Is Holosteum glutinosum (M. Bieb.) Fisch. et C. A. Mey. (Caryophyllaceae: Alsinoideae) just a subtaxon of H. umbellatum L. or a distinct species?

Andrey V Yena,Alexander V Fateryga,Irina V Sokolova,Sergey A Svirin,Pavel E Yevseyenkov,Valentina V Fateryga

doi:10.14258/turczaninowia.23.4.5

Abstract

The genus Holosteum L. distributed mostly in temperate Eurasia has very confused taxonomy. Modern estimation of the species richness varies from one species worldwide to seven species occurring just in Eastern Europe. One of the most problematic species of the genus is H. glutinosum(M. Bieb.) Fisch. et C. A. Mey. usually treated as a subspecies or a variety of H. umbellatum L. On the base of extensive study of the protologues, type material, a rich variety of other herbarium specimens, photos of all relevant taxa, and living plants in the field we recognize H. glutinosum as a distinct species. This species has three characters unique in the genus Holosteum: pure green color of leaves and sepals, completely herbaceous bracts, and lanceolate leaves; additional diagnostic characters are 10 stamens, dense glandular pilosity of leaves, sepals, bracts, stem, and pedicels, and entire petals longer than sepals. The species also has statistically significant differences from H. umbellatum (longer leaves, longer and wider petals, and longer capsule) while occurring in sympatry with it. Two subspecies are recognized within H. glutinosum: H. glutinosum subsp. glutinosumdistributed in Caspian Depression, Transcaucasia, Western and Middle Asia, and H. glutinosum subsp. liniflorum Fateryga, nom. et stat. nov. (≡ H. liniflorum Steven ex Fisch. et C. A. Mey. 1840 [non 1837], nom. illeg.), presumably endemic to the Crimea. The lectotypes are designated for the latter name and also for H. glandulosum Bertol., H. umbellatum var. pleiandrum Fenzl, H. imberbe J. Gay, nom. illeg. superfl., H. imberbe var. brachypetalum J. Gay, and H. imberbe var. macropetalum J. Gay. Reports of H. glutinosum from most European countries (other than Russia) are considered to be erroneous due to numerous misidentifications in herbaria and incorrect synonymy (e. g., with H. heuffelii Wierzb., which is actually conspecific with H. umbellatum). A key to the species and subspecies is provided; a total of six taxa are recognized in the genus: H. breistrofferi Greuter et Charpin, H. glutinosum subsp. glutinosum, H. glutinosum subsp. liniflorum, H. marginatum C. A. Mey., H. tenerrimum Boiss., and H. umbellatum.

Highlights

Holosteum L. (Caryophyllaceae: Alsinoideae) is a small genus of annual herbs native to temperate Eurasia (Hernández-Ledesma et al, 2015) and North Africa (Greuter et al, 1984) with the type species H. umbellatum L. that has naturalized in the United States of America, Canada, Argentina, and the Republic of South Africa (Rabeler, Hartman, 2005)
We found in 2013 a peculiar population of H. glutinosum in the Crimea, which occurred in the same habitat with H. umbellatum and showed remarkably distinct characters from the latter
What is Holosteum glutinosum? Studying of all available materials has revealed that H. glutinosum is a well recognized species clearly distinct from four other well recognized species in the genus by three unique characters: pure green color of leaves and sepals, completely herbaceous bracts, and lanceolate leaves

Summary

Introduction

Holosteum L. (Caryophyllaceae: Alsinoideae) is a small genus of annual herbs native to temperate Eurasia (Hernández-Ledesma et al, 2015) and North Africa (Greuter et al, 1984) with the type species H. umbellatum L. that has naturalized in the United States of America, Canada, Argentina, and the Republic of South Africa (Rabeler, Hartman, 2005). (Caryophyllaceae: Alsinoideae) is a small genus of annual herbs native to temperate Eurasia (Hernández-Ledesma et al, 2015) and North Africa (Greuter et al, 1984) with the type species H. umbellatum L. that has naturalized in the United States of America, Canada, Argentina, and the Republic of South Africa (Rabeler, Hartman, 2005). The genus is not species-rich, its taxonomy is very confused and requires a revision (Fateryga et al, 2017). Modern estimations on the number of species in the genus vary. World Flora Online (2020) accepts the one species H. umbellatum with four subspecies: H. umbellatum subsp. Viscosissimum (Čelak.) Dvořák, and the type subspecies, while many other names in the genus Holosteum remain unresolved in this database. Marhold (2011) in Euro+Med PlantBase lists four species occurring in Europe and the Mediterranean

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