Four new sorediate species in the Hypogymnia austerodes group (lichens) from northwestern North America, with notes on thallus morphology

The Hypogymnia austerodes group is an assemblage of mostly boreal and arctic-alpine lichens traditionally comprising three wide-ranging sorediate and/or isidiate species, H. austerodes, H. bitteri and H. subobscura. Here we describe four additional members of this group - H. dichroma sp. nov., H. protea sp. nov., H. salsa sp. nov. and H. verruculosa sp. nov. - which have until now been treated within H. austerodes s. lat. Our new species are primarily epiphytic, and are currently known only from Cordilleran western North America. They differ from other members of the H. austerodes group both morphologically and in their virtually consistent production of apinnatic acid. Hypogymnia protea is by far the most variable of the new species, uniting two putative taxa here designated as morphs disjuncta and tessellata. Reliable discrimination of the segregate species requires careful attention to their vegetative reproductive structures, which are described in detail. A key to all treated species and their recognized morphs is provided. Earlier reports of H. farinacea from western North America appear to be based on schizidiate material of H. protea morph tessellata. Whether H. farinacea actually occurs in North America remains an open question.