TANE 28,1982

LICHENS ON RAKITU (ARID) ISLAND, NORTH-EAST NEW ZEALAND

by Bruce W. Hayward and Glenys C. Hayward* New Zealand Geological Survey, P.O. Box 30368, Lower Hutt *35 Trafalgar Street, Waterloo, Lower Hutt

SUMMARY

One hundred and twenty-four species of from 50 genera are recorded from Rakitu Island, off the east coast of Great Barrier Island. This is one of the richest floras recorded to date from any of the offshore islands of northern New Zealand and is a reflection of the diversity of habitat, higher altitude (200 m) and the presence of forest patches sheltered from salt spray. Sixteen species (especially Parmelia erumpens, Hypotrachyna formosana and Ramalina geniculate) are recorded for the first time from a northern offshore island. Graphina monospora is recorded over 1 000 km further north than its previously known occurrence in Southland.

INTRODUCTION

The lichens recorded here were collected and studied during the Offshore Islands Research Group trip to Rakitu Island, New Year 1980 - 1981. Rakitu (Arid) Island lies 2.5 km off the east coast of Great Barrier Island, north-east New Zealand (Fig. 1). Rakitu Island (350 hectares) is divided into two high-standing blocks (each rising to 220 m A.S.L.) by the central valley of Abbott's Stream. Steep rocky cliffs surround most of the island and rocky bluffs are common around the summits of the two upstanding blocks. Open grassland covers approximately half the island (especially Abbott's Stream valley). Kanuka and mixed coastal forest grows in the incised tributary valleys of Abbott's Stream and in pockets on the steep, seaward-facing slopes and cliffs. Representative collections were made from the major vegetation types (Fig. 1; species list). Voucher specimens are lodged in the Herbarium of the Auckland Institute and Museum. There has been no previous work on the lichens of Rakitu Island.

125 ! RAKITU (ARID) ISLAND km

Te Akau Pi «4 taraire-kohekohe-tawa forest

Fig. 1. Lichen collecting localities on Rakitu Island. Inset maps show the location of Rakitu Island off the east coast of Great Barrier, north-east New Zealand.

126 SPECIES LIST

Key to distribution symbols: Habitat Substrate 1. maritime b = bark 2. open cliff tops r = rock 3. kanuka forest s = soil 4. taraire-tawa-kohekohe forest

CLASS ASCOMYCOTINA ORDER LECANORALES Suborder Lecanorineae Baeomycetaceae Baeomyces fungoides (Sw.)Ach. 3r B. heteromorphus Nyl. 3r aurella (Hoffm.)Zahlbr. 2r Candelariella sp. lr Cladoniaceae Cladia aggregata (Sw.)Nyl. lr 2r 3r Cladonia capitellata (Tayl.)Bab. 2s 3r C. I carassensis Vainio 2s C. chlorophaea (Floerke) Spreng. 2s C. coniocraea (Floerke)Sandst. 2s C. I cylindrica (Evans)Evans 2s C. fimbriata (L.)Fr. 2s C. floerkeana (Fr.)Floerke 2s C. gracilis (L.)Willd. 2s C. leptoclada Des.Abb. 2s C. pityrea (Floerke)Fr. 2s 4b C. scabriuscula Sandst. 2s C. "(squamosa (Scop.)Hoffm. 2s C. subcervicornis (Vainio)Du Rietz 2s Cladonia spp. lr 2s Gymnoderma melacarpa (F.Wils.)Yoshimura 2s Coccocarpiaceae Coccocarpia erthroxyli (Spreng.)Swinsc. & Krog. 3b C. palmicola (Sprang.)Arvidas & Galloway 3b C. pellita MulIArg. 3b 4b Erioderma sorediatum Galloway & P.M. Jorg. 3b Collemataceae Collema subflaccidum DegeL 3b Collema sp. 3b Leptogium cyanescens (Ach.)Kremp. 3b 4b L. denticulatum Nyl. 3b Leptogium sp. 4r Heppiaceae Peltula euploca (Ach.)Wetm. lr Lecanoraceae Brigantiaea chrysosticta (J.D.Hook. & TayL) Haffelner & Bellemere 3b 4b Lecanora spp. lr 3b 4b Lecideaceae Catillaria sp. 4r Lecidea furfuracea Pers. 3b Lecidea spp. 4br Megalospora allani Zahlbr. 4b M. marginiflexa (Hook f. & TayL) Zahlbr. 3b 4b M sulphurata Mey. & Flot. 3b 4b Pannariaceae Leioderma sp. 3r Pannaria fulvescens NyL 3b P. granulifera Mull. Arg. 4b

