Aquatic plant species are often widespread, even across continents. They pose a challenge to species delimitation and taxonomy due to their reduced morphology and high phenotypic plasticity. These difficulties are even more pronounced in the case of interspecific hybridization. We investigate the aquatic plant genus Stuckenia for the first time on a worldwide scale. Expert species determination is aided by sequencing of nuclear ribosomal ITS and 5S-NTS regions and the plastid intergenic spacers rpl20-5'rps12 and trnT-trnL. Nuclear markers are used to infer hybridization, and the maternal origin of hybrids is addressed with plastid markers. Pure species are subjected to phylogenetic analyses. Two main Stuckenia lineages are found: one consists of S. amblyphylla, S. filiformis, S. pamirica, and S. vaginata, the other includes S. pectinata and S. striata. The widespread species S. pectinata, S. filiformis, and S. vaginata show intraspecific genetic variation, which is structured geographically. Many intraspecific hybrids, which are usually fertile, occur between those genotypes. Interspecific hybrids, which are consistently sterile, are detected among all widespread species; some are reported for the first time in several countries and regions. They originated multiple times from reciprocal crosses and reflect the geographical origins of parental genotypes. Intraspecific genetic variation can be higher than interspecific differences between closely related species. Comparison of phenotypic variation in the field and in cultivation with genotypic variation shows that numerous conspicuous forms have been overestimated taxonomically. These are resolved as phenotypes responding to unusual environments, have recurrently evolved adaptations, or represent extreme forms of continuous variation of the recognized species. However, some specific regional lineages, which have evolved from variable species, may be interpreted as early steps of the speciation process. Hybridization has been underestimated in some regions as a source of Stuckenia diversity, and the respective hybrid plants have been misidentified as intraspecific taxa or even as separate species. Many erroneous entries in sequence databases are detected and summarized. This work provides a sound basis for species delimitation and hybrid recognition in this difficult genus.

Department of Biology Massachusetts College of Liberal Arts North Adams MA United States

Department of Botany Faculty of Science Charles University Prague Czechia

Institute of Botany Czech Academy of Sciences Průhonice Czechia

Papanin Institute for Biology of Inland Waters Russian Academy of Sciences Borok Russia

Tyumen State University AquaBioSafe Tyumen Russia

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Acosta M. C., Premoli A. C. (2010). Evidence of plastid capture in South American PubMed DOI

Álvarez I., Wendel J. F. (2003). Ribosomal ITS sequences and plant phylogenetic inference. Mol. Phylogenet. Evol. 29, 417–434. doi:  10.1016/s1055-7903(03)00208-2 PubMed DOI

Aykurt C., Fehrer J., Sarı D., Kaplan Z., Deniz İ. G., Aydemir E., et al. (2017). Hybridization between the linear-leaved DOI

Aykurt C., Fehrer J., Sarı Yol D., Kaplan Z., Bambasová V., Deniz İ. G., et al. (2020). Taxonomic treatment and phylogenetic analysis of the family Potamogetonaceae in Turkey. Taxon 69, 1172–1190. doi:  10.1002/tax.12364 DOI

Bobrov A. A. (2007).

Bobrov A. A. (2020). “Sem. 23. Potamogetonaceae Bercht. Et J. Presl – rdestovye,” in Opredelitel’ vyssikh rastenii yakutii [Manual to the higher plants of yakutia], 2nd ed., revised and completed. Ed. Nikolin E. G. (Moscow: KMK; Novosibirsk: Nauka; ), 77–85.

Bobrov A. A., Chemeris E. V. (2006). Zametki o rechnykh rdestakh (

Borchsenius F. (2009) FastGap 1.2 (Denmark: Department of Biosciences, Aarhus University; ). Available at: http://www.aubot.dk/FastGap_home.htm (Accessed August 3, 2022).

Busik V. V. (1979). “Semeistvo Potamogetonaceae – rdestovyje,” in Flora tsentral’noi Sibiri [Flora of central Siberia], vol. 1 . Eds. Malyshev L. I., Peshkova G. A. (Novosibirsk: Nauka; ), 57–65 & 444–445.

Dandy J. E. (1975). “

Du Z., Wang Q. (2016). Allopatric divergence of PubMed DOI PMC

Fehrer J., Iida S., Kaplan Z. (2022). Cryptic species of pondweeds (Potamogetonaceae) at an intercontinental scale revealed by molecular phylogenetic analyses. Taxon 71, 531–551. doi:  10.1002/tax.12686 DOI

Fehrer J., Krak K., Chrtek J., Jr. (2009). Intra-individual polymorphism in diploid and apomictic polyploid hawkweeds ( PubMed DOI PMC

Hagström J. O. (1916). Critical researches on the Potamogetons. Kungl. Svenska Vetenskapsakad. Handl. 55 (5), 1–281.

