Evaluating the efficacy of continuous quantitative characters for reconstructing the phylogeny of a morphologically homogeneous spider taxon (Araneae, Mygalomorphae, Antrodiaetidae, Antrodiaetus)

The use of continuous quantitative characters for phylogenetic analyses has long been contentious in the systematics literature. Recent studies argue for and against their use, but there have been relatively few attempts to evaluate whether these characters provide an accurate estimate of phylogeny, despite the fact that a number of methods have been developed to analyze these types of data for phylogenetic inference. A tree topology will be produced for a given methodology and set of characters, but little can be concluded with regards to the accuracy of phylogenetic signal without an independent evaluation of those characters. We assess the performance of continuous quantitative characters for the mygalomorph spider genus Antrodiaetus, a group that is morphologically homogeneous and one for which few discrete (morphological) characters have been observed. Phylogenetic signal contained in continuous quantitative characters is compared to an independently derived phylogeny inferred on the basis of multiple nuclear and mitochondrial gene loci. Tree topology randomizations, regression techniques, and topological tests all demonstrate that continuous quantitative characters in Antrodiaetus conflict with the phylogenetic signal contained in the gene trees. Our results show that the use of continuous quantitative characters for phylogenetic reconstruction may be inappropriate for reconstructing Antrodiaetus phylogeny and indicate that due caution should be exercised before employing this character type in the absence of other independently derived sources of characters.     

Morphological responses to nutrient availability in four clonal herbs

This paper examines morphological plasticity of clonal plants of contrasting habitats and of contrasting architectures in response to nutrient supply. The hypotheses were tested that plants from rich habitats possess greater plasticity in response to variation in resource supply than species from poor habitats, and that rhizomatous species are less plastic in their response than stoloniferous species. Two sympodial rhizomatous herbs (Carex flacca, C. hirta) and two monopodial stoloniferous herbs (Trifolium fragiferum, T. repens) were subjected to four levels of nutrient supply in a garden experiment. One of the two species of each genus (C. hirta, T. repens) is from fertile and the other from infertile habitats. We measured 1) whole plant characters: total plant dry weight, number of modules (product of a single apical meristem) and number of ramets; 2) ramet characters: ramet leaf area and ramet height; and 3) spacer characters: branches per module, length per module and length per module internode.All measured characters in the Trifolium species significantly responded to treatment: the values for all measured characters increased with higher levels of fertilization. The differences in plant characters between fertilization levels were larger in Trifolium repens than in T. fragiferum in terms of whole plant characters, ramet characters and stolon internode length. The two Carex species did not differ in their responses to treatment in terms of most characters measured. In ramet characters and in some whole plant characters the species from fertile habitats were more plastic than those from infertile habitats. In spacer characters this pattern was not found. Foraging could not be demonstrated unequivocally.Morphological plasticity in the stoloniferous (Trifolium) species was much larger than in the rhizomatous (Carex) species. This seems in accordance with a foremost storage function of rhizomes, as against a foremost explorative function of stolons.     

Principal component analysis as an alternative treatment for morphometric characters: phylogeny of caseids as a case study

In a recent study, the phylogeny of Caseidae (a herbivorous family of Palaeozoic synapsids belonging to the paraphyletic grade known as pelycosaurs) was analysed with a dataset employing more than three hundred continuous morphological characters in an effort to follow the principles of total evidence. Continuous characters are a source of great debate, with disagreements surrounding their suitability for and treatment in phylogenetic analysis. A number of shortcomings were identified in the handling of continuous characters in this study of caseids, including the use of gap weighting to discretize the characters and potential issues with redundancy and character non‐independence. Therefore, an alternative treatment for these characters is suggested here. First, rather than using gap weighting, the continuous characters were analysed in the program TNT, in which the raw values can be treated as continuous rather than discrete. Second, prior to the phylogenetic analysis, the continuous characters were subjected to a log‐ratio principal component analysis, and then the principal components were included in the character matrix rather than the raw ratios. Analysing the original data in TNT produced little difference in the results, but using the principal components as continuous characters resulted in alternative positions for Caseopsis agilis, Ennatosaurus tecton and Caseoides sanangeloensis. The differences are judged to be due to the reduced redundancy of the characters, the smaller number of principal components not overwhelming the discrete characters and the use of a scaling method which allows principal components with a higher variance to have a greater influence on the analysis. The positions of highly fragmentary fossils depended heavily on the method used to treat the missing characters in the principal component analysis, and so the method proposed here is not recommended for analysing very incomplete taxa.     

