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Type: Article
Published: 2018-04-23
Page range: 271–294
Abstract views: 124
PDF downloaded: 1

Revision of the Australian Wet Tropics endemic rainbowfish genus Cairnsichthys (Atheriniformes: Melanotaeniidae), with description of a new species

Museum and Art Gallery of the Northern Territory, PO Box 4646, Darwin, Northern Territory 0801.
Western Australian Museum, Locked Bag 49, Welshpool DC, Perth, Western Australia 6986.
P.O. Box 520 Clifton Beach Qld 4879 Australia.
Evolutionary Biology Unit, South Australian Museum, North Terrace, Adelaide, South Australia 5000 School of Biological Sciences, The University of Adelaide, Adelaide, South Australia 5005 Institute for Applied Ecology, University of Canberra, Australian Capital Territory 2617
TropWATER, James Cook University, C/O CSIRO PO Box 780, Atherton, Queensland 4883
Arthur Rylah Institute for Environmental Research, Department of Environment, Land, Water and Planning, PO Box 137, Heidelberg, Victoria 3084. Department of Ichthyology, Museum Victoria, Melbourne, Victoria 3001
Institute for Applied Ecology, University of Canberra, Australian Capital Territory 2617
Pisces fishes freshwater biodiversity conservation taxonomy molecular systematics northern Australia


The freshwater melanotaeniid genus Cairnsichthys is endemic to a relatively small area of specialised habitat within the Wet Tropics bioregion of north-eastern Queensland, Australia. It was previously considered as monotypic, including only a single species, C. rhombosomoides (Nichols & Raven, 1928). The recent discovery of an apparently-isolated population in the Daintree rainforest, approximately 120 km north of the known range extent, prompted a detailed investigation of its taxonomic status using a combined lines of evidence approach. We provide compelling evidence from multiple nuclear genetic markers (52 allozyme loci), mitochondrial DNA sequence data (1141 bp cytochrome b) and morphology (examination of a suite of 38 morphometric and meristic characters) that supports north-south splitting of C. rhombosomoides. Accordingly, we describe the northern population as a distinct species, C. bitaeniatus sp. nov., on the basis of 25 specimens, 34.7–65.6 mm SL. The new species differs morphologically primarily by having a more slender and narrow shape, featuring a flatter, straighter predorsal profile and shorter second dorsal fin base; possession of slightly smaller scales, reflected in higher counts of lateral scales and predorsal scales; typically more vertebrae; and colour differences including a more robust, short black stripe across the upper operculum, a pronounced yellow patch on the anteroventral body and usually a more conspicuous second dark stripe on the lower body, with adult males generally having yellowish compared to reddish fins. We also provide a generic diagnosis for Cairnsichthys and a redescription of C. rhombosomoides. Information on the known distribution, habitats and conservation status of species in the genus is summarised, the new species being of particular concern as a narrow range endemic with specific environmental requirements.



  1. Aarn & Ivantsoff, W. (1997) Descriptive anatomy of Cairnsichthys rhombosomoides and Iriatherina werneri (Teleostei: Atheriniformes), and a phylogenetic analysis of Melanotaeniidae. Ichthyological Exploration of Freshwaters, 8, 107–150.

    Adams, M., Raadik, T.A., Burridge, C.P. & Georges, A. (2014) Global biodiversity assessment and hyper-cryptic species complexes: more than one species of elephant in the room? Systematic Biology, 63, 518–533.

    Allen, G.R. (1980) A generic classification of the rainbowfishes (family Melanotaeniidae). Records of the Western Australian Museum, 8, 449–490.

    Allen, G.R. (1989) Freshwater Fishes of Australia. T.F.H. Publications, New Jersey, 240 pp.

    Allen, G.R. (1995) Rainbowfishes in Nature and the Aquarium. Tetra-Verlag, Velten, 179 pp.

    Allen, G.R. & Cross, N.J. (1982) Rainbowfishes of Australia and Papua New Guinea. Angus and Robertson Publishers, Sydney, 141 pp.

    Allen, G.R., Cross, N.J., Bray, D.J. & Hoese, D.F. (2006) Melanotaeniidae. In: Beesley, P.L. & Wells, A. (Eds), Zoological Catalogue of Australia. Vol. 35. Part II. ABRS & CSIRO Publishing, Melbourne, pp. 689–695.

    Allen, G.R., Hadiaty, R.K., Unmack, P.J. & Erdmann, M.V. (2015a) Rainbowfishes (Melanotaenia: Melanotaeniidae) of the Aru Islands, Indonesia with descriptions of five new species and redescription of M. patoti Weber and M. senckenbergianus Weber. aqua, International Journal of Ichthyology, 21, 66–108.

    Allen, G.R., Midgley, S.H. & Allen, M. (2002) Field Guide to the Freshwater Fishes of Australia. Western Australian Museum, Perth, 394 pp.

