A NOTE ON LICHENS FROM RUAMAHUA-ITI, ALDERMEN ISLANDS. by B.W. Hayward* SUMMARY

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1 87 A NOTE ON LICHENS FROM RUAMAHUA-ITI, ALDERMEN ISLANDS by B.W. Hayward* SUMMARY Thirty-five lichen species from twenty genera are recorded from Ruamahuaiti, Aldermen Islands. A description of the lichen communities is given and an attempt made to relate these to light intensity and growth form. Of the thirty-five species, only one occurs on soil (epigean), seventeen on bark (epiphytic), and nineteen on rock (saxicolous) - ten on rock of the littoral and maritime zones, nine on rocks on open cliff-tops, and one on dark shaded rock {Xanthoma parietina occurred on rocks of both the maritime zone and open cliff-tops). The lichen associations of Ruamahua-iti, Red Mercury Island and Whale Island are briefly compared. INTRODUCTION A collection of lichen specimens was made from Ruamahua-iti, Aldermen Islands, during the Auckland University Field Club scientific camp in May Lichens were collected from all available habitats and at all altitudes on the island, as well as from coastal rocks around Tuatara Bay. All saxicolous lichens referred to were found on rocks of rhyolite lava (Hayward and Moore, 1973). SPECIES LIST Nomenclature follows that of Murray (1963a, b), Martin (1966, 1969) and Martin and Child (1972). Caloplaaceae Caloplaca acheila Caloplaca sp. Cladoniaceae Cladonia leptoclada Collemaceae Leptogium inflexum L. phyllocarpum Habitat soil, open cliff-top bark, beneath dense canopy bark, beneath dense canopy * Geology Department, University of Auckland.

2 88 Graphidaceae Opegrapha sp. Lecanoraceae Lecanora 2 spp. Lecideaceae Lecidea 2 spp. Lichinaceae Lichina pygmaea var. intermedia Parmeliaceae Parmelia caperata P. cetrata P. laevigata P. perlata P. sax a tills P. subtiliacea P. tiliacea Parmelia sp. Pertusariaceae Pertusaria sp. Physciaceae Anaptychia speciosa Physcia sp. Pyrenulaceae Arthopyrenia sp. Stictaceae Lobaria lacinata L. montagnei Pseudocyphellaria aurata Sticta lacera S. variabilis Sticta sp. Teleoschistaceae Teleoschistes chrysopthalmus Xanthoria parietina rock, midlittoral rock, beneath dense canopy rock, midlittoral bark and rock, open coastal forest and cliff-top and open cliff-top

3 89 Usneaceae Ramalina cf. leiodea R. menziesii Usnea sp. Verrucariaceae Verrucaria sp. rock, midlittoral LICHEN HABITATS 1. Forest habitats Open coastal forest covers most of the north-western slopes of Ruamahua-iti (Court, Hardacre and Lynch, 1973) and supports a rich lichen flora. A considerable quantity of light filters through the semi-open canopy, and epiphytic lichens abound on both smooth and rough-barked trees. These lichens include abundant individuals of Usnea sp. and Ramalina menziesii, crustose Lecanora sp., as well as numerous foliose species including Sticta lacera, Physcia sp., Parmelia caperata, P. laevigata, P. perlata, P. saxatilis, and.p. subtiliacea. Three lichens found in darker conditions under a dense canopy on the upper southern slopes of the highest point on the island are a rock-inhabiting Pertusaria sp. and epiphytic, lead-grey Leptogium inflexum and L. phyllocarpum. The canopy opens out around the margins of the coastal forest at the top of the high cliffs which surround much of the island. Here Metrosideros excelsa is the dominant tree species present and supports a rich lichen flora of Usnea sp., Ramalina menziesii, Lobaria lacinata, Parmelia saxatilis, Pseudocyphellaria aurata, and Teleoschistes chrysophthalmus. A separate lichen association has colonised the rocks that lie in this open cliff-top area beneath the Metrosideros excelsa. Yellow Xanthoria parietina, crustose Lecidea sp. and foliose Parmelia cetrata and P. tiliacea are the most abundant lichen species present here, but the yellow Caloplaca sp. and foliose species Lobaria montagnei, Sticta lacera and S. variabilis also occur. The epigean lichen Cladonia leptoclada is found occasionally nearby. 2. Littoral and maritime saxicolous habitats All these lichens from around Tuatara Bay were found growing on large, angular, stable boulders (l-10m across). Three species growing in the upper midlittoral zone (Saies, 1973) are the three black lichens, Lichina pygmaea, Verrucaria sp., and the barnacle-encrusting Arthopyrenia sp. Above high tide in the maritime zone, encrusting lichens predominate and include species of Lecanora, Lecidea, Opegrapha, and the yellow Caloplaca acheila. Other lichens commonly present are Ramalina sp., species of the foliose genera Physcia and Anaptychia, and the yellow Xanthoria parietina.

