Abstract
Easter Island is known for a depauperate terrestrial and aquatic biota. The discovery of new taxa is unusual, even among the island’s micro-invertebrates. A new cladoceran, Ovalona pascua sp. nov. (Crustacea: Cladocera: Anomopoda: Chydoridae), is described from freshwater environments. The chydorid, the only known extant cladoceran on the island, is the dominant aquatic invertebrate in the surface waters. Based on detailed morphological comparison, including a character similarity matrix applied across the species in the genus (12 characters/17 spp), the new taxon is proposed here as an insular endemic with affinities in the East (New World). The revision challenges the theory that invasive zooplankton species were introduced from the subantarctic islands during the 18th century. Human introduction is not the main mechanism through which cladocerans could have arrived on Easter Island. Late Pleistocene – Early Holocene fossils in Cañellas-Boltà et al. (2012) from cores in Rano Raraku Lake are identified here as Daphnia O.F. Müller, 1785 (subgenus Ctenodaphnia Dybowski & Grochowski, 1895). The establishment of Daphnia before human colonization on Easter Island provides strong proof of successful long distance dispersal by ephippia over thousands of kilometers of open sea.
References
Bernard, E.C., Soto-Adames, F.N. & Wynne, J.J. (2015) Collembola of Rapa Nui (Easter Island) with descriptions of five endemic cave-restricted species. Zootaxa, 3949 (2), 239–267.
http://dx.doi.org/10.11646/zootaxa.3949.2.6Boyko, C.B. (2003) The endemic marine invertebrates of Easter Island: how many species and for how long? In: Loret, J. & Tanacredi, J.T. (Eds.), Easter Island. Part II. Springer US, pp. 155–175.
http://dx.doi.org/10.1007/978-1-4615-0183-1_10Brehm, V. (1937) Notizen sur Süsswasserfauna der Hawaii-Inseln. [Mitteilung XXIII de Wallacea-Expedition Woltereck, 1931–1932.] Int. Rev. Ges. Hydrobiol. Hydrogeogr., 34, 331–36.
http://dx.doi.org/10.1002/iroh.19370340118Cañellas-Boltà, N., Rull, V., Sáez, A., Margalef, O., Giralt, S., Pueyo, J.J., Birks, H.H., Birks, H.J.B. & Pla-Rabes, S. (2012) Macrofossils in Raraku Lake (Easter Island) integrated with sedimentary and geochemical records: towards a palaeoecological synthesis for the last 34,000 years. Quaternary Science Reviews, 34, 113–126.
http://dx.doi.org/10.1016/j.quascirev.2011.12.013Cañellas-Boltà, N., Rull, V., Sáez, A., Margalef, Pla-Rabes, S., Valero-Garcés & Giralt, S. (2016) Vegetation dynamics at Raraku Lake catchment (Easter Island) during the past 34,000 years. Paleogeography, Palaeoclimatology, Palaeoecology, 446, 55–69.
http://dx.doi.org/10.1016/j.palaeo.2016.01.019Crease, T.J., Omilian, A.R., Costanzo, K.S. & Taylor, D.J. (2012) Transcontinental Phylogeography of the Daphnia pulex Species Complex. PLoS ONE, 7 (10), e46620.
http://dx.doi.org/10.1371/journal.pone.0046620De Los Ríos-Escalante, P. & Ibáñez, E. (2015) Inland water crustaceans of Easter Island. Crustaceana, 88, 1061–1064.
http://dx.doi.org/10.1163/15685403-00003465De Los Ríos-Escalante, P. & Kotov, A.A. (2015) A checklist of Branchiopoda (Anostraca and Cladocera) of Chilean continental waters. Zootaxa, 4027 (3), 366–388.
http://dx.doi.org/10.11646/zootaxa.4027.3.3De Meester, L., Gómez, A., Okamura, B. & Schwenk, K. (2002) The Monopolization Hypothesis and the dispersal-gene flow paradox in aquatic organisms. Acta Oecologica, 23, 121–135.
http://dx.doi.org/10.1016/S1146-609X(02)01145-1Dumont, H.J. & Martens, K. (1996) The freshwater microcrustacea of Easter Island. Hydrobiologia, 325, 83–99.
http://dx.doi.org/10.1007/BF00028269Dumont, H.J. (1994) On the diversity of the Cladocera in the tropics. Hydrobiologia, 272, 27–38.
http://dx.doi.org/10.1007/BF00006510Dumont, H.J. (1997) Cladoceran studies: Where do we go from here? Hydrobiologia, 325, 83–99.
http://dx.doi.org/10.1007/BF00028269Dumont, H.J. (2002) Impoverished fauna of Easter Island. Rapa Nui Journal, 16, 29–30.