Change of adaptations from entomophily to autogamy inParahebe linifolia (Scrophulariaceae)

Measurements of 16 inflorescence and floral characters from 5 populations ofParahebe linifolia (3 of entomophilous subsp.linifolia; 2 of autogamous subsp.brevistylis) were analysed. Discontinuous variation of three characters associated with the mechanisms of pollination suggests these are under strong selection towards different optima in each subspecies. Variation which is continuous and associated with the type of pollination in 4 characters mostly concerned with display is thought to result from selection for metabolic economies, counteracted strongly in subsp.linifolia, but less so in subsp.brevistylis, by selection for display. Nine more characters vary in a way not known to be associated with the two pollination systems.     

Convergence and parallelism: is a new life ahead of old concepts?

In comparative biology, character observations initially separate similar and dissimilar characters. Only similar characters are considered for phylogeny reconstruction; their homology is attested in a two‐step process, firstly a priori of phylogeny reconstruction by accurate similarity statements, and secondly a posteriori of phylogeny analysis by congruence with other characters. Any pattern of non‐homology is then a homoplasy, commonly, but vaguely, associated with “convergence”. In this logical scheme, there is no way to analyze characters which look similar, but cannot meet usual criteria for homology statements, i.e., false similarity detected a priori of phylogenetic analysis, even though such characters may represent evolutionarily significant patterns of character transformations. Because phylogenies are not only patterns of taxa relationships but also references for evolutionary studies, we propose to redefine the traditional concepts of parallelism and convergence to associate patterns of non‐homology with explicit theoretical contexts: homoplasy is restricted to non‐similarity detected a posteriori of phylogeny analysis and related to parallelism; non‐similarity detected a priori of phylogenetic analysis and necessarily described by different characters would then correspond to a convergence event s. str. We propose to characterize these characters as heterologous (heterology). Heterology and homoplasy correspond to different non‐similarity patterns and processes; they are also associated with different patterns of taxa relationships: homoplasy can occur only in non‐sister group taxa; no such limit exists for heterology. The usefulness of these terms and concepts is illustrated with patterns of acoustic evolution in ensiferan insects. © The Willi Hennig Society 2005.     

Molecular phylogeny,analysis of character evolution,and submersible collections enable a new classification of a diverse group of gobies (Teleostei: Gobiidae: Nes subgroup), including nine new species and four new genera

The Nes subgroup of the Gobiosomatini (Teleostei: Gobiiformes: Gobiidae) is an ecologically diverse clade of fishes endemic to the tropical western Atlantic and eastern Pacific oceans. It has been suggested that morphological characters in gobies tend to evolve via reduction and loss associated with miniaturization, and this, coupled with the parallel evolution of adaptations to similar microhabitats, may lead to homoplasy and ultimately obscure our ability to discern phylogenetic relationships using morphological characters alone. This may be particularly true for the Nes subgroup of gobies, where several genera that are diagnosed by ‘reductive characters’ have been shown to be polyphyletic. Here we present the most comprehensive phylogeny to date of the Nes subgroup using mitochondrial and nuclear sequence data. We then evaluate the congruence between the distribution of morphological characters and our molecular tree using maximum‐likelihood ancestral state reconstruction, and test for phylogenetic signal in characters using Pagel's λ tree transformations (Nature, 401 , 1999 and 877). Our results indicate that all of the characters previously used to diagnose genera of the Nes subgroup display some degree of homoplasy with respect to our molecular tree; however, many characters display considerable phylogenetic signal and thus may be useful in diagnosing genera when used in combination with other characters. We present a new classification for the group in which all genera are monophyletic and in most cases diagnosed by combinations of morphological characters. The new classification includes four new genera and nine new species described here, many of which were collected from rarely sampled deep Caribbean reefs using manned submersibles. The group now contains 38 species in the genera Carrigobius gen. nov., Chriolepis, Eleotrica, Gobulus, Gymneleotris, Nes, Paedovaricus gen. nov., Pinnichthys gen. nov., Psilotris, and Varicus. Lastly, we provide a key to all named species of the Nes subgroup along with photographs and illustrations to aid in identification.     

