A formicine in New Jersey Cretaceous amber (Hymenoptera: Formicidae) and early evolution of the ants

Abstract

A worker ant preserved with microscopic detail has been discovered in Turonian-aged New Jersey amber [ca. 92 mega-annum (Ma)]. The apex of the gaster has an acidopore and, thus, allows definitive assignment of the fossil to the large extant subfamily Formicinae, members of which use a defensive spray of formic acid. This specimen is the only Cretaceous record of the subfamily, and only two other fossil ants are known from the Cretaceous that unequivocally belong to an extant subfamily (Brownimecia and Canapone of the Ponerinae, in New Jersey and Canadian amber, respectively). In lieu of a cladogram of formicine genera, generalized morphology of this fossil suggests a basal position in the subfamily. Formicinae and Ponerinae in the mid Cretaceous indicate divergence of basal lineages of ants near the Albian (ca. 105-110 Ma) when they presumably diverged from the Sphecomyrminae. Sphecomyrmines are the plesiomorphic sister group to all other ants, or they are a paraphyletic stem group ancestral to all other ants-they apparently became extinct in the Late Cretaceous. Ant abundance in major deposits of Cretaceous and Tertiary insects indicates that they did not become common and presumably dominant in terrestrial ecosystems until the Eocene (ca. 45 Ma). It is at this time that modern genera that form very large colonies (at least 10,000 individuals) first appear. During the Cretaceous, eusocial termites, bees, and vespid wasps also first appear-they show a similar pattern of diversification and proliferation in the Tertiary. The Cretaceous ants have further implications for interpreting distributions of modern ants.

Decoupling the spread of grasslands from the evolution of grazer-type herbivores in South America

“…Thus, the rise to ecological dominance of openhabitat grasses lagged taxonomic diversification by at least 20 million years in southern South America. This decoupling ARTICLE parallels the North American record 14 , suggesting that it reflects an evolutionary/ecological phenomenon rather than incomplete fossil records; similar patterns have been recorded in C 4 grasses 14 and several other organisms, such as early flowering plants and certain insect groups 48,49 . If true, the lag implies that different factors influenced pooid and PACMAD diversification versus ecological expansion 14 .…”

Corrigendum to: Phylogeny and biogeography of the ant subfamily Myrmeciinae (Hymenoptera : Formicidae)

“…This tree is based on those clades that received more than 50% bootstrap support in either the morphological or molecular analyses. We feel that this schema more faithfully represents the current state of knowledge than the more 'resolved' ant phylogenies appearing in recent papers, in which basal relationships are very poorly supported (Baroni Urbani et al 1992;Grimaldi et al 1997;Grimaldi and Agosti 2000). In conjunction with estimated divergence times (Table 3), Fig.…”

“…20, based on Bayesian analysis Also indicated are the minimum age constraints applied to seven nodes before the analysis, and the justification for these constraints (14) was assigned a prior date of 120 Mya (± 20 million years s.d. ), after Grimaldi and Agosti (2000). Paraponera.…”

“…Crozier et al 1997;Rust and Andersen 1999;Lattke in press). The fossil record has not yielded definitive ants (Formicidae) from this period (Grimaldi and Agosti 2000), but the existence of two genera of stem-group formicoids (Armaniidae) in the lower Cretaceous (Dlussky 1999a) adds to the plausibility of crown-group origin at that time. These Cretaceous origins can be contrasted with the apparent delay until the early Tertiary of the attainment of high species diversity and behavioural dominance by ants (Grimaldi and Agosti 2000).…”

The wasps, bees and ants (Insecta: Vespida=Hymenoptera) from the Insect Limestone (Late Eocene) of the Isle of Wight, UK

“…In this comparison, we rely on the following sources: for Late Cretaceous - Dlussky (1975Dlussky ( , 1983Dlussky ( , 1987Dlussky ( , 1996Dlussky ( , 1999a, Dlussky et al (2004), Grimaldi et al (1997), Grimaldi & Agosti (2000), Engel & Grimaldi (2005); for Green River (Middle Eocene of western North America) - Dlussky & Rasnitsyn (2002) The comparison traditionally refers to composition of past assemblages at the subfamily level (Table 3). It has been shown (Dlussky 1983(Dlussky , 1987Dlussky & Rasnitsyn 2002) that the Late Cretaceous assemblages were dominated by extinct Armaniidae and Sphecomyrminae, with extant subfamilies Aneuretinae, Dolichoderinae, Formicinae, Ponerinae and Myrmicinae known from rare (usually unique) plesiomorphic fossils.…”