98t pY

6W sap1o11tt1d'upue DlntDllap 'v lo uosuedluoJ 6It uollnqFtslc 8tt tellq?H 8tt ,43o1oueqdeltlcnPordea 9rn sueS:o o,ttlcnporda: 3o lueudole,tep pu€ e.lnlcnjlS tw snlleq] eql Jo lueludole^ep pue-eJnlcnrlS n, &uduou,{S II' uotldt.rcseP1eut3t:g VNJV )I7S O YINS I,\tA A O H{ 'Y NSSNAISIIIHJ 3DAJ 0Iv aDtella 'JeA oltttulodoPnasd pue oloturtdoPnasd rcr olotulotlopnasd y 1o uostredruo3 'uellrJA\ sEA\ 1r qcrq,\\ JoJ esc 80t uollnqlJlslcl ou sr orollJ '.{pu€q sr )ooq eq} puE 1e1lq"H 80t e:e sqderSoloqd eq1'pscnpo:der 1 .(3olouaqd e,tllcnPo:deg 80t s8ur,,te.rpeurl eql Jo lso1 tr'uorl€urqr sueS:o e,ttlcnpoldar 3o lueludole^op pue elnlcnlls 90n ert] o1 sueurrcedsujnr.r€qJeq 3o sqder8 €0t snlieql Joruerudore^on n"i:jll?lii! oqt s,{a,uns e3rq} s,ur1,{; s>il1 t0t "rogsluepnts ,{8o1oc.{qd roJ pre u? se ol t0v uoridtrcsepI?utBuO eql Jo uorlBsrpur ue sr e3ueJaJrp gVISI77l'dY A VJYI^ITVJOO NTSJ VINSWTO OHV 'Surr^o-l 'pelse^€l) Tl eplof 'zluuc uorlnqlrlsl(l ssol )ooq slq pug IIr,r c "r^eurpuers 86t r"Iq3H '13}]€l eql roJ Js L6t osorloJpue s3srp 1c L6t ,{8o1oueqde'ttlcnPo-tdea ]ueLuqJeltv'^€.4 ,64 sueS:oa,ttlcnporder Jo ]uerudole^eppue elnlcnlls 11tuo,tisouoW]"q].{tprBu os'pe,t\ollo 'sluolu}e oog snit€q]oql 3o lusrudola'teppu€.ernlrnrls Eraue8 eqt ol serldde srr.{J 06t ,{ru,{uou'{5 uooq oleq sqde:Souoru re3:e1,lte; vJVWTVdOOnssd lou e^erl sreded :elroqs ur peqsrlqr .dY A, VJVW 7V JOG NS Sd VI NEW'{ O OHV e;e ee8le uee:8 pue u,roJq uo slald€ I€uosJed IeJeAesoslE el€ eror{I oe6 serf,edsr{srtug eql ot -clursop eql 'araq,raslo poqsrlqnd s 06€ ^oX 68€ uoll€JsIluepI ecuereedde oql eroJoq ue1lr,tr 8ure, snue8 uotldt:cseq L8t Jo s,,\\olloJ 1l eJnl€lJusluou uT ,{Lu,{uou^S 98€ .{luo^luIeLU uJ 'eJoU selteds ed^I oq] sle^.o3lr lcBJ l€8f 98€ .pu€ruep aql uolldtrcsaP I€urEuO 98t 'el€p 01 dn Sureq ruo{ l€J ere'esr VIN7NTOOHY SNNEC AHI s,ury,{;g'ern1e:eill qsrpe.r\Ssrq} Jo eurJ?ruJo sluepnls 'eurlls?of,s.uep: SINAINOJ dq slJoi rilriA palueuolddns 'ls€o -opoqd er{t Jo s,{e^rnss.urTf,X dq sr 179_1s8g_rxet) ouuelu qsru€c oql Jo lunocJ€ 31el( tnq spuelsl eorEd eq] pu€ puEIeJl S(I8 tN uopuo'I 'Peog '{e'Lro11o11 serog eleldruoc oJor[ ueq] eouls '6 pue 'uopuol LIlroNJo cruql+rloa bq1 '(8o1otgJo lueluu"de([ '{reurueq Jo I€8lE eql inoq€ u "{3o1oaC) "rog -IIYHJIIA *AulnD'c ,{B 'ra8e1:o.;statrsra,runIlyyy'1d'sa. 'SS]SI YINTWAAOHY SNNE9 IIHJ'OI HSIJIUTI 1Yl EHI CO AVC-IV ENIUVI^I NO SAICINIS

