A peer-reviewed open-access journal PhytoKeys 91: 105–124Nahuatlea (2017): a new genus of compositae (Gochnatieae) from North America 105 doi: 10.3897/phytokeys.91.21340 RESEARCH ARTICLE http://phytokeys.pensoft.net Launched to accelerate biodiversity research Nahuatlea: a new genus of Compositae (Gochnatieae) from North America Vicki A. Funk1, Gisela Sancho2, Nádia Roque3 1 US National Herbarium, Department of Botany, Smithsonian Institution – NMNH, MRC 166, Washington DC, 20560, USA 2 Museo de La Plata, Paseo del Bosque s/n, 1900 La Plata, BA, Argentina 3 Instituto de Bio- logia, Universidade Federal da Bahia, Campus Universitário de Ondina, 40170-110 Salvador, Bahia, Brazil Corresponding author: Vicki A. Funk ([email protected]) Academic editor: A. Sennikov | Received 30 September 2017 | Accepted 15 November 2017 | Published 18 December 2017 Citation: Funk VA, Sancho G, Roque N (2017) Nahuatlea: a new genus of compositae (Gochnatieae) from North America. PhytoKeys 91: 105–124. https://doi.org/10.3897/phytokeys.91.21340 Abstract In the course of a detailed molecular study of the tribe Gochnatieae (Compositae: Gochnatioideae) it became apparent that the genus Gochnatia (sensu Cabrera) was not monophyletic but composed of a number of morphologically, geographically, and molecularly distinct clades. All but one of these clades had previously been recognized at the generic or sectional level and therefore had a name that could be applied. However, one clade, whose members are from Mexico and adjacent parts of the United States, had never been recognized as a distinct taxon. The Mexican clade is the sister group of the Caribbean clade which seems to indicate a dispersal event from Southern South America to Mexico and from Mexico to the Caribbean. Here we provide the Mexican clade with a genus name, Nahuatlea, and make the necessary new combinations. The name is derived from Nahuatl, the major indigenous language that is spoken in the area where most of the collections were gathered. A genus description, key to species, images and short descriptions are provided. Keywords Asteraceae, Gochnatia, Gochnatioideae, Mexico, Texas, Arizona, South American-Mexican disjunct distribution Introduction Cabrera (1971) in his comprehensive treatment of Gochnatia Kunth recognized six sections in the genus all mainly from the Americas. He placed all known species of Gochnatia from Mexico, in the section Hedraiophyllum (Less.) DC. along with two southern South American species: G. palosanto Cabrera and G. cordata Less., which are now part of Gochnatia s.s. and Moquiniastrum, respectively. Although one species from Copyright Vicki A. Funk et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. 106 Vicki A. Funk et al. / PhytoKeys 91: 105–124 (2017) Mexico is rather widespread (it has been collected from a number of states in Mexico, a few counties in Texas, and there is one disjunct record from Arizona) all of the species can be found in Mexico (Figs 1, 2). Cabrera recognized five species of Gochnatia from Mexico and adjacent USA: G. arborescens Brandegee, G. hypoleuca (DC.) A. Gray, G. magna M.C. Johnson ex Cabrera, G. purpusii Brandegee, and G. smithii Robins. & Greenm. Gochnatia obtusata S.F. Blake, although accepted by Jervis (1954), was not accepted as a species by Cabrera (1971), instead it was placed as subspecies under the widespread G. hypoleuca. According to data from molecular studies (Funk et al. 2014), Gochnatia section Hedraiophyllum (Cabrera 1971) is not supported but it is interesting to note that Cabrera considered the section Hedraiophyllum to be somewhat artificial. The next comprehensive treatment of Gochnatia was by Freire et al. (2002). In this treatment, the authors placed 21 species from South America in section Hedraiophyl- lum but not the Mexican species as Cabrera did (1971); in fact, their concept of this section was very different from Cabrera’s (1971). Freire et al. (2002) placed five species in Gochnatia sect. Leucomeris (D. Don) Cabrera, two of which were from Mexico: G. hypoleuca (including G. obtusata) and G. smithii. The other three species inG . sect. Leucomeris were distributed in Brazil, the Andean region of Bolivia and Argentina, and southeastern Asia. Freire et al. (2002) described a new section, G. sect. Glomerata S. E. Freire, L. Katinas & G. Sancho, consisting entirely of the final three Mexican species: G. arborescens, G. magna, G. purpusii. Freire et al. (2002) placed the Caribbean species (now in Anastraphia) in section Anastraphioides Jervis ex S.E. Freire, L. Katinas & G. Sancho. The molecular based study of Funk et al (2014) did not support the arrange- ment of taxa as proposed by Freire et al. (2002) except for section Anastraphioides (the Caribbean species) which formed a strongly supported clade. In 2004 González-Medrano et al. described a new species of Gochnatia from