ISSN 2415-8860 (online), ISSN 0372-4123 (print)
logoUkrainian Botanical Journal
  • 1 of 8
Ukr. Bot. J. 2019, 76(2): 95–100
Plant Taxonomy, Geography and Floristics

Trithuria brevistyla (Hydatellaceae), a new combination for the New Zealand endemic species from the South Island

de Lange P.J.1, Mosyakin S.L.2

A new combination, Trithuria brevistyla (K.A.Ford) de Lange & Mosyakin, is proposed for the recently described New Zealand, South Island endemic taxon originally published as T. inconspicua subsp. brevistyla K.A.Ford. Species rank for that taxon is advocated on the basis of morphological and reproductive distinctions between that species and the closely related North Island, New Zealand endemic T. inconspicua Cheeseman sensu stricto. Some general considerations on optional species versus subspecies ranks for plant taxa in need of conservation are provided.

Keywords: conservation, endemic species, Hydatellaceae, new combination, New Zealand, nomenclature, taxonomy, Trithuria

Full text: PDF (Eng) 582K

  1. APG (Angiosperm Phylogeny Group). 1998. An ordinal classification for the families of flowering plants. Annals of the Missouri Botanical Garden 85(4): 531–553.
  2. APG II. 2003. An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG I. Botanical Journal of the Linnean Society 141(4): 399–436.
  3. APG III. 2009. An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III. Botanical Journal of the Linnean Society 161(2): 105–121.
  4. APG IV. 2016. An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG IV. Botanical Journal of the Linnean Society, 181(1): 1–20.
  5. Casacci L.P., Barbero F., Balletto E. 2014. The "Evolutionarily Significant Unit" concept and its applicability in biological conservation. Italian Journal of Zoology, 81(2): 182–193.
  6. Connor H.E. 1998. Festuca (Poaceae: Gramineae) in New Zealand 1. Indigenous Taxa. New Zealand Journal of Botany, 36(3): 329–367.
  7. Cronquist A. 1981. An integrated system of classification of flowering plants. New York: Columbia University Press, xviii + 1262 pp.
  8. Dahlgren R.M.T., Clifford H.T., Yeo P.F. 1985. The families of the Monocotyledons. Berlin; Heidelberg: Springer, xii + 520 pp.
  9. de Lange P.J. 2012. Taxonomic notes on the New Zealand flora: new names in Piper (Piperaceae). New Zealand Journal of Botany, 50(4): 485–487.
  10. de Lange P.J., Murray B.G. 1998. Senecio repangae (Asteraceae): a new endemic species from the northeastern North Island, New Zealand. New Zealand Journal of Botany, 36(4): 509–519.
  11. de Lange P.J., Cameron E.K., Murray B.G. 1999. Alectryon excelsus subsp. grandis (Sapindaceae): a new combination for an uncommon small tree endemic to the Three Kings Islands, New Zealand. New Zealand Journal of Botany, 37(1): 7–16.
  12. de Lange P.J., Heenan P.B., Norton D.A., Rolfe J.R., Sawyer J.W.D. 2010. Threatened plants of New Zealand. Christchurch: Canterbury University Press, 471 pp.
  13. de Lange P.J., Rolfe J.R., Barkla J.W., Courtney S.P., Champion P.D., Perrie L.R., Beadel S.M., Ford K.A., Breitwieser I., Schönberger I., Hindmarsh-Walls R., Heenan P.B., Ladley K. 2018. Conservation status of New Zealand indigenous vascular plants, 2017. [New Zealand Threat Classification Series 22]. Wellington, New Zealand: Department of Conservation, 82 pp.
  14. Edgar E. 1986. Poa L. in New Zealand. New Zealand Journal of Botany, 24(3): 425–503.
  15. Garnett S.T., Christidis L. 2007. Implications of changing species definitions for conservation purposes. Bird Conservation International, 17: 187–195.