116l requere( I gzv-ggt'.Zf't'tn{Ud' rg 386 M. D. GUIRY

ORIGINAL DESCRIPTION DE! The genus Rhodomenia (sic) was proposed by Greville (1830, p. xlviii) to include 16 species. ( most of which are now referred to tl-reKallymeniaceae. J. Agardh 1841) added n-ranyspecies, Thallus of multiaxial construct In 1851 changedlhe concept oflhe genus and adopted Montagne's (1839, p.44 J. Agaidh or slightly fl attened, monopodiall' thai the orthography Rhodl.menia be adopted. The latter spelling has footnote) suggestion (200) mm broad, entire or dichott conserved over the original "Ilhodomenia". J. Agardh (185i) divided the genus into two been or lobed; regeneration fron stol Ihe Palmatae and the Palmettae, and characterized the Palmatae as sections or subgenera, red, somelintespurplish red: subt scattered over the whole surface or in scattered sori while bearing tetrasp6rangia sparsely tiated into an assimilatory laYer the Pctlmettae-(as the type species of the genus was included in the Palmettae it should be of (2) 4 13 (20) layers of large, hYr referred to the or iubgenus Rhodymenia) as having tetrasporangia collected in sori as section iridescent body of unknown func J. Agardh created a further section or subgenus lhe Clinophora, -just below the apices.In 1876 Tet rttsporanll ia with cruciaiely whicl-r in small sori just below the apices but the cortical layers had tetraiporangia aggregated r.nents,interspersed with sterile f underwent to-Eive a nore or less nemathecoid structure. Dawson (1941) dis- modihcation sori which n-raybe confined to a tinguished a new section the Pertustte, mainly on the basis tlrat the specieshad tetrasporangla scaitered over the surface of the lrond in a relatively unn-rodifiedcortical layer and not in sori, and l-replaced the sections Rhodl'1nsn\o,Palmatae, Clinophora and Pertusae i! the subgenus Eurhodyntenia (which, as it contains the type speciesof the genus, sl-rouldbe refened to as the subgenirs Rhoiyntenia) and reduced the genus Dendrymenia Skottsberg to a subgenus of the genus Rhodymenia, with one section, the Dendrymeniae. Guiry (1974a, b) has proposed that the gents Palmaria Stackhouse, over rvl.rich the genus Rhodyitenia l-rad been conserved, should be teinstated for the species Rhodyntenia lnlntttttr. The spelling "Rhodymenia" has been conserved over the original "Rhodomenia". The genui Rhodyinenia is represented in Britain only by speciesof the subgenus Rhotlynrctia and tl-resection Rhodymeniu. TYPE SPECIES Greville(1830)didnotindicateatypespeciesof thegenus RhodameniaGreville;apparently- rhe earliest lectoiypification is tl-rat of'schmitz [1889, p.444, as Rhodynenio palmettu (Espet) Grevillel. Rhodl,minia palmetta sen}J Greville would seem to be the type speciesas it has been shown that Fulus palmetta Esper is a misinterpretation of FucLrspalmettd S. G. Gl-nelin (a delesscriaceousalg-a; see Silva, 1952). In his treatment of Rhodotttenia palnrctto, Greville (1830,p. 88) cited, amongst others, the following synonyms: "Delesseria Palmetta, Lamour. Essai p. 37. Fu(us Palntetta, Esp. lc. Fuc. p.84.1.40. excluding all the synonyms.,Stackh. Ner. Brit. p. 102. t. 16. Sn.r.Eng. Bot. t. 1120.Turn. Syn. Fuc. p.2J. Hist. Fuc. t.76. Fucus bi.fidus,Huds. Fl. Aug. p. 581." It would aDDear that the confusion between Fucus palmetta Esper and Fucus palntetta S. G. Gmelin was appreciatedby Stackl.rouse(1801, p. 102) and by Turner (1809'p. 5) both of whor.n refused to clioose a new epithet, rnainly as a consequence of the then current distaste for ". . . that constant and arbitrary changing of narnes affixed to plants . . ." (Turner 1809, p. 5.).In elTect,therefore, it would seern that there exists a Futus palmetta Stackhouse, a later homonym of Fucus polmetta S. G. Grnelin. The earliest name fot this entity seems to be Ftc. l. Rlndynenio psetrdop, Delessiriapalmetta iamouroux (1813,p. 125).As Greville (1830,p. 88) obviously recognized pseudopalmatu.rLamouroux ( this confus-ion by his clear citation of these synonyms, the con-rbination Rh_odymeniapolmet.ttl (1805,p.23, Fig.2) illustrati can be attrjbuted to "(Lamouroux) Greville", which is the type species of the genus. As the earliest taxonomically correct synonym cited by Greville (1830) is Fucus palmetta Stackhouse, (BM) a lectotype of this eniity has been chosen by the present author from herb. Stackhouse Ga nte t ang ial p Iant s apParentll and this should serve as the type specimenof the type species. sporophyte; spermatia h5'aline,{ (.Lamouroux) to Gleville Tlre earliest name for Rhodomenia palmetta Greville is, according spermatangial mother cells forn (1778, p. name is a (1830) and Papenfuss(1950, p. l9O), Fucus bry'ZrsHudson 581), which small rounded subapical sort o plant as later homonyil ol Fucus bifidtrs S. G. Gmelin, a laminariaceous now known llattened blade; procarps l-ornte Arthrothamtti,s bifittus (5. G. Gn'relin) Ruprecl-rt.Mrs L. M. Irvine (pers. coml.n.) has,expressed quantities; carpogonial branche the opinion that Hudson's description of Fucus bifdus does not suggesla speciesof Rhodynenia borne on a large supPorting cel genuine sensu stricto, particularly as the speciesis said to be diaphanous; ntaterial of Fucus tilization the nucleus is transfel brfdas Hudson has not as yet been located. cystocarps hen-rispherical,large' "Silva (Lat-nouroux) (1952) has pointed-out that the correct name for Rhodymenia palmetta sometlmes necKed, perlcarp sm Greville is Rhodymenia pseudopalmato (Lamouroux) Silva. fill:ing the cystocarpic cavitY w. carposporangia; gonin-roblast e SYNONYMY branched, centrally-placed, colu sporophyte nourished b1 an irre Dawson (1941, p. 124,143) proposed that DendrymeniaSkottsberg (1923, p. 16)be reduced between the gonimoblast and th to a subgenusof-the genusRl'totd)'menia. Sparling (1957)agreed with Dawson but Taylor Speciesentirely marine and w (1945),Ktlin(1956)andothershaveretainedDendrymeniaasagenusdistinctfromRhodymenia. and coldtemperate waters of th Tlrc genus llhotl 1,tttenia 387

