PROVISIONAL ATLASof the

MARINE ALGAEof

BRITAIN & IRELAND

Edited for theBritish Phycological Society

byProfessor T.A. NORTON(University of Liverpool)

1985

BIOLOGICAL RECORDS CENTRE

Monks Wood Experimental Station

nstitute of Terrestrial Ecology, Nature Conservancy Council,donks Wood Experimental Station, Northrninster House,iuntingdon. Peterborough

á

NATURAL ENVIRONMENT RESEARCH COUNCIL

INSTITUTE OF TERRESTRIAL ECOLOGY

PROVISIONAL ATLAS

OF THE

MARINE ALGAE

OF BRITAIN AND IRELAND

Edited for the

British Phycological Society

by

Professor T A Norton(University of Liverpool)

1985

Institute of Terrestrial Ecology Nature Conservancy CouncilBiological Records Centre Northminster HouseMonks Wood Experimental Station PETERBOROUGHAbbots Ripton PEI lUAHUNTINGDON PE17 2LS

Printed in Great Britain byNERC Reprographics

C NERC Copyright 1985

Published in 1985 byInstitute of Terrestrial EcologyAdministrative HeadquartersMonks Wood Experimental StationAbbots RiptonHUNTINGDONPE17 2LS

ISBN 0 904282 89 9

The Institute of Terrestrial Ecology (ITE) was established in 1973,from the former Nature Conservancy's research stations and staff,joined later by the Institute of Tree Biology and the Culture Centreof Algae and Protozoa. ITE contributes to, and draws upon, thecollective knowledge of the 13 sister institutes which make upthe Natural Environment Research Council, spanning all theenvironmental sciences.

The Institute studies the factors determining the structure,composition and processes of land and freshwater systems, and ofindividual plant and animal species. It is developing a sounderscientific basis for predicting and modelling environmental trendsarising from natural or man-made change. The results of this researchare available to those responsible for the protection, management andwise use of our natural resources.

One quarter of ITE's work is research commissioned by customers, suchas the Department of Environment, the European Economic Community, theNature Conservancy Council and the Overseas DevelopmentAdministration. The remainder is fundamental research supported byNERC.

ITE's expertise is widely used by international organizations inoverseas projects and programmes of reiearch.

The Biological Records Centre is operated by ITE, andreceives financial support from the Nature ConservancyCouncil. It seeks to help naturalists and researchbiologists to coordinate their efforts in studying theoccurrence of plants and animals in the British Isles,and to make the results of these studies available toothers.

Biological Records CentreInstitute of Terrestrial EcologyMonks Wood Experimental StationAbbots RiptonHUNTINGDONPE17 2LS

048 73 (Abbots Ripton) 381

Foreword

Introduction

Methods

Geographical coverage

Selection of species iv

Uses of the data bank iv

Future recording

Acknowledgements vi

References vii

Distribution maps

Map 1 Coverage map

Maps 2-24 Chlorophyta

Maps 25-70 Phaeophyta

Maps 71-156 Rhodophyta

Index to maps

CONTENTS

Page

ii

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FOREWORD

This Provisional Atlas of the Marine Al ae of Britain and Ireland isthe result of the dedicated efforts of many people. Whilst part ofthose efforts was directed specifically at providing data for theBritish Phycological Society'sMarine Algal Recording Scheme, asubstantial amount of the data used was extracted from informationassembled for other purposes. Nevertheless, all the distributionalrecords, from whatever source, have been assessed and validated beforetheir incorporation into the data base summarized in this Atlas. Mostof the recorders, both professional and amateur, have given their timeand data freely. The true economic cost of collecting and collatingthis information by any other means would have been prohibitive.

As indicated in the Introduction, the BPS Marine Algal RecordingScheme is to continue until it is reckoned that there are sufficientspecies distribution data to prepare a definitive Atlas. Anadditional objective is to record the location of species with moreprecision, together with some indication of the habitat type, so thatthe information base for the final Atlas is of even greater use thanthis provisional atlas. In particular, such information will be ofconsiderable use to the Nature Conservancy Council in preparing theproposed Marine Nature Conservation Review of Great Britain. As withits terrestrial counterpart, the purpose of this review will be toclassify and describe the range of marine habitats, communities andspecies and identify those sites considered to be of the highestimportance and which should be conserved ie as Sites of SpecialScientific Interest, National Nature Reserves or, especially, MarineNature Reserves. This Review will also act as a basis for advice onthe wider marine environment. For many habitats, the marine algalcommunities will be the prime attributes used in classifying andassessing sites. We therefore hope that this extra and importantrequirement in field recording will provide a new interest and,indeed, a stimulus to the next phase of marine algal recording toachieve the final Atlas.

We record our particular thanks to the Biological Records Centre atMonks Wood for applying their experience and expertise to thecollation and presentation of the data and the publication of thisAtlas. However, without the considerable effort of Professor TrevorNorton and the recorders of the British Phycological Society, thisAtlas could not have been produced; we are indebted to them.

Dr Roger MitchellSarah Fowler

Chief Scientist DirectorateNature Conservancy Council

INTRODUCTION

A Marine Algae Recording Scheme was launched by the BritishPhycological Society (BPS), in conjunction with the Biological RecordsCentre (BRC), in 1971. The aim of the scheme, organised by ProfessorT A Norton, is to map the distribution of the British seaweeds. Itcovers all the benthic members of the Chlorophyta, Phaeophyta andRhodophyta, plus the genus Vaucheria (Xanthophyta). Only attachedseaweeds are recorded, drift plants being ignored as their provenanceis unknown. A Preliminar Atlas of fifteen species was published byBRC in 1978; since then recording has progressed steadily and aProvisional Atlas of 155 taxa can now be published.

Methods

The seaweeds, limited by their requirements for both light and secureattachment, are largely confined to shallow waters close inshore.Therefore their distribution, like that of terrestrial organisms, canbe recorded and mapped using the Ordnance Survey National GridReference System for Great Britain, the Suirbheireacht Ordonais/Ordnance Survey National Grid for Ireland and the Universal TransverseMercator Grid (Channel Islands).

A standard recording card was produced at the start of the scheme, andwas used for field recording by an enthusiastic group including bothprofessional phycologists and amateur collectors. In addition,records have been extracted from the herbarium of the Department ofBotany, University College, Galway (GALW), and from papers publishedsince 1950.

The accumulated record cards were passed over to BRC towards the endof 1982, and put on to computer file in 1983-84. The following data(if provided by the original recorder) were included for each record:species code number, site name, grid reference (in full), date ofrecord, code number of recorder, source of record. In addition,records made during Nature Conservancy Council (NCC) surveys and heldby NCC on computer file were made available to BRC and incorporatedinto the data bank. Most of the data processing at BRC was carriedout by Francesca Griffith and Mrs D M Greene.

Maps of all species were plotted from the resulting data. These mapswere examined by T A Norton and R Mitchell (NCC) and 155 were selectedfor inclusion in a Provisional Atlas. The presence of a dot on themap indicates that there is at least one record from that 10 kmgridsquare. Only records dating from 1950 onwards have been maPped,although some older records are included in the data bank.

Geo ra hical covera e

Records have now been received for about 80% of the approximately 1120squares covering the coastline of the British Isles (map 1). Irelandis the most poorly covered region, especially the north-west althoughthis area offers some of the most promising collecting grounds in theBritish Isles.

For a frequently encountered species that is readily identifiable, upto 1000 independent records have been received. However, as there isoften more than one record from a given 10 km square, there may beonly 500-600 dots on the map.

