46 
PROCEEDINGS OF THE CALIFORNIA ACADEMY OF SCIENCES 
Series 4, Volume 65, 28 Sept. 2018, No. 2 
thaceae. Louteridium differs conspicuously from other genera of Trichantherinae by its three-lobed 
calyx, gibbous-throated corolla, elongate thecae (6.5-17 mm long), and large (> 100 pm diam.) 
pantoforate (vs. loxodicolporate) pollen (Tripp et al. 2013; Daniel 1998,2015). Each of these char¬ 
acters would thus appear to be synapomorphic for the genus. A possible additional synapomorphy 
for Louteridium, early abscission of unpollinated flowers at or near the base of the pedicel, is 
discussed below under Floral Ecology and Reproductive Biology. 
Intrageneric Phylogenomics. — Our single lane of 96 multiplexed samples yielded a total 
of 493,303,821 reads (GC content = 49%) prior to trimming. Trim min g removed Illumina single 
end adapter sequences as well as other overrepresented sequences, yielding a remaining set of 
327,927,454 reads (sequence lengths between 35 and 92 bp; GC content = 40%). The total number 
of reads kept per sample (after filtering in PyRAD) is reported in Table 1. Of these, 51,072545 
reads were “unmatched” during the demultiplex process and thus discarded from further consider¬ 
ation. We recovered no correlation between the year that herbarium material was collected and the 
total number of reads generated per sample (r=0.05; p=0.79; Table 1). The final phylip alignment 
file contained data from 31 samples and was 9,881,851 bp in length. Gaps and Ns constituted -71% 
of this matrix. 
The 27 accessions of Louteridium included in our final analysis were recovered as mono- 
phyletic with strong support (100% ML bootstrap [hereafter, BS]) based on outgroup sampling of 
two other genera (and four species) of Ruellieae (Fig. 1). Within Louteridium, our analyses recov¬ 
ered three major clades corresponding to three sections treated in the present study (Fig 1). 
Louteridium sections Tetrandrium and Parcostamium were strongly supported (100% and 96% BS, 
respectively), whereas section Louteridium was weakly supported (77% BS). Section Parcostami¬ 
um was resolved as early diverging with respect to sections Louteridium and Tetrandrium, the 
latter two of which were resolved as sister lineages albeit without support. In all cases, multiple 
accessions representing a given species were recovered as reciprocally monophyletic to the exclu¬ 
sion of other species. 
Thus, RADsequencing yielded a highly resolved and for the most part (only two branches 
unsupported) strongly supported phylogenetic hypothesis for relationships among species of 
Louteridium. Whereas section Tetrandrium reflects prior classification of four-staminate species 
comprising this group (Richardson 1972), our study recognizes two distinct, non-monophyletic 
lineages of two-staminate species (sections Louteridium and Parcostamium). This departs from 
Richardson’s (1972) classification in which he treated members of both of these clades as 
comprising the single section Louteridium. 
Morphological characters indicative of or synapomorphic for each of the three clades varies. 
The presence of four stamens is a strong synapomorphy for species in section Tetrandrium, which 
are furthermore characterized by occurrence in dry forests, the presence of clustered leaves, and 
leaves that are seasonally deciduous. In contrast, species in both sections Parcostamium and 
Louteridium, which are characterized by flowers with two stamens, occur in moist to wet forests 
and have leaves that both persist throughout the year and are more or less evenly distributed along 
young stems. Morphological synapomorphies separating the latter two lineages are tenuous as cur¬ 
rently understood; plants in section Parcostamium have somewhat succulent leaves, whereas plants 
Figure 2. Louteridium brevicalyx (A-E) and L. dendropilosum (F-L). A. Habit and habitat. B. Trunk with adventitious 
roots on rocks. C. Six-year old cultivated plant with clusters of new leaves. D. Flower. E. Shoot apex showing clustered leaf 
scars. F. Base of trunk with adventitious roots on rocks. G. Six-year old cultivated plant with clusters of new leaves. 
H. Shoot apex showing clustered leaf scars. I Young inflorescence with bracts, bracteoles, and flower buds. J. Flower. 
K. Corolla showing invagination along base of throat. L. Internal view of corolla showing invaginations along base of 
throat. (A, B, Daniel & Steinmann 11913; C-E, Daniel & Steinmann 11913cv; F, Daniel et al. 11784; G-L, Daniel et al. 
11894cv). Photos by T. Daniel. 