127 P. immixta Nyl. 4br P. periptera Knight 3b Pannaria n.sp. 3b 4b Parmellialla nigrocincta Mull.Arg. 4b Hypogymnia subphysodes (Krempelh.)Filson 3r Hypotrachyna formosana (Zahlbr.)Hale 2r 3b Menegazzia circumsorediata R.Sant. 3b 4b Neofuscelia pulla (Ach.)EssI. lr 2r N. verrucella (Essl.)Essl. lr Parmelia cunninghamii Cromb. 4b P. erumpens Kurok. lr Parmelina horrescens Tayl. 2r 4r Parmotrema cetratum (Ach.)Hale 3br 4b P. crinitum (Ach.)Choisy 3b 4b P. mellissii (Dodge)Hale 2r 3br P. perlatum (Huds.)Choisy lr 2r 3br P. reparatum (Stirton) lr P. reticulatum (Tayl.)Choisy lr 3b 4br P. tinctorum (Nyl.)Hale 4br Parmotrema sp. 3b 4b Pseudoparmelia cf. caperata (L.)Hale lr P. soredians (Nyl.) Hale lr Xanthoparmelia australasica Galloway lr 2r X. furcata (Mull.Arg.)Hale lr 2r 3r Placynthiaceae Psoroma cf. athroophyllum Stirton 4r P. contortum Mull.Arg. 3b 4b P. leprolomum (Nyl.)Ras. 3b 4b P. microphyllizans (Nyl.)Galloway 4b Ramalinaceae Ramalina geniculata J.D.Hook. & Tayl. lr R. linearis Ach. lr 3r R. myrioclada Mull.Arg. lr Stereocaulaceae Stereocaulon ramulosum (Sw.)Rausch. lr 2r 3r Usneaceae Usnea arida Mot. 3b U. flexilis Stirton 2r 3br 4b U. cf. neocaledonica Mot. 2r U. cf. xanthopoga Stirton 2r 3br Usnea spp. lr 2r 3r Suborder Lichinineae Lichinaceae Lichina confinis (O.F.Mull.)C.Ag. lr Suborder Teloschistineae Teloschistaceae Caloplaca elegans (Link.)Th.Fr. lr Teloschistes flavicans (Sw.)Norm. 4b Xanthoria parietina (L.)Th.Fr. lr Suborder Peltigerineae Peltigeraceae Peltigera dolichorhiza (Nyl.)Nyl. 2s 3s Stictaceae Pseudocyphellaria aurata (Sm.) Vainio 3br P. colensoi (Bab.)Vainio lr 2r 3b P. coriacea (Hook f. & Rayl.) Galloway & James 3b 4r P. crocata (L.)Vainio 3r 4r P. delisea (Fee)Galloway & James 4br P. episticta (NyL)Vainio 3b 4b P. faveolata (Del.)Malme 3br 4br • P. flavicans (Hook f. & Tayl.)V«inio 3br 4b P. intricata (1 )el.)Vainio 3b