    Allen, G.R., Unmack, P.J. & Hadiaty, R.K. (2015b) Melanotaenia rubrivittata, a new species of rainbowfish (Melanotaeniidae) from northwestern Papua Province, Indonesia. Fishes of Sahul, 29, 846–858.

    Beheregaray, L.B. & Caccone, A. (2007) Cryptic biodiversity in a changing world. Journal of Biology, 6, 9.

    Bloom, D.D., Unmack, P.J., Gosztonyi, A.E., Piller, K.R. & Lovejoy, N.R. (2012) It’s a family matter: molecular phylogenetics of Atheriniformes and the polyphyly of the surf silversides (Family: Notocheiridae). Molecular Phylogenetics and Evolution, 62, 1025–1030.

    Campanella, D., Hughes, L.C., Unmack, P.J., Bloom, D.D., Piller, K.R. & Ort, G. (2015) Multi-locus fossil-calibrated phylogeny of Atheriniformes (Teleostei, Ovalentaria). Molecular Phylogenetics and Evolution, 86, 8–23.

    Corlis, D. (2004) Four new genera of monogenea (Dactylogridae) from the gills of Australian atheriniform freshwater fishes. Memoirs of the Queensland Museum, 49, 537–572.

    Ebner, B.C., Fulton, C.J., Cousins, S., Donaldson, J.A., Kennard, M.J., Meynecke, J.O. & Schaffer, J. (2015) Filming and snorkelling as visual techniques to survey fauna in difficult to access tropical rainforest streams. Marine and Freshwater Research, 66, 120–126.

    Ebner, B.C. & Thuesen, P. (2010) Discovery of stream-cling-goby assemblages (Stiphodon species) in the Australian Wet Tropics. Australian Journal of Zoology, 58, 331–340.

    Eschmeyer, W.N. (2017) Catalog of Fishes, Online Version (updated 31 July 2017) California Academy of Sciences. Available from: (accessed 31 November 2017)

    Hammer, M.P., Adams, M. & Hughes, J.H. (2013) Evolutionary processes and biodiversity. In: Humphries, P. & Walker, K. (Eds.), Ecology of Australian Freshwater Fishes. CSIRO Press, Melbourne, pp. 49–79.

    Hammer, M.P., Adams, M., Unmack, P.J. & Walker, K.F. (2007) A rethink on Retropinna: conservation implications of new taxa and significant genetic substructure in Australian smelts (Pisces: Retropinnidae). Marine and Freshwater Research, 58, 327–341.

    Hammer, M.P., Unmack, P.J., Adams, M., Raadik, T.A. & Johnson, J.B. (2014) A multigene molecular assessment of cryptic biodiversity in the iconic freshwater blackfishes (Teleostei: Percichthyidae: Gadopsis) of south-eastern Australia. Biological Journal of the Linnean Society, 113, 521–540.

    Herbert, B. & Peeters, J. (1995) Freshwater Fishes of Far North Queensland. DPI Queensland, Brisbane, 74 pp.

    Hubert, N., Hanner, R., Holm, E., Mandrak, N.E., Taylor, E., Burridge, M., Watkinson, D., Dumont, P., Curry, A., Bentzen, P., Zhang, J., April, J. & Bernatchez, L. (2008) Identifying Canadian Freshwater Fishes through DNA Barcodes. PLoS ONE, 3, e2940.

    ICZN (International Commission on Zoological Nomenclature) (1999) International Code of Zoological Nomenclature. 4th Edition. International Trust for Zoological Nomenclature, London, 306 pp.

    IUCN (2017) The IUCN Red List of Threatened Species. Version 2017-1, International Union for Conservation of Nature. Available from: (accessed 31 November 2017)

    Johnson, J. (2003) Freshwater and upper estuarine fishes. In: Ryan, M. & Burwell, C. (Eds.), Wildlfie of Tropical North Queensland. Queensland Museum, Brisbane, pp. 135–169.

    Kleiberg, T. (1988) The Cairns rainbowfish Cairnsichthys rhombosomoides (Nicholson and Raven). Fishes of Sahul 5, 215–216.

    Kroon, F., Phillips, S., Burrows, D. & Hogan, A. (2015) Presence and absence of non‐native fish species in the Wet Tropics region, Australia. Journal of Fish Biology, 86, 1177–1185.

    Kumar, S., Stecher, G. & Tamura, K. (2016) MEGA7: Molecular Evolutionary Genetics Analysis version 7.0 for bigger datasets. Molecular Biology and Evolution, 33, 1870–1874.

    Lake, J.S. (1971) Freshwater Fishes and Rivers of Australia. Thomas Nelson, Melbourne, 61 pp.

    Leggett, R. & Merrick, J.R. (1987) Australian Native Fishes for Aquariums. JR Merrick Publications, Artarmon NSW, 241 pp.

    Lintermans, M. (2016) Conservation Status of Australian Fishes—2016. Australian Society for Fish Biology Newsletter, 46, 142–144.

