Electromyrmococcus

''Electromyrmococcus'' is an extinct genus of mealybug in the Pseudococcidae subfamily Rhizoecinae. The genus currently contains three species, all from the early Miocene, Burdigalian stage, Dominican amber deposits on the island of Hispaniola.

History and classification

The genus was first described by Douglas Williams as an appendix to a 2001 paper published in the journal ''American Museum Novitates''. The genus name is a combination of ''electro'', from the Greek (') meaning "amber", ''myrmo'' from the Greek (') meaning "ant" and ''Coccus'' from the ant-tended genus of mealybugs, in reference to the association of ant and mealybugs in amber. Along with the genus description, the paper contained the description of the type species ''E. abductus'' and the two additional species ''E. inclusus'' and ''E. reginae''.

Description

''Electromyrmococcus'' possesses a combination of traits which are not found in any one modern genus belonging to the Rhizoecinae, a subfamily of the mealybugs. Living Rhizoecinae are separated into two groups of closely related genera, the '' Rhizoceus'' group and the '' Eumyrmococcus'' group. Antennae of the '' Rhizoceus'' group have six segments, at least as wide as they are long. The antennae of the ''Eumyrmococcus'' group have two to five long slender segments. ''Electromyrmococcus'' has long slender antennae with six segments.

''Electromyrmococcus'' species have an enlarged cephalothorax and an abdomen that gradually tapers down to a pointed end. Along the last segments of the abdomen are a number of setae which may be grouped on small poorly developed anal lobes or spaced out on the ventral margin of the abdominal segment.

All known specimens of ''Electromyrmococcus'' are preserved in amber, and all are either being clutched in the mandibles of ''Acropyga glaesaria'' species ants, or in other close association with them. Mealybugs in the Rhizoecinae subfamily are often obligatorily symbiotic with ''Acropyga'' species; when forming new nests the queens and gynes will bring a seed "herd" of mealybugs from the old colony. This carrying behavior is the probable reason for the preservation of the ''Electromyrmococcus'' specimens and represents the oldest record of this symbiosis.

''E. abductus''

''E. abductus'' was described from the holotype, a single elongated piriform female long, clutched in the mandibles of an ''Acropyga glaesaria'' adult. Very weakly formed anal lobes are found on segment eight of the abdomen and each lobe has four setae. Setae are also present on the abdominal segments leading to segment eight. The amber was recovered from the La Toca mine group northeast of Santiago de los Caballeros in the Cibao Valley. The holotype is deposited in the Senckenberg Museum of Frankfurt, Germany. The species epithet ', which is Latin for "carried off", was chosen by Williams in reference to the mealybug being preserved in the ant's mandibles.

''E. inclusus''

''E. inclusus'' is the second species which was named in the 2001 paper. The holotype female, and only specimen, is deposited in the American Museum of Natural History as "number DR-14–403". The female is long with a typical tapering abdomen. The abdomen has well-defined segments with segment eight possessing slightly developed anal lobes sporting four setae each, and segment two with a pair of submedial projections. The female has a notable constriction present between the abdomen and the thorax. However the constriction was probably not a feature possessed by the species in life, but rather though to be a result of being compressed by the ant closely associated with it when they became trapped in resin. Williams collaborated with Donat Agosti in the description of ''E. inclusus''. They chose the specific epithet ' which is a Latin participle meaning "enclosed" or "imprisoned" in allusion to the female's preservation in amber.

''E. reginae''

The third known species is ''E. reginae'', which, like the other known species, is known from a single female specimen preserved in amber. ''E. reginae'' is the largest of the three species at in length. Noted to be closely related to ''E. inclusus'', the anal lobes of ''E. reginae'' are not as well developed but do possess four setae each. The well-developed legs of ''E. reginae'' also have some setae present. Like ''E. abductus'' the ''E. reginae'' female was preserved in the mandibles of an ''Acropyga glaesaria'' ant, this one a queen. In reference to this the specific epithet ''reginae'' comes from the Latin ' meaning "belonging to a queen".

References

{{Taxonbar, from=Q16752647

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Extinct Hemiptera
Prehistoric insect genera
Burdigalian life
Neogene Dominican Republic
Miocene insects of North America
Prehistoric insects of the Caribbean
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Fossils of the Dominican Republic
Dominican amber
Fossil taxa described in 2001