The new genus Sinuicella, an early successional lichen, was found on bare soil in Oregon, USA. The thallus is minute fruticose, grey to nearly black, branching isotomic dichotomous, branches round, 20–90 μm wide in water mount. The cortex is composed of interlocking cells shaped like jigsaw puzzle pieces. Spores are hyaline, 1-septate, 25–40(–50) × 6.5–9(–11) μm. Maximum likelihood phylogenetic analyses on multilocus data sets, first spanning the entire order Peltigerales and then restricted to Peltigeraceae with extended sampling from Solorina and Peltigera, revealed the placement of Sinuicella outside of currently recognized genera, sister to Peltigera, with high support. Based on the phylogenetic, morphological and ecological distinctness of Sinuicella, we formally introduce a new genus represented by the single species S. denisonii. The cyanobiont of S. denisonii is Nostoc from phylogroup XL, Clade 2, Subclade 3 based on the rbcLX marker.