DOI: 10.5091/plecevo.138752

Authors: Marco O.O. Pellegrini, David R. Hunt, Jason R. Grant, Avery Rowe, Higor Antonio-Domingues, Rafael F. de Almeida

Abstract: Background and aims – Tradescantia subg. Campelia is the most morphologically diverse and one of the most taxonomically complex subgenera of Tradescantia. This makes taxonomic efforts within this group challenging, especially due to the current lack of formal recognition of monophyletic infrageneric groups and their widespread horticultural use. Thus, continuing our previous efforts, we provide a sectional classification for the subgenus, combined with a taxonomic revision of T. sect. Rhoeo. Material and methods – This study was based on a combination of systematic, micro- and macromorphological, palynological, and horticultural data. We analysed type specimens, protologues, field images, and herbarium sheets of all names, in addition to growing all species and cultivars. We have also reviewed previously published palynological data for the recognised species and provided all needed corrections and updates, in addition to a novel interpretation of their taxonomic relevance. Key results – We propose the subdivision of T. subg. Campelia into four sections: 1) T. sect. Campelia; 2) T. sect. Corinna; 3) T. sect. Cymbispatha; and 4) T. sect. Rhoeo. These sections are supported by a combination of molecular, micro- and macromorphological, anatomical, palynological, cytological, and phytochemical data. Within T. sect. Rhoeo, we accept two species, T. spathacea and the newly recognised T. concolor. Horticulturally, we propose the T. spathacea Bantam Group, including five dwarf cultivars, while T. spathacea ‘Vittata’ is the only regular-sized variegated cultivar of wild origin. We also explore the palynology of T. sect. Rhoeo, highlighting palynotaxonomically relevant characters in Tradescantia and T. subg. Campelia. Conclusions – We lay the groundwork for ongoing and future studies on T. subg. Campelia. The recognition of sections within this subgenus will facilitate identification, communication, and enable the recognition of functional taxonomic groups for future systematic and taxonomic studies. The combination of palynology and horticulture provides further support for the taxonomy and systematics of Tradescantia, and should be consistently included in future studies of the group.

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DOI: 10.5091/plecevo.170279

Authors: Gaik Ee Lee, S. Robbert Gradstein, Xiaolan He, Julia Bechteler, Alfons Schäfer-Verwimp, Tamás Pócs

Abstract: Background and aims – The genus Lejeunea, with about 375 accepted species, is one of the most species-rich and intricate genera of liverworts. Here, we present the first integrative, worldwide infrageneric classification of Lejeunea based on morphology and molecular-phylogenetic analyses. Material and methods – Maximum likelihood analysis and Bayesian inference of sequences from two chloroplast regions (trnL-trnF, rbcL) and the nuclear ITS region of about 35% of the species, combined with morphological evidence. Key results and conclusions – The phylogenetic analyses revealed numerous robust clades within two major lineages, corresponding to subgenera Lejeunea and Crossotolejeunea. Integrating molecular phylogenetic evidence and morphological data, we describe 15 sections: four in subg. Lejeunea (sect. Glaucescentes, sect. Lamacerinae, sect. Lejeunea, sect. Macrolejeunea) and 11 in subg. Crossotolejeunea (sect. Apolejeunea, sect. Crossotolejeunea, sect. Echinocolea, sect. Flavae, sect. Heterolejeunea, sect. Inflatolejeunea, sect. Minutilobae, sect. Nanolejeunea, sect. Papillolejeunea, sect. Sordidae, sect. Xenantholejeunea). Four sections have a neotropical distribution, three are pantropical, two are pantropical and extend into temperate regions, two are Afro-American, two are Asian, one is Asian-Australasian, and one has a tropical amphi-Pacific range.

