Belongs within: Euaculeata.
Contains: Amblyoponinae, Proceratiinae, Ponerinae, Dorylinae, Aenictus, Ecitoninae, Cerapachyinae, Myrmeciinae, Pseudomyrmecinae, Ectatomminae, Myrmicinae, Formicinae, Dolichoderinae.
The Formicidae are the ants, a diverse and familiar clade of social wasps with a caste division between wingless workers and winged reproductives. Female reproductives (the ‘queens’) shed their wings after mating. Males are typically smaller than queens with larger eyes and longer antennae, and do not live long after mating. An elongate scape (first antennal segment) is present in living ants, but was absent in the Cretaceous Sphecomyrminae (Grimaldi & Engel 2005). The morphology of Sphecomyrma indicates that it was an epigean (above-ground) forager, but two of the most basally diverging living ant lineages, the Leptanillinae and Martialis heureka, are hypogean (below-ground) foragers with reduced pigmentation and eyes. Leptanillinae are found in the tropics of the Old World and are characterised by a two-segmented petiole and twelve-segmented antennae without frontal lobes concealing the base.
Other small subfamilies of ants include the Agroecomyrmecinae, little-known ants from Africa and South America with eyes placed far back on the head and antennae spaced widely apart. The shape of the gaster in Agroecomyrmecinae is also distinctive, with abdominal sternite 4 reduced while the corresponding tergite is much larger and vaulted. The Heteroponerinae are relatively cryptic ants with a median longitudinal cephalic carina extending from the occipital margin to the anterior margin of the clypeus (Heterick 2009).
Eureka! It’s an ant!
Published 16 September 2008
But not as we know it.
I have learnt through Alex Wild of a paper currently in press for PNAS (Rabeling et al. 2008) describing a new species of ant. With more than 12,000 ant species already on the books, this may sound like something of a non-event, but trust me, it’s not. This new ant, Martialis heureka, has been placed not only in a new genus, but in a whole new subfamily. In fact, Martialis appears to be the sister group to all other living ants. A quick request later, and the lead author, Christian Rabeling, was kind enough to send me a copy of the paper*.
*For those without ready journal access, don’t be afraid to contact authors of articles you might be interested in and ask if they have spare copies. Most researchers will be all too happy to help you.
As yet, Martialis is known only from a single worker specimen collected in 2003 in leaf litter from the Brazilian Amazon. One of the authors had found two workers in a soil sample five years previously, but these specimens were subsequently lost. The species name heureka (Greek for “Give me a towel!”) reflects this history of disappointment and elation. The genus name Martialis refers to the unusual appearance of the specimen which looked like it may as well have come from Mars. Martialis is a pale-coloured, eyeless ant with long, thin, pincer-like mandibles. Because of the absence of eyes and its being found in litter and soil samples, the authors infer that Martialis lives hypogaeically (under the ground) or in some other low-light habitat such as within logs. However, the new species lacks any noticeable adaptations for digging, so it may inhabit pre-existing cavities such as rotting roots or burrows made by other animals. The fine mandibles, unlike those of any other ant, may be used for drawing out soft-bodied burrowing prey such as insect larvae. Features such as the presence of a sting indicate that Martialis belongs to the basal grade of ants, and molecular analysis of the specimen indicated Martialis to be sister to all other ants.
Interestingly, Rabeling et al.‘s analysis also corroborates an earlier analysis by Brady et al. (2006) in finding the basalmost clade in the ants other than Martialis to be the Leptanillinae, another small hypogaeic subfamily. If this topology is correct, it is possible that the ancestor of all ants was hypogaeic. However, the current analysis was unable to statistically reject a number of alternative rootings.
The earliest fossil record of ants from the Cretaceous consists of the extinct subfamily Sphecomyrminae and a single species of the basal subfamily “Ponerinae” (Dlussky 1999—recent analyses indicate that the Ponerinae as previously recognised should be divided between a number of subfamilies and I don’t know whether the Cretaceous species would belong to the Ponerinae in the stricter sense). Dlussky (1999) recognises a separate family Armaniidae from the Cretaceous closely related to Formicidae but Wilson (1987) argued that the “armaniids” are most likely winged castes of Sphecomyrminae. While the basal lineages of living ants might be hypogaeic, cryptic forms, the Sphecomyrminae, previously identified by its morphology as sister group to living ants, were wasp-like, probably epigaeic forms. Alternative positions for Sphecomyrminae within the crown clade seem unlikely in light of the absence of other ant fossils from the Cretaceous. I personally suspect that despite their basal position, there is a strong possibility that the hypogaeic lifestyle was acquired independently in Leptanillinae and Martialis rather than being ancestral for living ants as a whole.
