Jason R. Grant

A community-derived classification for extant lycophytes and ferns

Phylogeny has long informed pteridophyte classification. As our ability to infer evolutionary trees has improved, classifications aimed at recognizing natural groups have become increasingly predictive and stable. Here, we provide a modern, comprehensive classification for lycophytes and ferns, down to the genus level, utilizing a community‐based approach. We use monophyly as the primary criterion for the recognition of taxa, but also aim to preserve existing taxa and circumscriptions that are both widely accepted and consistent with our understanding of pteridophyte phylogeny. In total, this classification treats an estimated 11 916 species in 337 genera, 51 families, 14 orders, and two classes. This classification is not intended as the final word on lycophyte and fern taxonomy, but rather a summary statement of current hypotheses, derived from the best available data and shaped by those most familiar with the plants in question. We hope that it will serve as a resource for those wanting references to the recent literature on pteridophyte phylogeny and classification, a framework for guiding future investigations, and a stimulus to further discourse.

Monophyly and relationships of the tribe Exaceae (Gentianaceae) inferred from nuclear ribosomal and chloroplast DNA sequences.

Both chloroplast trnL (UAA) intron and nuclear ribosomal ITS sequences highly confirmed the monophyly of the tribes of the Gentianaceae defined by the recent classification, and revealed the tribe Exaceae as a basal clade just next to the basal-most lineage, the tribe Saccifolieae. Within the tribe Exaceae, Sebaea (except Sebaea madagascariensis) appeared as the most basal clade as the sister group to the rest of the tribe. The Madagascan endemic genera Gentianothamnus and Tachiadenus were very closely related to each other, together standing as sister to a clade comprising Sebaea madagascariensis, Ornichia, and Exacum. The saprophytic genus Cotylanthera nested deeply inside Exacum. Sebaea madagascariensis was shown closer to the Madagascan endemic genus Ornichia than to any other sampled Sebaea species. Exacum appeared as the most derived taxon within this tribe. The topology of the phylogenetic trees conform with the Gondwana vicariance hypothesis regarding the biogeography of Exaceae. However, no evidence for matching the older relationships within the family to the tectonic history could be corroborated with various divergence time analyses. Divergence dating estimated a post-Gondwana diverging of the Gentianaceae about 50 million years ago (MYA), and the tribe Exaceae as about 40 MYA. The Mozambique Channel land-bridge could have played an important role in the biogeographic history of the tribe Exaceae.

Phylogenetic relationships and character evolution in Primula L.: The usefulness of ITS sequence data

ABSTRACT The main goals of this research were to reconstruct the infrageneric phylogeny of the genus Primula based on both nuclear and chloroplast DNA sequences, and to use the resulting phylogenies to elucidate the evolution of breeding systems, morphological characters, chromosome number, and biogeographic distribution in the genus. In this paper, the results of a pilot study based on the nuclear ribosomal Internal Transcribed Spacer (ITS) region are described. ITS sequences from 21 taxa produced a number of variable characters sufficient to resolve relationships among sections. The resulting phylogeny confirmed the monophyly of sections Auricula and Aleuritia. Sections Armerina, Proliferae, Crystallophlomis, Parryi, and Auricula, with a base chromosome number of x = 11, and sect. Aleuritia, with a base chromosome number of x = 9, formed two well supported clades. The ITS topology also suggested that leaves with revolute vernation, previously believed to be a derived state, might represent the ancestral condition in Primula, with later reversals to the involute condition. Finally, this initial ITS tree provides preliminary support to the proposed role of the widespread, diploid and heterostylous P. mistassinica as having given origin to the polyploid, homostylous P. incana and P. laurentiana.

Andean Speciation and Vicariance in Neotropical Macrocarpaea (Gentianaceae-Helieae)