Dumont, H.J., Cocquyt, C., Fontugne, M., Arnold, M., Reyss, J.L., Bloemendal, J., Oldfield, F., Steenbergen, C.L.M., Korthals, H.J. & Zeeb, B.A. (1998) The end of moai quarrying and its effect on Lake Rano Raraku, Easter Island. Journal of Paleolimnology, 20, 409–422.
http://dx.doi.org/10.1023/A:1008012720960Eldredge, L.G. & Miller, S.E. (1997) Numbers of Hawaiian Species: Supplement 2, Including a Review of Freshwater Invertebrates. Records of the Hawaii Biological Survey for 1996. Bishop Museum Occasional Papers, 48, 3–22.
Flenley, J.R., King, A.S.M., Jackson, J. & Chew, C. (1991) The late quaternary vegetational and climatic history of Easter Island. Journal of Quaternary Science, 6, 85–115.
http://dx.doi.org/10.1002/jqs.3390060202Forró, L., Korovchinsky, N.M., Kotov, A.A. & Petrusek, A. (2008) Global diversity of cladocerans (Cladocera; Crustacea) in freshwater. Hydrobiologia, 595, 177–184.
http://dx.doi.org/10.1007/978-1-4020-8259-7_19Frey, D.G. (1964) Remains of animals in Quaternary lake and bog sediments and their interpretation. Archiv für Hydrobiologie–Beiheft Ergebnisse der Limnologie, 2, 1–114.
Frey, D.G. (1982) Questions concerning cosmopolitanism in Cladocera. Archiv für Hydrobiologie, 93, 484–502
Frey, D.G. (1998) Alona weinecki Studer on the subantarctic islands, not Alona rectangula Sars (Chydoridae, Cladocera). Limnology and Oceanography, 6, 1386–1411.
Gillespie, T.G., Baldwin, B.G., Waters, J.M., Fraser, C.I., Nikula, R. & Roderick, G.K. (2012) Long-distance dispersal: a framework for hypothesis testing. Trends in Ecology and Evolution, 1, 47–56.
http://dx.doi.org/10.1016/j.tree.2011.08.009Green, A.J. & Figuerola, J. (2005) Recent advances in the study of long-distance dispersal of aquatic invertebrates via birds. Diversity and Distribution, 11, 149–156.
http://dx.doi.org/10.1111/j.1366-9516.2005.00147.xHagen, R.A., Baker, N.A., Naar, D.F. & Hey, R.N. (1990) A SeaMARC II survey of recent submarine volcanism near Easter Island. Marine Geophysical Research, 12, 1573–1581.
http://dx.doi.org/10.1007/BF02428200Hammer, M. (1970) A few Oribatid Mites from Easter Island. Pacific Insects, 12, 105–122.
Hann, B.J. & Goldsborough, L.G. (1997) Responses of a prairie wetland to press and pulse additions of inorganic nitrogen and phosphorus : invertebrate community structure and interactions. Archiv für Hydrobiologie, 140, 169–174.
http://dx.doi.org/10.1127/archiv-hydrobiol/140/1997/169Havel, J.E. & Medley, K.A. (2006) Biological invasions across spatial scales: Intercontinental, regional, and local dispersal of cladoceran zooplankton. Biological Invasions, 8, 459–473.
http://dx.doi.org/10.1007/s10530-005-6410-4Havel, J.E. & Shurin, J.B. (2004) Mechanisms, effects, and scales of dispersal in freshwater zooplankton. Limnology and Oceanography 49, 1229–1238.
http://dx.doi.org/10.4319/lo.2004.49.4_part_2.1229Hunt, T.L. (2007) Rethinking Easter Island’s ecological catastrophe. Journal of Archaeological Science, 34, 485–502.
http://dx.doi.org/10.1016/j.jas.2006.10.003Jeong, H.G., Kotov, A.A. & Lee, W. (2013) A new species of the genus Pleuroxus Baird (Cladocera: Anomopoda: Chydoridae) from Jeju Island, South Korea. Zootaxa, 3666 (1), 31– 40.
http://dx.doi.org/10.11646/zootaxa.3666.1.3Karanovic, I. (2012) Recent freshwater Ostracods of the World - Crustacea, Ostracoda, Podocopida. Springer, London. 608 pp.
http://dx.doi.org/10.1007/978-3-642-21810-1Kirillova, I.V., van der Plicht, J., Gubin, S.V., Zanina, O.G., Chernova, O.F., Lapteva, E.G., Trofimova, S.S., Zinovyev, E.V., Zharov, A.A., Fadeeva, E.O., van Kolfschoten, T., Shidlovskiy, F.K. & Kotov, A.A. (2016) Taphonomic phenomenon of ancient hair from Glacial Beringia: perspectives for palaeoecological reconstructions. Boreas.
http://dx.doi.org/10.1111/bor.12162Korovchinsky, N.M. (2001) Review of Sididae (Crustacea: Cladocera: Ctenopoda) of the Pacific Ocean islands, with description of a new species of Diaphanosoma from West Samoa. Hydrobiologia, 455, 171–181.
http://dx.doi.org/10.1023/A:1011981332027Kotov, A.A., Sinev, A.Y. & Berrios, V.L. (2010) The Cladocera (Crustacea: Branchiopoda) of six high altitude water bodies in the North Chilean Andes, with discussion of Andean endemism. Zootaxa, 2430, 1–66.