What to do with a dead hummingbird
Published 11 November 2011
We’ve all been there: that dead hummingbird is just cluttering things up, you don’t really know what to do with it, but you don’t really want to throw it out because, hey, you never know when that sort of thing might come in handy. Well, fear not! A dead hummingbird can be a very practical thing:
You need never be without a scale bar again!
The above figure, from Archibald et al. (2011), shows a rufous hummingbird Selasphorus rufus alongside the newly described early Eocene giant ant Titanomyrma lubei. This fossil comes from the American Green River Formation, in present-day Wyoming. At 51 mm in length, this is one of the largest known ants, rivalled in the modern fauna only by the marginally longer but possibly less robust driver ant Dorylus wilverthi. The title of largest ant ever goes, so far as we know, to Titanomyrma giganteum (or Formicium giganteum*) from the Messel Formation of Germany.
*There’s a bit of skullduggery in Archibald et al.‘s paper viz. the relative status of the pre-existing genus Formicium and their new genus Titanomyrma, whereby Titanomyrma is not diagnostically different from Formicium, but Formicium is relegated to the status of a form taxon for wing fossils only. This is all above board, ICZN-wise, but I’m not sure I’d condone it.
Living giant ants (which, except for Dorylus, are all under 35 mm) are mostly tropical in distribution, but the locality from which Titanomyrma lubei hails would have been within the Arctic Circle when it was alive (Update: Neil has corrected me: the Green River Formation was not Arctic, but northern temperate). The Eocene was a much seamier time than today and, though not tropical, the Arctic would have been far from a frozen wasteland.
Systematics of Formicidae
Synapomorphies (Grimaldi & Engel 2005): Eusocial habits, with wingless female caste(s) present; metapleural gland opening on propodeum; petiole present.
<==Formicidae [Formicariae, Formiciformes, Formicoidea, Paleosminthuridae, Poneridae]
|--Sphecomyrminae [Sphecomyrmidae]BS06
| |--CretomyrmaWB03
| |--Baikuris mandibularis Dlussky 1987RJ93
| |--Dlusskyidris zherichiniWB03, GE05
| |--Paleomyrmex Dlussky 1975H02
| | `--P. zherichiniH02
| `--Sphecomyrma Wilson & Brown 1967RBV08, V10
| |--S. canadensis Wilson 1985P92
| `--S. freyi Wilson et al. 1967P92
`--+--Martialis Rabeling & Verhaagh in Rabeling, Brown & Verhaagh 2008 [Martialinae]RBV08
| `--*M. heureka Rabeling & Verhaagh in Rabeling, Brown & Verhaagh 2008RBV08
`--+--LeptanillinaeRBV08
| |--ProtanillaRBV08
| `--Leptanilla Emery 1870FT08
| |--*L. revelierii Emery 1870TB85
| |--L. japonica Baroni Urbani 1977I92
| |--L. kubotai Baroni Urbani 1977I92
| |--L. morimotoi Yasumatsu 1960I92
| |--L. oceanica Baroni Urbani 1977I92
| |--L. swani Wheeler 1932TB85
| `--L. tanakai Baroni Urbani 1977I92
`--+--+--AmblyoponinaeRBV08
| `--AgroecomyrmecinaeRBV08
| |--Tatuidris tatusiaMB06
| `--AgroecomyrmexP92
`--+--+--ProceratiinaeRBV08
| `--Paraponera [Paraponerinae, Paraponerini]RBV08
| `--P. clavataRBV08
`--+--PonerinaeRBV08
`--+--+--+--+--+--DorylinaeBS06
| | | | `--Aenictogiton [Aenictogitoninae]BS06
| | | `--AenictusMB06