Reassessment of the cranial characters of Glossotherium and Paramylodon (Mammalia: Xenarthra: Mylodontidae)

Nomenclatural confusion has existed within the Mylodontinae for several genera, and has resulted in the supposition that Paramylodon of North America is synonymous with Glossotherium of South America. A taxonomic revision of crania for Glossotherium and Paramylodon upholds their separation as distinct genera and provides a list of diagnostic characters that have been lacking. Assessment was made using principal components analysis for suites of cranial and mandibular measurements, evaluation of ratios and measurement distribution, and by examining qualitative characters. Results show the greatest characterization for the skull comes from differences relating to cranial length versus width, whereas the mandible is predominantly distinguished by qualitative characters of the predental spout. Examination of the Pliocene species Glossotherium chapadmalense from South America shows a combination of characters indicative of each genus, but exhibits more with Glossotherium and is tentatively retained under that genus. The mix of characters indicates that G. chapadmalense is the likely ancestor to Paramylodon, although when and where the transition took place is still unclear. During the evolutionary transition, Paramylodon crania emphasized an increase in length of the palate, whereas those of Glossotherium emphasized an increase in cranial width. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 155 , 885–903.     

Karyotaxonomic study of some species ofPeucedanum (Umbelliferae)

A study of morphometric karyotype characters was carried out in 14 species ofPeucedanum s. lat. (Umbelliferae — Apioideae) and in one species of the related genusLomatium. The differences of the species in their karyotype characters are correlated only to a limited degree with their similarities of dissimilarities in morphological (i. a. carpological) characters, and thus with their taxonomic position. The evolution of these two sets of characters seems to have proceeded not synchronously or even in different directions in the group of platycarpousUmbelliferae united in the genusPeucedanum. Therefore, it is unlikely that morphometric chromosome characters revealed by monochrome staining can be used appropriately in the taxonomic revision of the polymorphous genusPeucedanum.     

QUANTITATIVE VARIATION IN PHLOX: COMPARISON OF SELFING AND OUTCROSSING SPECIES

Variation of 20 quantitative characters was examined within and among 10 populations of the predominantly outcrossing Phlox drummondii and 4 populations of the predominantly selfing P. cuspidata grown in a greenhouse. Multivariate analysis of variance, considering all characters simultaneously, indicated that there were significant differences among populations in both species while analysis of individual characters demonstrated that there were significant population differences for 19 characters in P. drummondii and 13 characters in P. cuspidata. On average, 16% of the total phenotypic variation in P. drummondii occurred among populations compared to less than 4% of the total variation in P. cuspidata. In addition, P. drummondii exhibited significant differences among families within populations more frequently than P. cuspidata. Most observed variation in both species occurred within families where environmental and genetic sources of variation could not be partitioned. There was a trend for P. drummondii to have higher heritabilities than P. cuspidata for most characters even when assumptions about breeding systems were relaxed. Thus, the outbreeding species exhibited larger genetic differences among populations and among families within populations than the selfing species in the greenhouse environment. These data suggest that P. drummondii has the greater evolutionary potential of the two species and are consistent with the hypothesis that differences in population structure result from differences in the breeding systems of the two species.     

Identification of instars and species in some larval Polypedilum (Polypedilum) (Diptera: Chironomidae)

Instars II and III of Polypedilum aviceps Townes, Polypedilum convictum (Walker), and Polypedilum illinoense (Malloch) can be identified to species by associating them with instar IV because key taxonomic characters remain relatively unchanged from instar to instar. Instars I cannot be identified to species or genus unless they are associated with older, identifiable larvae reared from the same egg masses. No single character evaluated on slide material can be used to clearly separate instars in all three species. Larvae of P. aviceps can be separated into instars based on any four of seven characters; P. convictum by either of two characters; and, P. illinoense by a combination of two characters. Changes in structures of instars II, III, and IV are described for all three species. Growth ratios for some structures are compared and discussed with regard to Dyar's Rule.     

