The first fossil representatives of the harvestman subfamily Ortholasmatinae (Opiliones, Dyspnoi, Nemastomatidae) are described as Balticolasma wunderlichi gen. et sp. nov. One male is preserved in Eocene Baltic amber and a presumably conspecific female in Eocene Rovno amber (northwest Ukraine). Ortholasmatines are typically highly ornate arachnids, and for the first time with an amber harvestman we applied computed tomography using synchrotron radiation to investigate its three-dimensional morphology and surface structure in considerable detail. Some of its morphological characters, appear to be closer to extant Asian genera. In a wider biogeographic context, our amber record is a significant find for the Paleogene of Europe given that (i) it is another species apparently found in both Baltic and Rovno amber and (ii) all modern ortholasmatines are restricted to East Asia and North and Central America.

Key words: Nemastomatidae, Ortholasmatinae, Baltic amber, Rovno amber, micro-CT, Priabonian, Eocene.

Christian Bartel [bartel@snsb.de; ORCID: http://orcid.org/0000-0003-2949-6890] (corresponding author), Naturkundemuseum Bamberg, Fleischstraße 2, 96047 Bamberg, Germany. Plamen G. Mitov [pl_mitov@yahoo.com; ORCID: http://orcid.org/0000-0002-6191-4135], Department of Zoology and Anthropology, Faculty of Biology, Sofia University, 8 Dragan Zankov Blvd., 1164 Sofia, Bulgaria. Jason A. Dunlop [jason.dunlop@mfn.berlin; ORCID: http://orcid.org/0000-0002-0179-6640], Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Invalidenstraße 43, 10115 Berlin, Germany. Jörg U. Hammel [joerg.hammel@hereon.de; ORCID: http://orcid.org/0000-0002-6744-6811], Institute of Materials Physics, Helmholtz-Zentrum Hereon, Max-Planck-Straße 1, 21502 Geesthacht, Germany.