Selection of s ecies

The 155 species mapped in this Atlas were selected to indicate theprogress of the scheme and to stimulate collecting in areas whererecords are sparse or completely lacking. The maps are also intendedto draw attention to the distribution patterns that are emerging sothat they may be verified or challenged by collectors deliberatelysearching for species beyond their recorded limits.

Some poorly recorded species have been included to draw attention tothe neglect that befalls species that are critical or are laborious toidentify, eg the calcareous crustose Rhodophyta Dermatolithoncorallinae (map 99) and Ph tolithon lenormandii (map 135). Speciesthat produce small, inconspicuous plants, eg M rionema stran ulans(map 58), or that inhabit cryptic habitats, eg Tellamia intricata (map21) and parasitic plants, eg Choreocolax ol si honiae (map 139) arerarely noted in passing but are usually present if looked for.

A remarkable feature of the maps is the number of species which appearto reach their geographical limits in the British Isles, a regionwhich occupies a latitudinal range of little more than 10°. In thecaptions to the maps, the terms 'northern' and 'southern' refer to thedistribution of the species outside the British Isles.

Uses of the data bank

It is clear that we now have a more detailed knowledge of thedistribution of seaweeds around the British Isles than in any othercomparable region.

Detailed records, such as those now available in the data bank, are anessential prerequisite if we are to monitor the changes that occur incoastal waters. Some species have retreated in the face of industrialpollution: many species no longer grow far into the Firth of Forth orthe Tees estuary where once they thrived. On the other hand,introduced invasive species are expanding their ranges. A strikingrecent example is Sar assum muticum, a Japanese species first found inBritain in 1971 but now firmly established all along the south coastof England and on the coast of continental Europe from The Netherlandsto Brittany.

There are other indications that our coastal vegetation may bechanging faster than we appreciate. In recent years divingphycologists have added dozens of species to the British flora.Usually, however, it is difficult to be sure that these additions arereally newcomers to our shores rather than long established residentsthat awaited discovery in rarely visited sites. The maps in thisAtlas are merely a manifestation of a large and growing repository ofdistributional data that will serve as the reference against which allfuture records can be compared.

iv

Future recordin

The BPS recording scheme will continue, with a view to the enlargementof the data bank and the publication of a final Atlas containing mapsof all species. It is hoped that all future records will includefull details of locality, grid reference, recorder and date so as toenhance the quality of the data in the data bank. Further details canbe obtained from Professor T A Norton, Department of Marine Biology,Port Erin, Isle of Man.

v

ACKNOWLEDGEMENTS

First and foremost I would like to thank the British PhycologicalSociety under whose auspices the scheme was inaugurated. Although Iam most grateful for every record received, it would be remiss not tomention those who as regular recorders, referees, or advisers havecontributed so much to the scheme. I am particularly indebted to thefollowing: D. Ballantine, G.T. Boalch, the late M.C.H. Blackler,E.M. Burrows, H.L. Caldwell, Y.M. Chamberlain, O.F. Conran, J.Cremona, I.C. Cross, F. Dipper, P.S. Dixon, W.F. Farnham, M.D. Guiry,N. Hammond, F.G. Hardy, R. Harvey, J. Hayward, C.G.L. Hepton, S.Hiscock, D.E.G. Irvine, L.M. Irvine, J.M. Jones, S.J.T. Knight, K.Kozicki, C.A. Maggs, R. Merritt, O. Morton, E. Pickervance, C. Pybus,C. Roden, M. Scannell, M.McL. Smith, D.A. Strand, I. Tittley, S.M.Turk, M. de Valera, A. Wallace. Finally my sincerest thanks areextended to the the members of the Biological Records Centre and theNature Conservancy Council whose advice and help made this Atlaspossible; in particular Christopher D. Preston and Roger Mitchell, andFrank Perring, now of the Royal Society for Nature Conservation.

vi

REFERENCES

Adey, W.H. & Adey, P.J. 1973. Studies on the biosystematics andecology of the epilithic crustose Corallinaceae of the BritishIsles. Br. phycol. J., 8, 343-408.

Critchley, A.T., Farnham, W.F. & Merrell, S.L.A. 1983. A chronologyOf new European sites of attachment for the invasive brown alga,Sar assum muticum 1973-1981. J. mar. biol. Ass. U.K., 63,799-812.

Cullinane, J.P. & Whelan, P.M. 1981. The ecology and distribution ofSteno amne interru ta (C. Agardh) Montague ex Harvey on thecoast of Ireland. Proc. R. Ir. Acad. B, 81, 111-116.

Guiry, M.D. 1975. An assessment of Palmaria palmate forma mollis (S.et G.) comb. nov. Rhod menia almata forma mollis S. et G.) inthe eastern North Pacific. Syesis, 8, 245-261.

Guiry, M.D. 1977. Studies on marine algae of the British Isles 10.The genus Rhodymenia. Br. phycol. J., 12, 385-425.

Guiry, M.D. & Hollenberg, G.J. 1975. Schottera gen. nov. andSchottera nicaeensis (Lamour. ex Duby) comb. nov. Petroglossum nicaeense (Lamour. ex Duby) Shotter) in the British Isles. Br.phycol. J., 10, 149-164.

Hiscock, S. & Beggs, C.A. 1982. Notes on Irish marine algae - 6.Zanardinia roto s (Nardo) Nardo. Ir. Nat. J., 30, 414-416.

Hiscotk, S. & Maggs, C.A. 1984. Notes on the distribution and ecologyof some new and interesting seaweeds from south-west Britain.Br. phycol. J., 19, 73-87.

Irvine, D.E.G., Guiry, Tittley, I. & Russell, G. 1975. New andinteresting marine algae from the Shetland Isles. Br. phycol. J., 10, 57-71.

Jephson, N.A., Fletcher, R.L. & Berryman, J. 1975. The occurrence ofZanardinia roto us on the south coast of England. Br.phycol. J.,10,253-255.

McLachlan, J., Chen, L.C.-M. & Edelstein, T. 1969. Distribution andlife history of Bonnemaisonia hamifera Hariot. Proc. Int. Seaweed S . 6th Santi o de Com ostela 1968, 245-249.

Beggs, C.A. & Guiry, M.D. 1982a. Notes on Irish marine algae - 5.Preliminary observations on deep water vegetation off westDonegal. Ir. Nat. J., 20, 357-361.

Mama, C.A. &-Guiry, M.D. 1982b. The taxonomy, morphology anddistribution of species of Scinaia Biv.-Bern. (Nemaliales,Rhodophyta) in north-western Europe. Nord. J. bot., 2, 517-523.

Magna, R. 1980. Laurencia lat ce hala Rae. (Rhodophycée) espècemiconnue des cates de la Manche. Cah. Biol. Mar., 21, 227-237.

Mitchell, R., Earll, E.G. & Dipper, F.A.1983. Shallow sublittoralecosystems in the Inner Hebrides. Proc. R. Soc. Edinb.B, 83,161-184.

vii

Norton, T.A.1977. Experiments on the factors influencing thegeographical distributions of Saccorhiza ol schides andSaccorhiza dermatodea. New Phytol.,78,625-635.

Norton, T.A.1978. Mapping species distributions as a tool in marineecology. Proc. R. Soc. Edinb. B, 76,201-213.