DESCRIPTION OF GENUS ( tefele Thallus rtl ntr-rltiarialconstrllction, crect or pfostratL'. | 100 1000) ttlttr.1ottg.stipes 20 ..r,.itigr-1itt,ilattenecl,n.'onopo.iiilly or's1'mpodiiri.l;brancl-red. blades tlattened or 11at500 i'nr palmately irregr'r1ar-ly'split iiOOl-n1'-1ibioacl. entire or clichotirr.t.rou.sly,pseuci6dicl.totomously, or bright i;."i;f;;i, l"g.ni*ti.rr l'iorl stolons. apical or..nrarginal nreristemscorrln.ron. colour i.a..""r",i"r?r purplish rcd: substancesoft cartilaginollsto stiiTlycartilaginous; cells dillelen- a rnedulla tiatcd into an assirrtilatoryla1'er o1'srlrall corticai filaments 2 5 cells in lengtlr and ,,riiUi+ i:f20yla1,-er.soflirgc,hyaline,ariallyclongatcdccllsrvlrichoftenhaveasrlallparietal ir-iclescentbocly ol unknou'n function. tila- fit,.r,rp,r,'r,,,1yrawith cr-uciaielyarranged-sp-ores. fornrccl fr-on.rthe cells ol assil.tlilatorv- ,,.,ents,iirtersper-scd *'ith steiiie'fitanten-ts2 3 cclls lont,- aggregated.in rclativell'unrtrodifiecl i..,ii i"l-1i.f,-"r'^ibe confincd to a slrecilicpart of thc rlralluior spread ovel thc rvl.tolesurfacc' ry