Kotov, A., Forró, L., Korovchinsky, N.M. & Petrusek, A. (2013) World checklist of freshwater Cladocera species. World Wide Web electronic publication. Available online at http://fada.biodiversity.be/group/show/17 (Accessed 1 April 2016)
Kuschel, G. (1963) Composition and relationship of the terrestrial faunas of Easter, Juan Fernandez, Desventuradas, and Galapágos Islands. California Academy of Sciences, Occasional Papers, 44, 79‒95.
http://dx.doi.org/10.5962/bhl.part.2341Mann, D., Edwards, J., Chase, J., Beck, W., Reanier, R., Mass, M., Finney, B. & Loret, J. (2008) Drought, vegetation change, and human history on Rapa Nui (Isla de Pascua, Easter Island). Quaternary Research, 69, 16–28.
http://dx.doi.org/10.1016/j.yqres.2007.10.009Mockford, E.L. & Wynne, J.J. (2013) Genus Cyptophania Banks (Psocodea: 'Psocoptera': Lepidopsocidae): unique features, augmented description of the generotype, and descriptions of three new species. Zootaxa, 3702 (5), 437–439.
http://dx.doi.org/10.11646/zootaxa.3702.5.3Neall, V.E. & Trewick, S.A. (2008) The age and origin of the Pacific Islands: a geological overview. Philosophical Transactions of the Royal Society B, 363, 3293–3308.
http://dx.doi.org/10.1098/rstb.2008.0119Popova, E.Y. & Kotov, A.A. (2013) Latitudinal patterns in the diversity of two subgenera of the genus Daphnia O.F. Müller (Crustacea: Cladocera: Daphniidae). Zootaxa, 3736 (2), 159–174.
http://dx.doi.org/10.11646/zootaxa.3736.2.4Rull, V., Cañellas-Boltà, N., Sáèz, A., Margalef, O., Bao, R., Pla-Rabes, S., Valero-Garcés, B. & Giralt, S. (2013) Challenging Easter Island’s collapse: the need for interdisciplinary synergies. Frontiers in Ecology and Evolution, 1 (3), 1–5.
http://dx.doi.org/10.3389/fevo.2013.00003Sáez, A., Valero-Garcés, B.L., Giralt, S., Moreno, A., Boa, R., Pueyo, J.J., Hernández, A. & Casas, D. (2009) Glacial to Holocene climate changes in the SE Pacific. The Raraku Lake sedimentary record (Easter Island, 27°S). Quaternary Science Reviews, 28, 2743–2759.
http://dx.doi.org/10.1016/j.quascirev.2009.06.018Sars, G.O. (1904) Pacifischen Plankton-Crustaceen. Zoologische Jahrbuecher Systematik, 14, 629–646.
Schabetsberger, R., Drozdowski, G., Rott, E., Lenzenweger, R., Jersabek, C.D., Fiers, F., Traunspurger, W., Reiff, N., Stoch, F., Kotov, A.A., Martens, K., Schatz, H. & Kaiser, R. (2009) Losing the Bounty? Investigating species richness in isolated freshwater ecosystems of Oceania. Pacific Science, 63, 153–179.
http://dx.doi.org/10.2984/049.063.0201Segers, H. & Dumont, H.J. (1993) Zoogeography of Pacific Ocean islands: a comparative study of the Rotifer faunas of Easter Islands with that of the Galapagos archipelago. Hydrobiologia, 255, 475–480.
http://dx.doi.org/10.1007/BF00025876Sinev A.Y. & Silva-Briano, M. (2012) Cladocerans of genus Alona Baird, 1843 (Cladocera: Anomopoda: Chydoridae) and related genera from Aguascalientes State, Mexico. Zootaxa, 3569, 1–24.
Sinev, A.Y. (2001a) Redescription of Alona glabra Sars, 1901, a South American species of the pulchella-group (Chydoridae, Anomopoda, Branchiopoda). Arthropoda Selecta, 10 (4), 273–280.
Sinev, A.Y. (2001b) Separation of Alona cambouei Guerne & Richard, 1893 from Alona pulchella King, 1853 (Branchiopoda, Anomopoda, Chydoridae). Arthropoda Selecta, 10 (1), 5–18.
