Electromyrmex

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Electromyrmex
Temporal range: Bartonian, Middle to Late Eocene Baltic amber, Baltic Sea region
Electromyrmex klebsi
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Genus: Electromyrmex
Wheeler, W.M., 1910
Type species
Electromyrmex klebsi
Diversity
2 fossil species
(Species Checklist)

Wheeler (1915) established a fossil myrmicine ant genus Electromyrmex from the Late Eocene Baltic amber (Priabonian stage, 33.9–37.2 Ma), based on the species Electromyrmex klebsi. The single worker of this species, believed lost (A. Gehler, pers. comm., 2017), is morphologically peculiar and can be easily recognized based on the description and Wheeler's figure (1915, fig. 21). It is characterized primarily by the slender body, big and convex eyes situated very closely to the anterior head margin so that the genae are extremely short, long and narrow mandibles with serrate masticatory margin, slender, subcylindrical petiole without a distinct node, etc. Wheeler (1915: 56) emphasized: “This singular ant is so unlike any of the recent species … in the structure of its mandibles, thorax and petiole that it evidently deserves to rank as the type of a new genus”. (Radchenko & Dlussky 2018)

Photo Gallery

  • Electromyrmex klebsi, Baltic amber.jpg

Identification

Radchenko & Dlussky (2018) - Morphologically peculiar and easily recognized based on the description of the Electromyrmex klebsi worker: (Wheeler 1915) characterized primarily by the slender body, big and convex eyes situated very closely to the anterior head margin so that the genae are extremely short, long and narrow mandibles with serrate masticatory margin, slender, subcylindrical petiole without a distinct node, etc.

The males of Electromyrmex wheeleri share several characters with some modern Myrmicinae genera: resembling Aphaenogaster, Messor and Pheidole by the forewing venation, but differing from the first two genera by the presence of Mayrian furrows, and from the latter by the antennal structure. Additionally, males of E. wheeleri have a set of specialized characters, e. g., subcylindrical petiole, mandible with an only single apical tooth, and quite peculiar shape of mesosoma.

Distribution

This taxon is known from Baltic amber (Bartonian, Middle to Late Eocene) and Bitterfeld amber (Bartonian, Middle to Late Eocene).

Notes

Radchenko & Dlussky (2018) - Based on the main diagnostic features of the worker, Electromyrmex looks to be highly specialized extinct myrmicine genus that cannot be considered either as an ancestor or as a descendant of any known extinct or extant ant genera; its taxonomic position within the subfamily Myrmicinae is uncertain (Bolton, 2013; Ward et al., 2015). The species described after the type species, Electromyrmex wheeleri, is based on two male types, also provides little that sheds any light on the taxonomic placement of the genus.

Castes

Nomenclature

The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

  • ELECTROMYRMEX [incertae sedis in Myrmicinae]
    • Electromyrmex Wheeler, W.M. 1910g: 164 (by indication). Type-species: †Electromyrmex klebsi, by monotypy.
    • [†Electromyrmex Wheeler, W.M. 1908g: 413. Nomen nudum. †Electromyrmex also described as new by Wheeler, W.M. 1915h: 55.]

References

  • Barden, P. 2017. Fossil ants (Hymenoptera: Formicidae): ancient diversity and the rise of modern lineages. Myrmecological News 24: 1-30.
  • Bolton, B. 1994. Identification guide to the ant genera of the world. Cambridge, Mass.: Harvard University Press, 222 pp. (page 106, Electromyrmex incertae sedis in Myrmicinae)
  • Bolton, B. 1995b. A new general catalogue of the ants of the world. Cambridge, Mass.: Harvard University Press, 504 pp. (page 187, Electromyrmex incertae sedis in Myrmicinae)
  • Bolton, B. 2003. Synopsis and Classification of Formicidae. Mem. Am. Entomol. Inst. 71: 370pp (page 258, Electromyrmex incertae sedis in Myrmicinae [Electromyrmex Wheeler, W.M. 1908b:413, nomen nudum. Electromyrmex also described as new by Wheeler, W.M. 1915e:55 (diagnosis).])
  • Dlussky, G. M.; Fedoseeva, E. B. 1988. Origin and early stages of evolution in ants. Pp. 70-144 in: Ponomarenko, A. G. (ed.) Cretaceous biocenotic crisis and insect evolution. Moskva: Nauka, 232 pp. (page 80, Electromyrmex incertae sedis in Myrmicinae)
  • Donisthorpe, H. 1943g. A list of the type-species of the genera and subgenera of the Formicidae. [part]. Ann. Mag. Nat. Hist. 11(10): 617-688 (page 642, Electromyrmex in Myrmicinae, Myrmicini)
  • Wheeler, W. M. 1910b. Ants: their structure, development and behavior. New York: Columbia University Press, xxv + 663 pp. (page 164, Electromyrmex as genus (by indication))
  • Wheeler, W.M. 1915i. The ants of the Baltic Amber. Schriften der Physikalisch-Ökonomischen Gesellschaft zu Königsberg 55: 1-142. (page 55, Electromyrmex in Myrmicinae, Myrmicini; Electromyrmex also described as new)