New colonial acritarch Involusphaeridium gutschicki gen. et sp. nov. from the Lower Sappington Formation (Upper Famennian), western Montana, USA

Palynological investigation carried on the samples from the Unit 1 of the Sappington Formation (Upper Famennian, Montana, USA) reveals a presence of rich phytoplankton and microflora assemblages. The presence of spheroidal vesicles approx. 20 μm in diameter having a rigid smooth wall and frequently arranged in clusters connected by an external coating are proposed as a new taxon named Involusphaeridium gutschicki gen. et sp. nov. The coating on individual vesicles and colonies of I. gutschicki gen. et sp. nov. suggests a link with algal or fungal groups but also, with the eggs of arthropods. Hence, it is considered as incertae sedis (acritarch group). •Involusphaeridium gutschicki gen. et sp. nov. appears in the Lower Sappington Formation.•Involusphaeridium gutschicki gen. et sp. nov. is considered as an acritarch.•Affinity with algae, fungi, or arthropods are not excluded.