''Xylolaemus sakhnovi'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of cylindrical bark beetle in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Zopheridae The Zopheridae family of beetles has grown considerably in recent years as the members of two other families have been included within its circumscription; these former families are the Monommatidae and the Colydiidae, which are now both incl ...

. The species is solely known from the Middle Eocene

Baltic amber The Baltic region is home to the largest known deposit of amber, called Baltic amber or succinite. It was produced sometime during the Eocene epoch, but exactly when is controversial. It has been estimated that these forests created more than 1 ...

deposits in the

Baltic Sea The Baltic Sea is an arm of the Atlantic Ocean that is enclosed by Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia, Sweden and the North and Central European Plain. The sea stretches from 53°N to 66°N latitude and from ...

region of Europe. The genus '' Xylolaemus'' contains a total of six extant species distributed from western Europe through the Canary Islands and North Africa to India. The species is the first in the genus to be described from a fossil specimen.

History and classification

''Xylolaemus sakhnovi'' is known from a single fossil insect which is an

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in a transparent chunk of Baltic amber. The amber specimen contains the beetle

imago In biology, the imago (Latin for "image") is the last stage an insect attains during its metamorphosis, its process of growth and development; it is also called the imaginal stage, the stage in which the insect attains maturity. It follows the f ...

along with a number of ''

Quercus An oak is a tree or shrub in the genus ''Quercus'' (; Latin "oak tree") of the beech family, Fagaceae. There are approximately 500 extant species of oaks. The common name "oak" also appears in the names of species in related genera, notably '' ...

'' stellate hairs and a partial aphid. When the fossil was described it as part of a private collection, with the intent that it would be donated to the Paleontological Institute, Russian Academy of Science. The amber was recovered from fossil-bearing rocks in the

Kaliningrad Kaliningrad ( ; rus, Калининград, p=kəlʲɪnʲɪnˈɡrat, links=y), until 1946 known as Königsberg (; rus, Кёнигсберг, Kyonigsberg, ˈkʲɵnʲɪɡzbɛrk; rus, Короле́вец, Korolevets), is the largest city and ...

region of

Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...

. Estimates of the age date between 37 million years old, for the youngest sediments and 48 million years old. This age range straddles the middle Eocene, ranging from near the beginning of the Lutetian to the beginning of the Pribonian. The holotype was first studied by researchers Vitaly I. Alekseev of

Kaliningrad State Technical University Kaliningrad State Technical University Kaliningrad State Technical University (russian: Калининградский государственный технический университет, (КГТУ); abbreviated KSTU) is a technical u ...

and Nathan P. Lord of

Brigham Young University Brigham Young University (BYU, sometimes referred to colloquially as The Y) is a private research university in Provo, Utah. It was founded in 1875 by religious leader Brigham Young and is sponsored by the Church of Jesus Christ of Latter-day ...

. Alekseev and Lord's 2014

type description A species description is a formal description of a newly discovered species, usually in the form of a scientific paper. Its purpose is to give a clear description of a new species of organism and explain how it differs from species that have be ...

of the species was published in the

entomology Entomology () is the science, scientific study of insects, a branch of zoology. In the past the term "insect" was less specific, and historically the definition of entomology would also include the study of animals in other arthropod groups, such ...

journal ''Baltic Journal of Coleopterology''. The

specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

''sakhnovi'' was coined as a

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in honor of Nikolay I. Sakhnov, an entomologist and animal painter from the Kaliningrad region.

Description

The holotype ''X. sakhnovi'' specimen is a mostly complete adult beetle, with the left legs, antennae, and pronotal region are all damaged, and the left half of the insect shows blackening (possibly from the amber having been processed with an autoclave). Overall the specimen has a body length of and has a width in the humeral region of being elongated and flattened in shape. In general, the coloration of the beetle was a uniform dark grey, with setae in some areas of the prosternum. The species is distinguished from extant ''Xylolaemus'' and at least one undescribed Baltic amber fossil in that the end segments of the antennae do not form a tight club; rather, they form a loose club and the tenth segments are the same size as the other segments. Also, ''X. sakhnovi'' is smaller overall, and the elytra do not have the patches of setae seen in the modern species.

References

{{Taxonbar, from=Q22287081 Zopheridae Prehistoric life of Europe Fossil taxa described in 2014 Beetles of Europe Baltic amber