Abstract The genus Macrocarpaea (Griseb.) Gilg (Gentianaceae, Helieae) is among the largest woody genera of tropical gentians, with most of its species occurring in the wet mountainous forests of the Andes. Phylogenetic and dispersal-vicariance analyses (DIVA) of 57 of the 105 currently recognized species in the genus, using two data sets from nuclear DNA (ITS and 5S-NTS sequences) and morphology, show a single origin of the Andean species from an ancestral distribution that includes southeastern Brazil. Within the Andes, species divide into two major clades: (1) northern species from the cordilleras of northern Ecuador, Colombia, and Venezuela; and (2) southern species of the Andean Amotape–Huancabamba Zone in Ecuador and Peru, as well as the Andes of central and southern Peru and Bolivia. The Amotape–Huancabamba Zone is supported as the ancestral area for Macrocarpaea within the Andes. There are repeated speciation patterns within the Andes, and three Mesoamerican species derive from the northern clade, as is the single sampled species from the Guayana Shield. The position of the subclade of the three Caribbean species is less certain, but it currently nests among Andean species. An Atlantic coastal Brazilian clade is placed as sister group to all other Macrocarpaea, providing further support for an ancestral refuge in southeastern Brazil for the Helieae. The biogeographic analysis showed that local speciation is more common than long-distance dispersal, and allopatric speciation is more common than sympatric speciation. Using detailed, georeferenced herbarium collection data, patterns in environmental characteristics between clades and sister species were analyzed with Spatial Evolutionary and Ecological Vicariance Analysis (SEEVA), utilizing geographic information system (GIS) and statistical methods. Sister clades and taxa were evaluated for statistical significance in variables such as annual rainfall and temperature, elevation, temperature and rainfall seasonality, geological bedrock age, and soil type to evaluate ecological vicariance between sister groups. The results indicate that there are no general patterns for each variable, but that there are many significant divergences in ecological niches between both larger sister groups and sister species, and ecological niche conservation was also observed when subsequent nodes in the phylogeny were compared.

Molecular phylogenetics supports widespread cryptic species in moonworts (Botrychium s.s., Ophioglossaceae)

PREMISE OF THE STUDY Previous phylogenetic studies of moonworts (Botrychium sensu stricto (s.s.)) included few taxa from outside of North America. This low geographical representation limited interpretations of relationships of this group rich in cryptic species. With 18 out of 30 species in the genus being polyploid, understanding their evolutionary history remains a major challenge. METHODS A new molecular phylogeny was reconstructed using Maximum Likelihood (ML) and Bayesian Inference (BI) analyses based on multiple accessions of the most wide-ranging Arctic taxa of Botrychium in North America and Europe using three noncoding plastid DNA regions (psbA-trnH(GUG), trnL(UAA)-trnF(GAA) intergenic spacer, and rpL16 intron). KEY RESULTS The new phylogeny confirms the identity of several recently described species and proposed new taxa. Nine subclades are newly identified within the two major clades in Botrychium s.s.: Lanceolatum and Lunaria. Chloroplast DNA was variable enough to separate morphologically cryptic species in the Lunaria clade. On the contrary, much less variation is seen within the morphologically variable Lanceolatum clade despite sampling over the same broad geographic range. The chloroplast region psbA-trnH(GUG) is identified as an efficient DNA barcode for the identification of cryptic taxa in Botrychium s.s. CONCLUSIONS The combined increase in species representation, samples from throughout the geographic range of each species, and sequencing of multiple plastid DNA regions supports morphologically cryptic species in Botrychium s.s.

Wood anatomy of Gentianaceae, tribe Helieae, in relation to ecology, habit, systematics, and sample diameter

Twenty collections representing one species each ofSymbolanthus andTachia, and 17 species ofMacrocarpaea were studied by means of light microscopy and scanning electron microscopy (SEM). Wood details show that the three genera form a coherent group;Tachia differs from the others in only a few minor characters. Because the species studied form a natural group, wood variations within Helieae offer the basis for correlations and interpretations with respect to habit and ecology. Diameter of stems studied proves to be an important variable that must be taken into account. Correlations with stem diameter include wider vessels in outer wood of wider samples. This would correspond to deeper penetration of reliable water tables by roots of helioid trees or large shrubs. Ray height decreases with increase in stem diameter, an indication of paedomorphosis. Rays of all species are paedomorphic in histology by virtue of relative paucity or even absence of procumbent cells in multiseriate rays. Pseusoscalariform lateral wall pitting of vessels is also a feature characteristic of paedomorphosis. The assemblage of paedomorphic features correlates well with the conclusion, reached by authors who used cladistic methods, that Gentianaceae other than Gentianeae are derived from suffrutescent prennials. The Mesomorphy Ratio, which incorporates three vessel features, correlates with leaf length and with stem diameter. All Helieae are mesophytic, but to various degrees. Septate fiber-tracheids, where present, are typically near vessels and form a substitute for or an addendum to vasicentric axial parenchyma as a mechanism for photosynthate storage. Vestured pits occur on lateral wall pits of vessels of all Helieae, but not on the fibertracheids. Vestured pits show diversity withinMacrocarpaea, a feature of possible systematic significance.