.t' tlOmm ,.*:::....i:., ,.$l' ,'r':ri:i '':lii.'i .$ .{l "11

Ftt;. l. Rlttul)'iltertittp.:eLrd0pulnktt(r lLanlluror.rx) Silva. LeCiOtyLresllecitlen of fhtttt s DsetrrloD0lttttrt'tt.iLar.r.riru|oux (CN). On the right thc Original clr'arvinglOr Lanlirrtt-trrtr ifSOj.'rr. 2i, Fig. l) illustr-ationand on the left ihe ictraspo.angial specitrlen.

()upteturtlliulpla2t.ialtparcnlly al*ay's cljoecitlr,tsand nlorpholergicall)'sinrilar.to the tetfa- pair-s :Ltoloirhvre:spefl.tatia iryaline,ion.'.'cd singlf in spermatangiaderi.ved singly or in ftonr itl ,i,.""'"tonglof'gtor5.-r-ee-ll:forrlcd fronr ternrinal assirttil:rtorycells and aggregatcdeitlrcl ,i-t,,ii ,:oun'.1.dsr-rbaprcal sori or spread tn irregr'tlar:patclres o\cl..the r'r^hole.:urfaceof lhe rjoii.n.A ttlua.: procarps folnteci in tlre yor-rngJrpar[s o1'tlrc thallu:, oftcn in considerable uuantities. eirrDogonialbt-anclres 3- or''l-cclleci' ternlinated by an elongaterltrichogync a-nd aftel ter- il;;;;.;;;l;; !;:,"ptr;, ring cell u'hicl'ralso bears a 2-ccllcd auxiliary cell brtrnch: iiii.ution the n-ucleus'istra'nsierrcd to tl-reaurilizrly cell (sometir.llesvia a connecting cell)i is .yr,o.iip. f.1.n-,iipherical.large, not sunken. rvitlr.r snrall centrally-placedostiole rvhich sontetintesnecked, pericarp imooth r.r'ithoutprojections; carposporophyte r'rsuallyentircl)'- filling the cystocaipic caviiy u,hen uraturc, usually-cor.uposecl of three lobes or nlasscsot few large. gonimoblast cntireJy lransfot'med to sporangia .except..for a ":oip5tpoiungiu: cells which originate from tl're auxiliary cell: carpo- -p..;'-;;l-1ti.b':anched,ce-ntrali-y-placecl, colunrnar _ nourisheclby an irregular basal group of snrallnutritivccells; connectingfilarllents betr.r'eenthe gonirnoblast and the pericarp absent- Specieseniirely nrarinc and widely clistributcd in the tropical, subtropical, warm-tcnlperate and cold-tentperatewaters of the world. 388 M. D. GUIRY

The British speciesof Rlc other red algae, particular phoraceae;Gigartinaies). T scarcityof fertile materialof to providesorne anatomica be made.The Bririshspecj variablein form, not only v The anatomical structur speciesofthe genusRhodyn can be distinguishedfrom str mentand sizeof theircortic cortex ofirregularly sizedce the apexcorrcsporrding to t most cortical cellsof the thz arrangedand the less-pigme (Figs 2-4). Speciesofphyllol (Fig. i0), on the otherhand usuallyclosely packed ar:rd c in surfaceview. Speciesof Rhodymeniaha (particularly older, more , (()* (usuallysterile, depauperate ,0d young specimensof Palmar OA is easily distinguishedfrom 'oY angularcortical cells (Fig. I I Kiitzin-s are, on the other hat no problem.Tlre surlacece similarto thoseof speciesof but are iarger and more obv

