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Cretaceous termite castes



I find Mesozoic insects fascinating - not just in their own right, but
because of the impact they may have had on dinosaur evolution (and
vice versa).  One new study (below) shows direct evidence of termite
castes from the Early Cretaceous, with queens, soldiers, and workers
preserved in amber from Myanmar.  Two new genera and species are
described: _Krishnatermes yoddha_ and _Gigantotermes rex_.

Among insects, termites were the first to evolve eusociality (probably
in the Late Jurassic).  In today's world the most persistent and
aggressive enemies of termites are ants, which provide the major
selection pressure for the specialized soldier caste of termites.  The
weird thing is that soldier termites evolved tens of millions of years
before ants.  So what were the 'enemies' that soldier termites were
targeting prior to ants?  Possibly insectivorous/myrmecophagous
theropods, especially alvarezsaurids, which have been inferred to have
targeted termite nests (e.g., Longrich & Currie, 2008
doi:10.1016/j.cretres.2008.07.005).  Alvarezsaurids are currently
known only from the Late Cretaceous, but they may have existed since
the Late Jurassic (although the basal alvarezsauroid _Haplocheirus_
doesn't appear adapted for myrmecophagy).  Myrmecophagous mammals such
as _Fruitafossor_ are another possibility.


M.S. Engel, P. Barden, M.L. Riccio, D.A. Grimaldi (in press).
Morphologically specialized termite castes and advanced sociality in
the Early Cretaceous.  Current Biology (2016),
https://urldefense.proofpoint.com/v2/url?u=http-3A__dx.doi.org_10.1016_j.cub.2015.12.061&d=CwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=x82f3Wlkwtmbr1z8IAt9jA&m=epPG2EUb2XThbbfxikIAjhF1oDCvKo0woENQ8Gfj3Ls&s=Tig3g7XQRlA_s09wninW5FSYT0rLFEK85l9d-fI7MT0&e=
 

Summary

"A hallmark of animals that are eusocial, or those with
advanced sociality, is reproductive specialization
into worker and queen castes [1–3]. In the most
derived societies, these divisions are essentially
fixed and in some arthropods, include further
specialization—a tripartite system with a soldier
caste that defends the colony [1]. Eusociality has
originated numerous times among insects but is
believed to have appeared first in the termites
(Isoptera), in the Early Cretaceous [4]. However, all
termites known from the Cretaceous have, until
now, only been winged reproductives (alates and
dealates); the earliest soldiers and definitive workers
were known from just the Miocene (ca. 17–20 million
years ago [mya]) [4]. Here, we report six termite species
preserved in Early Cretaceous (ca. 100 mya)
amber from Myanmar, one described as _Krishnatermes
yoddha_ gen. et sp. nov., comprising the
worker/pseudergate, winged reproductive, and
soldier, and a second species, _Gigantotermes rex_
gen. et sp. nov., based on one of the largest soldier
termites yet known. Phylogenetic analysis indicates
that Krishnatermes are in the basal ‘‘Meiatermesgrade’’
of Cretaceous termites. Workers/pseudergates
of another four species are briefly described,
but not named. One of these workers/pseudergates
reveals that ants—the most serious enemies of modern
termites—lived in close proximity to termites in
the Burmese paleofauna. These discoveries demonstrate
the Mesozoic antiquity of specialized termite
caste systems and corroborate that among all social
species, termites probably had the original societies."

For Star Wars fans, the etymology of _K. yoddha_ includes this: "The
specific epithet is from the Hindi Yod’dha, meaning "warrior", in
reference to the earliest termite soldier (it is unknown whether the
name of the fictional Jeddi [sic] Master from Star Wars, Yoda, was
adapted from this Hindi word)."

Finally, there is a possibility that the genus name _Gigantotermes_
might be preoccupied (_Gigantotermes_ Haase 1890, a genus of fossil
lacewing, originally _Apochrysa excelsa_ Hagen 1862).