J. Bot. Res. Inst. Texas 12(1): 1 – 15. 2018 RESOLVING THE ANOMALY OF LOMATIUM ANOMALUM: DISCOVERY OF A NEW SPECIES IN SOUTHWESTERN IDAHO (U.S.A.), LOMATIUM ANDRUSIANUM (APIACEAE) Mckayla Stevens, Donald H. Mansfield James F. Smith The College of Idaho Boise State University 2112 Cleveland Blvd. 1910 W. University Drive Caldwell, Idaho 83605, U.S.A. Boise, Idaho 83725, U.S.A. Mary Ann E. Feist University of Wisconsin-Madison 430 Lincoln Drive Madison, Wisconsin 53706, U.S.A. ABSTRACT Apparent polyphyly within the unresolved clade of Lomatium (Apiaceae) containing L. triternatum, L. anomalum, L. thompsonii, and L. pack- ardiae suggests conflict among current taxonomic classification schemes. To recover this clade and more clearly define species boundaries, we examined populations of L. anomalum from three geographic regions in Idaho and adjacent Oregon. Using phylogenetic, morphological, and ecological data, we conclude that the L. anomalum complex currently circumscribes multiple species. Phylogenetic analysis of the nuclear ribosomal ITS and ETS, and cpDNA rpl32-trnLUAG, rps-16 intron, trnD-trnT, ndhA intron, and psbA-trnH recovered populations from the Boise foothills as a distinct, monophyletic clade. Principal Components Analysis of 30 reproductive and vegetative characters show two distinct groups: one of Boise foothills and one of the combined Mann Creek and Camas Prairie vicinities. Principal Components Analysis of 16 soil characteristics show that soils occupied by Boise foothills populations are distinct from those occupied by Mann Creek and Camas Prairie populations. Based on phylogenetic, morphometric, and ecologic criteria, populations of what had been considered L. anomalum from the Boise foothills and vicinity are here described as a new species—Lomatium andrusianum. RESUMEN La aparente polifilia en el clado no resuelto de Lomatium (Apiaceae) que contiene L. triternatum, L. anomalum, L. thompsonii, y L. packardiae supone un conflicto en los esquemas de la clasificación taxonómica actual. Para recuperar este clado y de una forma más especifica definir los límites entre sus especies, hemos examinado poblaciones de L. anomalum de tres regiones geográficas en Idaho y de la zona adyacente de Oregón. Utilizando datos filogenéticos, morfológicos y ecológicos, hemos concluído que el complejo de L. anomalum comprende a múltiples especies. El análisis filogenético del nuclear ribosómico del ITS y ETS, y del cpDNA rpl32-trnLUAG, el intrón rps-16, trnD-trnT, el intrón ndhA, y psbA-trnH recupera estas poblaciones de las estribaciones de Boise como diferentes, como un clado monofilético. El análisis en componentes principales de 30 caracteres reproductores y vegetativos muestra dos grupos distintos: uno de las estribaciones de Boise y otro del combinado de las cercanías de Mann Creek y Camas Praire. El análisis de componentes principales de 16 características edáficas mues- tra que los suelos ocupados por las poblaciones de las estribaciones de Boise son distintas que las de aquellos terrenos ocupados por las poblaciones de Mann Creek y Camas Prairie. Basándose en criterios filogenéticos, morfométricos y ecológicos, las poblaciones de lo que ha sido considerado como L. anomalum de las estribaciones de Boise y sus cercanías son aquí descritas como una nueva especie—Lomatium andrusianum. INTRODUCTION Lomatium (Apiaceae) is a western North American genus in which over 100 species will be recognized in the upcoming publication of Flora of North America, vol. 13 (Barbara Wilson, pers. comm.). It is part of one of the largest plant radiations in North America, the Perennial Endemic North American Apiaceae (PENA) clade, the evolution of which is poorly understood (Downie et al. 2002; Downie et al. 2010; Sun & Downie 2010; George et al. 2014). Many species of Lomatium are tracked as rare by Natural Heritage Programs in several states, including L. bentonitum, L. erythrocarpum, L. greenmanii, L. knockei, L. latilobum, L. observatorium, L. pastorale, L. stebbinsii, and L. tarantuloides; two species—Lomatium bradshawii and Lomatium cookii—are federally listed under the Endangered Species Act. Close to 40% of the genus is comprised of narrowly endemic taxa (Mark Darrach, This document is intended for digital-device reading only. Inquiries regarding distributable and open access versions may be directed to jbrit@brit.org.