Norton, T.A. & Mathiesan, A.C.1983. The biology of unattachedseaweeds. In: Pro ress in h colo ical research vol. 2, editedby F.E. Round & D. Chapman, 333-386. Amsterdam: ElsevierBiomedical Press.

Norton, T.A. & Parkes, H.M.1972. The distribution and reproductionof Pterosi honia com lanata. Br. phycol. J., 7, 13-19.

Powell, H.T.1957. Studies in the genus Fucus L. II. Distributionand ecology of forms of Fucus distichus L. emend. Powell inBritain and Ireland. J. mar. biol. Ass. U.K.,36, 663-693.

Price, J.H., Tittley, I. & Richardson, W.D.1979. The distribution ofPadina avonica (L.) Lamour. (Phaeophyta, Dictyotales) onBritish and adjacent European shores. Bull. Br. Mus. Nat.Hist.,7, 1-67.

Prud'Howne van Reine, W.F. 1982. A taxonomic revision of the Euro eanPhaeo h ceae). Leiden: E.J.Sphacelariaceae (S hacelariales

Brill/Leiden University Press.

Van den Hoek, C. 1979. The(Chlorophyceae) in the northernthat of other benthic algalMeeresunters.,32, 374-393.

evidence from life history studies.Meeresunters.,35, 153-214.

viii

phytogeography of Cladophora Atlantic Ocean, in comparison tospecies. Hel oländer wiss.

Van den Hoek, C. 1982a. Phytogeographic distribution groups of marinealgae in the North Atlantic Ocean. A review of experimental

Hel oländer wiss.

Van den Hoek, C. 1982b. The distribution of benthic marine algae inrelation to the temperature regulation of their life histories.Biol. J. Linnean Soc. Lond.,18, 81-144.

á

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Map 1 Coverage map The map shows all squares from which atleast one record has been received.

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Map 2 Blidingia minima (Nag. ex Kiltz.) Kylin Quite acommon species especially on the upper shore, butoften overlooked owing to its superficial resemblanceto a small Enteromorpha.

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Map 3 Bryopsis plumosa (Huds.) C. Ag. A distinctivespecies but under-recorded because, living on thesides of deep pools and under overhanging ledges, itis easily overlooked.

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Map 4 Chaetomorpha linun (0.F. Mull.) Kiitz. A widespreadpool-dweller, probably under-recorded because of aspurious belief that it is difficult to differentiatefrom other species in the genus.

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Map 5 Chaetonorpha melagonium (Web. et Mohr) Katz. Adistinctive large-celled species frequently overlookedbecause it tends to occur as scattered individualfilaments.

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Map 6 Cladopbora butchinsiae (Dillw.) Kiitz. One of themore distinctive, but rarer, subtidal species ofCladophora. Locally abundant in the south. See vanden Hoek (1979).

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See van den Hoek (1979).

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Cladophorapellucida (Huds.) Klitz. A verydistinctive species usually inhabitingthe shallowsubtidal zone or lower shore pools. Far morecommonthan formerly thought, especially in the southwest.

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Map 8 Cladophora rupestris(L.) Kiitz. One of the commonestgreen algae found around our shores, but woefullyunder—recorded in Ireland. See van den Hoek (1979,1982a). The map illustrates the unsuitability for arock—dwelling seaweed of the sandy and muddy beacheson the east coast of England and bordering the IrishSea.

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Map 9 Cladophora sericea (Huds.) Kiitz. A common species,under-recorded because it is difficult to distinguishfrom other species of Cladophora with confidence. Seevan den Hoek (1979, 1982a).

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Map 10 Codium fragile(Sur.) Hariot subsp. atlanticum(Cotton) Silva A widespread subspecies beingsteadily displaced from the south by Codium fra ilesubsp. tomentosoides (map 11).

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Map 11 Codium fragile (Sur.) Hariot subsp. tomentosoides(Goor) Silva An introduced taxon that probably cameto Britain in the 1940s. It seems to have spreadprogressively northwards and is now locally abundant,especially in the south. To some extent its invasionwas overlooked because of the plant's superficialsimilarity to the other Codium species that itdisplaced. See Norton (1978).

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Map 12 Codiun tonentosumStackh. Generally less commonthan C. fragile and only distinguishable from itunder the microscope.

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Map 13 Codium vermllara (Olivi) Chiaje Another speciessuperficially similar to those preceding, but is isdistinct under the microscope and seems to have amore restricted distribution.

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Map 14 Enteroaorpha intestinalis(L.) Link A ubiquitousspecies that now includes E. compressa. Veryunder-recorded in Ireland.

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Map 15 Enteroaorpha prolifera(0.F. Will.) J. Ag. A fairlycommon species which is under—recorded, especially inIreland, perhaps because it is often intermingledwith other species of Enteromorpha and thereforeoverlooked.

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Map 16 Epicladia perforans(Huber) R. Nfelsen A tiny plantwhich forms inconspicuous patches in shells,especially those of periwinkles, Littorina spp. Itis therefore not surprising that it is rarelyrecorded.

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Map 17 Percursaria percursa(C. Ag.) Rosenv. Inconspicuousfilaments only distinctive under the microscope,therefore probably very under-recorded.

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Map 18 Prasiola stipitata Suhr Although unmistakable underthe microscope and forming a distinctive band at thetop of the shore, the species is an ephemeral andtherefore under-recorded.

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Map 19 Rhizoclonium ripariva (Roth) Harv. A veryunder-recorded plant, especially in Ireland, althoughwith the aid of a microscope it is readilyidentified.

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Map 20 Spongomorpba arcta (Dillw.) Katz. This species isso frequently encountered in Scotland and in southwest England that the sparsity of records in betweenis inexplicable, although it could be limited toclean water and exposed shores. See van den Hoek(1982a).

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Map 21 intricataBatt. A distinctive and probablycommon plant but rarely recorded because it is onlyfound beneath the superficial membrane covering theshells of flat periwinkles of the genus Littorina.

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Map 22 Ulothrix flacca (Dillw.) Thur. A common intertidalalga, under-recorded because it is recognisable onlyunder the microscope and is often mixed with largerplants of other species.

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Map 23 Ulva lactuca L. The records for this nearlyubiquitous species clearly illustrate howunder—recorded much of Ireland is for the greenseaweeds.

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Map 24 Ulva rigida C. Ag. This species of often overlookedbecause only under the microscope can it bedistinguished from U. lactuca. It is neither rarenor confined to the extreme south of Britain asformerly thought.

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Map 25 Ascophyllum nodosum (L.) Le Jol. Except on exposedcoasts this is one of the dominant and most easilyrecognised of the intertidal brownseaweeds.The mapillustrates the unsuitability for a rock-dwellingplant of stretches of sandy or muddy coast.

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Map 26 Bifurcaria bifurcata Ross A pool-dwelling'southern' species of sheltered shores. Itpenetrates further north on the Welsh coast than waspreviously known.

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Map 27 Chorda filum (L.) Stackh. A distinctive widespreadand locally abundant species, but its distribution isrestricted by a propensity to grow only on pebblesand shell fragments in sheltered localities.

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Map 28 Chorda tomentosa Lyngb. Probably a fairly uncommonspecies. No doubt it is often overlooked because itresembles a young C. filum, although its halo ofhairs is distinctly golden.

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Map 29 Cladostephus spongiosus(Huds.) C. Ag. This speciesnow includes C. verticillatus (Lightf.) C.Ag. Afairly common plant, especially in tide pools andchannels.

