Within Isopoda (woodlice and relatives), there are lineages characterised by a parasitic
lifestyle that all belong to Cymothoida and likely form a monophyletic group. Representatives
of Epicaridea (ingroup of Cymothoida) are parasitic on crustaceans and usually go
through three distinct larval stages. The fossil record of Epicaridea is sparse and
thus little is known about the palaeoecology and the origin of the complex life cycle
of modern epicarideans. We present an assemblage of over 100 epicarideans preserved
in a single piece of Late Cretaceous Myanmar amber. All individuals are morphologically
similar to cryptoniscium stage larvae. The cryptoniscium stage usually constitutes
the third and last larval stage. In modern representatives of Epicaridea, the cryptoniscium
larvae are planktic and search for suitable host animals or adult females. These fossil
specimens, though similar to some extant species, differ from other fossil epicaridean
larvae in many aspects. Thus, a new species (and a new genus), Cryptolacruma nidis,
is erected. Several factors can favour the preservation of multiple conspecific animals
in a single piece of amber. However, the enormous density of epicarideans in the herein
presented amber piece can only be explained by circumstances that result in high local
densities of individuals, close to the resin-producing tree.