128 P. lividofusca (Krempelh.)Filson 3r P. montagnei (Bab.)Galloway & James 3b 4b P. cf. polyschista (Mey. & Flot.)Zahlbr. 3br 4b P. psilophylla (Mull.Arg.)Galloway & James 4br Sticta subcaperata Nyl. 2b S. fuliginosa (Dicks.)Arn. 2b 3r S. latifrons Rich. 2br 4br Suborder Physciineae Physciaceae Buellia stellulata (Tayl.)Mudd. 2r Hue ilia sp. lr Heterodermia cf. dendritica (Pers.)Poelt. lr 2r 3b H. japonica (Sato) Swinsc. & Krog. 2r 3b 4br II pseudospeciosa (Kurok.)Culb. lr 2r 3b 4b H. speciosa (Wulfen)Trevisan lr Suborder Pertusariineae Pertusariaceae Pertusaria spp. lr 3b 4b ORDER GYALECTALES implexum Nyl. 4b ORDER Suborder Ostropineae Thelotramaceae Thelotrema lepadinum (Ach.)Ach. 3b 4br Suborder Graphidineae Graphidaceae Graphina monospora (Knight)MulLArg. 4b G. novaezelandiae (Knight)G. Hayward 4r Graphis inquinata (Knight & Mitt.)Hook f. 2b Phaeographis australiensis Mull.Arg. 2b P. exaltata (Mont. & v.d. Bosch)Mull.Arg. 4b ORDER SPHAERIALES Porinaceae exocha (Nyl.)MulLArg. 4br Pyrenulaceae Pyrenula knuthii (Fee)Fee 4b Pyrenula sp. 2b 4b ORDER VERRUCARIALES Verrucariaceae maura Wahlenb. ex Ach. lr ORDER ARTHONIALES Opegraphaceae Opegrapha agelaeoides Nyl. 4b O. diaphoriza Nyl. lr

RESULTS

Fruticose lichens The black, tufted lichen Lichina confinis is confined to intertidal rhyolite rocks (exposed in the north end of Shag Bay) but does not occur on the softer, more crumbly ignimbrites and pyroclastic rocks that comprise most of the island. The fruticose genus Ramalina grows in abundance on rocks in the maritime zone. R. geniculate and R. myrioclada were only found in this zone, but R. linearis also occurs on rocks in grassland and in clearings in kanuka forest. The reindeer lichen Cladia aggregate, the small tufted Gymnoderma melacarpa and the common soil-inhabiting genus Cladonia are most

129 abundant on soil on the open cliff tops, but occasionally occur on rocky soil in the maritime zone or in canopy gaps in the kanuka forest. Clumps of Stereocaulon ramulosum frequently occur on rocks on the open cliff tops, in the maritime zone or beneath kanuka forest. Short, stumpy Baeomyces is restricted to weathered rocks beneath the semi-open canopy of kanuka forest. Species of old man's beard lichen (Usnea) occur sporadically in many habitats but particularly on cliff top rocks and on kanuka bark. The orange, pendulous Teloschistes flavicans occurs in low abundance in the canopy of mixed coastal forest.

Foliose lichens Yellow Xanthoria parietina, orange Caloplaca elegans and brown, squamulose Peltula euploca are all restricted to maritime rocks, whereas the grey Peltigera dolichorhiza is a soil inhabiting lichen found mostly beneath kanuka forest. Within the large foliose family Parmeliaceae, Pseudoparmelia spp., Neofuscelia spp., Parmelia erumpens and Parmotrema reparatum were found mainly on maritime rocks; Parmotrema cetratum, P. perlatum, P. reticulatum, Xanthoparmelia australasica and X. furcata occur commonly on both rock and bark in a wide variety of habitats from open maritime and cliff top situations to semi-open canopied coastal forest areas; Hypogymnia subphysodes and Parmelina horrescens were only found on rocks, whereas Menegazzia circumsorediata, Parmelia cunninghamii and Parmotrema crinitum are confined to bark in kanuka and mixed forest. Foliose members of the Physciaceae are common on both rock and bark in the open and in semi-open canopied locations. The majority of Stictacean species are restricted to forest habitats where they occur on both rocks and bark. The three Sticta species also grow on bark in open cliff top situations and Pseudocyphellaria colensoi was the only Stictacean recorded from the maritime zone. Lichens of the families Coccocarpiaceae, Collemataceae, Pannariaceae and Placynthiaceae only occur in forest areas, mostly on bark but some also on rock. Leioderma and Psoroma cf. athroophyllum were only found on rock.