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Map 30 Cutleria aultifida (Sm.) Grey. Although foundthroughout the length of the British Isles, thisspecies is very rare in the north. It usually occurson sublittoral stones.

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Map 31 Aglaozonia parvula (Grev.) Zanard. Not a truespecies, but merely a distinct diploid phase in thelife history of Cutleria multifida (map 30). UnlikeCutleria is it probably quite common all around theBritish Isles, but as it forms fairly inconspicuousprostrate membranes creeping on subtidal rock it isfrequently overlooked.

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Map 32 Cystoseira baccata (Gmel.) Silva A 'southern'species of limited distribution, but locally abundantsubtidally or in pools. The most striking andreadily identified of our Cystoseira species.

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Map 33 Cystoseira foeniculacea (L.) Grey. A fairly rarespecies in the British Isles and with a restricteddistribution. Usually found in pools low on theshore.

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Map 34 Cystoseira nodieaulis (With.) M. Roberts Anuncommon species with a restricted distribution.Usually subtidal, but occasionally in tide pools.

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Map 35 pystoseira tamariscifolia (Huds.) Papenf. The mostwidely distributed of the Cystoseira species found inBritain. Locally abundant in the south.

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Map 36 Desmarestia aculeata (L.) Lamour. One of thecommonest and most distinctive of the larger subtidalbrown algae. It is particularly abundant in areas ofboulders with intermittent sand scour.

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Map 37 Desnarestia ligulata (Lightf.) Lamour. A verydistinctive subtidal plant of widespread occurrence,but far less common than D. aculeata (map 36). Seevan den Hoek (l982a).

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Map 38 Dictyopteris sembranacea (Stackh.) Batt. Thisspecies is locally abundant in the south, especiallyin deep water in the kelp forest and just beyond thelower limits of the Laminaria forest. Thenorthernmost record is for the Hebridean island ofColl which seems to support an outlying enclave ofsouthern species (see Mitchell et al. 1983).

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Map 39 Dictyota dichotoma (Huds.) Lamour. A widespread andcommon species thriving in tide pools and throughoutthe subtidal zone. Its apparent absence from much ofthe east coast of England requires verification. Seevan den Hoek (1982a).

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Map 40 Ectocarpus siliculosus(Dillw.) Lyngb. One of thecommonest of the small brown algae, but oftendifficult to distinguish from E. fasciculatus andtherefore not always recorded.

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Map 41 Elachista fucicola . (Vell.) Aresch. Probably thecommonest epiphyte infesting Fucus plants. It isconspicuous in summer, but not so in winter.

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Map 42 Fucus ceranoides L. A distinctive species confinedto estuaries, places where freshwater runs over theshore and other brackish—water habitats. Irregularswellings on the thallus, caused by exposure tofreshwater, may give it a very superficialresemblance to Fucus vesiculosus.

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Map 43 Fucus distichus L. subsp. anceps (Marv. et Ward exCarr.) Powell A 'northern' taxon confined to veryexposed and wave-battered shores (see Powell, 1957).It superficially resembles Pelvetia canaliculata (map60) when seen on the shore, but is quite distinctiveif examined closely.

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Map 44 Fucus serratusL. An easily recognised species thatusually dominates the lower intertidal on all but themost exposed and most sheltered shores.

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Map 45 Fucus spiralisL. One of the commonest high—shoredwelling brown algae, but probably somewhatunder—recorded as it is not always easy to identifywith certainty unless fertile.

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Map 46 Fucus vesiculosusL. One of the commonest of thelarge intertidal brown algae. Its characteristicbladders are, however, not developed in wave-exposedsituations and therefore it is sometimes overlookedor misidentified.

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Map 47 Fucus muscoides (Cotton) Feldm. et Magne Smallsterile plants forming a moss-like cushion on saltmarshes. It is not known whether it is really adistinct species or just a stunted growth form of a'normal' Fucus. See Norton & Mathieson (1983).

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•

•

Map 48 Halidrys siliquosa (L.) Lyngb. A distinctive andcommon pool-dweller. It also forms a zone in thesublittoral below the lower limit of Laminaria hyperborea in many places. The common name 'Sea Oak'is very misleading,DUE the plant is easilyrecognised by its seedpod-like gas bladders.

9 KM 190

MILES 100

•

•

Map 49 Halopteris filicina(Grat.) Katz. This small, butattractive, plant is an inconspicuous and oftenoverlooked component of the under-flora beneath theLaminaria forest.

KM 190

MILES 100

•

'stt,W

Map 50 Halopteris scoparia (L.) Sauv. This species isfound in the subtidal and in sandy pools on the lowershore. It is fairly common in the south, but muchrarer further north.

I Kr, 100100PI/LES

4

•

•

•

‘18e.

•

Map 51 Hiaanthalia elongata (L.) S.F. Gray Probably themost distinctive of all brown algae. It seems to bemuch less common on the east coast of England thanelsewhere, but this needs verification.

•9 KM 1',0

100MILES

°es

•

•

•

'4ge

•

Map 52 Laminaria digitata (Huds.) Lamour. Usually the

dominant alga at, and just below, low water mark.

Absent from stretches of coast which consist of muddy

and sandy shores unsuitable for rock-dwelling

seaweeds. See van den Hoek (1982b).

0 Km 100

0 MILES 100

1

•

•

•

• •

•

Map 53 Lamlnaria hyperborea (Gunn.) Fosl. The dominantforest-forming seaweed in the subtidal zone. As formost brown algae, Ireland is vastly under-recorded.See van den Hoek (1982b).

1 0 0

1 0 0

•

•

Map 54 Laminaria ochroleuca Pyl. A pale-colouredlaminarian that spread from France in about 1943, butseems to have extended its range very little since.See Norton (1978) and van den Hoek (1982b).

KIt

/11LES

100100

•

0}

•

•

•

•

Map 55 Laminaria saccharina (L.) Lamour. A common anddistinctive alga in lower shore tide pools and on therock from low watermark downwards, especially inslightly sheltered sites. In the sublittoral it ischaracteristic of intermittently disturbed sites.See van den Hoek (1982b).

0 „ 100

0 MILES 100

•

•

evf•

•

Map 56 Leathesia difformis(L.) Aresch. This species isfairly common on many shores. Its apparent absencefrom most of the east coast of England requiresverification.

9 KM 1°°

MILES 100

3

•

•

•

Map 57 Litosiphon laulnariae (Lyngb.) Harv. Tinyinconspicuous tufts on Alaria. Easily overlookedand, in consequence, probably grossly under-recorded.

0 ICM '9n

MILES 100

3

•

•

•

Map 58 Myrionesa strangulans Grey. Tiny disc-likeepiphytic plants easily missed. Most conspicuous onUlva and often found if looked for.

Km 100

M/LE5 100

GGID

Map 59 Padina pavonia (L.) Lamour. A distinctive southernspecies occasionally (and probably dubiously)reported far beyond the northern limits of thedistribution shown on the map. See Price et al.(1979).

°

•

Km 190ooMILES

•

•

4.

Map 60 Pelvetia canaliculata(L.) Dcne et Thur. Adistinctive and common high shore dweller. Itsapparent scarcity on the east and south-east coastsof England requires investigation.

0 ,,,, 100

0 ' MILES100

•

le

SQ

•

Map 61 Pilayella littoralis (L.) Kjellm. One of thecommonest filamentous brown algae. Superficiallysimilar to Ectocarpus. Woefully under-recorded inIreland.

