The Phylogeny ofErrazurizia(Fabaceae: Amorpheae) and Description of the New Monotypic GenusPictarena

Abstract

Abstract—Errazurizia(Fabaceae) is a genus comprised of four species of New World desert shrubs with an ambiguous evolutionary history. Prior studies determined the North American species ofErrazuriziawere polyphyletic and the relationship ofE. rotundatawith other genera in the tribe Amorpheae remained undetermined. The sole South American species, which is also the type species, has never been included in a molecular study. We inferred the phylogenetic relationships ofErrazuriziaand six closely related genera using data from the cpDNA genome and nrDNA cistron from reference guided assemblies. Maximum likelihood and Bayesian analyses found two of the North American and the South American species were a monophyletic group, but thatE. rotundatawas sister to the monotypic genusParryella. Gland and pollen surface characters confirm the close relationship betweenP. filifoliaandE. rotundata. Cytonuclear discordance yielded partially incongruent tree topologies, and while the cpDNA phylogeny indicated a monophyleticAmorphawas sister to theE. rotundataandP. filifoliaclade, the nrDNA cistron phylogeny recovered a paraphyleticAmorpha, withA. californicasister to theE. rotundataandP. filifoliaclade. Molecular and morphological evidence support the elevation ofE. rotundatato its own monotypic genus,Pictarena. The new genusPictarenais defined by subsessile, suborbicular leaflets, mammiform leaflet glands, spicate inflorescences, and flowers with either all petals absent or rarely with a banner petal. ElevatingE. rotundatatoPictarenaresolves the confusing classification of the species, an imperiled endemic known only from four localities in northern Arizona and lends support for continued conservation.