trrcs 2-i3. Surface view of th, other-specieswhich nray be cor pselrdopal mqla var. pseudopal, August 1974, leg. M. D. Gurr ellisiae (Dtby) Guiry, Seaford the apex. Fig.4. Rhodymeniade 1973.leg. M. D. Cuiry, 3 mm f Shanklin. lsle ol Wighr, 9 Ap P. rraillii Hotmes ex-Batrers,'l J3nhsorr, 3 nm from apex. Fig Cove, Dorset, I7 Februarv 197 f orma brodiaei (Turner) Newr< Isles, 28 July 1973,subtidal, le (Lanrouroux ex Duby) Guiry Jeg. M. D. Guiry, 1b mni fio Ftcs.2-l 3. Seecaprions opposite. Montagne, Sherkin Island. Cc apex. Fig. 12. Callophyllis lar Harnpshire.subtidalj 2-5 m, I trig. 13. Pdlmaria palmaro (Lin 1973,leg. M. D. Guiry, 10 mn The genus Rhodtnrcnl. 389

IDENTIFTCATION The Britishspecies of RhodyntetTidhave been frequently contused with various other red algae, particularly speciesof Phyllophora a'nd Scltottera(Phyllo- phoraceae:Gigartinales). This colfusiott has arisenlargely as the result of a scarcityof fertilen.raterial of speciesof thesegenera. It seemsdesirable to attempt to providesome anatomical features upon which tentativedeterrrinatiotts cittl be rrade. The British speciesof Ph):llopltora,St'hottera and Rhodl'ttteniqare variablein forrn. not or.rlywithin populatiorrs,but alsoseasonally. The anatomicalstructure of representativesof the Phy'llophoraceileand speciesof tl.regenus Rhod.t'ntenia are very sinrilar,but specimet*of Rltodyntenia can be distinguishedfron.r spccimens of Ph.r'llopltoraon the basisof the arrange- nrenrnnd sizeof tl.reircortical cells.Species of RlndJ'nteniahave relatively loose corte.rof irregularlysized cells. These cells should be viewedat a distancefrorr the apexcorresponding to one tenth the total len-ethof the plant. The upper- lltostcortical cells of the thiillusat this stageof developrnentare ratherloosell' arrangcdand the less-pigmentedcells of the next (subcortical)layer are visible (Figs2-4). Speciesof Pln.llophora(Figs 5 8), Schottera(Fig. 9) and Stenogr(tnilll( (Fi-r.l0). ot-tthe other hand,lrave smaller, Irtore regularly-sized cells which are usuallyclosely packed and consequentlythe subcorticalIayers are rarelyvisible in surfaceview. Speciesol Rhodlmenrahave oftcn tieenconfused with speciesof Rlrctlopltrlli.r (paiticularll, older, trore cartilaginousspecirrens), species of Callopltrlli.t (usuallysterile, depauperate, irrtertidal specin.rens) and. ot.toccttsion, witl.r ver-r'- young specilrensof Palntaria.Rhodophl'lli,s diraricato (Stackhouse)Papenf-uss is easilydistinguished 1'ronr species of Rhod.rnteniaby nreansof its very large. apgularcorticalcells(Fi-s. ll).Thesur1'acecellsof Ca1loplt.r'llislaciniata(Hucisott) Kiitzingare, on the otherhand. ve ry small(Fig. I2) and this speciesshor-rld pose no problem. The surfitcecells of Palntariapalntatct (Linnaer-rs) O. I(untze are sirrrilartothoseofspecies of Phvllophorainthattheyarecloselypacked(Figl3) but are largerarrd more obviousll,hexagonal