Making the cryptic visible – resolving the species complex of Aphodius fimetarius (Linnaeus) and Aphodius pedellus (de Geer) (Coleoptera: Scarabaeidae) by three complementary methods

Species in cryptic complexes are, per definition, difficult to identify using morphological characters. One such complex was recently detected in the dung beetle Aphodius fimetarius (Linnaeus) sensu lato, an abundant dung beetle with a wide distribution. While the two component taxa, Aphodius fimetarius sensu stricto and Aphodius pedellus (De Geer) exhibit distinctly different karyotypes, the validity of subtle morphological characters proposed to distinguish between them has been debated. Given the variability and minor interspecific differences in external characters, the large‐scale distribution of respective taxa has remained unknown, as have potential differences in ecology and habits. In this study, we ask how A. fimetarius and A. pedellus can best be distinguished, whether the use of different types of characters (karyotypes, DNA sequences and morphological traits) results in consistent species identification, where these species occur and whether they exhibit ecological differences. In total, we inspected a material of 4401 individuals from across the globe, of which 183 were examined for both mtDNA sequences and morphology, 154 for both morphology and karyotype, and 9 (including the recently proposed neotype of Aphodius fimetarius) for all three types of characters. As a marker gene, we sequenced a 590 bp region of the cytochrome c oxidase I gene for 183 individuals. Overall, DNA sequences offered a clear‐cut distinction between taxa: sequences of A. fimetarius and A. pedellus differed by an average pairwise distance of 8.2%, whereas variation within species was only 0.9% for A. fimetarius and 0.5% for A. pedellus. Morphological and chromosomal characters offered species identifications consistent with that of molecular characters: karyotypes identified as A. pedellus consistently fell within one of the molecular clades, whereas karyotypes identified as A. fimetarius fell within the other clade. Likewise, the majority of individuals identified by morphological characters were assigned to the same species by sequence‐based characters. Both taxa thus defined were found to be Holarctic in distribution, with major sympatry within Central and Southern Europe and mixed patterns of sympatry within the US. Northern areas of Europe, Asia and North America are dominated by A. pedellus alone. Within A. pedellus, patterns of sequence diversity were indicative of a recent population expansion. In the western US, the phenology of a population of A. fimetarius was observed to significantly differ from that of a sympatric population of A. pedellus, thereby revealing an ecological difference between the two cryptic taxa. Overall, we conclude that all types of characters offered a consistent classification of the two species. Thus, the laborious karyotyping techniques used to originally establish the presence of two cryptic taxa can now be substituted by characters more easily applied to large ecological samples. Using this approach of integrative taxonomy, we were able to establish the global distribution and species‐specific ecology of these ecologically important cryptic taxa. This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:4033473E-8BF7-40F4-852D-916E4F858593 .     

Anatomy of Brazilian Eriocaulaceae: correlation with taxonomy and habitat using multivariate analyses

In this study we present a survey on vegetative anatomy in species of Actinocephalus, Blastocaulon, Eriocaulon, Leiothrix, Paepalanthus, Philodice, Syngonanthus, and Tonina (Eriocaulaceae). Multivariate analyses were used to correlate anatomical characters to taxa and the habitats where the species occur. Root and stem anatomical characters seem to be more affected by environmental factors where these species occur, and seem of little value for delimiting major taxonomic groups within the family. Other characters in the leaves, such as epidermis with thickened wall cells, compartmented substomatal chambers, mesophyll with hypodermis, compact chlorenchyma, collenchymatous bundle sheath extensions, and numerous vascular bundles, were shown to be important for defining species clusters in Leiothrix, Syngonanthus, and Paepalanthus subg. Platycaulon. Similarly, loosely aggregated chlorenchyma caused Blastocaulon, Eriocaulon, Philodice, Syngonanthus sect. Carpocephalus, S. sect. Syngonanthus, and Tonina, genera from humid environments, to cluster. Scape characters appear to be more informative in discriminating groups. This situation probably reflects lower selection pressures determining anatomical characters of this organ.     

