Taxonomic Delimitation Research Articles

Taxonomic implications of the morphological and genetic variation of cultivated and domesticated populations of the Agave angustifolia complex (Agavoideae, Asparagaceae) in Oaxaca, Mexico

The Agave angustifolia complex, distributed from Mexico to Costa Rica, comprises four species and five varieties, including three species used for mescal production. The complex is represented in the Mexican state of Oaxaca by two wild taxa, A. angustifolia var. angustifolia and A. angustifolia var. rubescens, the cultivated form A. angustifolia “Espadin” and the partially cultivated species A. rodacantha. The aims of this study were to investigate the morphological and genetic variation of the A. angustifolia complex in the state of Oaxaca and to identify traits useful for taxonomic delimitation. Four wild and three cultivated populations of A. angustifolia from Oaxaca, one population of A. tequilana from Guanajuato and one population of A. angustifolia from Sonora were sampled for morphological, genetic and cytometric analyses. We showed that cultivated populations of A. angustifolia “Espadin,” A. rhodacantha and A. tequilana could be clearly differentiated from wild populations. Furthermore, the domesticated populations of A. angustifolia, known locally as “Espadin,” had a higher ploidy level and lower genetic variation than their related wild populations. The population of A. angustifolia from Sonora could be recognized as a different entity. Populations of A. rhodacantha need to be studied throughout their entire distribution area to further evaluate their taxonomic delimitation.

Leaf characters of Lavoisiera, Microlicia and Trembleya (Microlicieae, Melastomataceae) and their implications for taxonomy

In Microlicieae taxonomical delimitation of Lavoisiera, Microlicia and Trembleya is problematic. This study aims to fill this gap by identifying leaf characters that are useful for taxonomy of these genera. Species of Rhynchanthera were also included in this study for comparison, since it is an early‐diverging genus of the tribe. Diagnostic characters of Lavoisiera include sessile leaves with spongy parenchyma composed of isodiametric cells, and acute margins with supporting tissue. Trembleya is distinguished by petiolate, microphyllous, and hypostomatic leaves. The presence of depressions on the leaf surface and a homogeneous mesophyll is observed only in species of Microlicia. The leaf characters observed in Rhynchanthera, together with the available phylogenetic studies, were important to indicate evolutionary tendencies in the leaf structure within Microlicieae. Thus, our results indicate a tendency for reduction in leaf size within the tribe, in relation to both the petiole and the lamina. This reduction, which is more pronounced in Microlicia, results in a greater anatomical heterogeneity, due to variations in the organization of both vascular and fundamental tissues.

Chromosome mapping of rDNA sites in "Zygopetalum maculatum" (Orchidaceae) polyploid complex

The "Zygopetalum maculatum" complex (Orchidaceae) comprises species with similar morphological characters making difficult their taxonomic delimitation. Cytogenetic data has been widely used as an additional information to the taxonomy of several plant genus. Zygopetalum was recently described as a polyploid genus with 2n=48; 2n=72 and 2n=96 chromosomes. Here, we investigated the karyotype of "Z. maculatum", which mainly occurs in “Campo ruspestre” and "Campos de altitude" environments. The objective was to contribute for the understanding of cytoevolutionary events and speciation mechanisms in the genus Zygopetalum, also contributing to the taxomomy of the group. We investigated individuals with 48 chromosomes from the Corico, Pico do Itambé, Pico do Garrafão and Cotia populations. The individuals with 72 chromosomes were collected at Pico do Itambé and Serra do Cipó. Individuals with 96 chromosomes, were sampled at Finas, Parque Estadual do Ibitipoca and Bocaina. Individuals with 48 chromosomes showed 5S rDNA sites in four chromosomes, being two signals at the subterminal position. The 45S rDNA sites were also identified on four chromosomes at the terminal positions. Individuals with 2n=72 revealed six chromosomes labeled with 5S rDNA, being three of them subterminal. Six terminal 45S rDNA sites were identified on six chromosomes. Finally, in individuals with 96 chromosomes, four out of eight labeled chromosomes with 5S rDNA showed signal at subterminal regions. Considering 45S rDNA, eight sites were also detected, all of them at terminal regions. Taking all data, the number of 5S and 45S chromosome sites increased proportionally as the chromosome number increased, being exactly equal to the number of sites expected for each cytotype, considering 2n=48 individuals as the reference. The results suggest that polyploidization events has to be considered to understand the diversification and speciation in the "Zygopetalum maculatum" complex, helping to explain the morphological pattern observed within the group.Financial support: Fapemig, Capes, CNPq