  16. Haig S.M., Beever E.A., Chambers S.M., Draheim H.M., Dugger B.D., Dunham S.M., Elliott-Smith E., Fontaine J.B., Kesler D.C., Knaus B.J., Lopes I.F., Loschl P., Mullins T.D., Sheffield L.M. 2006. Taxonomic considerations in listing subspecies under the U.S. Endangered Species Act. Conservation Biology, 20(6): 1584–1594.
  17. Hamann U. 1998. Hydatellaceae. In: The families and genera of vascular plants, vol. 4: Flowering plants, Monocotyledons: Alismatanae and Commelinanae (except Gramineae). Ed. K. Kubitzki, in collaboration with H. Huber, P.J. Rudall, P.S. Stevens, and T. Stützel. Berlin; Heidelberg: Springer, pp. 231–234.
  18. Heenan P.B., Millar T.R., Smissen R.D., McGlone M.S., Wilton A.D. 2017. Phylogenetic measures of neo- and palaeo-endemism in the indigenous vascular flora of the New Zealand archipelago. Australian Systematic Botany, 30(2): 124–133.
  19. Iles W.J.D., Rudall P.J., Sokoloff D.D., Remizowa M.V., Macfarlane T.D., Logacheva M.D., Graham S.W. 2012. Molecular phylogenetics of Hydatellaceae (Nymphaeales): sexual-system homoplasy and a new sectional classification. American Journal of Botany, 99(4): 663–676.
  20. Isaac N.J.B., Mallet J., Mace G.M. 2004. Taxonomic inflation: its influence on macroecology and conservation. Trends in Ecology & Evolution, 19(9): 464–469.
  21. IUCN Species Survival Commission. 2012. IUCN Red List Categories and Criteria. Version 3.1. 2nd ed. Gland, Switzerland: IUCN, iv + 32 pp.
  22. IUCN Standards and Petitions Subcommittee. 2017. Guidelines for Using the IUCN Red List Categories and Criteria. Version 13 (March 2017). Prepared by the Standards and Petitions Subcommittee of the IUCN Species Survival Commission. 108 pp. Available at:
  23. Joseph L.N., Maloney R.F., O’Connor S.M., Cromarty P.; Jansen P., Stephens T., Possingham H.P. 2008. Improving methods for allocating resources among threatened species: the case for a national approach for New Zealand. Pacific Conservation Biology, 14(3): 154–158.
  24. Mallet J. 2007. Subspecies, semispecies, superspecies. In: Encyclopedia of Biodiversity. Ed. S.A. Levin. San Diego: Academic Press (Elsevier online edition), pp. 5.
  25. Mallet J. 2013. Subspecies, semispecies, superspecies. A brief history of subspecific taxonomy. In: Encyclopedia of Biodiversity, vol. 7. Ed. S.A. Levin. 2nd ed. San Diego: Academic Press. (Elsevier online edition), pp. 45–48.
  26. McGlone M.S. 1985. Plant biogeography and the late Cenozoic history of New Zealand. New Zealand Journal of Botany, 23(4): 723–749.
  27. McGlone M.S., Duncan R.P., Heenan P.B. 2001. Endemism, species selection and the origin and distribution of the vascular plant flora of New Zealand. Journal of Biogeography, 28(2): 199–216.
  28. Meudt H.M., Lockhart P.J., Bryant D. 2009. Species delimitation and phylogeny of a New Zealand plant species radiation. BMC Evolutionary Biology, 9: 111 (17 pp.).
  29. Meudt H.M., Prebble J.M., Lehnebach C.A. 2014. Native New Zealand forget-me-nots (Myosotis, Boraginaceae) comprise a Pleistocene species radiation with very low genetic divergence. Plant Systematics and Evolution, 301(5): 1455–1471.
  30. Meudt H.M., Prebble J.M. 2018. Species limits and taxonomic revision of the bracteate-prostrate group of southern hemisphere forget-me-nots (Myosotis, Boraginaceae), including description of three new species endemic to New Zealand. Australian Systematic Botany, 31(1): 48–105.
  31. Mildenhall D.C. 1980. New Zealand late Cretaceous and Cenozoic plant biogeography – a contribution. Palaeogeography, Palaeoclimatology, Palaeoecology, 31: 197–234.
