New Euphorbiaceae from Mexico

Abstract

This article co nta ined descriptions of five new taxa of Me xican Euphorbiaceae. Euphorbia (sub g. Agaloma) na yaren sis is e nde mic to pine-oak woodland in the mount ains of central Nayarit. It appears related to E. so ob yi but differs by possessing linear to linear-ovate leaves. Croton varelae is also endemic to central Nayarit. A key was provided to distinguish this spec ies. a member of sect. Geiseleria, from the sev en othe r Mex ican species of this section. Cr ot on ram illatus var. magniglandulifer occurs in the states of Guerre ro and Morelos. This new varie ty differs from var. ramillatus by the possession of larger peti olar g lands . Croton michaelii occurs in Agu ascaliente s and Durango. It is uncertain to which sectio n of C rot on this species belongs. It resembl es C ro ton yecorensis but is distinguished by possessing a lepid ote indumentum and by lacking con spicu ou s s tipitate glands. Crot on disjun ctus has been coll ected in Chihuahua and Agua scalientes, at localiti es se parated by more than 600 km . Thi s species appea rs to be most closely akin to Cro ton fru tic ulosus Torr., from which it is se parated by g labrous, ev ident (vs. pube scent, nearl y o bso lete) stipules and multifid (vs. bifid) sty les.

Apparent similarity, underlying homoplasy: Morphology and molecular phylogeny of the North American clade of Manihot

“…None of our concatenated analyses indicated that M. mcvaughii , M. obovata , or Manihotoides paucifl ora are closely related, implying that condensed stems and unifl orous infl orescences might have evolved at least twice. Furthermore, these results add support to the hypothesis that these features have evolved in response to arid environments ( Steinmann, 2005 ) given that these three unrelated species are located in some of the driest areas of occurrence of Manihot in Mexico, which also have the highest minimum temperatures. This association might imply that the evolution of stature is infl uenced by water availability, with larger plants being favored in areas where drought is less severe ( Moles et al, 2009 ).…”

“…Our results also suggested that the unusual features of Manihotoides ( Rogers and Appan, 1973 ) are examples of the morphological lability in Manihot . Manihotoides paucifl ora shares with Manihot mcvaughii and M. obovata reduced inflorescences ( Martínez-Gordillo et al, 2002 ;Steinmann, 2005 ), and with M. obovata the presence of leaves clustered on short shoots ( Martínez-Gordillo et al, 2002 ;Webster, 1994 ). None of our concatenated analyses indicated that M. mcvaughii , M. obovata , or Manihotoides paucifl ora are closely related, implying that condensed stems and unifl orous infl orescences might have evolved at least twice.…”

“…Mexican species, M. obovata ( Jiménez-Ramírez, 1990 ) and M. mcvaughii ( Steinmann, 2005 ) have been described. Jiménez-Ramírez (1990) described the section Obovatae to include M. obovata , while Steinmann (2005) did not designate a sectional affi nity for M. mcvaughii .…”

“…Manihotoides was erected for it ( Rogers and Appan, 1973 ) because it has condensed stems and unifl orous infl orescences, conditions that made it unique in Manihot . The subsequent description of M. obovata ( Jiménez-Ramírez, 1990 ) and M. mcvaughii ( Steinmann, 2005 ), which share with Manihotoides these features, suggested that M. paucifl ora should again be subsumed within Manihot ( Webster, 1994( Webster, , 2014Radcliffe-Smith, 2001 ;Martínez-Gordillo et al, 2002 ). We test its position here.…”