Correct taxonomic delimitation of Nasturtium microphyllum Rchb. from Nasturtium officinale R. Br. (Brassicaceae) in Kashmir Himalaya, India

The correct taxonomic delimitation of Nasturtium microphyllum Rchb., previously misidentified as Nasturtium officinale R. Br., in the Kashmir Himalaya, India, is reported. This species differs from its closely allied N. officinale in the shape, size, and arrangement of seeds in the fruit. A detailed taxonomic account, including complete description and photoplates of diagnostic characters are provided to resolve the misidentification of the taxa in the Kashmir Himalaya.

Structure, distribution and taxonomic significance of leaf and petiole anatomical characters in five species of Terminalia (L.) (Combretaceae: Magnoliopsida)

This paper presents a synthesis of a comparative leaf anatomy (lamina and petiole) of five species of the genus Terminalia found in southwest Nigeria. Collections of plants were made from different locations in Southwest Nigeria as the geographic locations of the sites of collection were also geo-referenced with a GPS device. The samples were identified at the Herbarium of Botany Department, Obafemi Awolowo University (Ife), Nigeria, and were subjected to anatomical examinations. Quantitative data were subjected to statistical analysis and the characters vary significantly (P = 0.05). Anatomical characters which separate the taxa include petiole outline, epidermal features, vascular pattern, occurence of cortical and pericyclic fibres, presence/absence of, and types of trichomes etc, all found to be useful in identification of different species. The variations in the anatomical traits could be effectively used in taxonomic delimitation of the species and are helpful characters in determining the complexes in the genus such as adaptation of the species to xeric environments. The presence of 2-3 layers of palisade mesophyll cells in Terminalia mantaly, which is an adaptation of the species to drought, is diagnostic for the species. It is suggested that a comprehensive consideration of leaf lamina and petiole anatomy should be used as basis of taxonomy.

Characterization of Two Complete Chloroplast Genomes in the Tribe Gnaphalieae (Asteraceae): Gene Loss or Pseudogenization of trnT-GGU and Implications for Phylogenetic Relationships

The tribe Gnaphalieae is one of the largest and most complex in the Asteraceae family. The taxonomic delimitations of the tribe Gnaphalieae have been inferred by researchers; however, the exact relationships between it and other tribes remain in dispute, likely because of complicated evolutionary histories. To improve our understanding of this tribe, we investigated the complete chloroplast (cp) genomes of two Asian Gnaphalieae taxa, namely that within Anaphalissinica and Leontopodium leiolepis, and used this information to infer their phylogenetic relationships and evolution. The cp genomes of A. sinica and L. leiolepis were found to be 152,718 bp and 151,072 bp long, respectively, with gene contents and orders that resembled those of other Asteraceae species. However, we determined that the trnT-GGU genes within the two Gnaphalieae cp genomes were either pseudogenized or lost. Because these gene features have also been identified in other Gnaphalieae genera, but not among other Asteraceae species, they reinforce the taxonomic boundary of the tribe Gnaphalieae as an independent group. Moreover, based on the trnT-GGU gene features in members of the HAP clade, we speculate that the parental lineages of the genera Anaphalisand Pseudognaphalium have an allopolyploid origin. Thus, mutations in the trnT-GGU gene may be used in future studies as indicators of generic and/or tribal relationships. Using 52 protein-coding genes, we performed a phylogenetic analysis which further indicated that, alongside the tribes Astereae and Anthemideae, the tribe Gnaphalieae is a monophyletic taxon. We also identified 63 and 81 SSRs in L. leiolepis and A. sinica cp genomic sequences, respectively. The results described here will be useful for inferring the evolutionary history of the tribe Gnaphalieae, and specific genomic information can be applied in conservation strategies for endangered edelweiss ( Leontopodium R. Br. ex Cass.) and pearly everlasting ( AnaphalisDC.) species.

