''Protoclaviger'' 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 ...

Early

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

transitional fossil A transitional fossil is any fossilized remains of a life form that exhibits traits common to both an ancestral group and its derived descendant group. This is especially important where the descendant group is sharply differentiated by gross a ...

myrmecophile Myrmecophily ( , ) is the term applied to positive interspecies associations between ants and a variety of other organisms, such as plants, other arthropods, and fungi. Myrmecophily refers to mutualistic associations with ants, though in its m ...

of the

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 ...

subfamily

Pselaphinae Pselaphinae are a subfamily of beetles in the family Staphylinidae, the rove beetles. The group was originally regarded as a separate family named Pselaphidae. Newton and Thayer (1995) placed them in the Omaliine group of the family Staphylinida ...

, and a

stem group In phylogenetics, the crown group or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor. ...

of the modern supertribe Clavigeritae, of which '' Claviger'' is a representative. All modern Clavigeritae are morphologically specialized obligate colony

parasites Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted structurally to this way of lif ...

of ant nests, soliciting food via

trophallaxis Trophallaxis () is the transfer of food or other fluids among members of a community through mouth-to-mouth ( stomodeal) or anus-to-mouth ( proctodeal) feeding. Along with nutrients, trophallaxis can involve the transfer of molecules such as pher ...

from worker ants, and preying on the nest brood. The

amber Amber is fossilized tree resin that has been appreciated for its color and natural beauty since Neolithic times. Much valued from antiquity to the present as a gemstone, amber is made into a variety of decorative objects."Amber" (2004). In Ma ...

-embedded

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

specimen of the single species, ''Protoclaviger trichodens'', was recovered from a piece of 52 million-year-old

Cambay Cambay, Kambay or Khambhat was a princely state in India during the British Raj. The City of Khambat (Cambay) in present-day Gujarat was its capital. The state was bounded in the north by the Kaira district and in the south by the Gulf of Cam ...

amber from

Gujarat Gujarat (, ) is a state along the western coast of India. Its coastline of about is the longest in the country, most of which lies on the Kathiawar peninsula. Gujarat is the fifth-largest Indian state by area, covering some ; and the ninth ...

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

. ''P. trichodens'' differs to modern Clavigeritae in its possession of a segmented dorsal abdomen; in

extant Extant is the opposite of the word extinct. It may refer to: * Extant hereditary titles * Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English * Extant taxon, a taxon which is not extinct, ...

species, the abdominal

tergites A ''tergum'' (Latin for "the back"; plural ''terga'', associated adjective tergal) is the dorsal ('upper') portion of an arthropod segment other than the head. The anterior edge is called the 'base' and posterior edge is called the 'apex' or 'mar ...

are fused into single large segment. ''P. trichodens'' also possesses 8 antennal segments and mouthparts that extend outside the oral cavity, whereas modern species have between 3 and 6 antennal segments, and mouthparts that are contained within the oral cavity. ''Protoclaviger'' is believed to represent an intermediate stage in the evolution of morphological specialization that adapted modern Clavigeritae to life inside ant colonies. Its discovery in Cambay amber, which holds one of the earliest diverse assemblages of modern ant subfamilies, indicates that the ant-beetle symbiosis is evolutionarily ancient.

References

{{Taxonbar, from=Q19636634 Transitional fossils Eocene insects Prehistoric beetle genera Clavigeritae Pselaphinae genera Fossil taxa described in 2014 Fossils of India Paleogene India