Leptomyrmex

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Leptomyrmex
Leptomyrmex darlingtoni casent0012024 profile 1.jpg
L. darlingtoni worker from Australia
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Dolichoderinae
Tribe: Leptomyrmecini
Genus: Leptomyrmex
Mayr, 1862
Type species
Formica erythrocephala
Diversity [1]
28 species

Leptomyrmex, or spider ants, is a genus of ants and a distinctive member of the ant subfamily Dolichoderinae. [2] Commonly known as "spider ants" for their long legs and spider-like movements, these orange and black ants are prominent residents of intact wet forest and sclerophyll habitats throughout their range. One extant species, Leptomyrmex relictus , is known from central Brazil; [3] otherwise, the global distribution of this genus is restricted to eastern Australia, New Caledonia and New Guinea, as well as the nearby Indonesian islands of Aru and Seram. [4]

Contents

Newly hatched Extatosoma tiaratum stick insects mimic these ants to avoid predation. [5]

Workers of Leptomyrmex can be easily recognized by elongate antennal scapes which surpass the posterior margin of the head by more than one half their length, a medially notched hypostoma, mandibles with 7–15 teeth and 5–12 denticles, and a laterally located anterior tentorial pit. [4]

Queens are known from only seven species. All known macro-Leptomyrmex queens are wingless (ergatoid). They can be differentiated from workers by the presence of ocelli and their larger size, including enlarged mesosoma and gaster. Whereas the workers possess a mesosoma that is smooth in profile, the profile of queens is distinctly impressed at the promesonotal suture and the metanotal groove. Appendages are noticeably stouter. Queens of at least one micro-Leptomyrmex species possess wings. [6]

Species groups

The species are informally split into two groups: the macro-Leptomyrmex (21 species), and its sister group, the micro-Leptomyrmex (six species). [4] Macro-Leptomyrmex are large, diurnal and many are conspicuously colored in black, orange or bicolorous black and orange. Micro-Leptomyrmex species have been recently described from Australia, [7] and were placed in Leptomyrmex based on mandibular dentition, anterior clypeal margin configuration, elongate scapes and head, cleft medial hypostomal margin, anterior tentorial pit location, keeled fourth gastral sternite and reduced hind tibial spurs. In some cases, scapes are shorter than in the macro species, and in one species ( L. ramorniensis ) the hypostoma is only weakly notched. All six species are readily distinguished from their larger congeners by their small size (head width < 0.80mm), brown coloration, relatively short dorsal face of the propodeum, angular (not rounded) petiole and gaster lacking lateral compression. [4] [8] All micro species occur in eastern Australian rainforests. [9]

Evolution

Simplified cladogram depicting relationships within the genus Leptomyrmex. Triangles represent species complexes not fully resolved by molecular phylogenetic analyses; AU = Australia, NC = New Caledonia, NG = New Guinea. Zootaxa 2688 1-67 plate 26 Leptomyrmex cladogram.jpg
Simplified cladogram depicting relationships within the genus Leptomyrmex. Triangles represent species complexes not fully resolved by molecular phylogenetic analyses; AU = Australia, NC = New Caledonia, NG = New Guinea.

With exception of the South American species Leptomyrmex relictus, the Leptomyrmex species are currently confined to eastern Australia and several nearby Pacific islands. However, the discovery of fossil specimens from the Dominican Republic (20 my) and a supposedly related genus, Leptomyrmula , from Sicily (30 my) led Wilson to describe the evolutionary history of this genus as a "considerable biogeographic anomaly". [12] The assertion that extant species of Leptomyrmex are relicts of a lineage once widespread across the globe that have survived in the tropical refuges of Australasia, is compelling, and similar biogeographic patterns are seen in other so-called "relictual" lineages in Australia, New Guinea and New Caledonia (among them the ant subfamily Myrmeciinae). [13]

The sister group relationship of the winged micro-Leptomyrmex to the wingless macro- clade suggests that the loss of wings may have occurred relatively recently in this lineage, and that stem lineages may not necessarily have been wingless. These observations, in addition to the fact that the sister group of Leptomyrmex (i.e., ( Forelius + Dorymyrmex )) also has winged queens, may help explain the proposed widespread former distribution. On the other hand, a recent molecular phylogenetic analysis of the Dolichoderinae places Leptomyrmex firmly within a clade of species (tribe Leptomyrmecini) whose origins appears to be in the Neotropics, with two main dispersal events to Australia. [14] This suggests that the Sicilian fossil Leptomyrmula is not part of this group. [13]

Related Research Articles

<span class="mw-page-title-main">Dolichoderinae</span> Subfamily of ants

Dolichoderinae is a subfamily of ants, which includes species such as the Argentine ant, the erratic ant, the odorous house ant, and the cone ant. The subfamily presents a great diversity of species throughout the world, distributed in different biogeographic realms, from the Palearctic, Nearctic, Afrotropical region and Malaysia, to the Middle East, Australian, and Neotropical regions.