Taxonomic importance of seed macro‐ and micro‐morphology in Abelmoschus (Malvaceae)

Seed morphology of Abelmoschus is known to be variable, but patterns of variation have never been critically studied. We studied seed macro‐ and micro‐morphological characters, including seed shape/size, seed coat pattern and trichome density/structure in multiple samples to evaluate the taxonomic significance of seed characters. Among the studied characters, seed shape and trichome structure were found to have major taxonomic importance and proved to be valuable characters for separating taxa. Two main seed types were present: seeds with deciduous trichomes and seeds with persistent trichomes. These characters offer significant evidence to the distinctness of certain species (A. esculentus, A. moschatus subsp. moschatus, A. moschatus subsp. tuberosus, A. crinitus and A. angulosus). Further, our results indicate that A. moschatus subsp. tuberosus should be maintained as a separate subspecies while A. manihot subsp. tetraphyllus var. pungens may be merged in A. angulosus. No significant intraspecific variation was observed, except in A. esculentus. We conclude that seed coat sculpturing and seed trichomes do indeed provide stable and diagnostic characters for many morphologically closely related taxa of Abelmoschus and that LM/SEM techniques can be useful in solving systematic problems and management of Abelmoschus genetic resources.     

Insights on Using Morphologic Data for Phylogenetic Analysis in Sedges (Cyperaceae)

Sedges are often viewed as difficult subjects for morphology-based phylogenetic analysis, due to several difficulties, including finding an adequate number of characters to yield well-resolved and well-supported trees, correctly assessing homology of characters and character states, and selecting appropriate outgroups for character state polarizations. The published literature holds only 11 papers with morphology-based phylogenetic analyses of sedges. This paper reviews those studies, and presents the phylogeny of two groups of sedges: (1) Carex section Deweyanae, and (2) Carex sections Careyanae, Granulares, and Griseae. This paper also presents recommendations for using morphologic data to reconstruct sedge phylogenies, based on comparisons of the trees resulting from the present study with the previous sedge studies and with similar studies of phylogeny of other groups of flowering plants. In the two groups of Carex examined, morphology does provide sufficient characters to infer well-resolved trees, with some nodes having good to strong support at levels consistent with those found in morphology-based analyses of other groups of flowering plants. The inclusion of micromorphologic and anatomic characters substantially enhances the resolving power of macromorphologic characters in sedge analyses, and increases the support for some clades.     

Phylogeny of prickly poppies,Argemone (Papaveraceae), and the evolution of morphological and alkaloid characters based on ITS nrDNA sequence variation

Evolutionary relationships withinArgemone (Papaveraceae) were inferred from nucleotide variation in nuclear ribosomal DNA. A complete representation of the genus was achieved by using herbarium material to a large extent (74%). Four distinct clades can be recognized based on the molecular results. The support for the different clades varies greatly due to a very uneven distribution of characters. Although some clades are largely unresolved, some unexpected relationships, for example the sister group relationship of the relict speciesA. subintegrifolia to the rest ofArgemone, were found. The evolution of morphological and alkaloid characters against the background of the obtained phylogeny is discussed. Whereas the morphological characters provide some support for the phylogeny found, the alkaloid characters turned out not to contain much phylogenetic information. Past difficulties in recognizing phylogenetic relationships withinArgemone result from largely continuous morphological variation and from parallelisms correlated with and probably caused by polyploidization.     

DEVELOPMENT,FUNCTION, AND THE QUANTITATIVE GENETICS OF WING MELANIN PATTERN IN PIERIS BUTTERFLIES

Do genetic correlations among phenotypic characters reflect developmental organization or functional coadaptation of the characters? We test these hypotheses for the wing melanin pattern of Pieris occidentalis butterflies, by comparing estimated genetic correlations among wing melanin characters with a priori predictions of the developmental organization and the functional (thermoregulatory) organization of melanin pattern. There were significant broad-sense heritabilities and significant genetic correlations for most melanin characters. Matrix correlation tests revealed significant agreement between the observed genetic correlations and both developmental and functional predictions in most cases; this occurred even when the overlap between developmental and functional predictions was eliminated. These results suggest that both developmental organization and functional coadaptation among melanin characters influence the genetic correlation structure of melanin pattern in this species. These results have two important implications for the evolution of melanin pattern in P. occidentalis and other butterflies: 1) most phenotypic variation in pattern may reflect variation among, rather than within, sets of developmentally homologous wing melanin characters; and 2) in a changing selective environment, genetic correlations may retard the disruption of functionally coupled melanin characters, thus affecting the evolutionary response to selection.     