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DOI: 10.5091/plecevo.152748

Authors: Eileen J. Cox

Abstract: Background and aims – Over 40 years ago, I explored the use of symmetry and structure as taxonomic criteria for naviculoid diatoms, arguing that structure was the more informative character. This paper examines subsequent progress in the understanding and systematics of naviculoid diatoms with particular reference to the treatment of symmetry as a taxonomic criterion. Methods and key results – The diatom literature since 1979 has been reviewed showing how SEM studies and data on wall morphogenesis have improved our knowledge of diatom wall structure and ontogenetic pathways. Understanding the inherent asymmetry in raphid diatom valves led to the recognition of two types of dorsiventrality within the Cymbellales and underpins the separation of cymbelloid taxa in different families. Hypotheses of character homology in the Naviculaceae have been supported by more recent molecular phylogenetic analyses, also revealing how shape and symmetry can vary within this family. Over-emphasising the significance of a particular character (out of familiarity or a priori preference?) can lead to relevant discriminative characteristics being ignored. The validity of some new genera is questioned and generic descriptions should be revised. Conclusion – Whereas valve shape and symmetry remain useful features when identifying taxa, systematic relationships are revealed through wall structure and should be the basis for diatom systematics. Nevertheless, it is important to discriminate between homologous and homoplasious characters and to apply terminology accurately.

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DOI: 10.5091/plecevo.121829

Authors: David M. Williams, Tsvetoslav Georgiev, Tanja M. Schuster, Carlos E. Wetzel

Abstract: Background and aims – Euodia frauenfeldii has the characteristic ‘semi-circular’ or ‘crescent-shaped’ valves found in most species of Euodia, but as it also has a pair of conspicuous transapical costae, it was later transferred to Eunotogramma. Examination of the structure of its valves and girdle has led to a reassessment of its taxonomic position. Material and methods – We discuss various aspects of terminology used for the parts of the valve, their abbreviations used throughout the literature and provide a detailed taxonomic background to both Euodia and Eunotogramma. Key results – A new genus, Moralesonia is described and its relationships discussed.

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DOI: 10.5091/plecevo.101135

Authors: Rafael Felipe de Almeida, Marco O.O. Pellegrini, Isa L. de Morais, Rosangela Simão-Bianchini, Pantamith Rattanakrajang, Martin Cheek, Ana Rita G. Simões

Abstract: Background and aims – Keraunea is a Brazilian endemic genus that has sat uncomfortably in Convolvulaceae where it was placed due to an enlarged and adnate fruit bract typical of Neuropeltis. A recent molecular phylogeny suggested that two of its five morphologically almost identical species actually belong to two different families, Malpighiaceae (superrosids) and Ehretiaceae (superasterids). Later studies have demonstrated that Keraunea effectively belongs to Ehretiaceae, but the proposal of one species belonging to Malpighiaceae has remained problematic. In this study, we re-assess this hypothesis, discuss the issues that have led to this assumption, and offer insights on the importance of carefully using herbarium collections and incorporating morphological evidence in systematic studies. Material and methods – Sequences of matK, rbcL, and ITS for all 77 currently accepted genera of Malpighiaceae, K. brasiliensis and Elatinaceae (outgroup) were compiled from GenBank and analysed with Maximum Likelihood and Bayesian Inference criteria for nuclear, plastid and combined datasets. Additional database and herbarium studies were performed to locate and analyse all duplicates of the holotype of K. brasiliensis to check for misidentified or contaminated material. Key results – Our examination of expanded DNA datasets and herbarium sheets of all K. brasiliensis isotypes revealed that a mistake in tissue sampling was, in fact, what led to this species being proposed to belong in Malpighiaceae. Kew’s isotype had a leaf of Malpighiaceae (likely Mascagnia cordifolia) stored in the fragment capsule, which was sampled and sequenced instead of the actual leaves of K. brasiliensis. Recently published studies have settled the placement of Keraunea in Ehretiaceae (Boraginales) and proposed three additional species. Conclusions – DNA sequences can be helpful in classifying taxa when morphology is conflicting or of a doubtful interpretation, with molecular phylogenetic placement being established as a popular tool accelerating the discovery of systematic relationships. Nonetheless, molecular techniques are also susceptible to methodological mistakes, which necessitates building a solid foundation of plant morphology and taxonomy to avoid artefacts in phylogenetic studies.

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