9 KM 19°

MILES 100

•

•

klr•

Map 62 Ralfsia spongiocarpa Batt. An under-recordedpool-dwelling brown crust.

0 1000 ' 100MILES

4

•

•

<Z2

Map 63 Saccorhiza polyschides(Lightf.) Batt. Even thoughit reaches its northern limit in Norway just south ofthe Arctic circle, its centre of distribution issouthern, and like many southern species it has apredominantly westerly distribution around theBritish Isles. See Norton (1977).

° KM 190MILES 100

Map 64 Sargassum nuticum (Yendo) Fensholt A japanesespecies that appeared on the Isle of Wight in 1973.It spread from France, where it was perhapsintroduced originally with oysters from the Pacific.This invasive plant is spreading inexorably along thesouth coast of England. Across the Channel its rangenow extends from Brittany to The Netherlands. SeeCritchley et al. (1983) and van den Hoek (1982b).

Km 100

NILES 100

"No

•

•

•

Map 65 Scytosiphon losentaria (Lyngb.) Link A distinctiveand common intertidal pool-dweller, most in evidencefrom winter to early summer. See van den Hoek(1982b).

KM "P

MILES 100

4

•0

•

<41e:

Map 66 Sphacelaria pluaulaZanard. A fairly distinctivebut inconspicuous deep water plant. Undoubtedlyuncommon, but even so, under-recorded. SeePrud'homme van Reine (1982).

KM 190

MILES 100

•

4vest;

Map 67 Stictyosiphon tortilis (Rupr.) Reinke Clearly a'northern' species, but its southern limits have notbeen established with any certainty.

9 KM 190MILES 100

:i•

Map 68 Stilophora rhizodes (Turn.) J. Ag. A 'southern'species locally common in the south of England. Itis reputed to occur much further north than the mapindicates, but this requires investigation.

KM

MILES

b .

100

100

•

•

Map 69 Taonia atonaria (Woodw.) J.Ag. A fairly distinctivespecies, locally abundant in the south but becomingprogressively rarer northwards. It is characteristicof places with intermittent sand scour.

MILES

KM "'CIloo

LI7

•

.K?

4114;

SII

Map 70 Zanardinia prototypus (Nardo) Nardo Although a'southern' species, the map reveals that it occursmuch further north and is rather more common thanpreviously thought. See Jephson et al. (1975) andHiscock & Maggs (1982).

100

MILES 100

,Z)

•

Map 71 Acrosorium reptans (Crouan frat.) Kylin This plant

is probably merely a prostrate creeping form of

Cry to leura ramosa (map 95). It is inconspicuous

and probably under-recorded.

° KM 10°

MILES 100

be

•

Map 72 Acrosorium uncinatum (Turn.) Kylin A subtidalspecies that is far less rare than formerly thought.It is particularly abundant at some wave-exposedsites in the shallow sublittoral. The hook-likeappendages on the thallus are very distinctivealthough Acrosorium re tans may also possess hookedmarginal proliferations.

0 100KM ia100 V1DP11LE

•

•

•

•

Map 73 Ahnfeltia plicata (Huds.) Fries A distinctivespecies. Its apparent absence from much of the eastcoast of England needs checking as this coast shouldnot be unsuitable for such a sand-tolerant plant.

KIM 190100MILES

ar

•

Map 74 Apoglossum ruscifoliumspecies whose apparentrequires investigation.subtidal zone either onLaminaria h berborea.

•

Turn.) J. Ag. A distinctiverarity on eastern coastsIt inhabits the shallowrock or on the stipes of

0 Km 1000 MIES ' 100

,

.*

'v.

f"--

111

.

.

Oi••

.a'

•

•

•

,,,

Map 75 Audouinella floridula (Dillw.) Woelkerling A commonfilamentous alga most characteristically foundbinding intertidal carpets of sand. It is moreeasily seen in winter, when the cover of otherspecies is reduced.

0 Km 100

MILES 100

••

(te

Map 76 Asparagopsis armata Marv. Since it was firstrecorded in the British Isles in 1939 this verydistinctive species seems to have consolidated itsposition on the south and west coasts. See Irvine et—al. (1975).

"et

9 KM 190100MILES

•

•

'gra

Map 77 Falkenbergia rufolanosa (Marv.) Schm. Not a truespecies, merely the distinct tetrasporic phase ofAs arago sis armata (map 76). Since its firstdiscovery in the British Isles in 1949 it has spreadprogressively northwards up the west coast,apparently independently of the Asparagopsis phase.It often occurs with the superficially similarTrailliella phase of Bonnemaisonia (map 78). SeeIrvine et al. (1975).

9 KM 190MILES 100

3

•

<4,

Map 78 Bonnemaisonia hamifera Hariot A distinctivespecies, probably of japanese origin. The firstcertain record for Britain was in 1893. Since thenit has spread northwards, apparently largely byvegetative means. See van den Hoek (1982a).

0, 100KM

MILES 100

:•

fig

•

•

•

Map 79 Trailliella intricata Batt. A distinctive butinconspicuous and therefore under-recorded plant.Not a true species, but merely the tetrasporic phaseof Bonnemaisonia hamifera (map 78). Since itsinitial discovery on the south coast of England in1890 it has extended its range, largely independentlyof the Bonnemaisonia phase. It is worth searchingthe subtidal for it in areas where it is sparselyrecorded, such as Ireland and the east coast ofEngland. See van den Hoek (1982a) and McLachlan etal. (1969).

-.09 KM 190

0 MILES 100 a,

I.

di

<7

Map 80 Bornetia secundiflora (J. Ag.) Thur. A verydistinctive, but uncommon, 'southern' species thathas a toe-hold in south-west England.

looMILlS '

a

•

17;

•

Map 81 Calliblepharis ciliata (Huds.) Kiitz. A subtidalplant. Like most 'southern' species it has a westerndistribution in the British Isles where it approachesits northern limit.

'No

•

9 KM 590100MILES

•

Map 82 Calliblepharis jubata (Good. et Woodw.) Kiltz. Adistinctive 'southern' species showing a westerndistribution similar to that of C. ciliata (map 81),a species with which it is easily confused. Aninhabitant of lower shore tide pools and the shallowsubtidal zone.

100KM

PIILEStoo

a .

Map 83 Callophyllis cristata (C. Ag.) Kiitz. A circumpolarspecies that extends south into northern Britain. Itseems to be rare, but it resembles Sphaerococcus andPlocamium and if confused with these species it mayhave gone unrecorded.

KM to,.MILES 100 ogs

SO

•

a •

Map 84 Callophyllis laciniata (Huds.) Kütz. A commonsubtidal species, generally distributed butapparently absent from much of the eastern half ofthe south coast of England.

-e•.00 .0

S.

f•-•-

•

•

Map 85 Callocolax neglectus Schmitz ex Batt. A tinyinconspicuous pale cushion, epiphytic and possiblyparasitic on Cello h llis laciniata (map 84), rarelyrecorded but often present if looked for.

Km 100

MILES 100

X

•

•

•

•

Vs

Map 86 Ceramlum rubrun (Huds.) C. Ag. This species isreally an aggregate embracing all the fully corticatenon-spiny species of Ceramium. It is very common,but is clearly under-recorded in Ireland.

".0

° KM 100 .‘70 100 Li?

MILES

•

cl

Map 87 Champia parvula (C. Ag.) Harv. This 'southern'species appears to be more restricted in itsdistribution than previously thought. Many earlierrecords in the literature are misidentifications ofCh locladia verticillata (map 89).