Frcs 2 13. Sulface view of tl.rccortical cells ol the British speciesof Rhodl'nenio ant) otlrer speciesr.vhiclr nray be confusedwith thent. Scaleline 50 pm. Fig. 2. Rhocl)'ntenia pseuclopalnntu var. p.teutlopalntala (.Lantouroux) Silva, Treaddur Bay, Anglesey, l9 Ar-rgr,rst197.1, leg. M. D. Guiry. 10 trlrtt front the apex. Fig. 3. R. psetrclopalntutavar. e/1rs:rae(Duby) Guiry, Seafold Bay, Susscx,I July 1973,leg. M. D. Guiry, l0 nrnr front theaper. trig.4. Rhod),nteniadelicatulctP.J. L. Dangeard, Cenrlyn Bay, Anglesey,5 April 1973,leg. N4.D. Guiry, 3 mm from thc apex. Fig.5. Phvllophoracrislttr (Hudson) Dixon, Shanklin, Isle of Wight, 9 April 1975, leg. N. A. Jephson, 10 t.trnrfrom apex. Fig. 6 P. traillii Holmes ex Batters,Benrbridge, Isle of Wight, ll September 1975,leg. N. A. Jeplrson,3 rnrr fronr apex. Fig. 7. P. sicula (Kiitzing) Guily & L. M. Irvine, Lulworth Cove, Dorset. l7 February 1973,leg. M. D. Guiry, 10 mrn from apex. Fig. 8. P. trLtntuta forna brotliaei(Turner) Newroth & A. R. A. Taylor, Dale Voe, nr. Lerwick, Shetland tsles,28 Jufy 1973,subtidal, leg. divers, 10mnr front apex. Fig.9. Sthotterctnicueensit (Lamouroux ex Duby) Guiry & Hollenberg, Lulworth Cove, Dorset,20 March 1973, leg. M. D. Guiry, 10r-nm fror.n apex. Fig. lO. Stenogramrneinterrllpta (C. Aga'dh) Montagne, Sherkin lsland, Co. Cork, August 1975, leg. N. A. Jeplrson, l0nrnr fronr apex. Fig. 12. Callophyllis ktciniata (Hudson) Kiitzing, Horse Sound Fort, Solent, Hanrpshire,subtidal :2 5 m, I September 1974,leg. N. A. Jephson, l0mnl frorn apex. trig. f 3. Palnariu ltalmata (Linnaeus) O. Kiintze, Lulworth Cove, Dorset, l7 Fcbruary 1973,leg. M. D. Guiry, l0mm frorl apex. 390 M. D. GUIRY

KEY TO THE BRITISH SPECIESAND VARIETIES

1. Mature plant -.- 30 r-nnrhigh and < 80 pm thick 10 mm frorn the apex . . D )^t:^^,..r^ Mature plant :'30 mm high and :'80 prn thick l0 mm from the apex . 2. Plants not with extensive stoloniferous growth; blades >5mm wide 10n-rm from the apices; cystocarps, if present, borne in a predominantly apical or subapical position on the flattened fronds . . R. pseudopalmota yar. pseudopolrnatcr Plants with extensivestoloniferous growth; blades <5 mm wide 10 mnr from the apices; cystocarps, if present, borne in a median or basal position on the ffattened fronds . R. pseudopalmctta var. ellisiae

RHO D YMEIV IA P.SEUDOPALM ATA VAR. P,SET/'OPAI.MATA SYNONYMY RhodynteniupseLtdopalntattt (Lamouroux) Silva, 1952, p. 265. Basionym: Fucus pseudopcrlntatusLantouroux, 1805, p. 29, pl. 25, Fig. 2. [See Fig. 1 ol the present study.l Synonyms: Fucusbi./tdus Hudson, 1778,p.581 (?) lseep. 386] nonFacus bifdus S. G. Gr-nelin, i768, p.201, pI.29, Fig.2[- Art]rrothamnusbificlus (S. G. Gmelin) Ruprechtl. non Fucus bi/tduss.ensu Goodenough & Woodward, 1797,p.159, pl. 17, Fig. 1 f: Rhoclophyllisdiuaricata (Stackhouse) Papenfussl. Spltaerocottus bi.fidus(Hudson) Stackhouse, 1797, p. xxiv (as to name only). \E Rhodomenia birtda(Hudson) Greville, 1830, p. xlviii,85 (as to nar-r-reonly). Rhodophyllis bifida (Htdson) Kiitzing, 1847, p. 23 (as to name only). 6 Fucus polmettcr tar. p bifidus (Hudson) Turner, I 809, p. 4, pl. 4, Fig. g. ,-..) * Sphaerococcuspalnettct var. p bffidus (Hudson) C. Agardh, 1822, p. 246. Delesseriapttln?elld Lamouroux, 1813, p. 125. - Fut'uspalmetta sensuTurner, 1809, pp. 4-5, p|.4, (pro parte, as to materials, Fig. a, b, c, d, e, f, g only). - Fut'uspalnel/a sensuStackhouse, 1801, p. 102, pl. 16 (as to naterials). (as -\en - Fucus polnette sensu Esper, 1798, p. 84, pl. 40, pro parte, excl. syn. to materials, partly). nonFutuspalmertaS.G. Gnelin, l768,p. 183,p1.22,Fig.3,p|.23,1- Dsletter'o clnteliniLanouroux, 1813, p. i241. Delesseriapseudopalntata (Lair-rouroux) Lamouroux, 1813, p. 125. Sphaerococcuspolntetta (Lamouroux) C. Agarcih, 1822, p. 245. Htrlynenia patnrella (Lar.nouroux) Gaillon, 1828, p. 361. Rhodctnrcniapalrnettcr (Lanouroux) Greville, 1830,p. xlviii, 88.