The many faces of Peridinium cinctum (Peridiniaceae, Peridiniales): morphological and molecular variability in a common dinophyte

ABSTRACTPeridinium cinctum is a common freshwater dinophyte with a long history of research. Erich Lindemann was the first to assess intraspecific variability in this species focusing on plate pattern variation. Since then, this issue has been neglected but with the application of DNA sequence diagnostics, a combination of morphological and molecular characters may enable taxonomic delimitations. Our aim was to identify distinct morphotypes using plate pattern as the main characteristic and then compare them to the geographic occurrence of particular ribotypes (as inferred from sequences of the Internal Transcribed Spacer: ITS) in samples from Central Europe. Approximately 200 observations were carried out under the inverse light microscope for each of a total of 15 strains. We observed two main variations from the abundant plate pattern in P. cinctum, namely an unusual position of the 2a plate and the irregular shape of the 1a plate. In 88 (predominantly clonal) strains, we identified five different ribotypes (submitted as 71 new GenBank entries) which had no clear correlation to the defined morphotypes and/or spatial occurrences. In four cases, we detected two distinct ribotypes at the same locality. However, samples collected south of the Danube River presented a different predominant morphotype from the rest of the samples, thus implying a potential biogeographic signal as inferred from morphology. In general, there is morphological and molecular variability in P. cinctum, which is under-studied and which may uncover geographic or ecological correlations or even the existence of cryptic species.

Comparative anatomy, nutraceutical potentials and heavy metal composition of two varieties of<i> Lasianthera africana</i> (P. Beauv)

This study investigated the anatomical features, nutraceutical potentials and heavy metal compositions in two varieties of Lasianthera africana (P. Beauv) which is a member of the family Icacinaceae predominantly found mostly in southern Nigeria. The anatomical studies were carried out with free hand sectioning using a systematic arrangement of 5 razor blades. The slides were viewed using the light microscope and microphotographs were taken after careful examination from good preparations. The heavy metals, nutrients and antinutrients were analysed by standard methods. The anatomy of mid-ribs showed bicollateral vascular systems. There are three vascular traces and node is unilacunar. The vascular bundles and pith in mid-rib of dark variety is more extended than in white variety. The petiole anatomy of the two varieties has partially separated rib bundle wings. The stems have rings of open vascular systems and the pith of stem anatomy of dark variety is larger than that of white variety. The dark variety has more protein (28.00 + 0.04%) than white variety (24.94 + 0.02%), more oxalate (130.24 + 0.10 mg/100 g) as against (92.56 + 0.09 mg/100 g) in the white variety; and lead was also higher (0.692 mg/100 g) in the dark variety than in the white variety (0.038 mg/100 g). This study has shown that Lasianthera africana possesses anatomical features which are of taxonomic importance in the taxonomic delimitation of the varieties; has high nutritional contents and low levels of antinutrients except oxalate which is high and may be reduced to non-toxic level by processing, thus rendering it safe for human consumption.Keywords: Icacinaceace, bicollateral, unilacunar, microphotographs

Taxonomic delimitation of the rare, eastern North American endemic lichenSantessoniella crossophylla(Pannariaceae)

Abstract The taxonomic delimitation and generic placement of Santessoniella crossophylla (Old Gray Crosslobes), a cyanolichen endemic to eastern North America, are revisited based on newly generated nrITS and mtSSU sequences. A population from Nova Scotia whose identification as S. crossophylla has been questioned is confirmed as belonging to the species. The monospecific genus Rockefellera is introduced to accommodate lichens ascribable to S. crossophylla in light of molecular results herein presented. The new name honors the Rockefeller family for their century-long support of North American conservation efforts, particularly with respect to national parks.