DISSECTING CORRELATED CHARACTERS: ADAPTIVE ASPECTS OF PHENOTYPIC COVARIATION IN MELANIZATION PATTERN OF PIERIS BUTTERFLIES

In this study we address the question of how much of the covariation among phenotypic characters observed in natural populations is adaptive. We examine covariation among a set of phenotypic characters that describe the wing-melanization pattern of Pieris butterflies. Previous functional analyses of thermoregulatory performance allow us to predict a priori whether and how different wing melanic characters should be correlated. We quantify and analyze the variation in the wing-melanization pattern within species for a series of Pieris populations from relatively cool environments in North America and compare these results with the predictions based on our adaptive hypothesis. We consider adaptive covariation both for biogeographic variation among populations and for seasonal polyphenism (phenotypic plasticity) within populations. Our hypothesis correctly predicts many of the qualitative features of covariation in melanization among major regions of the wings, at the level of biogeographic variation among populations, for both males and females of Pieris occidentalis. When within-population variation is considered, agreement with the adaptive predictions varies considerably in different populations for both P. occidentalis and P. napi males and females. Agreement for P. napi, particularly the females, is generally poorer than for P. occidentalis. In both species, there is a consistent difference in melanization pattern between alpine and arctic sites; this difference is discussed in relation to the differences in the radiative environment between these two types of “cold” habitats. Our results suggest that some important aspects of phenotypic correlation among wing melanic characters in Pieris are adaptive. We emphasize the important distinction between covariation and co-occurrence of characters, and we discuss these results in relation to the extensive biogeographic variation and phenotypic plasticity (seasonal polyphenism) in Pieris wing-melanization patterns.     

New morphological characters for classifying Phoridae (Diptera) from the structure of the thorax

Forty‐six characters, mostly of the thoracic pleuron, are proposed for the reconstruction of the phylogenetic relationships among the major groups of the family Phoridae. Analysis of these characters, in conjunction with the pre‐existing suite of morphological characters from other body parts, provides a basis for a strongly supported new classification of the Phoridae, in which Sciadocerinae is the sister group of ((Chonocephalus Wandolleck & Cyphocephalus Borgmeier) + (Termitoxeniinae + (Metopininae + Phorinae s.l.))). A new subfamily, Chonocephalinae subfamily nov. , is proposed for Chonocephalus and Cyphocephalus, and a new genus, Hirotophora gen. nov. , is proposed for Chaetopleurophora multiseriata (Aldrich) ( comb. nov. ). © 2015 The Linnean Society of London     

Phylogeny of the Pyretophorus Series of Anopheles subgenus Cellia (Diptera: Culicidae)

A cladistic analysis based on morphological characters is presented for the Pyretophorus Series of subgenus Cellia of Anopheles. The cibarial armature was investigated for the first time since the pioneering work of Christophers (1933) , which is still used to define taxonomic series within Cellia, and for the first time ever using scanning electron microscopy. Christophers’ observations of characters of the cibarial armature were corroborated and several novel characters discovered. Despite difficulties in delimiting and encoding morphological characters at the species level, the analysis provided insights into relationships within the Pyretophorus Series. The data support the monophyly of the Series and establish the Oriental species as a monophyletic group. The Afrotropical species are basal and paraphyletic relative to the Oriental species, with Anopheles christyi placed in the most basal position. The pattern of relationships suggests that the capacity to transmit malaria is an ancestral condition subsequently lost independently in several lineages.     

GENETIC AND ENVIRONMENTAL DETERMINATION OF LEAF EPIDERMAL ANATOMY IN PUCCINELLIA (POACEAE)

Phenotypic plasticity of anatomical leaf epidermal characters was assessed in the halophytic grass genus Puccinellia, to identify those of potential taxonomic utility. Characters with the greatest taxonomic potential are those that exhibit genetic variation and low plasticity. For the analysis, field-collected clones were divided and grown under a series of moisture and salinity regimes. Genetic variation and plasticity in response to environmental variation were assessed for 39 anatomical characters by analysis of among-clone and among-treatment variation, respectively. Both genetic variation and plasticity are widespread among the characters, and both are detected in greater frequency among continuously variable characters than among discretestate characters. Among continuously variable traits, average cell dimensions exhibit more plasticity than do maximum cell dimensions or ratios that reflect shapes and relative sizes. Among discrete-state characters, plasticity in the occurrence of papillae is found in nonstomatal intercostal cellular ranks, but not in costal or stomatal intercostal ranks. In Puccinellia, anatomical characters are, in general, neither more nor less plastic than those of macromorphology.