telephanus (Erichson, 1845) occur on decaying leaves of a range of woody and herbaceous plants especially Heliconaceae (vines.) Outside temperate regions many silvanids occur in the soil and among leaf litter and several genera e.g. Nepharus (Laporte, 1869) or Nepharinus (Grouvelle, 1912) have become inquilines in ant nests in Australia. The genus Coccidotrophus (Schwarz & Barber, 1921) includes 2 Neotropical species both of which are adapted to live among the foliage of ant-plants (Tachigalia sp.), feeding upon the honeydew produced by mealybugs (Pseudococcidae.) At least one species of Eunausibius (Grouvelle, 1912) is thought to have a similar lifestyle.

Several genera have been transported along with commercial timber and foodstuffs and now have a cosmopolitan or near-cosmopolitan distribution e.g. Monanus (Sharp, 1879), Cryptamorpha (Wollaston, 1854), Silvanus (Latrielle, 1804), Ahasverus des (Gozis, 1881) and Oryzaephilus (Ganglbauer, 1899). Among these are several species which have become serious pests of stored products; the most economically important being 2 species of Oryzaephilus; O. Surinamensis (Linnaeus, 1758), The Saw-toothed Grain Beetle, and O. mercator (Fauvel, 1889), The Merchant Grain Beetle. Both are cosmopolitan and most prolific in tropical climates and both are secondary pests of stored grain, feeding upon fungal infections of damaged seeds and spreading spores although a wide range of other products may become infested e.g. oilseed, cereals of all kinds, nuts, copra, confectionary and any kind of milled products. Ahasverus advena (Waltl, 1834), The Foreign Grain Beetle, feeds upon moulds among damaged grain and milling refuse etc. and Cathartus quadricollis (Guérin-Méneville, 1844), The Square-necked Grain Beetle, is one of the commonest Nearctic pests of stored corn while also attacking developing plants in the field.