Fruticose lichens of the genus Usnea Dill. ex Adans. (Parmeliaceae), generally known as beard lichens, are among the most iconic epiphytic lichens in modern forest ecosystems. Many of the c. 350 currently recognized species are widely distributed and have been used as bioindicators in air pollution studies. Here we demonstrate that usneoid lichens were present in the Palaeogene amber forests of Europe. Based on general morphology and annular cortical fragmentation, one fossil from Baltic amber can be assigned to the extant genus Usnea. The unique type of cortical cracking indirectly demonstrates the presence of a central cord that keeps the branch intact even when its cortex is split into vertebrae-like segments. This evolutionary innovation has remained unchanged since the Palaeogene, contributing to the considerable ecological flexibility that allows Usnea species to flourish in a wide variety of ecosystems and climate regimes. The fossil sets the minimum age for Usnea to 34 million years (late Eocene). While the other similar fossils from Baltic and Bitterfeld ambers cannot be definitely assigned to the same genus, they underline the diversity of pendant lichens in Palaeogene amber forests.

Howardula helenoschini sp. n. (Tylenchida: Allantonematidae) is described from 40 million year-old Baltic amber. The nematodes are parasitic in the body cavity of an adult fly of the genus Triphleba (Phoridae: Diptera). Characteristics of the fossil species are the large size of the pre-adult juveniles and a small number of progeny compared with extant Howardula parasites of flies. Reasons are given why these features suggest that this species was at an early stage of adapting, evolutionarily, to its insect host.

A mermithid nematode emerging from a male ant, Prenolepis henschei Mayr, in Baltic amber is the first fossil record demonstrating nematode parasitism of ants. This parasite, described as Heydenius formicinus sp. n., is compared to extant mermithid parasites of ants, especially Allomermis myrmecophila Baylis 1921. The present fossil, together with earlier reports of braconid and mite parasitism of ants in Baltic amber, indicates that several diverse groups had already evolved parasitic associations with ants by the Eocene.