DE MACROCARPAEAE GRISEBACH (EX GENTIANACEIS) SPECIEBUS NOVIS VII: FOUR NEW SPECIES AND TWO NATURAL HYBRIDS

ABSTRACT Four new species, Macrocarpaea dies-viridis (Ecuador), M. luctans (Ecuador, Peru), M. lucubrans (Panama), and M. opulenta (Ecuador), and two natural hybrids, M. ×acuminata (Costa Rica) and M. ×mattii (Ecuador), are described. Macrocarpaea × acuminata Weaver (pro sp.) is recognized as a natural hybrid between M. subcaudata and M. valerii, rather than as a distinct species, and M. × mattii is described here as a natural hybrid between M. noctiluca and M. subsessilis. The average number of seeds per capsule of M. dies-viridis is reported. With 10,400–11,000 seeds per capsule, the is first report in the genus.

Convergent Vessel Diameter–Stem Diameter Scaling across Five Clades of New and Old World Eudicots from Desert to Rain Forest

Premise of research. Variation in average xylem vessel diameter across species has important functional consequences, but the causes of this variation remain unclear. Average vessel diameter is known to scale with stem size within and across species. Vessel diameter also seems to differ between clades and across environments, with dryland plants having narrower, more cavitation-resistant vessels. As a result, it is not clear to what extent phylogenetic affinity and environment are associated with differences in the vessel diameter–stem size relationship. Methodology. With linear models and correlations, we explored the influence of environment and phylogeny on the vessel diameter–stem diameter relationship in a molecular phylogenetic context across 83 species in four families spanning desert to rain forest in the Americas, Africa, Asia, and Madagascar. Pivotal results. Mean species vessel diameter was strongly predicted by trunk diameter (slope ∼0.33), and this slope was not affected by either phylogenetic affinity or environment. Clades differed only slightly in mean vessel diameter when controlling for stem size, and there was no tendency for plants of moist environments to have wider vessels. Of four climate indexes, only the temperature index contributed to explaining vessel diameter, although very weakly. Conclusions. Our results are congruent with models suggesting that natural selection should maximize vessel conductivity while minimizing cavitation risk via vessel taper in the context of conductive path length. Because neither environment nor phylogeny contributed to explaining vessel diameter–stem diameter scaling across species, our results appear congruent with the notion that selection favoring cavitation resistance via narrow vessels should lead to shorter statures independently of ancestry or habitat. The repeated finding of narrow vessels in dryland plants might therefore reflect the smaller average stem size of plants in drylands rather than the plants having vessels that are narrow for their stem diameters.

Molecular phylogeny and systematics of the tribe Chorisporeae (Brassicaceae)

Sequence data from nuclear (ITS) and chloroplast (trnL-F) regions for 89 accessions representing 56 out of 64 species from all five genera of the tribe Chorisporeae (plus Dontostemon tibeticus) have been studied to test the monophyly of the tribe and its component genera, clarify its boundaries, and elucidate its phylogenetic position in the family. Both data sets showed strong support for the monophyly of the Chorisporeae as currently delimited, though the position of its tentative member D. tibeticus was not resolved by ITS. Parrya and Pseudoclausia are poly- and paraphyletic with regard to each other, and Chorispora is either polyphyletic or at least paraphyletic (comprising Diptychocarpus) within a weakly supported monophyletic clade. The incongruence in branching pattern among the markers was most likely caused by hybridization and possibly influenced by incomplete lineage sorting. The present results suggest uniting Pseudoclausia, Clausia podlechii, and Achoriphragma with Parrya and transferring P. beketovii and P. saposhnikovii to Leiospora (Euclidieae). We also obtained support for splitting Chorispora into two geographically defined groups, one of which is closer to Diptychocarpus. Both data sets revealed a close relationship of the Chorisporeae to Dontostemoneae, while ITS also indicated affinity to Hesperideae. Therefore, the position of Chorisporeae needs further verification.

De Macrocarpaeae Grisebach (Ex Gentianaceis) Speciebus Novis VIII: Two New Species from Ecuador

ABSTRACT Two new species, Macrocarpaea claireae and M. quizhpei (Gentianaceae: Helieae), are described from the Huancabamba region of southern Ecuador. Macrocarpaea claireae occurs around Valladolid, adjacent to P. N. Podocarpus, and M. quizhpei occurs in the Nangaritza watershed. M. claireae is closely related to M. pringleana and M. sodiroana, yet differs notably in its glaucous-green, campanulate-urceolate calyx. Macrocarpaea quizhpei has affinities to M. dies-viridis, but differs in having a large, diffusely branched, open thyrse to 1.3 m high.