Walter H. Lewis: A Life Spent Pushing Back the Frontiers of Botany (1930–2020)

In memory of Dr. Walter H. Lewis

Synopsis of Ozobryum (Pottiaceae, Bryophyta), and Sequential Bayes Evaluation of Genus Integrity

Ozobryum G. L. Merr., once synonymized with Molendoa Lindb., is recognized as a good genus of Pottiaceae based on evaluation of it as a distinctive dissilient genus. Populations from Mexico are described as a new species, O. mexicanum R. H. Zander. The species Anoectangium warburgii Crundw. & M. O. Hill is transferred to Ozobryum. The genus is synthetically evaluated as integral in respect to other genera of the Pleuroweisieae through combination of critical methods of probabilism, including scientific theory, Granger causation, and verificationism, and of evidentialism, including constructivism, likelihoodism, Bayesianism, and analytic methods of classical taxonomy.

A Continuum of Conspicuousness, Floral Signals, and Pollination Systems in Rhynchospora (Cyperaceae): Evidence of Ambophily and Entomophily in a Mostly Anemophilous Family

Floral colors and odors are evolutionary strategies used by plants to attract pollinating animals and may be absent in mostly anemophilous groups, such as Cyperaceae. However, considering that insects are floral visitors of some Rhynchospora Vahl species, the objective of this study was to characterize the floral traits and pollination systems within this genus. We analyzed 16 Rhynchospora species with regard to flower morphology, colors of floral structures, floral scents, pollen vectors, and pollination systems. We verified factors that can favor abiotic or biotic pollination in a continuum of floral traits in Rhynchospora. The flower morphology of R. dissitispicula T. Koyama, with inconspicuous brown spikelets in open panicles, is interpreted as a complete adaptation to anemophily. Conspicuous floral traits in Rhynchospora were distinguished from the background by bees. Some species also emit floral volatiles, and we made the first record of floral scent chemistry within the genus. Most of the compounds emitted by these species are known as attractants to many floral-visiting insects. Bees, beetles, and flies visited species with conspicuous floral traits and contributed to fruit set. The investigated floral traits form a continuum across the different pollination systems in Rhynchospora, from anemophilous to ambophilous and then to entomophilous representatives.

Taxonomic Revision of Euphrasia (Orobanchaceae) in South America

Morphological boundaries between South American species of Euphrasia L. are controversial, rendering determination of specimens an arduous task. In this context, a comprehensive taxonomic revision of Euphrasia in South America is here provided for the first time. This study, based upon a classical morphological study of ca. 400 herbarium specimens, supports the recognition of eight species and one subspecies distributed in the Andean regions of Argentina, Bolivia, and Chile. From among native species, six belong to section Trifidae Benth. and one to the monotypic section Paradoxae Pugsley, endemic to Juan Fernández Islands; one adventive species, E. officinalis L., belongs to the section Euphrasia. The previously misunderstood presence of E. cockayniana Petrie is here untangled, and, consequently, the species is excluded from South America. A key to all Euphrasia taxa in South America, plus morphological descriptions, nomenclature items, geographical distribution and maps, habitat notes, illustrations, photographs, and discussion notes are included for the nine taxa. Eleven names are here synonymized, and lectotypes are designated for E. andicola Benth., E. debilis Wettst., E. flavicans Phil., E. intricata Phil., and E. philippii Wettst. Euphrasia andicola is reported for the first time for Argentina. This collaborative effort will represent a baseline for further investigations on Euphrasia in South America.

Synopsis of the Genus Pentacalia (Compositae, Senecioneae) in Bolivia

The Neotropical genus Pentacalia Cass. (Compositae, Senecioneae) is distributed from southern Mexico to northwestern Argentina, plus two disjunct species that thrive in Brazil. Most species diversity occurs in the montane forests of Colombia, Ecuador, and Peru. It comprises scandent woody plants characterized by displaying alternate leaves (opposite in three species), involucres with supplementary bracts, usually yellow ray florets (when present), sagittate to caudate anther bases, and truncate to obtuse style branches with a crown of sweeping trichomes (sometimes with a tuft of longer trichomes, but not strictly penicillate). The Bolivian species were revised for the first time by Cabrera (1985), who treated the group under Senecio L. sect. Streptothamni Greenm. Because of the subsequent addition of new species and the need of taxonomic arrangements, an updated synopsis of the genus recognizing 18 species is presented. The names P. brittoniana (Hieron.) Cuatrec. and P. miguelii (Cuatrec.) Cuatrec. are synonymized with P. psidiifolia (Rusby) Cuatrec., as well as P. inquisiviensis H. Rob. & Cuatrec. with P. cardenasii (Cuatrec.) Cuatrec. and P. sailapatensis (Cuatrec.) Cuatrec. with P. urubambensis (Cabrera) Cuatrec. Seven names are lectotypified and an epitype is designated for the name P. zongoensis (Cabrera) J. Calvo. The new species P. viburnifolia J. Calvo & A. Fuentes is described. Revised nomenclature, succinct descriptions, taxonomic discussions, lists of specimens examined, and distribution maps are provided for all accepted species, in addition to an identification key. Pictures of living plants are also presented for eight species.

