''Diochus electrus'' is an extinct

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 ...

rove beetle The rove beetles are a family (Staphylinidae) of beetles, primarily distinguished by their short elytra (wing covers) that typically leave more than half of their abdominal segments exposed. With roughly 63,000 species in thousands of genera, the ...

in genus ''Diochus'', the only definitive fossil species in subfamily

Staphylininae Staphylininae are a subfamily of rove beetles (family Staphylinidae). They contain the typical rove beetles with their long but fairly robust blunt-headed and -tipped bodies and short elytra, as well as some more unusually-shaped lineages. Syste ...

. The species is known only from the

middle Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', "dawn ...

Lutetian stage The Lutetian is, in the geologic timescale, a stage or age in the Eocene. It spans the time between . The Lutetian is preceded by the Ypresian and is followed by the Bartonian. Together with the Bartonian it is sometimes referred to as the Midd ...

Baltic amber found in the Blaue Erde deposits,

Baltic region The terms Baltic Sea Region, Baltic Rim countries (or simply the Baltic Rim), and the Baltic Sea countries/states refer to slightly different combinations of countries in the general area surrounding the Baltic Sea, mainly in Northern Europe. ...

Northern Europe The northern region of Europe has several definitions. A restrictive definition may describe Northern Europe as being roughly north of the southern coast of the Baltic Sea, which is about 54th parallel north, 54°N, or may be based on other g ...

History and classification

''Diochus electrus'' is known only from one fossil, the holotype, number "KU-NHM-ENT, B-244". It is a single complete adult female preserved as an inclusion in a specimen of clear orange amber. The fossil was recovered from an outcrop of the Blaue Erde deposits which contain the fossil resins in the Baltic region. The type specimen is currently preserved in the Division of Entomology at the

University of Kansas Natural History Museum The University of Kansas Natural History Museum is part of the University of Kansas Biodiversity Institute, a KU designated research center dedicated to the study of the life of the planet. The museum's galleries are in Dyche Hall on the unive ...

located in

Lawrence, Kansas Lawrence is the county seat of Douglas County, Kansas, Douglas County, Kansas, United States, and the sixth-largest city in the state. It is in the northeastern sector of the state, astride Interstate 70, between the Kansas River, Kansas and Waka ...

, USA. ''Diochus electrus'' was first studied by Stylianos Chatzimanolis of the

University of Tennessee at Chattanooga The University of Tennessee at Chattanooga (UT-Chattanooga, UTC, or Chattanooga) is a public university in Chattanooga, Tennessee, United States. It was founded in 1886 and is one of four universities and two other affiliated institutions in the ...

and Michael S. Engel of the University of Kansas. Their 2011

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 ...

for the new species was published online and in print in the journal ''

ZooKeys ''ZooKeys'' is a peer-reviewed open access scientific journal covering zoological taxonomy, phylogeny, and biogeography. It was established in 2008 and the editor-in-chief is Terry Erwin (Smithsonian Institution). It is published by Pensoft Publ ...

''. The

etymology Etymology ()The New Oxford Dictionary of English (1998) – p. 633 "Etymology /ˌɛtɪˈmɒlədʒi/ the study of the class in words and the way their meanings have changed throughout time". is the study of the history of the Phonological chan ...

of the specific name ''electrus'' is a derivation of the

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

word "''electrum''" meaning amber. When ''Diochus electrus'' was described, it was the first definitive species of the rove beetle subfamily Staphylininae to be described from the fossil record. The Baltic amber species '' Bembicidiodes inaequicollis'', described by L. W. Schaufuss in 1888, was formerly considered part of Staphylininae. However reevaluation of the species in 2001 by L.H. Herman raised doubts about the correct subfamily placement for ''B. inaequicollis''. ''Diochus electrus'' is one of eleven species of the genus ''Diochus'' inhabiting the

Palearctic realm The Palearctic or Palaearctic is the largest of the eight biogeographic realms of the Earth. It stretches across all of Eurasia north of the foothills of the Himalayas, and North Africa. The realm consists of several bioregions: the Euro-Sibe ...

Description

The ''Diochus electrus'' type specimen is a well preserved fully complete female with a total body length of . The head is ovoid in shape and has fine sculpturing with sporadic punctations. The antenna do not have a geniculate structure, which indicates placement of the species into the tribe Diochini. Though similar to the genus '' Coomania'', the neck of ''D. electrus'' is more robust, with ''Coomania'' having a neck that is approximately a fifth the width of the head. The

elytra An elytron (; ; , ) is a modified, hardened forewing of beetles (Coleoptera), though a few of the true bugs (Hemiptera) such as the family Schizopteridae are extremely similar; in true bugs, the forewings are called hemelytra (sometimes alterna ...

of ''D. electrus'' are in length and have a width of . They are longer than the

pronotum The prothorax is the foremost of the three segments in the thorax of an insect, and bears the first pair of legs. Its principal sclerites (exoskeletal plates) are the pronotum (dorsal), the prosternum (ventral), and the propleuron (lateral) on ea ...

. The other ten palearctic species of ''Diochus'' possess pronotum which are longer than the elytra, distinguishing ''D. electrus'' as a species.

References

{{Taxonbar, from=Q5279072 † Prehistoric beetles Lutetian insects Prehistoric insects of Europe Fossil taxa described in 2011 † Baltic amber