The first ant-termite syninclusion in amber with CT-scan analysis of taphonomy.

David Coty,Cédric Aria,André Nel,Romain Garrouste,Patricia Wils,Frédéric Legendre,Judith Korb

doi:10.1371/journal.pone.0104410

Abstract

We describe here a co-occurrence (i.e. a syninclusion) of ants and termites in a piece of Mexican amber (Totolapa deposit, Chiapas), whose importance is two-fold. First, this finding suggests at least a middle Miocene antiquity for the modern, though poorly documented, relationship between Azteca ants and Nasutitermes termites. Second, the presence of a Neivamyrmex army ant documents an in situ raiding behaviour of the same age and within the same community, confirmed by the fact that the army ant is holding one of the termite worker between its mandibles and by the presence of a termite with bitten abdomen. In addition, we present how CT-scan imaging can be an efficient tool to describe the topology of resin flows within amber pieces, and to point out the different states of preservation of the embedded insects. This can help achieving a better understanding of taphonomical processes, and tests ethological and ecological hypotheses in such complex syninclusions.

Highlights

Ants and termites represent ecologically critical organisms in intertropical and subtropical ecosystems, impacting by their abundance, organization and variety of occupied niches the availability of nutrients as well as the composition of soils [1,2,3,4,5]
The Neivamyrmex ant (Ne), the minor termite worker trapped between its mandibles (Na1), one Nasutitermes worker (Na2), and one Azteca ant (Az1) appear as empty structures inside the amber piece
Since the relative density of the insects is unrelated to their taxonomy (Azteca ants and Nasutitermes termites are present in different density sets), and since there is a clear spatial homogeneity between the two density groups (Figures 4A–B), variations of physical density between the specimens themselves is likely to express taphonomical disparities

Summary

Introduction

Ants and termites represent ecologically critical organisms in intertropical and subtropical ecosystems, impacting by their abundance, organization and variety of occupied niches the availability of nutrients as well as the composition of soils [1,2,3,4,5]. If tomographic analyses have already been widely used for taxonomical studies of insects, reconstructions of their external and internal morphology [20,21,22,23,24,25,26], and to illustrate a syninclusion in amber [27], we use here the CT-scan as a tool to analyze the results of taphonomical processes in an amber syninclusion This amber piece was discovered in a batch of crude amber acquired by one of us (DC) from locals exploiting the Totolapa amber deposit (Salt River Mine). The Neivamyrmex ant (Ne), the minor termite worker trapped between its mandibles (Na1), one Nasutitermes worker (Na2), and one Azteca ant (Az1) appear as empty structures inside the amber piece (in black on the slices, see Figures 3, 4C). Two coherent density sets can be distinguished in our piece of amber: the ‘Nasutitermes soldier density set’ and the ‘Neivamyrmex density set’ (Figures 4A– B)

Discussion

Conclusion