The Phylogenetic Position of Crenea in the Lythraceae Based on Molecular Evidence, and the Transfer of Its Two Species to Ammannia

Crenea Aubl. (Lythraceae) is a ditypic genus of subshrubs occurring in mangrove vegetation on the coasts of northern South America. Phylogenetic analyses based on morphology have offered unresolved and conflicting phylogenetic positions for the genus in the family. This study presents the first molecular sequences for Crenea, from nrITS, rbcL, trnL, trnL-F, and matK regions. Molecular phylogenetic analyses find full support for Crenea within Ammannia L., a relationship not previously recognized. Ammannia is a globally distributed genus of terrestrial to amphibious herbs mostly occurring in freshwater marshes and wetlands. It was recently reconfigured based on phylogenetic evidence to include the genera Nesaea Comm. ex Kunth and Hionanthera A. Fern. & Diniz. The transfer of Crenea to Ammannia further extends the morphological, ecological, and biogeographical diversity of Ammannia and provides the final evidence defining Ammannia as a monophyletic lineage of the Lythraceae. A revised circumscription of Ammannia s.l. adds several new morphological character states and the first species in the genus restricted to mangrove vegetation. Two changes in taxonomic status are made: Ammannia maritima (Aubl.) S. A. Graham, P. W. Inglis, & T. B. Cavalc., comb. nov., and Ammannia patentinervius (Koehne) S. A. Graham, P. W. Inglis, & T. B. Cavalc., comb. nov. The new combinations are described, a list of exsiccatae examined is provided, and the effects of the reconfiguration to the morphology and biogeography of the genus are detailed.

Toward an Updated Taxonomy of the South American Amaranthaceae II: Subfamily Salicornioideae, Tribes Salicornieae and Suaedeae

This paper is the second in a series treating the Amaranthaceae s.l. in South America. We present here a taxonomic revision of tribes Salicornieae and Suaedeae (subfamily Salicornioideae) based on the study of herbarium material, type specimens, digital images, original publications, and field observations. The South American Amaranthaceae s.l. flora includes Allenrolfea Kuntze, Heterostachys Ung.-Sternb., Mangleticornia P. W. Ball, G. Kadereit & Cornejo, and Salicornia L. from Salicornieae, and Suaeda Forssk. ex J. F. Gmel. from Suaedeae. Lectotypes for seven names are here designated. The distribution of all species is updated based on the revision and proper identification of many herbarium specimens and field observations. A new synonym for Salicornia neei Lag. is here proposed.

Comparative Floral Micromorphology in Mimosa sect. Calothamnos (Fabaceae)

The genus Mimosa L. is well known for its high morphological variability and the presence of taxonomic complexes—groups of taxa that are not adequately circumscribed and are therefore in continuous revision. For this study, we analyzed flowers from 28 different taxa in Mimosa sect. Calothamnos Barneby and five vegetatively similar taxa from Mimosa sect. Mimosa. We observed three calyx shapes and four (glabrous or pubescent) calyx border types, as well as describe glandular trichomes on the calyx border for the first time in section Calothamnos. While the corolla exhibits only two shape types, trichomes on the corolla are much more diverse, as we found one simple and 11 branched trichome types in diverse orientations and dispositions. Given the taxonomic value of trichomes and profuse terminology in different families, we focused on the detailed description of their micromorphology, type, and shape, finding morphological differences between trichome types, which is an easy way to adequately compare them between even unrelated taxa. Our results using trichome types on the corolla are consistent with the original differentiation of sections Calothamnos and Mimosa. Flower micromorphology also provides characters to distinguish species, groups of species, and varieties within section Calothamnos and could be useful in a future taxonomic treatment of the section. We also found that some floral features, such as inflorescence color and stamen fusion, are associated with the characters used in this study.

Taxonomic Revision of the Genus Podagrostis (Poaceae, Pooideae, Poeae)

A taxonomic revision of the genus Podagrostis (Griseb.) Scribn. & Merr. is presented, including two new combinations: P. meridensis (Luces) A. M. Molina & Rúgolo and P. novogaliciana (McVaugh) A. M. Molina & Rúgolo. Podagrostis bacillata (Hack.) Sylvester & Soreng constitutes a new report for Colombia. Information regarding synonymy, geographical distribution, habitat, iconography, and vernacular names is provided along with complete illustrations and a list of additional specimens examined. A key for the identification of the species is included as well as a comparative table based on macro- and micromorphological data. The anatomical character of Trichodium net on lemma epidermis, as well as its diagnostic value, is discussed in species of Podagrostis and most related genera (e.g., Agrostis L., Chaetotropis Kunth, and Polypogon Desf., among others).

Chromosome Numbers and Ploidy Levels of Some Paniceae and Paspaleae Species (Poaceae, Panicoideae)

Chromosome numbers and ploidy levels of 24 accessions of 17 species of tribe Panicoideae from Argentina, Cuba, and Brazil are given. Most of the studied species are endemics. The studied taxa are: Axonopus aureus P. Beauv., Dichanthelium aequivaginatum (Swallen) Zuloaga, D. stipiflorum (Renvoize) Zuloaga, D. surrectum (Chase ex Zuloaga & Morrone) Zuloaga, Homolepis isocalycia (G. Mey.) Chase, Paspalum arenarium Schrad., P. blodgettii Chapm., P. capillifolium Nash, P. coryphaeum Trin., P. distortum Chase, P. durifolium Mez, P. lindenianum A. Rich., P. oligostachyum Salzm. ex Steud., P. pumilum Nees, P. scutatum Nees ex Trin., P. strigosum Döll ex Chase, and Plagiantha tenella Renvoize; of these, the chromosome numbers of D. aequivaginatum, D. stipiflorum, D. surrectum (n = 9), Homolepis isocalycia (n = 20), Paspalum capillifolium, P. distortum, P. lindenianum, P. oligostachyum, and P. strigosum (n = 10) are presented for the first time. A new diploid cytotype (n = 10) for Paspalum blodgettii was found.