DANIEL & TRIPP: LOUTERIDIUM : TAXONOMY, BIOLOGY, AND CONSERVATION 45 
7 3 
90 
-H- 
96 
96 
99 
L. parayi 
L. parayi-2 
- L. costaricense-2 
L. costaricense 
j- L. tamaulipense 
J-LJamaulipense-2 
77 
28 
98 
t L-1 
41 
97 
98« 
L. purpusii-2 
purpusii 
L. mexicanum-3 
J.I— L. mexicanum 
99 n 
rn 1 — L. mexicanum-4 
L. mexicanum-2 
i- L. donnell-smithii-5 
L. donnell-smithii-6 
L. donnell-smithii-2 
L. donnell-smithii-4 
L. donnell-smithii 
L. donnell-smithii-3 
A, 
L. dendropilosum-2 
dendropilosum-3 
i*Cl 
*— L. dendropilosum 
L. brevicalyx 
koelzii 
L. rzedowskianum.2 
L. rzedowskianum 
L. chartaceum 
.. chartaceum-2 
T l 
— R. lasiostachya 
L R. violacea 
L R. puri 
L Petalidium halimoides x variabile 
0.02 
section 
Parcostamium 
section 
Louteridium 
section 
Tetrandrium 
Figure 1 . Most likely phylogenetic hypothesis for relationships among species of Louteridium, generated from ddRAD- 
seq loci analyzed under maximum likelihood (and implemented in RAxML). Our analyses yield strong support for a mono- 
phyletic Louteridium as well as support for three primary sections: Louteridium, Parcostamium, and Tetrandrium. Hash 
mark between outgroups and Louteridium indicate branch was shortened to reduced overall figure width for reproducibili¬ 
ty. Asterisks [*] indicate 100% ML bootstrap support. 
et al. 2013) reveal Louteridium to be sister to a morphologically similar and monophyletic lineage 
of five Neotropical genera treated as Trichanthereae (e.g., Lindau 1895; Bremekamp 1965; Daniel 
1988, 2015): Bravaisia DC., Sanchezia Ruiz & Pav., Suessenguthia Merxm., Trichanthera Kunth, 
and Trichosanchezia Mildbr. Although the phylogenetic relationships and generic status of 
Sanchezia, Suessenguthia, and Trichosanchezia have yet to be fully resolved (cf. Schmidt-Lebuhn 
et al. 2005; Tripp et al. 2013), these five genera that together contain about 80 species, plus 
Louteridium, were proposed to form an expanded subtribe Trichantherinae of Ruellieae (Tripp et 
al. 2013). 
Other than molecular characteristics, no synapomorphies are known for Trichantherinae. 
Louteridium shares a number of characteristics with remaining Trichantherinae, including arbore¬ 
al habit and prop roots. These attributes are otherwise known, but relatively rare, among Acan- 
