A colored painting from the Sesse and Mocifio expedition serves as the holotype for the validly published name angustifolia DC. ex Dunal, 1819 (= dunalii Sprengel, nom. nov., 1825; non angustifolia Kunth, in HBK, 1818). The illustration represents the species heretofore identified as Keerlia linearifolia DC., 1836 (= Gutierrezia alamanii A. Gray, nom. nov., 1852; non Gutierrezia linearifolia Lagasca & Segura, 1816), which occurs in the south-central Mexican states of Mexico and Morelos. Gutierrezia dunalii (Sprengel) Nesom, comb. nov., is proposed as the earliest valid name for this species. Gutierrezia megalocephala (Fernald) Nesom is proposed for a closely related entity (Gutierrezia alamanii var. megalocephala (Fernald) Lane = Xanthocephalum megalocephalum Femald). The Sess6 and Mocifio expedition to New Spain (1787-1803) recorded many interesting observations, especially regarding the flora of Mexico. For a description of the expedition and its aims, travels, collections, paintings, and in particular its botanical accomplishments, see articles by McVaugh (1977, 1980, 1987, 1990, 1998) and a recent summary and update by Bartholomew and McVaugh (1997). Plant collections from the expedition are housed at a number of European herbaria as documentation for various early reports and names, but the paintings made in situ by expedition artists also provided the basic information for descriptions of new taxa. A. P. De Candolle and contemporaries proposed approximately 370 new specific names based wholly or in part on these paintings. Considerations regarding the formal typification of these taxa are outlined by Bartholomew and McVaugh (1997) and McVaugh (1998). The original set of paintings is now housed under the name of the Torner Collection of Sesse and Mocifio Biological Illustrations at the Hunt Institute for Botanical Documentation (Carnegie Mellon University, Pittsburgh). Some of these remarkably detailed paintings have remained without corroboration or reevaluation of their initial identifications, if such were ever made. We examined one of them (Torner No. 0884; Fig. 1), which includes on the same sheet two species of Asteraceae tribe Astereae, the left-hand one annotated by De Candolle as Lemerya anthemoides and the other as Grindelia angustifolia. It is assumed that the plants were encountered by the expedition in Mexico, as surmised from the identities of the plants depicted. The illustration served as the basis for a formal description of the species in a publication by Michel-Felix Dunal in 1819 (see nomenclature below). The left-hand plant is white-rayed, a species of Aphanostephus. Details at the top of the illustration, showing white ray flowers, disc corollas, and achenes, are from this plant. The slender taproot of annual duration, pinnatifid leaves, basally unexpanded disc corollas, and achenes with a conspicuous coronal pappus are features of A. ramosissima DC. var. ramosus (DC.) Turner & Birdsong (Turner, 1984), which occurs over a wide area of central Mexico, from Durango to San Luis Potosf and south to MichoacAn, Guerrero, Morelos, and Veracruz. The yellow-rayed plant (on the right-hand side) represents the species heretofore identified as Gutierrezia alamanii A. Gray, which is known from the south-central Mexican states of Mexico and Morelos (Lane, 1985). Salient features shown in the illustration are these: a basally ascending stem arising from a fibrous-rooted rhizome; leaves linear-oblanceolate without a well-defined petiolar portion, 1nerved, entire, primarily basally disposed but continuing up the stem; several relatively large heads (compared to other species of Gutierrezia) with conspicuous yellow rays (18, 21, and 23 rays, respecNovoN 10: 67-70. 2000. This content downloaded from 157.55.39.215 on Wed, 31 Aug 2016 04:26:17 UTC All use subject to http://about.jstor.org/terms