Morphological, Anatomical and Cytological Studies of some Moss Species from Nigeria

Morphological, anatomical and chromosome studies of Hyophila crenulata C, Mull. Ex Dus, Thuidium gratum (P. Beauv) Jaeg., Barbula lambarenensis P. Vard.. Stereophyllum nitense Mitt. and Bryum coronatum Schwaegr from Nigeria, were carried out with a view to bridging some knowledge gaps that exist in their characterization and providing insightful information that could be useful in elucidating their taxonomic status. The morphological and anatomical studies revealed several gametophytic and sporophytic attributes which have not been previously reported and which were diagnostic for the moss species studied. The chromosome studies revealed the chromosome numbers to be Hyophila crenulata n = 4; Thuidium gratum n = 12 (10 + 2 m); Barbula lambarenensis n = 3; Stereophyllum nitense n = 9; and Bryum coronatum n = 10. The study concluded that the details of the morphological and anatomical descriptions as well as the chromosome numbers being reported for the first time in this study for the moss species studied could be very useful in their identification and taxonomic delimitation.

Morphometric variability among the species of the Sordida subcomplex (Hemiptera: Reduviidae: Triatominae): evidence for differentiation across the distribution range of Triatoma sordida

BackgroundThe Sordida subcomplex (Triatominae) comprises four species, Triatoma garciabesi, T. guasayana, T. patagonica and T. sordida, which differ in epidemiological importance and adaptations to human environments. Some morphological similarities among species make taxonomic identification, population differentiation and species delimitation controversial. Triatoma garciabesi and T. sordida are the most similar species, having been considered alternatively two and a single species until T. garciabesi was re-validated, mostly based on the morphology of male genitalia. More recently, T. sordida from Argentina has been proposed as a new cryptic species distinguishable from T. sordida from Brazil, Bolivia and Paraguay by cytogenetics. We studied linear and geometric morphometry of the head, wings and pronotum in populations of these species aiming to find phenotypic markers for their discrimination, especially between T. sordida and T. garciabesi, and if any set of variables that validates T. sordida from Argentina as a new species.ResultsHead width and pronotum length were the linear variables that best differentiated species. Geometric morphometry revealed significant Mahalanobis distances in wing shape between all pairwise comparisons. Triatoma patagonica exhibited the best discrimination and T. garciabesi overlapped the distribution of the other species in the morphometric space of the first two DFA axes. Head shape showed differentiation between all pairs of species except for T. garciabesi and T. sordida. Pronotum shape did not differentiate T. garciabesi from T. guasayana. The comparison between T. garciabesi and T. sordida from Argentina and T. sordida from Brazil and Bolivia revealed low differentiation based on head and pronotum linear measurements. Pronotum and wing shape were different between T. garciabesi and T. sordida from Brazil and Bolivia and T. sordida from Argentina. Head shape did not differentiate T. garciabesi from T. sordida from Argentina.ConclusionsWing shape best delimited the four species phenotypically. The proposed cryptic species, T. sordida from Argentina, differed from T. sordida from Brazil and Bolivia in all measured shape traits, suggesting that the putative new species may not be cryptic. Additional studies integrating cytogenetic, phenotypic and molecular markers, as well as cross-breeding experiments are needed to confirm if these three entities represent true biological species.

Beyond the carapace: skull shape variation and morphological systematics of long-nosed armadillos (genus Dasypus).