° KM 1 9 0' MILES 100

.*

NI

•

it

•

d

•

•

•

•

,atef

211

I

Map 88 Chondrus crispus Stackh. The sparsity of recordsfrom Ireland even for 'Irish Moss' is testimony tothe degree to which many common species areunder-recorded there. See van den Hoek (1982a).

KM

PIILES

100

100

• 11.

•

Map 89 Chylocladia verticillata (Lightf.) Bliding A'southern' species that is fairly common on westernshores, but rare on the east coast of England. It ismost commonly found in tide pools or in the subtidalzone.

á

á

9 KM 1°0100MILES

•

<7.

Map 92 Corynospora pedicellata (Sm.) J. Ag. A filamentousalga inhabiting deep pools and the subtidal zone.Only recognizable under the microscope and thereforeprobably under-recorded.

P nOKM *MP

100 (7?MUS

61.

•

<Z?

Map 93 Crouania attenuata(C. Ag.) J. Ag. An inconspicuousbut distinctive plant. Rare and with a very limiteddistribution in the British Isles.

á

á

„ 100

100MILES

e.

•

•

•

Map 96 Cystoclonium purpureum (Buds.) Batt. A 'northern'

species that is fairly common and widespread around

the British Isles.

9. KM 199MILES 100

•

Map 97 Dasya hutchinsiae Harv. An uncommon speciesconfined to intertidal pools and the subtidal zone onthe western coasts of the British Isles. Itsrecorded northern limit is off the Hebridean Islandof Coll, a region that seems to be the northernmostoutpost of many 'southern' species.

KM

MILES

1 0 0

4 100 044

,cY

•

•

•

•

•

l e:•

Map 98 Delesseria sanguinea (Huds.) Lamour. A common anddistinctive subtidal plant. In summer it is one ofour most beautiful seaweeds, but in winter it tendsto die back to the midribs. Its apparent scarcity onthe east coast of England requires investigation.

0. Km 100

MILES 100

4

`se

Map 99 Dernatolithon corallinae (Crouan frat.) Fosl. Asmall calcareous crust frequently found on Corallina officinalis (map 91) if searched for. Greatlyunder-recorded.

0 „ 100100MI LES

•

slt;r9;.>

•

Map 100 Wises carnosa (Schmidel) 0. Kuntze A common anddistinctive subtidal plant. Its apparent scarcityon the east coast of England requires investigation.

100

100MILES

•

Map 101 Drachiella spectabilis Ernst et J. Feldm. Thissubtidal plant is both more abundant and more widelydistributed than formerly thought. It is rarelyrecorded because, except in early summer when theplants display a striking blue iridescence, it isinconspicuous and easily overlooked. See Maggs andGuiry (1982a) and Hiscock and Maggs (1984).

KM 190MILES loo

'No

cl

•

Map 102 Dumontia contorts(S.C. Gmelin) Rupr. A 'northern'species common in British shores especially inintertidal pools. See van den Hoek (1982b).

100

MILES 100

•

•

•

3

•

•

dC4

;71

Map 103 Furcellaria lumbricalis (Huds.) Lamour. A'northern' species common and widespread around theBritish Isles. Found in the lower shore tide poolsand in the subtidal zone. Easily confused withPolyides rotundus.

-ee9 KM 190 0

100 VsMILES

•

•

K?

S if

Map 104 Gastroclonium ovatum (Huds.) Papenf. A distinctive'southern' species, fairly common on western shoresbut very rare on the east coast. Most often foundin lower shore tide pools or in the shallowsublittoral zone, especially on somewhat exposedcoasts.

100

NILES 100

Map 105 Gigartina acicularis(Wulf.) Lamour. A 'southern'species that is locally abundant in the south westof the British Isles. It is easily confused withseveral other species and therefore may sometimes beoverlooked.

0 „ 10,0

MILES 100

Map 106 Gigartina pistillata(S.G. Gmel.) Stackh. A'southern' species confined to south-westernshores. Unless cystocarps are present, it maysometimes be mistaken for Furcellaria or Polyides and therefore fail to get recorded.

a M lao100MILES

b6g•

Map 107 Gigartina teedii (Roth) Lamour. A cosmopolitaninhabitant of warm - temperate waters in thenorthern hemisphere, but rare in Britain.

0 100MM100MILES

Itcpf

Map 108 Gracilaria bursa—pastoris (S.G. Gmel.) Silva Aspecies widely distributed in warmer waters, butapparently rare in the British Isles. Found in theshallow subtidal zone on sheltered shores. It iseasily confused with G. verrucosa, a much commonerspecies, and may thus be overlooked.

1 0 0

0 100MILES

Map 109 Grateloupia dichotoma J. Ag. A widespread warm-water species occurring in south west Britain.The plants are quite small and not easy to identifywith certainty so may be under-recorded.

KM

MILKS

100

•

•

,trie

Map 110 Grateloupia filicina (Lamour.) C. Ag. A cosmo-politan species found in most warmer seas and,like several members of the genus, reaching itsnorthern limits around the British Isles.

9 KM 100100MILES

•

Map 111 Halarachnion ligulatum (Woodw.) Kiitz. A locallyabundant, largely deep water species. It should besearched for on the east coast where it may be morefrequent than present records suggest. The plantsare very variable in appearance and can be confusedwith Platoma unless examined microscopically.

»e

9 KM 100MILES

Map 112 Halopitys incurvus (Huds.) Batt. A distinctive'southern' species. Locally quite abundantsubtidally on the south coast of England and wellworth searching for in southern Ireland.

0 Km 100

0 MILES 100

•

•

Map 113 Halurus equisetifolius (Lightf.) Kütz. Adistinctive plant, locally abundant especiallysubtidally in the south but becoming progressivelyrarer northwards. Apparently very rare on the eastcoast.

0 „ 100

' MILES 100

.'•

5.•

• —

,

•

•

•

•C4

qtre;

tl t

,

Map 114 Heterosiphonia plumosa (Ellis) Batt. A beautifuland distinctive subtidal plant. Formerly consideredto be rare in Scotland, but in fact fairly commonoff western shores although uncommon on the eastcoast.

9 KM 100100

MILES

Map 115 Hildenbrandia crouanii J. Ag. Like all crustosealgae this species is almost certainly undet—recorded. It is certainly far less rare thanformerly thought.

9 K 1130

MILES 100

0Y,

•

•

Map 116 Hypoglossum woodwardii Kiitz. One of the more

distinctive red seaweeds. It is quite common in

Scotland although previously said to be rare. Found

from around low water mark downwards, often on the

stipes of Laminaria.

9 KM 100MILES

61'

•

•

•

Map 117 Kallymenia reniformis (Turn.) J. Ag. A 'southern'species with the usual westerly distribution aroundthe British Isles. Found in deep tide pools on thelower shore and in the subtidal zone, often on thestipes of Laminaria.

0 Km 190

0 MILES 100

U.

•

•

•

4.•

Map 118 Laurencia pinnatifida (Huds.) Lamour. One of thecommoner intertidal red algae. However, L.platycephala, a newly described species, is verysimilar (see Magne 1980) and all records must bechecked.

100

MILES 100

Map 119 Lithothamnion glacialeKjellm. An Arctic Oceanspecies reaching northern Britain (see Adey and Adey1973). It is a subtidal calcareous crust occurringon bed rock or pebbles or unattached as globularbranched ma6r1 or rhodoliths (see Norton andMathieson 1983). Like all crustose species it isprobably under-recorded.