Hall T. (1999). BioEdit: a user-friendly biological sequence alignment editor and analysis program for Windows 95/98/NT. Nucleic Acids Symp. Ser. 41, 95–98.

Haynes R. R., Hellquist C. B. (2000). “Potamogetonaceae Dumortier,” in Flora of North America North of Mexico, eds. Flora of North America editorial committee, vol. 22. (New York: Oxford University Press; ), 47–74.

Hettiarachchi P., Triest L. (1991). Isozyme polymorphism in the genus

Hollingsworth P. M., Preston C. D., Gornall R. J. (1996). Isozyme evidence for the parentage and multiple origins of DOI

Hultén E., Fries M. (1986). Atlas of North European vascular plants North of the Tropic of Cancer Vol. Vols 1–3 (Königstein: Koeltz Scientific Books; ).

Huson D. H., Bryant D. (2006). Application of phylogenetic networks in evolutionary studies. Mol. Biol. Evol. 23, 254–267. doi:  10.1093/molbev/msj030 PubMed DOI

Iida S., Ashiya M., Kadono Y. (2018). The hybrid origin of DOI

Iida S., Kosuge K., Kadono Y. (2004). Molecular phylogeny of Japanese DOI

Ito Y., Robledo G. L., Iharlegui L., Tanaka N. (2016). Phylogeny of

Kaplan Z. (2002). Phenotypic plasticity in DOI

Kaplan Z. (2005).

Kaplan Z. (2008). A taxonomic revision of DOI

Kaplan Z. (2010. a). Hybridization of

Kaplan Z. (2010. b). Tiselius’ DOI

Kaplan Z., Fehrer J. (2004). Evidence for the hybrid origin of DOI

Kaplan Z., Fehrer J. (2006). Comparison of natural and artificial hybridization in

Kaplan Z., Fehrer J. (2007). Molecular evidence for a natural primary triple hybrid in plants revealed from direct sequencing. Ann. Bot. 99, 1213–1222. doi:  10.1093/aob/mcm072 PubMed DOI PMC

Kaplan Z., Fehrer J. (2009). An orphaned clone of

Kaplan Z., Fehrer J. (2011). Erroneous identities of DOI

Kaplan Z., Fehrer J. (2013). Molecular identification of hybrids from a former hot spot of DOI

Kaplan Z., Fehrer J., Bambasová V., Hellquist C. B. (2018). The endangered Florida pondweed ( PubMed DOI PMC

Kaplan Z., Fehrer J., Hellquist C. B. (2009). New hybrid combinations revealed by molecular analysis: The unknown side of North American pondweed diversity ( DOI

Kaplan Z., Fehrer J., Hellquist C. B. (2011). DOI

Kaplan Z., Fehrer J., Jobson R. W. (2019). Discovery of the Northern Hemisphere hybrid DOI

Kaplan Z., Jarolímová V., Fehrer J. (2013). Revision of chromosome numbers of Potamogetonaceae: A new basis for taxonomic and evolutionary implications. Preslia 85, 421–482.

Kaplan Z., Štěpánek J. (2003). Genetic variation within and between populations of DOI

Kaplan Z., Uotila P. (2011). DOI

Kaplan Z., Wolff P. (2004). A morphological, anatomical and isozyme study of

Kaplan Z., Zalewska-Gałosz J. (2004). DOI

Kashina L. I. (1988). “Potamogetonaceae – rdestovye,” in Flora Sibiri [Flora of Siberia], Lycopodiaceae – Hydrocharitaceae. Ed. Krasnoborov I. M. (Novosibirsk: Nauka; ), 93–105 & 165–176.

King R. A., Gornall R. J., Preston C. D., Croft J. M. (2001). Molecular confirmation of DOI

Kumar S., Stecher G., Li M., Knyaz C., Tamura K. (2018). MEGA X: Molecular evolutionary genetics analysis across computing platforms. Mol. Biol. Evol. 35, 1547–1549. doi:  10.1093/molbev/msy096 PubMed DOI PMC

Kuzmina M. L., Braukmann T. W. A., Fazekas A. J., Graham S. W., Dewaard S. L., Rodrigues A., et al. (2017). Using herbarium-derived DNAs to assemble a large-scale DNA barcode library for the vascular plants of Canada. Appl. Plant Sci. 5, apps.1700079. doi:  10.3732/apps.1700079 PubMed DOI PMC

Kuzmina M. L., Braukmann T. W. A., Zakharov E. V. (2018). Finding the pond through the weeds: eDNA reveals underestimated diversity of pondweeds. Appl. Plant Sci. 6, e01155. doi:  10.1002/aps3.1155 PubMed DOI PMC