| | `--EcitoninaeMB06
| `--CerapachyinaeMB06
`--+--Dolichoformica helferiGE05
`--+--+--MyrmeciinaeMB06
| `--PseudomyrmecinaeBS06
`--+--+--+--HeteroponerinaeMB06
| | | |--Acanthoponera panamensisBS06
| | | |--AulacoponeH09
| | | `--Heteroponera Mayr 1887 [incl. Paranomopone Wheeler 1915]TB85
| | | |--*H. carinifrons Mayr 1887TB85
| | | |--H. imbellis (Emery 1895) (see below for synonymy)TB85
| | | |--H. leae (Wheeler 1923) [=Acanthoponera (Anacanthoponera) leae]TB85
| | | |--H. panamensisBS06
| | | `--H. relicta (Wheeler 1915) [=*Paranomopone relicta]TB85
| | `--EctatomminaeMB06
| `--+--MyrmicinaeBS06
| `--FormicinaeMB06
`--+--DolichoderinaeMB06
`--AneuretinaeBS06
|--AneuretellusGE05
|--Aneuretus Emery 1893B03
| `--*A. simoni Emery 1893B03
|--GerontoformicaMB06
| |--G. cretacicaGE05
| `--G. occidentalisBS23
`--BurmomyrmaMB06
Formicidae incertae sedis:
Huberia striata (Smith 1876)H82
Brownimecia clavataGE05
Haidomyrmex cerberusGE05
StrongylognathusE89a
|--S. aferE89a
|--S. caeciliaeES12
|--S. christophi Emery 1889E89a
|--S. huberiE89a
|--S. koreanus Pisarski 1965I92
`--S. testaceusA71
Anergates atratulusA71
Eoponera berryiGE05
Canapone dentataGE05
ProtoponeGE05
Trapeziopelta malignaE89b
Lordomyrmex caledonica Andre 1889E14
Sphecomyrmodes occidentalis Perrichot, Nel et al. 2007V10
Eusphinctus Emery 1893TB85
Chalepoxenus muellerianusES12
Cretacoformica explicata Jell & Duncan 1986Z01
Formicium giganteumS12
Eomyrmex Hong 1974H02
`--E. guchengziensis Hong et al. 1974P92
Aeromyrma sophiae Emery 1890H02
ArchaeoponeP92
ArmaniellaP92
CretoponeP92
DolichomyrmaP92
PetroponeP92
PoneropterusP92
PseudarmaniaP92
AsymphylomyrmexP92
BradoponeraP92
ElectromyrmexP92
ElectroponeraP92
EnneamerusP92
MonoriscusP92
NothomyrmicaP92
ParameranoplusP92
ParaneuretusP92
PronolepisP92
ProtaneuretusP92
RhopalomyrmexP92
StigmomyrmexP92
StiphromyrmexP92
HypopomyrmexP92
Ilemomyrmex caecusP92
Oxyidris antillanaP92
ParacryptocerusP92
Heteroponera imbellis (Emery 1895) [=Acanthoponera imbellis; incl. Ectatomma (Acanthoponera) imbellis hilare Forel 1895, A. nigra Clark 1930, A. occidentalis Clark 1926, A. (Anacanthoponera) imbellis scabra Wheeler 1923]TB85
*Type species of generic name indicated
References
Archibald, S. B., K. R. Johnson, K. W. Mathewes & D. R. Greenwood. 2011. Intercontinental dispersal of giant thermophilic ants across the Arctic during early Eocene hyperthermals. Proceedings of the Royal Society of London Series B—Biological Sciences 278 (1725): 3679–3686.
[A71] Askew, R. R. 1971. Parasitic Insects. Heinemann Educational Books: London.
[B03] Bingham, C. T. 1903. The Fauna of British India, including Ceylon and Burma. Hymenoptera vol. 2. Ants and Cuckoo-Wasps. Taylor and Francis: London.
[BS23] Blaimer, B. B., B. F. Santos, A. Cruaud, M. W. Gates, R. R. Kula, I. Mikó, J.-Y. Rasplus, D. R. Smith, E. J. Talamas, S. G. Brady & M. L. Buffington. 2023. Key innovations and the diversification of Hymenoptera. Nature Communications 14: 1212.
[BS06] Brady, S. G., T. R. Schultz, B. L. Fisher & P. S. Ward. 2006. Evaluating alternative hypotheses for the early evolution and diversification of ants. Proceedings of the National Academy of Sciences of the USA 103 (48): 18172–18177.