  32. Millar T.R., Heenan P.B., Wilton A.D., Smissen R.D., Breitwieser I. 2017. Spatial distribution of species, genus and phylogenetic endemism in the vascular flora of New Zealand, and implications for conservation. Australian Systematic Botany, 30(2): 134–147.
  33. Morrison III W.R., Lohr J.L., Duchen P., Wilches R., Trujillo D., Mair M., Renner S.S. 2009. The impact of taxonomic change on conservation: Does it kill, can it save, or is it just irrelevant? Biological Conservation, 142(12): 3201–3206.
  34. Mosyakin S.L. 2000. "Battles over taxonomy" and conservation of taxa of vascular plants in Ukraine. In: Planta Europa: Proceedings of the Second European Conference on the Conservation of Wild Plants (9–14 June 1998, Uppsala, Sweden). Eds H. Synge, J. Akeroyd. Uppsala: Swedish Threatened Species Unit; London: Plantlife, pp. 119–120.
  35. Padial J.M., De la Riva I. 2006. Taxonomic inflation and the stability of species lists: The perils of ostrich's behavior. Systematic Biology, 55(5): 859–867.
  36. Ryder O.A. 1986. Species conservation and systematics: the dilemma of subspecies. Trends in Ecology & Evolution 1(1): 9–10.
  37. Ryder O.A., Shaw J.H., Wemmer C.M. 1988. Species, subspecies and ex situ conservation. International Zoo Yearbook, 27: 134–140.
  38. Saarela J.M., Rai H.S., Doyle J.A., Endress P.K., Mathews S., Marchant A.D., Briggs B.G., Graham S.W. 2007. Hydatellaceae identified as a new branch near the base of the angiosperm phylogenetic tree. Nature, 446: 312–315.
  39. Sangster G. 2009. Increasing numbers of bird species result from taxonomic progress, not taxonomic inflation. Proceedings of the Royal Society. Series B, Biological Sciences, 276(1670): 3185–3191.
  40. Sokoloff D.D., Macfarlane, T.D., Rudall P.J. 2008. Classification of the early-divergent angiosperm family Hydatellaceae: one genus instead of two, four new species and sexual dimorphism in dioecious taxa. Taxon, 57(1), 179–200.
  41. Sokoloff D.D., Remizowa M.V., Yadav S.R., Rudall P.J. 2010. Development of reproductive structures in the sole Indian species of Hydatellaceae, Trithuria konkanensis, and its morphological differences from Australian taxa. Australian Systematic Botany, 23(4): 217–228.
  42. Sokoloff D.D., Remizowa M.V., Macfarlane T.D., Yadav S.R., Rudall P.J. 2011. Hydatellaceae: A historical review of systematics and ecology. Rheedea, 21(2): 115–138.
  43. Sokoloff D.D., Marques I., Macfarlane T.D., Remizowa M.V., Lam V.K.Y., Pellicer J., Hidalgo O., Rudall P.J., Graham S.W. 2019. Cryptic species in an ancient flowering-plant lineage (Hydatellaceae, Nymphaeales) revealed by molecular and micromorphological data. Taxon, 68(1): 1–19.
  44. Smissen R.D., Ford K.A., Champion P.D., Heenan P.B. 2019. Genetic variation in Trithuria inconspicua and T. filamentosa (Hydatellaceae): a new subspecies and a hypothesis of apomixis arising within a predominantly selfing lineage. Australian Systematic Botany, 32(1): 1–11.
  45. Takhtajan A.L. 1987. Systema magnoliophytorum. Leningrad: Nauka, 439 pp.
  46. Takhtajan A.L. 1997. Diversity and classification of flowering plants. New York: Columbia University Press, x + 643 pp.
  47. Takhtajan A. 2009. Flowering Plants. Dordrecht: Springer, xlv + 871 pp.
  48. Tillich H.-J., Tuckett R., Facher E. 2007. Do Hydatellaceae belong to the monocotyledons or basal angiosperms? Evidence from seedling morphology. Willdenowia, 37(2): 399–406.
  49. Yadav S.R., Janarthanam M.K. 1994. Hydatellaceae: A new family to the Indian flora with a new species. Rheedea, 4(1): 17–20.
  50. Yadav S.R., Janarthanam M.K. 1995. Trithuria konkanensis (Hydatellaceae), eine neue Art aus Indien. Aqua-Planta, 3: 91–97.