0 Km 100

' 1001 MILES

.m.,

•

I

.

.

•

.

Map 120 Loaentaria articulata(Huds.) Lyngb. One of thecommonest and most distinctive of intertidal redalgae.

-

lie

II

I0 ,..„:`,7Es •4et

•

•

•

•

..,

Map 121 Losentaria clavellosa (Turn.) Gaill. A widespreadspecies sometimes confused with Gloiosiphonia capillaris.

0 „ 100

MILES 100

• h-

ss

•

•

• •

•

SS

Map 122 Mastoearpus stellatus(Stackh.) Guiry (= Gigartina stellata (Stackh.) Batt.) A distinctive althoughvery variable plant. One of the 'commonerinhabitants of the lower shore and shallow subtidal,sometimes forming very dense stands.

„ 100

100MILES

A

•

Map 123 Melobesia membranacea (Esper)Lamour. A smallinconspicuous encrusting membranous alga foundmostly on other seaweeds. Probably common, buteasily overlooked.

9 Km 1001 0 0MI LES

.1

•

•

•

se;

Map 124 Menbranoptera alata (Huds.) Stackh. A common,easily recognised inhabitant of shady lower-shorepools and the subtidal zone, where it is often foundon Laminaria stipes.

„ 100

0 100MILES

•

Map 125 Meredithia aicrophylla (J. Ag.) J. Ag. (= Kally—menia micro h lla J. Ag.) Another 'southern'species with a westerly distribution around theBritish Isles. Although it was formerly consideredto be rare, the species is in fact locally abundant,especially on subtidal cliffs and overhangs. It isprobably frequently mistaken for Kallymenia reniformie (map 117).

9 KM 190

MILES 100

•

Map 126 Mesophyllum lichenoides (L.) Lemoine The mostreadily recognised of the calcareous crusts. Mostcharacteristically found growing epiphytically onCorallina. It is a 'southern' species occurring onthe western coasts of the British Isles. See Adeyand Adey (1973).

KM

MILES

100

100

•

eite;

Map 127 Myriogrsnne bonnenalsonii (C. Ag.) Kylin A notuncommon subtidal plant on western shores, but veryunder-recorded. It usually occurs on kelp stipes.

KM

MILES

100

100

r,-

•

Map 128 Naccaria wriggii (Turn.) Endl. A subtidal plant of

somewhat sporadic occurrence. A 'southern' species

well worth looking for off southern and western

shores.

KM

MILES

100

100

Map 129 Odonthalia dentata (L.) Lyngb.distinctive of the subtidal redinhabitant of the Arctic Oceansouthern limit around the British

•

One of the mostalgae. It is anthat reaches itsIsles.

•

KM

MILES

100loo

•

•

•

•

•

Map 130 Palmaria palmata (L.) O. Kuntze One of thecommoner inhabitants of the shallow subtidal zone,usually found on Laminaria stipes. It is under-recorded in Ireland, but appears to be genuinelyabsent from parts of the east coast of England. SeeGuiry (1975).

100

0 100RILES

•

• •

Map 131 Petrocelis cruenta J. Ag. An under-recordedspecies, like all crustose reds.- It may be a phasein the life history of Mastocar us stellatus (map122).

KM

MILES

100

100

°67:1•

CS

Map 132 Phyllophora truncata (Pall.) Zinova A subtidalinhabitant of the Arctic Ocean that reaches itssouthern limit around the British Isles. Probablycommoner than the records suggest.

0 KJ, 1000 MILES 100

:

,

t

SO

•

•

•

Map 133 Phycodrys rubens (L.) Batt. One of our morebeautiful algae. Although superficially similar toDelassaria san uinea, it is readily identified. Itis one of the commoner subtidal plants and is foundboth on rock and on the stipes of Laminaria hyperborea (map 53). Like many other species, itseems to be absent from parts of the east coast ofEngland where there is both turbid water and ascarcity of suitable substrate.

aKM

MILES

100100

66?

q.

•

Map 134 sicula (Kiitz.)Guiry et L. Irvine.PhyllophoraOnly distinctive in winter when fertile. A'southern' species found subtidally or inlower-shore pools.

0 100

0 100MILES

•

••

Map 135 Phymatolithon lenormandii(Aresch.) Adey One ofthe commoner and best recorded of the calcareouscrustose species, but even so, more often ignoredthat identified. Woefully under-recorded inIreland. See Adey and Adey (1973).

0 KM 100

100MILES

•

if

•

S.

•

•

•

•

Map 136 Plocamlum cartilagineum(L.) Dixon One of thecommonest and most distinctive of the subtidal redseaweeds, found both on rock and on the stipes ofLaminaria. Greatly under-recorded in Ireland.

0 Km 100

1 100MILES

I

v

•

.3:

so

•

• •

le

•

.

Map 137 Polysiphonia urceolata (Lightf. ex Dillw.) Grey.The commonest subtidal member of the genus,frequently found on Laminaria stipes. It tends todie down in winter and becomes very much lessobvious. Very under-recorded in Ireland.

100KM

MILES 100

•

4.•

Map 138 Polysiphonla lanosa (L.) Tandy A common epiphyte

wherever its main host plant Ascophyllum (map 25) isfound. Probably the most readily identified ofPolysiphonia species.

0 100

0 700MILES

•

•

•

Map 139 Choreocolax polysiphoniae Reinsch A tiny palecushion that grows parasitically on Polysiphonia lanosa (map 138). It is rarely recorded, but isusually found if looked for.

KM 1°P

MILES 100

a

•

•

•

if

Map 140 Plumaria elegans (Bonnem.) Schmitz A commoninhabitant of shady gullies and caves on the shore.

KM

MILES

N..

100100

7

•

•

•

Map 141 Porphyra linearis Grey. Probably fairly commonhigh on rocky shores throughout the British Isles,but, because it is quite small and a winterephemeral, it is often overlooked.

<tre

° KM 19°100MILES

Ir•

S.

•

•

• •

Map 142 Porphyra umbilicalis(L.) J. Ag. By far thecommonest member of the genus and abundant on manyrocky shores. It tolerates a greater degree of waveexposure than most other red algae.

0 KM 19°100MILES

0

a

•

<Sec:

Map 143 Conchocelis rosea Batt. Not a true species, merelya phase in the life histories of Porphyra spp. andBangia. However, unlike these intertidal plants, itis frequently found subtidally, where it is thecommonest cause of red stains on dead shells. It isone of the most under-recorded entities in theentire flora.

/

MI

100

' 100

•

K?

•g.tre

'Map 144 Pterocladia capillacea (S.G. Gmel.) Born. et Thur.A 'southernspecies inhabiting deep pools on thelower shore in the south and west. No fertileplants have ever been found in this region, where itmust be propagating itself by vegetative means.

0 Kr, 100

MILES 100

6e,

•

1

Map 145 Pterosiphonia conplanata (Clem.) Falkenb. Aninhabitant of the warmer waters of the NorthAtlantic that just extends northwards into the southwest of the British Isles. See Noiton and Parkes(1972) and Hiscock and Maggs (1984). Its northernlimit on the west coast of Ireland remains exactlythe same as that recorded in 1847. This is probablybecause the plants reproduce largely vegetatively attheir northern limit and this precludes furthe'spread.

EM

MILES

100

100

•

7

•

•

Map 146 Ptilota plunosa (Huds.) C. Ag. A common subtidalspecies most frequently found on Laminaria stipes.It is a 'northern' species and sporadic records fromthe south of England have all proved to be robustspecimens of Plumaria ele ans (map 140).