Hidalgo, Mexico: G. hiriartiana Medrano, Villaseñor & Medina. It differs from all the other Mexi- can species because of its few, large heads, and greater number of disc flowers. The authors included a key to seven taxa: six species and the subspecies G. hypoleuca subsp. obtusata. The authors placed the new species inG . sect. Glomerata based on the key in Freire et al. (2002). It seems that González-Medrano et al. (2004) are the only authors to refer to the “Mexican species of Gochnatia” but they left them in two groups in different sections and never explicitly said that they thought the taxa formed a closely related group. The recent molecular study of the tribe Gochnatieae (Funk et al. 2014) showed eight well-supported clades: most species had previously been included in the large genus Gochnatia. All but one of the clades had previously been recognized at the generic or subge- neric level: 1) Gochnatia Kunth: Eight species from the Central Andes (more or less equal to G. sect. Gochnatia of Freire et al. 2002) 2) Pentaphorus D. Don: Southern Andean clade of two species that, at various times, had been recognized as a genus, subgenus, or section (resurrected by Hind 2007). Nahuatlea: a new genus of compositae (Gochnatieae) from North America 107 Figure 1. Distribution map of Nahuatlea arborescens and N. hypoleuca. 3) Mexican Gochnatia: A group of seven species that had never been recognized as a separate genus nor had they been placed in a section by themselves was recovered as a monophyletic group. 4) Anastraphia: The 33 Caribbean species fell into one strongly supported clade that had previously been recognized as a genus and a section (re-established as a genus by Ventosa and Herrera 2011a; Robinson and Funk 2012). 5) Moquiniastrum: The 21 species that form this clade are mainly from central and south- ern Brazil and previously formed the majority of Gochnatia sect. Moquiniastrum (Sancho et al. 2013). 6) Richterago Kuntze: A clade of 16 species, all endemic to the campos rupestres of Brazil (redefined by Roque and Pirani 2001, 2014). 7) Cnicothamnus Griseb.: A genus of two species found in Bolivia and northwestern Argentina: it has never been included in Gochnatia. 8) Cyclolepis Gilles ex D. Don: A monospecific genus that has never been included in Gochnatia: found from Paraguay to the northern Patagonia area of Argentina. This lineage was regarded as “incertae sedis” in Funk et al. (2014) and so it remains. A key to the genera of Gochnatieae along with additional discussion on the tribe is contained in a upcoming paper (Funk et al. in prep). 108 Vicki A. Funk et al. / PhytoKeys 91: 105–124 (2017) Figure 2. Distribution map of Nahuatlea hiriartiana, N. magna, N. obtusata, N. purpusii, and N. smithii. In the Funk et al. biogeographic analysis (2014), it was hypothesized that the tribe had a southern South America origin (including the Central and Southern Andes, Argentina, and southern Brazil). Based on this, plus the fact that the Mexi- can clade is the sister group of the Caribbean clade (Anastraphia) suggests, or is best explained by, a dispersal event from Southern South America to Mexico and from Mexico to the Caribbean. We order the dispersal events in this direction be- cause the Mexican Gochnatia are morphologically more similar to the Andean genus Gochnatia s.s. than the Caribbean species. This Mexican + Caribbean clade (MCC) is believed to have separated from the rest of the Gochnatieae between 11 and 23 mya at a time when there was a gradual climate warming (early Miocene; Petuch 2003, Zachos et al. 2001). MCC is the sister group of a large clade containing Richterago + Moquiniastrum (RM) which is mainly from Brazil and Southern South America. The sister groups to these two large clades (MCC + RM) are from the Andes (Gochnatia s.s., Pentaphorus, Cnicothamnus), so just where in southern South America the MCC clade originated is uncertain especially since some of the sister group relationships are not well supported, although all of the segregate genera are individually clearly monophyletic. The Mexican members of Gochnatia clearly do not belong in the genus Gochnatia s.s., therefore, we are here describing the genus Nahuatlea for these seven species. Nahuatlea: a new genus of compositae (Gochnatieae) from North America 109 Materials and methods All types and other specimens deposited at LP and US were examined. The remaining types were viewed on line using the JSTOR-GP portal (http://plants.jstor.org; Fig 3). Distributions are based on data derived from databasing and georeferencing the collections at US (available online http://collections.mnh.si.edu/search/bota- ny/) with additional records from ARIZ (http://ag.arizona.edu/herbarium/home), MEXU (http://unibio.unam.mx/minero/index.jsp?accion=sc&colecciones=MEXU ,Herbario), MO (http://www.tropicos.org/Home.aspx), TEX (http://orchid.biosci.