BackgroundThe systematics of long-nosed armadillos (genus Dasypus) has been mainly based on a handful of external morphological characters and classical measurements. Here, we studied the pattern of morphological variation in the skull of long-nosed armadillos species, with a focus on the systematics of the widely distributed nine-banded armadillo (Dasypus novemcinctus).MethodsWe present the first exhaustive 3D comparison of the skull morphology within the genus Dasypus, based on micro-computed tomography. We used geometric morphometric approaches to explore the patterns of the intra- and interspecific morphological variation of the skull with regard to several factors such as taxonomy, geography, allometry, and sexual dimorphism.ResultsWe show that the shape and size of the skull vary greatly among Dasypus species, with Dasypus pilosus representing a clear outlier compared to other long-nosed armadillos. The study of the cranial intraspecific variation in Dasypus novemcinctus evidences clear links to the geographic distribution and argues in favor of a revision of past taxonomic delimitations. Our detailed morphometric comparisons detected previously overlooked morphotypes of nine-banded armadillos, especially a very distinctive unit restricted to the Guiana Shield.DiscussionAs our results are congruent with recent molecular data and analyses of the structure of paranasal sinuses, we propose that Dasypus novemcinctus should be regarded either as a polytypic species (with three to four subspecies) or as a complex of several distinct species.

Impact of species delimitation and sampling on niche models and phylogeographical inference: A case study of the East African reed frog Hyperolius substriatus Ahl, 1931

Ecological niche models (ENMs) have been used in a wide range of ecological and evolutionary studies. In biogeographic studies these models have, among other things, helped in the discovery of new allopatric populations, and even new species. However, small sample sizes and questionable taxonomic delimitation can challenge models, often decreasing their accuracy. Herein we examine the sensitivity of ENMs to the addition of new, geographically isolated populations, and the impact of applying different taxonomic delimitations. The East African reed frog Hyperolius substriatus Ahl, 1931 was selected as a case study because it has been the subject of previous ENM predictions. Our results suggest that addition of new data and reanalysis of species lineages of H. substriatus improved our understanding of the evolutionary history of this group of frogs. ENMs provided robust predictions, even when some populations were deliberately excluded from the models. Splitting the lineages based on genetic relationships and analysing the ENMs separately provided insights about the biogeographical processes that led to the current distribution of H. substriatus.

Phylogeny, biogeography and taxonomic consequences in a bird-of-paradise species complex, Lophorina–Ptiloris (Aves: Paradisaeidae)

Biogeographical history and taxonomic delimitation in the Australo-Papuan bird-of-paradise Lophorina-Ptiloris species complex is examined with a combination of DNA and morphological markers. The re ...

The complete chloroplast genome of Daphne kiusiana, an evergreen broad-leaved shrub on Jeju Island

Plants of Daphne kiusiana on Jeju Island exhibit morphologically and genetically unique traits. Its taxonomic entity is still unclear and populations are decreasing in size because of human activity. Taxonomic delimitation and conservation efforts are required at the genomic level. We determined the complete chloroplast (cp) genome of this endangered species on Jeju Island, South Korea. Its sequence is 171,491 bp long, and comprises a pair of 41,891 bp inverted repeats, a large-single-copy (LSC) region (85,028 bp), and a diminished small-single-copy region (2681 bp). The cp genome has 135 genes, including 89 that encode proteins, plus 38 tRNAs, and eight rRNAs. Five genes (rpl32, ndhF, accD, clpP, and ndhK) are pseudogenized or lost in its cpDNA. When compared with that of a related species, Aquilaria sinensis, its LSC region contains a large inversion event between rbcL and rps12 that caused pseudogenization of clpP and accD.

What actually is Vriesea? A total evidence approach in a polyphyletic genus of Tillandsioideae (Bromeliaceae, Poales).

The taxonomic delimitation of Vriesea is challenging because several diagnostic traits of the genus are shared with other genera in Tillandsioideae. The genus has no unique morphological features that distinguish it from other taxa. Earlier phylogenetic studies suggested a polyphyletic status of this genus, but taxon sampling was limited, and tests of congruence for morphological characters have not yet been performed. Here we used a total evidence approach and a more comprehensive Brazilian taxon sampling to help circumscribe Vriesea s.s. (the lineage that contains the type species). We concatenated morphological and molecular datasets for the first time to reconstruct phylogenetic hypotheses. We used 99 morphological characters and ~4 kb of plastid data (psbA-trnH, trnK5'-rps16, matK, trnL-trnF) for 172 terminals, including nine genera of Tillandsioideae. We analysed datasets by parsimony analyses, with several weighting schemes considered for character-state changes (equal weights and an implied weighting scheme that we used as a sensitivity analysis). The concatenated data resulted in a well-resolved phylogenetic inference that provided strong evidence that the genus is not monophyletic as traditionally circumscribed. Given the congruence between morphological, molecular and geographical sources of data, we separated Vriesea into distinct lineages, and proposed a new circumscription that includes only species of Vriesea s.s. found in the Chacoan and Parana subregions.