9 KM 190MILES 100

•

Map 147 Radicilingua thysanorhizans (Holm.) Papenf. A'southern' species that just reaches the south westcorner of the British Isles. Although rarelyrecorded, it can be locally abundant subtidallyespecially in pebble sites exposed to currents andscouring, and on cliff faces and overhangs.

9 KM 19°

MILES 100

••

S.

•

••

•

,7•

Map 148 Rhodomela confervoides (Huds.) Silva A species

found from approximately low water mark downwards.

The bushy summer plants die back to the main axes in

winter. Widely distributed in the North Atlantic.

9 KR 190

MILES 100

•

•

Map 149 Rhodomela lycopodioides (L.) C. Ag. An inhabitant

of the Arctic Ocean that reaches its southern limit

around the British Isles. It can be relatively

common in the extreme north.

KM

MILES

100

•

•

Map 150 Rhodymenia pseudopalmata(Lamour.) Silva A largelysubtidal 'southern' species reaching its northernlimit here. It is easily confused with severalother species, but is not uncommon in the south andwest. See Guiry (1977).

0, 10,0

RILES 100

•

Map 151 Schottera nicaeensis (Lamour. ex Duby) Guiry etHollenberg A 'southern' species exhibiting theusual westerly distribution around the BritishIsles. It is nothing like as rare as formerlythought and its recently discovered abundance offsome of the Inner Hebridean Islands suggests that itmay extend even further north. See Guiry andHollenberg (1975) and Mitchell et al. (1983).

Km 10,0

MILES 100

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Map 152 Scinaia forcellata (Turn.) Biv. A 'southern'species, restricted in the British Isles to thesouth and west coasts. The belief that this speciesis more widely distributed seems to stem from thefrequency with which S. turgida, a wider rangingspecies, has been mistaken for it. See Maggs andGuiry (1982b).

KM 190

MILES100

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Map 153 Sphaerococcus coronopifolius Stackh. Yet another'southern' species exhibiting a westerly pattern ofdistribution. It is probably commoner than the mapindicates as it can easily be mistaken forPlocamium.

KM

MILES

100

100

r--

-1

gLi\g

•

Map 154 Sphondylothannion nultifidum (Huds.) Nag. Hereagain the westerly pattern is a reflection of aspecies whose centre of distribution is to the southof the British Isles. Recent diving surveys off theInner Hebrides have revealed it to be almost ascommon close to its northern limits as it is furthersouth.

WO

'

70

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Map 155 Spyridia filamentosa (Wulf.) Marv. A 'southern'species locally abundant in south-western Britain.It is now known to occur in Ireland where it iscertain to be more widespread than the mapindicates.

0 KM 190i o0 100 MILESC7 4

<X.,40!.15

Map 156 Stenograsme interrupts (C. Ag.) Mont. Adistinctive 'southern' species locally abundant inthe shallow subtidal zone, especially on fairlyunstable substrata such as stones and shells.Occurs down to a depth of 15 m off Skomer. Morewidely distributed in Ireland than the map implies.See Cullinane and Whelan (1981).

INDEX TO MAPS

Species Map

Acrosorium reptans 71uncinatum 72

Aglaozonia parvula 31Ahnfeltia plicata 73Apoglossum ruscifolium 74Ascophyllum nodosum 25Asparagopsis armata 76Audouinella floridula 75Bifurcaria bifurcata 26Blidingia minima 2Bonnemaisonia hamifera 78Bornetia secundiflora 80Bryopsis plumosa 3Calliblepharis ciliata 81

jubata 82Callocolax neglectus 85Callophyllis cristata 83

laciniata 84Ceramium rubrum 86Chaetomorpha linum 4

melagonium 5Champia parvula 87Chondrus crispus 88Chorda filum 27

tomentosa 28Choreocolax polysiphoniae 139Chylocladia verticillata 89Cladophora hutchinsiae 6

pellucida 7rupestris 8sericea 9

Cladostephus spongiosus 29Codium fragile subsp. atlanticum 10

fragile subsp. tomentosoides 11tomentosum 12vermilara 13

Compsothamnion thuyoides 90Conchocelis rosea 143Corallina officinalis 91Corynospora pedicellata 92Crouania attenuata 93Cruoria pellita 94Cryptopleura ramosa 95Cutleria multifida 30Cystoclonium purpureum 96Cystoseira baccata 32

foeniculacea 33nodicaulis 34tamariscifolia 35

Dasya hutchinsiae 97Delesseria sanguinea 98Dermatolithon corallinae 99

Species Map

Desmarestia aculeata 36ligulata 37

Dictyopteris membranacea 38Dictyota dichotoma 39Dilsea carnosa' 100Drachiella spectabilis 101Dumontia contorta 102Ectocarpus siliculosus 40Elachista fucicola 41Enteromorpha intestinalis 14

prolifera 15Epicladia perforans 16Falkenbergia rufolanosa 77Fucus ceranoides 42

distichus 43muscoides 47serratus 44spiralis 45vesiculosus 46

Furcellaria lumbricalis 103Gastroclonium ovatum 104Gigartina acicularis 105

pistillata 106teedii 107

Gracilaria bursa-pastoris 108Grateloupia dichotoma 109

filicina 110Halarachnion ligulatum 111Halidrys siliquosa 48Halopitys incurvus 112Halopteris filicina 49

scoparia 50Halurus equisetifolius 113Heterosiphonia plumosa 114Hildenbrandia crouanii 115Himanthalia elongata 51Hypoglossum woodwardii 116Kallymenia reniformis 117Laminaria digitata 52

hyperborea 53ochroleuca 54saccharina 55

Laurencia pinnatifida 118Leathesia difformis 56Lithothamnion glaciale 119Litosiphon laminariae 57Lomentaria articulata 120

clavellosa 121Mastocarpus stellatus 122Melobesia membranacea 123Membranoptera alata 124Meredithia microphylla 125Mesophyllum lichenoides 126Myriogramme bonnemaisonii 127Myrionema strangulans 58

Species Map

Naccaria wiggii 128Odonthalia dentata 129Padina pavonia 59Palmaria palmata 130Pelvetia canaliculata 60Percursaria percursa 17Petrocelis cruenta 131Phycodrys rubens 133Phyllophora sicula 134

truncata 132Phymatolithon lenormandii 135Pilayella littoralis 61Plocamium cartilagineum 136Plumaria elegans 140Polysiphonia lanosa 138

urceolata 137Porphyra linearis 141

umbilicalis 142Prasiola stipitata 18Pterocladia capillacea 144Pterosiphonia complanata 145Ptilota plumosa 146Radicilingua thysanorhizans 147Ralfsia spongiocarpa 62Rhizoclonium riparium 19Rhodomela confervoides 148

lycopodioides 149Rhodymenia pseudopalmata 150Saccorhiza polyschides 63Sargassum muticum 64Schottera nicaeensis 151Scinaia forcellata 152Scytosiphon lomentaria 65Sphacelaria plumula 66.Sphaerococcus coronopifolius 153Sphondylothamnion multifidum 154Spongomorpha arcta 20Spyridia filamentosa 155Stenogramme interrupta 156Stictyosiphon tortilis 67Stilophora rhizodes 68Taonia atomaria 69Tellamia intricata 21Trailliella intricata 79Ulothrix flacca 22Ulva lactuca 23

rigida 24Zanardinia prototypus 70

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