A New Name in Mexican Asclepias (Asclepiadaceae)

Abstract

Asclepias lynchiana Fishbein is proposed as a new name for the species commonly known as A. grandiflora E. Fournier, a later homonym of A. grandiflora L. f. The other available name for this species, A. insignis (Brandegee) Woodson, is a later homonym ofA. insignis (Schlechter) Schlechter. Asclepias lynchiana has among the largest flowers of any North American species of Asclepias and is widely distributed from central to southern Mexico. In the course of phylogenetic study of Asclepias (Fishbein, 1996), it became apparent that the species commonly known as A. grandflora E. Fournier (see Woodson, 1954) lacks a legitimate name. Therefore, the following new name is proposed. Asclepias lynchiana Fishbein, nom. nov. Replaced name: Asclepias grandiflora E. Fournier, Ann. Sci. Nat. Bot., ser. 6, 14: 379. 1882; not Asclepias grandiflora L. f., Suppl. Plant. 170. 1781. TYPE: Mexico, Hahn s.n. (holotype, P not seen). Asclepiodora insignis Brandegee, Zoe 5: 253. 1908. Asclepias insignis (Brandegee) Woodson, Ann. Missouri Bot. Gard. 28: 207. 1941; not Asclepias insignis (Schlechter) Schlechter, J. Bot. 34: 455. 1896. TYPE: Mexico, Purpus 2624 (holotype, UC not seen; isotype, MO not seen). Asclepias lynchiana grows on rocky slopes, occasionally on limestone, in tropical deciduous forest, oak woodland, and pastures. It has been found in the Mexican states of Jalisco and Puebla south to Michoacin, Guerrero, and Oaxaca. Although widely distributed, populations of this species are apparently highly dispersed, judging by the relatively few specimens in herbaria. Some variation in flower morphology has been observed, especially in flower size (S. Lynch, pers. comm.), but no infraspecific taxa have been recognized. The species is closely related to A. glaucescens HBK and A. crocea Woodson, as noted by Woodson (1954), as well as to A. elata Bentham and A. mirifica Woodson (Fishbein, 1996). This species has been known as A. grandiflora E. Fournier; however, use of the specific epithet was predated by A. grandiflora L. f. [= Pachycarpus grandiflorus (L. f.) E. Meyer]. In recognition of the illegitimate status ofA. grandiflora E. Fournier, specimens at some herbaria have been annotated using the only other available name, A. insignis (Brandegee) Woodson. Unfortunately, this combination was published previously as A. insignis (Schlechter) Schlechter [= Pachycarpus transversalis (Schlechter) N. E. Brown; see Smith, 1988]. No other validly published names for this species have been found, necessitating the publication of the new name. It is appropriate to rename this magnificent milkweed in honor of Steven P. Lynch, Louisiana State University at Shreveport. Lynch is the foremost student of Mexican Asclepias, and his assistance and encouragement have been invaluable to my research on the genus. Acknowledgments. I thank John R. Reeder for his patient advice regarding taxonomic issues, and the staff at the University of Arizona Herbarium (ARIZ) for assistance in many aspects of my work. I am also grateful to the curators at MEXU, MO, and other herbaria for loans of specimens. This work was supported in part by funding from the Research Training Group in the Analysis of Biological Diversification, University of Arizona.