Checklist of fossil liverworts suitable for calibrating phylogenetic reconstructions

The number of available liverwort fossils substantially increased within the past decade, which is mainly due to new findings from Cretaceous and Cenozoic amber deposits. Many of them, however, are fragmentary and not predestined for consideration in evolutionary analyses. Here, we list those liverwort fossils that we suggest as suitable for calibrating phylogenetic reconstructions, along with brief descriptions, justification of their use, and age information. Our recommendations are based on thorough microscopic investigation of available fossils from worldwide amber collections including recent findings. We recommend that the following 42 fossil taxa can be used as confident minimum age constraints in phylogenetic reconstructions: Acrolejeunea ucrainica (35 Ma), Anastrophyllum rovnoi (35 Ma), Bazzania polyodus (34 Ma), Blepharolejeunea obovata (15 Ma), the genus Bryopteris with B. bispinosa and B. succinea (15 Ma), Calypogeia stenzeliana (34 Ma), Cephaloziella nadezhdae (35 Ma), the genus Ceratolejeunea with C. antiqua, C. palaeomexicana, and C. sublaetefusca (15 Ma), Cheilolejeunea latiloba (34 Ma), Cheirorhiza brittae (158 Ma), Cololejeunea sp. (15 Ma), Cyclolejeunea archaica (15 Ma), Dibrachiella grollei (15 Ma), Diettertia montanensis (112 Ma), Drepanolejeunea eogena (15 Ma), the genus Frullania with F. baerlocheri, F. cretacea, and F. partita (99 Ma), Frullania subgen. Frullania with F. casparyi (34 Ma) and F. riclefgrollei (35 Ma), F. subgen. Trachycolea with F. rovnoi (35 Ma) and F. schumannii (34 Ma), Gackstroemia cretacea (99 Ma), Geocalyx heinrichsii (34 Ma), the genus Lejeunea with L. hamatiloba, L. miocenica, L. resinata, and L. urbanioides (15 Ma), Lopholejeunea subnigricans (15 Ma), Marchantites cyathodoides (228 Ma), Marchesinia brachiata (15 Ma), Metzgeriothallus sharonae (383 Ma), Microlejeunea nyiahae (52 Ma), Neurolejeunea macrostipula (15 Ma), Nipponolejeunea europaea (34 Ma), Notoscyphus balticus (34 Ma), Odontoschisma (sect. Iwatsukia) dimorpha (34 Ma), Plagiochila groehnii (34 Ma), Porella subgrandiloba (34 Ma), Protolophozia kutscheri (34 Ma), Radula (subgen. Odontoradula) cretacea (99 Ma), R. (subgen. Amentuloradula) heinrichsii (99 Ma), Scapania hoffeinsiana (34 Ma), Solenostoma berendtii (34 Ma), Spruceanthus polonicus (34 Ma), Stictolejeunea squamata (15 Ma), Tetralophozia groehnii (34 Ma), Thysananthus auriculatus (15 Ma), Thysananthus contortus (34 Ma). Furthermore, we transfer Lophozia kutscheri to Protolophozia, Archilejeunea grollei to Dibrachiella, Frullania ucrainica to Acrolejeunea, and Mastigolejeunea extincta to Spruceanthus, based on new fossil evidence and morphological revisions.