Sinev, A.Y. (2002a) Place of a Central American bromeliad-inhabiting cladoceran Alona bromelicola Smirnov, 1988 within the genus (Branchiopoda: Anomopoda: Chydoridae). Arthropoda Selecta, 11 (2), 109–116.
Sinev, A.Y. (2002b) Redescription of Australian cladocera Alona archeri Sars, 1888 (Branchiopoda: Anomopoda: Chydoridae). Arthropoda Selecta, 11 (4), 247–254.
Sinev, A.Y. (2009) Notes on morphology and taxonomic status of some North American species of the genus Alona Baird, 1843 (Cladocera: Anomopoda: Chydoridae). Fundamental and Applied Limnology – Archiv fur Hydrobiologie, 175, 59–77.
http://dx.doi.org/10.1127/1863-9135/2009/0175-0059Sinev, A.Y. (2015) Revision of the pulchella-group of Alona s. lato leads to its translocation to Ovalona Van Damme et Dumont, 2008 (Branchiopoda: Anomopoda: Chydoridae). Zootaxa, 4044, 451–492.
http://dx.doi.org/10.11646/zootaxa.4044.4.1Sinev, A.Y., Alonso, M., Miracle, M.R. & Sahuquillo, M. (2012) The West Mediterranean Alona azorica Frenzel & Alonso, 1988 (Cladocera: Anomopoda: Chydoridae) is composed of two species. Zootaxa, 3276, 51–68.
Sinev A.Y. & Silva-Briano, M. (2012) Cladocerans of genus Alona Baird, 1843 (Cladocera: Anomopoda: Chydoridae) and related genera from Aguascalientes State, Mexico. Zootaxa, 3569, 1–24.
Sousa, F.D.R., Elmoor-Loureiro, L.M.A. & Santos, S. (2015) Alona kaingang (Crustacea, Cladocera, Aloninae): a new species of the pulchella group, with identification key to Neotropical species. Zoological Studies, 54, 1–12.
http://dx.doi.org/10.1186/s40555-015-0128-5Steadman, D.W. (1995) Prehistoric extinctions of Pacific Island birds: Biodiversity meets Zooarchaeology. Science, 267, 1123–1131.
http://dx.doi.org/10.1126/science.267.5201.1123Taiti, S. & Wynne, J. (2015) The terrestrial Isopoda (Crustacea, Oniscidae) of Rapa Nui (Easter Island), with descriptions of two new species. Zookeys, 515, 27–49.
http://dx.doi.org/10.3897/zookeys.515.9477Uéno, M. (1936) Cladocera of Mauna Kea, Hawaii. Bernice P. Bishop Museum, Occasional Papers, 12 (11), 3–9.
Van Damme, K., Bekker, E.I. & Kotov, A.A (2013) Endemism in the Cladocera (Crustacea: Branchiopoda) of Southern Africa. Journal of Limnology, 72 (3), 440–463.
http://dx.doi.org/10.4081/jlimnol.2013.e36Van Damme, K. & Dumont, H.J. (2008a) Further division of Alona Baird, 1843: separation and position of Coronatella Dybowski & Grochowski and Ovalona gen.n. (Crustacea: Cladocera). Zootaxa, 1960, 1–44.
Van Damme, K. & Dumont, H.J. (2008b) The ‘true’ genus Alona Baird, 1843 (Crustacea: Cladocera: Anomopoda): characters of the A. quadrangularis-group and description of a new species from Democratic Republic Congo. Zootaxa, 1943, 1–25.
Van Damme, K., Kotov, A.A. & Dumont, H.J. (2010) A checklist of names in Alona Baird 1843 (Crustacea: Cladocera: Chydoridae) and their current status: an analysis of the taxonomy of a lump genus. Zootaxa, 2330, 1–63.
Van Damme, K., Elias-Gutierrez, M. & Dumont, H.J. (2011a) Three rare European “Alona” taxa (Branchiopoda: Cladocera: Chydoridae), with notes on distribution and taxonomy. International Journal of Limnology, 47, 45–63.
http://dx.doi.org/10.1051/limn/2010034Van Damme, K., Sinev, A.Y. & Dumont, H.G. (2011b) Separation of Anthalona gen.n. from Alona Baird, 1843 (Branchiopoda: Cladocera: Anomopoda): morphology and evolution of scraping stenothermic alonines. Zootaxa, 2875, 1–64.
Wynne, J.J., Bernard, E.C., Howarth, F.G., Sommer, S., Soto-Adames, F.N., Taiti, S., Mockford, E.L., Horrocks, M., Pakarati, L. & Pakarati-Horus, V. (2014) Disturbance relicts in a rapidly changing world: the Rapa Nui (Easter Island) Factor. Bioscience, 64, 711–718.
http://dx.doi.org/10.1093/biosci/biu090