Lindqvist C., De Laet J., Haynes R. R., Aagesen L., Keener B. R., Albert V. A. (2006). Molecular phylogenetics of an aquatic plant lineage, Potamogetonaceae. Cladistics 22, 568–588. doi:  10.1111/j.1096-0031.2006.00124.x PubMed DOI

McMullan J. J., Gornall R. J., Preston C. D. (2011). ITS rDNA polymorphism among species and hybrids of DOI

Posada D., Crandall K. A. (1998). Modeltest: testing the model of DNA substitution. Bioinformatics 14, 817–818. doi:  10.1093/bioinformatics/14.9.817 PubMed DOI

Preston C. D. (1995). Pondweeds of Great Britain and Ireland (London: Botanical Society of the British Isles; ).

Preston C. D., Croft J. M. (1997). Aquatic plants in Britain and Ireland (Colchester: Harley Books; ).

Preston C. D., Hollingsworth P. M., Gornall R. J. (1998).

Preston C. D., Hollingsworth P. M., Gornall R. J. (1999). The distribution and habitat of

Ronquist F., Teslenko M., van der Mark P., Ayres D. L., Darling A., Höhna S., et al. (2012). MrBayes 3.2: efficient Bayesian phylogenetic inference and model choice across a large model space. Syst. Biol. 61, 539–542. doi:  10.1093/sysbio/sys029 PubMed DOI PMC

Schultes J. A. (1814). Österreichs flora. Wien: C. Schaumburg und Compagnie.

Simmons M. P., Ochoterena H. (2000). Gaps as characters in sequence-based phylogenetic analyses. Syst. Biol. 49, 369–381. doi:  10.1093/sysbio/49.2.369 PubMed DOI

Small R. L., Cronn R. C., Wendel J. F. (2004). Use of nuclear genes for phylogeny reconstruction in plants. Aus. Sys. Bot. 17, 145–170. doi:  10.1071/SB03015 DOI

Štorchová H., Hrdličková R., Chrtek J., Jr., Tetera M., Fitze D., Fehrer J. (2000). An improved method of DNA isolation from plants collected in the field and conserved in saturated NaCl/CTAB solution. Taxon 49, 79–84. doi:  10.2307/1223934 DOI

Swofford D. (2002). PAUP*: Phylogenetic analysis using parsimony (*and other methods), version 4 (Sunderland, MA: Sinauer; ).

Tolmachev A. I. (1995). Flora of the Russian Arctic 1: Polypodiaceae – Gramineae (Edmonton: University of Alberta Press; ).

Tzvelev N. N. (1984). Zametki o nekotorych gidrofil’nykh rasteniyakh Dal’nego Vostoka [Comments on some hydrophilous plants of the Far East]. Nov. Sist. Vyssh. Rast. 21, 232–242.

Tzvelev N. N. (1987). “Rdestovye – Potamogetonaceae Dumort,” in Sosudistye rasteniya sovetskogo Dal’nego Vostoka [Vascular plants of the soviet Far East]. Ed. Kharkevich S. S. (Leningrad: Nauka; ).

Tzvelev N. N. (1996). O vidakh podroda

Tzvelev N. N. (1999). Ob ob’yome i nomenklature nekotorykh rodov sosudistykh rastenii Evropeiskoi Rossii [On size and nomenclature of some genera of vascular plants of European Russia]. Bot. Zhurn. 84 (7), 109–118.

Van Wijk R. J. (1988). Ecological studies on DOI

Volkova P. A., Kipriyanova L. M., Maltseva S. Yu., Bobrov A. A. (2017). In search of speciation: diversification of DOI

Wang Q. D., Zhang T., Wang J. B. (2007). Phylogenetic relationships and hybrid origin of DOI

Whittemore A. T., Schaal B. A. (1991). Interspecific gene flow in sympatric oaks. Proc. Natl. Acad. Sci. U. S. A. 88, 2540–2544. doi:  10.1073/pnas.88.6.2540 PubMed DOI PMC

Wiegleb G., Kaplan Z. (1998). An account of the species of DOI

Zalewska-Gałosz J. (2010). DOI

Zalewska-Gałosz J., Kaplan Z., Kwolek D. (2018). Reinterpretation of DOI

Zalewska-Gałosz J., Ronikier M., Kaplan Z. (2009). The first European record of

Zalewska-Gałosz J., Ronikier M., Kaplan Z. (2010). Discovery of a new, recurrently formed DOI

Zhang T., Wang Q., Li W., Cheng Y., Wang J. (2008). Analysis of phylogenetic relationships of DOI

Zhao T., Wang G., Ma Q., Liang L., Yang Z. (2020). Multilocus data reveal deep phylogenetic relationships and intercontinental biogeography of the Eurasian-North American genus PubMed DOI