Crustose lichens Verrucaria maura and Opegrapha diaphorhiza are restricted to rocks in the marine and maritime zones respectively. Candelariella spp. were only recorded from rocks in the open and Graphina novae-zelandiae on rocks beneath the canopy of coastal forest. Species of Pertusaria and Lecanora occur on both rock and bark in a wide variety of habitats from open maritime zone to beneath the semi-

130 open canopy of coastal forest. Graphis inquinata and Phaeographis australiensis occur on bark on the open tops of high cliffs Lecideaceans and Thelotrema lepadinum were found on both bark and rock in kanuka and mixed coastal forest. Brigantiaea chrysosticta, Pyrenula spp., Opegrapha agelaeoides, Phaeographis exaltata and Graphina monospora all occur on bark in semi-open canopied coastal forest, whereas Clathroporina exocha is restricted to darker locations beneath dense canopied forest where it is found on both bark and rocks.

DISCUSSION

Floristic diversity In this paper we record 124 species of lichens from 50 genera from Rakitu Island. This diversity is greater than that found on most other northern offshore islands, is comparable to that of Hen Island and the eastern Bay of Islands and considerably less than that of the much larger and higher Little and Great Barrier Islands (pers. obs.). The greater diversity of the lichen floras of Rakitu, Hen and Little Barrier Islands reflect the diversity of habitats present (from open grassland through regenerating kanuka forest to patches of pristine forest) and also their greater altitude than most other islands studied. A flora of 124 species represents about 50% of the lichen taxa recorded from offshore islands of northern New Zealand and about 30% of the taxa known to occur in New Zealand north of Auckland. On Rakitu Island we found 20 of the 32 species of Parmeliaceae so far recorded from northern offshore islands, 7 of the 15 species of Graphidaceae and Opegraphidaceae and 16 of the 27 species of Stictaceae.

New records (Fig. 2) These records of Graphina monospora and G. novaezelandiae are only the third specimens of each identified and the first North Island record of the former species. The Rakitu flora also contains the first records from an offshore island of northern New Zealand of Candelariella spp., Phaeographis exaltata, Megalospora allani, Coenogonium implexum, Pseudocyphellaria delis ea, P. Lividofusca, Pannaria periptera, Psoroma microphyllizans, Ramalina geniculata, Gymnoderma melacarpa, Parmelia erumpens, Parmotrema reparatum and Hypotrachyna formosana. The last two species have rarely been recorded from New Zealand.

Comparisons with elsewhere The maritime and open cliff top flora of Rakitu is very similar to that found elsewhere around northern New Zealand, but the forest lichen

131 Fig. 2. Lichens from Rakitu Island: a selection of those recorded from the first time from an offshore island of northern New Zealand; a. Graphina monospora, b. Hypotrachyna formosana, c. Pannaria periptera, d. Phaeographis exaltata, e. Psoroma microphyllizans, t. Pseudocyphellaria lividofusca. Scales with 1 mm divisions or a 17 mm diameter coin. flora is better developed than most other northern offshore islands. Several species (e.g. Brigantiaea chrysosticta, Coenogonium implexum, Megalospora allani, Parmeliella nigrocincta, Pseudocyphellaria delisea, P. montagnei, Sticta latifrons) that are characteristic of the flora of mixed broadleaf - podocarp forest of less coastal localities of North Auckland, are also present on Rakitu. These taxa are mostly found on Rakitu in forest growing above 150 m A.S.L. and usually on landward facing slopes, away from the influence of salt spray.

132 ACKNOWLEDGEMENTS

We would like to thank all members of the Offshore Islands Research Group trip to Rakitu Island for their assistance in the field. We are grateful to Mason Hale (Smithsonian Institution) and David Galloway (British Museum) for the identification of a number of the more unusual records.

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