4 90 DISCUSSION As stated by Puch (1972) it appears that the lichen flora present on offshore islands is a reflection of the vegetation present. In this respect Ruamahua-iti is similar to Red Mercury, as both have a semi-complete canopy of coastal forest over most of the island, whereas islands such as Whale Island have a predominance of grassland and manuka scrubland. Consequently, Ruamahua-iti lacks Peltigera sp. and Stereocaulon sp. (like Red Mercury Island (Puch, 1972)) and has a very poorly-developed epigean flora compared to that on Whale Island (Puch, 1971). The only epigean lichen flora on Ruamahua-iti is small patches of Cladonia leptoclada on the open cliff-tops, while that on Red Mercury is restricted to five species of Cladonia, including C. leptoclada, found on soil beneath a large patch of manuka scrub. The Ruamahua-iti coastal forest lichens differ considerably, however, from those found on Red Mercury. This is probably because the canopy on Ruamahua-iti is generally more open, especially near the cliff-tops, than it is on Red Mercury. On Ruamahua-iti, small patches exist within the coastal forest of dense canopy and therefore with poor light penetration, and within these patches lichens of denser forest associations do occur. The abundance of saxicolous lichens is dependent on the availability of suitable rocks. These are common beneath the dense canopy on Red Mercury, and therefore support saxicolous forest lichen associations. On Ruamahua-iti, suitable rocks within the forest are restricted mostly to the open cliff-tops and therefore support lichen associations with a forest margin character. The littoral and maritime lichen associations of Ruamahua-iti are fairly similar those on Red Mercury have colonised well-rounded boulders whilst the Ruamahua-iti boulders are larger and angular. The essential property common to this habitat on both islands is that the boulders colonised are relatively stable. ACKNOWLEDGEMENTS I would like to thank my wife Glenys for all her encouragement, and especially for checking identifications and critically reading the manuscript, and Mr J.E. Braggins for critically reading the manuscript. REFERENCES Court, D.J., Hardacre, A.K., Lynch, P.A. 1973: The vegetation of the Aldermen Islands: A reappraisal. Tane 19: Hayward, B.W., Moore, P.R. 1973: The geology of the Aldermen Islands. Tane 19: Martin, W. 1966: The Parmeliaceae of New Zealand and a key to the indigenous species of Parmelia. Tuatara 14: Martin, W. 1969: Key to the Stictaceae of New Zealand Tuatara 17: Martin, W., Child, J. 1972: "Lichens of New Zealand." A.H. and A.W. Reed. 193pp. Murray, J. 1963a: Keys to New Zealand lichens, Part 2. Tuatara 11(1): Murray, J. 1963b: Keys to New Zealand lichens, Part 3. Tuatara 11 (2):

5 91 Puch, G.C. 1971: A note on lichens from Whale Island. Tane 17: Puch, G.C. 1972: The lichens of Red Mercury Island. Tane 18: Saies, A.B. 1973: The intertidal life of Ruamahua-iti and Middle Islands (Aldermen Islands). Tane 19 (this volume)

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