Morphological diversity and evolution of Centrolepidaceae (Poales), a species‐poor clade with diverse body plans and developmental patterns

Sokoloff, Dmitry D.; Remizowa, Margarita V.; Barrett, Matthew D.; Conran, John G.; Rudall, Paula J.

doi:10.3732/ajb.1400434

Cited by 10 publications

(9 citation statements)

References 59 publications

(89 reference statements)

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“…However, this explanation does not encompass species‐poor lineages embedded in speciose clades. Importantly, we note that species richness and morphological diversity are not always correlated; hence, some species‐poor clades might still be remarkably diverse morphologically (Sokoloff et al ., ).…”

Section: Six Key Questionsmentioning

confidence: 97%

Key questions and challenges in angiosperm macroevolution

2018

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Contents Summary 1170 I. Introduction 1170 II. Six key questions 1172 III. Three key challenges 1177 IV. Conclusions 1181 Acknowledgements 1182 References 1183 SUMMARY: The origin and rapid diversification of angiosperms (flowering plants) represent one of the most intriguing topics in evolutionary biology. Despite considerable progress made in complementary fields over the last two decades (paleobotany, phylogenetics, ecology, evo-devo, genomics), many important questions remain. For instance, what has been the impact of mass extinctions on angiosperm diversification? Are the angiosperms an adaptive radiation? Has morphological evolution in angiosperms been gradual or pulsed? We propose that the recent and ongoing revolution in macroevolutionary methods provides an unprecedented opportunity to explore long-standing questions that probably hold important clues to understand present-day biodiversity. We present six key questions that explore the origin and diversification of angiosperms. We also identify three key challenges to address these questions: (1) the development of new integrative models that include diversification, multiple intrinsic and environmental traits, biogeography and the fossil record all at once, whilst accounting for sampling bias and heterogeneity of macroevolutionary processes through time and among lineages; (2) the need for large and standardized synthetic databases of morphological variation; and (3) continuous effort on sampling the fossil record, but with a revolution in current paleobotanical practice.

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Section: Six Key Questionsmentioning

confidence: 97%

Key questions and challenges in angiosperm macroevolution

2018

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“…In grasses, the ligule forms a membranous appendage or transversal row of hairs in the sheath-to-lamina transition zone and plays an important role in identification, not only at the generic level but also in distinguishing species in some genera. In restiids, a ligule occurs in some taxa of both monothecal and dithecal clades ( Cutler, 1969 ; Linder & Caddick, 2001 ; Sokoloff et al, 2015 ; Briggs, Connelly & Krauss, 2020a ; this study). Data on ligule distribution among monothecal Restionaceae as well as its morphology are scarce, but preliminary results of an investigation of this feature using herbarium material with subsequent character-mapping revealed a high level of homoplasy within the restiid clade and stability at the species level ( Fomichev, 2016 ).…”

Section: Discussionmentioning

confidence: 61%

“… Cutler & Airy Shaw (1965) and Cutler (1969) mentioned the occurrence of a leaf ligule in a species of Anarthria but did not name the species. To our knowledge, the ligule character has not been used so far in systematic accounts of Anarthria , even though it is considered an important taxonomic marker in various groups of Poales ( Goetghebeur, 1998 ; Kellogg, 2015 ), including the restiid clade ( Sokoloff et al, 2015 ).…”

Section: Introductionmentioning

confidence: 99%

Two centuries from species discovery to diagnostic characters: molecular and morphological evidence for narrower species limits in the widespread SW Australian Anarthria gracilis complex (Restionaceae s.l./Anarthriaceae, Poales)

