''Cryphalus'' is a large genus of tiny bark beetles, subfamily

Scolytinae A bark beetle is the common name for the subfamily of beetles Scolytinae. Previously, this was considered a distinct family (Scolytidae), but is now understood to be a specialized clade of the "true weevil" family (Curculionidae). Although th ...

, tribe

Cryphalini Cryphalini is a tribe of true weevils in the subfamily Scolytinae, the bark beetles. Genera '' Acorthylus'' – '' Allernoporus'' – '' Coriacephilus'' – ''Cosmoderes'' – ''Cryphalogenes'' – '' Cryphalus'' – '' Cryptocarenus'' – '' ...

in the family

Curculionidae The Curculionidae are a family of weevils, commonly called snout beetles or true weevils. They are one of the largest animal families with 6,800 genera and 83,000 species described worldwide. They are the sister group to the family Brentidae. Th ...

. The genus is widely distributed. The species feed and breed under the inner bark of trees. They infest mainly recently dead, dying or stressed trees. Some species are regarded as invasive pests, harmful to agriculture or forestry.

Taxonomy

The genus ''Cryphalus'' can be recognized by a combination of morphological characters mainly on the eyes, the antennae and tarsi. The genus has been revised in 2020 by Johnson et al. and currently includes 253 species. During that revision several genera have been combined with the genus ''Cryphalus'' like the genus ''Hypocryphalus'' which turned out to be polyphyletic and intermixed with ''Cryphalus''. See that revision for a complete list of synonyms for the genus ''Cryphalus''. Type species: '' Bostrichus asperatus'' Gyllenhal, 1813

Distribution

The genus ''Cryphalus'' has a world-wide distribution, but the species found in Central and South America are regarded as introduced. The large majority of species have been recorded in eastern Asia and the Pacific. In a checklist published in 2020, 140 species were listed in eastern Asia (including the Philippines), 90 in the Pacific and Australia (including New Guinea), 23 in Africa, 21 in western Asia, 6 each in Europe and North/Central America, and 2 in South America (some species were reported from more than one region).

Description

The adult beetles are tiny, dark brown and range in size from 0.8 to 3 mm. However, adults smaller than 1.2 mm and larger than 2.5 mm are rare. In dorsal view, the head is often hidden under the pronotum, which is large, domed, and with the anterior parts covered by tubercles. Many parts of the cuticle bear hair-like setae. Se
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for additional illustrations.

Biology

Species of ''Cryphalus'' either infest tree branches or the stems of young host trees, where they colonize the

phloem Phloem (, ) is the living tissue in vascular plants that transports the soluble organic compounds made during photosynthesis and known as ''photosynthates'', in particular the sugar sucrose, to the rest of the plant. This transport process is ...

tissue under the bark, feeding on the phloem and cambium. Weakened or stressed host trees are usually preferred. Most species are either monophagous or oligophagous. In Europe, the host trees of most species are

conifers Conifers () are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All e ...

. However, in other regions,

angiosperms Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed within a fruit. T ...

are also commonly infested. Cryphalus piceae wood

A typical life cycle has been described for ''Cryphalus piceae'' which mainly infests fir trees or

spruce A spruce is a tree of the genus ''Picea'' ( ), a genus of about 40 species of coniferous evergreen trees in the family Pinaceae, found in the northern temperate and boreal ecosystem, boreal (taiga) regions of the Northern hemisphere. ''Picea'' ...

in central and southern Europe. The adult beetles hibernate in short tunnels formed in healthy trees. They emerge in spring, mate and a

monogamous Monogamy ( ) is a relationship of two individuals in which they form a mutual and exclusive intimate partnership. Having only one partner at any one time, whether for life or serial monogamy, contrasts with various forms of non-monogamy (e.g. ...

pair forms a nuptial chamber under the bark of weakened or freshly dead branches, where the female lays 5–26 eggs. The larvae construct galleries radiating from the nuptial chamber, where the larvae develop and pupate. The adults emerge starting in April to May. Often there is a second generation in the summer.

Damage and disease transmission

Most species of ''Cryphalus'' cause only minor damage to their host trees. However, several species are regarded as pests, causing decline of trees like fig (''Ficus carica''),

mango A mango is an edible stone fruit produced by the tropical tree '' Mangifera indica''. It originated from the region between northwestern Myanmar, Bangladesh, and northeastern India. ''M. indica'' has been cultivated in South and Southeast As ...

(''Mangifera indica'') or

loquat The loquat (''Eriobotrya japonica'', Chinese: 枇杷; Pinyin: pípá) is a large evergreen shrub or tree grown commercially for its orange fruit. It is also cultivated as an ornamental plant. The loquat is in the family Rosaceae, subfamily Spi ...

(''Eriobotrya japonica''). Bark beetles are often vectors of plant diseases and have special structures for carrying symbiotic fungi called mycangia. Several species of ''Cryphalus'' have been associated with plant pathogenic fungi and are regarded or suspected as being vectors of these pathogens.

Species

The genus ''Cryphalus'' includes more than 250 species. The species recorded in more than one countries are listed here, based mainly on the 2020 checklist:

References

External links

{{Taxonbar, from=Q18240875 Scolytinae