<i>Amyrmex</i> Species of ant

Amyrmex golbachi is a rare Neotropical species of ant and the only known species in the genus Amyrmex. It is currently only known from males from the Amazon basin of Brazil and from northern Argentina.

<i>Iridomyrmex</i> Genus of ants

Iridomyrmex is a genus of ants called rainbow ants first described by Austrian entomologist Gustav Mayr in 1862. He placed the genus in the subfamily Dolichoderinae of the family Formicidae. It has 79 described species and five fossil species. Most of these ants are native to Australia; others are found in Asia and Oceania, and they have been introduced to Brazil, New Zealand, and the United Arab Emirates. Fossil species are known from China, France, and the United States.

<i>Usomyrma</i> Genus of ants

Usomyrma is an extinct genus of ant in the formicid subfamily Dolichoderinae. The genus contains a single described species, Usomyrma mirabilis, that is known from two Middle Eocene fossils which were found in Scandinavian amber in Denmark.

<i>Leptomyrmex darlingtoni</i> Species of ant

Leptomyrmex darlingtoni is a species of ant in the genus Leptomyrmex. Described by William Morton Wheeler in 1934, the species is endemic to Australia.

Leptomyrmex cnemidatus is a species of ant in the genus Leptomyrmex. Described by William Morton Wheeler in 1915, the species is endemic to Australia.

<i>Leptomyrmex erythrocephalus</i> Species of ant

Leptomyrmex erythrocephalus is a species of ant in the genus Leptomyrmex. Described by Johan Christian Fabricius in 1775, the species is endemic to Australia.

<i>Leptomyrmex fragilis</i> Species of ant

Leptomyrmex fragilis is a species of ant in the genus Leptomyrmex, commonly called ‘spider ants’. Described by Smith in 1859, the species is endemic to Indonesia and New Guinea and the Philippines.

<i>Leptomyrmex mjobergi</i> Species of ant

Leptomyrmex mjobergi is a species of ant in the genus Leptomyrmex. Described by Auguste-Henri Forel in 1915, the species is endemic to Australia.

Leptomyrmex neotropicus is an extinct species of Miocene ant in the genus Leptomyrmex. Described by Baroni Urbani in 1980, a total of 10 workers of this species were found in a single block of Dominican amber.

<i>Leptomyrmex nigriventris</i> Species of ant

Leptomyrmex nigriventris is a species of ant in the genus Leptomyrmex. Described by Félix Édouard Guérin-Méneville in 1831, the species is endemic to Australia.

<i>Leptomyrmex pallens</i> Species of ant

Leptomyrmex pallens is a species of ant in the genus Leptomyrmex. Described by Carlo Emery in 1883, the species is only endemic to New Caledonia.

Leptomyrmex rothneyi is a species of ant in the genus Leptomyrmex. Described by Auguste-Henri Forel in 1902, the species is endemic to Australia.

Leptomyrmex rufipes is a species of ant in the genus Leptomyrmex. Described by Carlo Emery in 1895, the species is endemic to Australia.

Leptomyrmex rufithorax is a species of ant in the genus Leptomyrmex. Described by Auguste-Henri Forel in 1915, the species is endemic to Australia.

<i>Leptomyrmex tibialis</i> Species of ant

Leptomyrmex tibialis is a species of ant in the genus Leptomyrmex. First described by Carlo Emery in 1895 as Leptomyrmex nigriventris tibialis, the species is endemic to Australia, and found in both New South Wales and Queensland. The arguments for synonymy were made by Lucky and Ward, and the decision was accepted by the Australian Faunal Directory.

<i>Leptomyrmex unicolor</i> Species of ant

Leptomyrmex unicolor is a species of ant in the genus Leptomyrmex. Described by Carlo Emery in 1895, the species is endemic to Australia.

<i>Leptomyrmex wiburdi</i> Species of ant

Leptomyrmex wiburdi is a species of ant in the genus Leptomyrmex. Described by William Morton Wheeler in 1915, the species is endemic to Australia.

<i>Myanmyrma</i> Extinct genus of ants

Myanmyrma is an extinct genus of ants not placed into any Formicidae subfamily. Fossils of the single known species, Myanmyrma gracilis, are known from the Middle Cretaceous of Asia. The genus is one of several ants described from Middle Cretaceous ambers of Myanmar.

References

  1. Bolton, B. (2014). "Leptomyrmex". AntCat. Retrieved 4 July 2014.
  2. "Genus: Leptomyrmex". AntWeb . Retrieved 11 October 2013.
  3. Boudinot et al. 2016.
  4. 1 2 3 4 Lucky & Ward 2010, p. 4
  5. Williams & Evans 1993, p. 175
  6. Lucky & Ward 2010, p. 14
  7. Smith & Shattuck 2009, p. 57
  8. Smith & Shattuck 2009, p. 58
  9. 1 2 Lucky & Ward 2010, p. 62
  10. Lucky & Ward 2010, pp. 8–9
  11. Lucky & Ward 2010, p. 25
  12. Wilson 1985, p. 35
  13. 1 2 Lucky & Ward 2010, p. 63
  14. Ward et al. 2010, pp. 356–357