    Martin, K.C. & Barclay, S. (2013) New distribution records for the Cairns rainbowfish Cairnsichthys rhombosomoides (Melanotaeniidae): implications for conservation of a restricted northern population. aqua, lnternational Journal of Ichthyology, 19, 155–164.

    McGuigan, K.L. (2001) An addition to the rainbowfish (Melanotaeniidae) fauna of north Queensland. Memoirs of the Queensland Museum, 46, 647–655.

    Merrick, J.R. & Schmida, G.E. (1984) Australian Freshwater Fishes: Biology and Management. Griffith Press, Adelaide, 409 pp.

    Munro, I.S.R. (1956–1961) Handbook of Australian Fishes. Reprinted from Fisheries Newsletter (Australia). Publicity Press, Sydney, 172 pp.

    Nichols, J.T. & Raven, H.C. (1928) A new melanotaeniid fish from Queensland. American Museum Novitates, 296, 1–2.

    Paxton, J.R., Hoese, D.F., Allem, G.R. & Hanley, J.E. (1989) Zoological Catalouge of Australia. Voulume 7 Pisces: Petromyzontidae to Carangidae. Australian Government Publishing Service, Canberra, 665 pp.

    Pusey, B., Kennard, M. & Arthington, A. (2004) Freshwater Fishes of North-Eastern Queensland. CSIRO Publishing, Collingwood, Victoria, 684 pp.

    Pusey, B.J., Arthington, A.H., Bird, J.R. & Close, P.G. (2001) Reproduction in three species of rainbowfish (Melanotaeniidae) from rainforest streams in northern Queensland, Australia. Ecology of Freshwater Fish, 10, 75–87.

    Pusey, B.J., Arthington, A.H., Close, P.G. & Bird, J.R. (2002) Larval fishes in rainforest streams: recruitment and microhabitat use. Proceedings of the Royal Society of Queensland, 110, 27–46.

    Pusey, B.J. & Kennard, M.J. (1996) Species richness and geographical variation in assemblage structure of the freshwater fish fauna of the wet tropics region of northern Queensland. Marine and Freshwater Research, 47, 563–573.

    Pusey, B.J. & Kennard, M.J. (2001) Guyu wujalwujalensis, a new genus and species (Pisces: Percichthyidae) from north-eastern Queensland. Ichthyological Exploration of Freshwaters, 12, 17–28.

    Raadik, T.A. (2014) Fifteen from one: a revision of the Galaxias olidus Günther, 1866 complex (Teleostei, Galaxiidae) in south-eastern Australia recognises three previously described taxa and describes 12 new species. Zootaxa, 3898 (1), 1–198.

    Regan, C.T. (1914) Report on the freshwater fishes collected by the British Ornithologists' Union expedition and the Wollaston expedition in Dutch New Guinea. Transactions of the Zoological Society of London, 20, 275–286.

    Richardson, B.J., Baverstock, P.R. & Adams, M. (1986) Allozyme Electrophoresis: A Handbook for Animal Systematics and Population Studies. Academic Press, Sydney, 430 pp.

    Sattler, P. & Williams, R. (Eds.) (1999) The Conservation Status of Queensland’s Bioregional Ecosystems. Environmental Protection Agency, Brisbane, 625 pp.

    Sparks, J.S. & Smith, W.L. (2004) Phylogeny and biogeography of the Malagasy and Australasian rainbowfishes (Teleostei: Melanotaeniodei): Gondwanan vicariance and evolution in freshwater. Molecular Phylogenetics and Evolution, 33, 719–734.

    Tappin, A.R. (2010) Rainbowfishes: Their Care and Keeping in Captivity. Art Publications, Brisbane, 510 pp.

    Thuesen, P. (2004) Biological barriers to gene flow and population genetic structure of an endemic rainbow-fish, Cairnsichthys rhombosomoides. BSc (Hons) thesis, James Cook University, Townsville, 89 pp.

    Thuesen, P.A., Pusey, B.J., Peck, D.R., Pearson, R. & Congdon, B.C. (2008) Genetic differentiation over small spatial scales in the absence of physical barriers in an Australian rainforest stream fish. Journal of Fish Biology, 72, 1174–1187.

    Unmack, P.J. (2001) Biogeography of Australian freshwater fishes. Journal of Biogeography, 28, 1053–1089.

    Unmack, P.J., Allen, G.R. & Johnson, J.B. (2013) Phylogeny and biogeography of rainbowfishes (Melanotaeniidae) from Australia and New Guinea. Molecular Phylogenetics and Evolution, 67, 15–27.

    Wager, R. (1996) Cairnsichthys rhombosomoides. The IUCN Red List of Threatened Species. Version 2015.2, Available from: (accessed 31 November 2017)

    Wager, R. & Jackson, P. (1993) The Action Plan for Australian Freshwater Fishes. Australian Nature Conservation Agency, Canberra, 122 pp.

    Ward, R.D., Hanner, R. & Hebert, P.D.N. (2009) The campaign to DNA barcode all fishes, FISH-BOL. Journal of Fish Biology, 74, 329–356.