Dlussky, G. M. 1999. The first find of the Formicoidea (Hymenoptera) from the lower Cretaceous of the Northern Hemisphere. Paleontologicheskii Zhurnal 1999 (3): 62–66 (translated: Paleontological Journal 33 (3): 274–277).
[E89a] Emery, C. 1889a. Intorno ad alcune formiche della fauna palearctica. Annali del Museo Civico di Storia Naturale di Genova, Serie 2a, 7: 439–443.
[E89b] Emery, C. 1889b. Viaggio di Leonardo Fea in Birmania e regioni vicine. XX.—Formiche di Birmania e del Tenasserim raccolte da Leonardo Fea (1885–87). Annali del Museo Civico di Storia Naturale di Genova, Serie 2a, 7: 485–520.
[E14] Emery, C. 1914. Les fourmis de la Nouvelle-Calédonie & des îles Loyalty. In: Sarasin, F., & J. Roux (eds) Nova Caledonia: Forschungen in Neu-Caledonian und auf den Loyalty-Inseln. A. Zoologie vol. 1 pt 4 pp. 393–436, pl. 12. C. W. Kreidels Verlag: Wiesbaden.
[ES12] Espadaler, X., & S. Santamaria. 2012. Ecto- and endoparasitic fungi on ants from the Holarctic region. Psyche 2012: 168478.
[FT08] Framenau, V. W., & M. L. Thomas. 2008. Ants (Hymenoptera: Formicidae) of Christmas Island (Indian Ocean): identification and distribution. Records of the Western Australian Museum 25 (1): 45–85.
[GE05] Grimaldi, D., & M. S. Engel. 2005. Evolution of the Insects. Cambridge University Press: New York.
[H82] Helmore, D. W. 1982. Drawings of New Zealand insects. Bulletin of the Entomological Society of New Zealand 8: 1–52.
[H02] Hong Y. 2002. Amber Insect of China. Beijing Scientific and Technological Publishing House.
[I92] Iwahashi, J. (ed.) 1992. Reddo Deeta Animaruzu: a pictorial of Japanese fauna facing extinction. JICC: Tokyo.
[MB06] Moreau, C. S., C. D. Bell, R. Vila, S. B. Archibald & N. E. Pierce. 2006. Phylogeny of the ants: diversification in the age of angiosperms. Science 312: 101–104.
[P92] Poinar, G. O., Jr. 1992. Life in Amber. Stanford University Press: Stanford.
[RBV08] Rabeling, C., J. M. Brown & M. Verhaagh. 2008. Newly discovered sister lineage sheds light on early ant evolution. Proceedings of the National Academy of Sciences of the USA 105 (39): 14913–14917.
[RJ93] Ross, A. J., & E. A. Jarzembowski. 1993. Arthropoda (Hexapoda; Insecta). In: Benton, M. J. (ed.) The Fossil Record 2 pp. 363–426. Chapman & Hall: London.
[S12] Schaal, S. 2012. Messel Pit fossil site—the legacy of the environment and life of the Eocene. In: Talent, J. A. (ed.) Earth and Life: Global biodiversity, extinction intervals and biogeographic perturbations through time pp. 225–236. Springer.
[TB85] Taylor, R. W., & D. R. Brown. 1985. Formicoidea. In: Walton, D. W. (ed.) Zoological Catalogue of Australia vol. 2. Hymenoptera: Formicoidea, Vespoidea and Sphecoidea pp. 1–149. Australian Government Publishing Service: Canberra.
[V10] Vršanský, P. 2010. Cockroach as the earliest eusocial animal. Acta Geologica Sinica (English Edition) 84 (4): 793–808.
[WB03] Ward, P. S., & S. G. Brady. 2003. Phylogeny and biogeography of the ant subfamily Myrmeciinae (Hymenoptera: Formicidae). Invertebrate Systematics 17: 361–386.
Wilson, E. O. 1987. The earliest known ants: an analysis of the Cretaceous species and an inference concerning their social organization. Paleobiology 13 (1): 44–53.
[Z01] Zhou, S. 2001. Ants of Guangxi. Guangxi Normal University Press: Guilin (China).