Fruit morphology of the genus Potamogeton L. in Kashmir Himalaya and its utility in taxonomic delimitation

The fruit morphology of eight species of the genus Potamogeton L. in Kashmir Himalaya was examined, using stereomicroscopy and scanning electron microscopy, in order to determine their utility in taxonomic delimitation. During the study, both macro- and micromorphological characters, including the fruit shape, size, color, and nature of the fruit beak, were investigated. The results reveal that the broad- and linear-leaved species have keeled fruits, whereas in filiform-leaved species the dorsal and lateral keels are either absent or obscure. The present study clearly shows the potential utility of fruit features as delimiting characters in order to distinguish different species of the genus Potamogeton in this Himalayan region.

Desarrollo de los gametofitos de especies mexicanas de Gleicheniaceae

In Mexico, the Gleicheniaceae family is represented by different species such as Dicranopteris flexuosa, Diplopterygium bancroftii, Gleichenella pectinata, Sticherus bifidus, S. brevipubis, S. palmatus and S. underwoodianus. Currently, few studies have described the gametophytes of some species in this family, and our objective was to contribute to the knowledge, and to describe and compare different aspects of their germination, gametophyte development, and to determine if the prothallus characters are useful for taxonomic delimitations in the group. For this purpose, specimens and spores of each taxon were collected in the field, spores were sown in Petri dishes containing agar and Thompson nutrient medium, and grown in a plant growing chamber under controlled conditions of light (12 hr light/darkness), (50 %) humidity, and temperature (18 °C night, 25 °C day). Additionally, observations of fresh materials were made and photomicrographs were taken using both optical and scanning electron microscopes. Our observations allowed distinguishing two types of germination Gleichenia and Cyathea; and three types of prothallial development Marattia, Osmunda and Drynaria. Gametangia presented more than three cells, and this is considered a primitive feature by other authors. As some variations in the germination type were observed and have not previously been reported in the literature for this family, and because of the heterogenity in the patterns of the prothallial cell development, and gametangia of more than four cells, it is important to broaden the study to other species, in order to determine the taxonomic value of the morphological characters of the gametophyte, as well as to determine if these variations are present in other species of the family.

Morphometric analysis of Milla biflora (Asparagaceae: Brodieaoideae), with an identification key for Milla

Background and aims The taxonomical delimitation of Milla biflora has been controversial and is possibly associated with the high morphological variation of this taxon. The aims of this study were to

Development and characterization of 21 microsatellite markers in <i>Daphne kiusiana</i>, an evergreen broad-leaved shrub endemic to Korea and Japan

Microsatellite markers were isolated for Daphne kiusiana var. kiusiana (Thymelaeaceae), an evergreen broad-leaved shrub endemic to Korea and Japan. Because its populations in Jeju Island are morphologically controversial, and consistently threatened by anthropogenic pressures, taxonomic delimitation and conservation effort are required at the genetic level. We developed 21 polymorphic microsatellite loci from Next Generation Sequencing data. The primer set included di-, tri-, and tetra-nucleotide repeats. Variability in the markers was tested for 80 individuals of D. kiusiana from three natural populations in Jeju Island and Japan. Among the 21 loci, three were unavailable for population JKJU of Japan. The Neighbor-Joining tree based on microsatellite markers described here classified the three populations into two groups according to geographical or morphological traits. These will be a powerful genetics tool for determining the taxonomic boundary and establishing suitable conservation strategies for D. kiusiana in Jeju Island.