Fomichev

Macfarlane²,

Valiejo‐Roman

et al. 2021

PeerJ

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Background The extreme southwest of Australia is a biodiversity hotspot region that has a Mediterranean-type climate and numerous endemic plant and animal species, many of which remain to be properly delimited. We refine species limits in Anarthria, a Western Australian endemic genus characterised by the occurrence of the greatest number of plesiomorphic character states in the restiid clade of Poales. In contrast to many other groups of wind-pollinated Australian Poales, Anarthria was traditionally viewed as having well-established species limits. All six currently recognised species, which are conspicuous members of some Western Australian plant communities, were described in the first half of the 19th century. They are traditionally distinguished from each other mainly using quantitative characters. Methods We examined extensive existing herbarium specimens and made new collections of Anarthria in nature. Scanning electron microscopy and light microscopy were used to study leaf micromorphology. Molecular diversity of Anarthria was examined using a plastid (trnL-F) and a low-copy nuclear marker (at103). This is the first study of species-level molecular diversity in the restiid clade using a nuclear marker. Results Material historically classified as Anarthria gracilis R.Br. actually belongs to three distinct species, A. gracilis s.str., A. grandiflora Nees and A. dioica (Steud.) C.I.Fomichev, each of which forms a well-supported clade in phylogenetic analyses. Both segregate species were described in the first half of the 19th century but not recognised as such in subsequent taxonomic accounts. Anarthria dioica was first collected in 1826, then wrongly interpreted as a species of Juncus (Juncaceae) and described as Juncus dioicus. We provide a formal transfer of the name to Anarthria and for the first time report its clear and qualitative diagnostic characters: an extremely short leaf ligule and distinctive pattern of leaf epidermal micromorphology. A long ligule is present in A. gracilis s.str. and A. grandiflora. These species differ from each other in leaf lamina morphology and anatomy and have mostly non-overlapping distribution ranges. The narrower definition of species provides a basis for future phylogeographic analyses in Anarthria. Our study highlights a need for more extensive use of nuclear DNA markers in Restionaceae. The use of the low copy nuclear marker at103 allowed a clade comprising all three ligulate species of Anarthria to be recognised. The ligule character is used here for the first time in the taxonomy of Anarthria and merits special attention in studies of other restiids. In general, our study uncovered a superficially hidden but, in reality, conspicuous diversity in a common group of wind-pollinated plants in the southwest of Western Australia.

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“…In Centrolepis, the receptacle elongation is strongly one-sided, which often allows spacing much more than the usual monocot number of three carpels. These form a single distorted whorl in Centrolepis [58,59]. The position of the median carpel at a slightly upper level than the lateral carpels in E. redactum resembles the condition found in Centrolepis, albeit in a less pronounced form.…”

Section: Discussionmentioning

confidence: 72%

Stability Despite Reduction: Flower Structure, Patterns of Receptacle Elongation and Organ Fusion in Eriocaulon (Eriocaulaceae: Poales)

Sokoloff

Yadav

Chandore³

et al. 2020

Plants

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Eriocaulaceae (Poales) differ from potentially related Xyridaceae in pattern of floral organ arrangement relative to subtending bract (with median sepal adaxial). Some Eriocaulaceae possess reduced and non-trimerous perianth, but developmental data are insufficient. We conducted a SEM investigation of flower development in three species of Eriocaulon to understand whether organ number and arrangement are stable in E. redactum, a species with a highly reduced calyx and reportedly missing corolla. Early flower development is similar in all three species. Male and female flowers are indistinguishable at early stages. Despite earlier reports, both floral types uniformly possess three congenitally united sepals and three petals in E. redactum. Petals and inner stamens develop from common primordia. We assume that scanning electron microscopy should be used in taxonomic accounts of Eriocaulon to assess organ number and arrangement. Two types of corolla reduction are found in Eriocaulaceae: suppression and complete loss of petals. Common petal–stamen primordia in Eriocaulon do not co-occur with delayed receptacle expansion as in other monocots but are associated with retarded petal growth. The ‘reverse’ flower orientation of Eriocaulon is probably due to strictly transversal lateral sepals. Gynoecium development indicates similarities of Eriocaulaceae with restiids and graminids rather than with Xyridaceae.

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Morphological diversity and evolution of Centrolepidaceae (Poales), a species‐poor clade with diverse body plans and developmental patterns

Cited by 10 publications

References 59 publications

Key questions and challenges in angiosperm macroevolution

Key questions and challenges in angiosperm macroevolution

Two centuries from species discovery to diagnostic characters: molecular and morphological evidence for narrower species limits in the widespread SW Australian Anarthria gracilis complex (Restionaceae s.l./Anarthriaceae, Poales)

Stability Despite Reduction: Flower Structure, Patterns of Receptacle Elongation and Organ Fusion in Eriocaulon (Eriocaulaceae: Poales)

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