STRUCTURE AND DEVELOPMENT OF THE THALLUS

IXTERNAL MORPHOLOGY Plants of R. pseudopalmatavar. pseudopalmataformed erect, flattened, thick, cartilaginousfronds frorn a small disc (to 5 rnm diam.) or, lesscomnronly, from creepingstololrs. The stolons were cylindrical or flattened,very stiff and car- tilaginous,and wereinverriably found ramifying in spongesor creepingir.r cracks in rock. Stolor.rswere lightly coloured when ernbeddedand ofter.rformed irre- gularly shapedsecondary attachment organs. Plants growing subtidallyon the 20mm stipes (Gunnerus) found of Lanlinaria hyperborea Foslie were usually to have Frc. 14A-H. Range of variati larger basaldiscs and neverformed stolons.Erect fronds l-rada bright crimson Rhodyntenia pseudopalmatu va colour when young, which tendedto be deeperor purplish in older plants. Head, Co. Clare, 19 April 19' Rhosneigr, Anglesey, 1l Decer There was considerablemorphological variation in the plants examined, Kilkee, Co. C1are,29June 197 particularly of the shapeand mode of branching of the fronds (Fig. I4C, D). hyperborea (Gunnerus) Foslie, j Plantscollected intertidally from rock pools tendedto have short stipes (Fig. 30 June I 972,vertical walls : EL, 3 July 1973,leg. M. D. Guiry. F l4F, G, H) which rapidly expandedto form the ffattenedportion of the fronds. MLWS, Ieg. M. D. Guiry. Suchir-rtertidal plants weregenerally less than 50 mm tall at maturity. Younger -fhe genus Rhod.t,nteniu 391

7*

Frc;. l,1A H. Range of variation in external nrorphology of British lslcs rlatertal ol Rltotl.ttnenitt pseutilpnlntutu var. pseudoltulnruttr(Lan'rtou;our) Silva. Fig. l44. Black Head. Co. Clarc. l9 Anril 1972. sr.rbtidal:5 m, lcg. W. F. Farnhanr. Fig. 1'+B.C,D. Rhosneigr. Anglesel, l1 Decer.trbcr1973, pool: MLWS, lqS. M. D Guiry- Fig. l4E Kilkce. i_-o.ctare. zg Jr-rne1972, tetrasporangial pJant, drift on the stipe of Lctntrnurtu h.rperboreo(Gunnerus) Foslic. Ieg. M. D. Guiry. trig.14tr. Caherrr-rslrFoint, Co. C-'lare' 30JLrne1972. rcrtical u,alls: EI-WS. leg. M. D. Cuiry. Fig. l4G. Elberry Covc, S. Devon' I9 Augr'rst197'1, pool: -l JLrlyi973, leg. M. D. Cuirl'. trig. l'lH. Treaddr-rrBay, Anglesey' MLWS, leg. M. D. Cuirl . M. D. GUIRY

intertidal plants had rounded apices(Fig. 144, B, C, D), while older plants oftentended to havebifid or irregularapices (Fig. laH). The baseof the flattened portion of the blade tended to be cuneateor rounded-cuneate.Branching of the fronds was usually dichoton.rousbut the first divisions were often very close together,giving the plants a fan-shapedappearance (Fig. 14A). Later divisions, particularly of intertidal plants, were more irregular but usually nraintaineda more or lessdichotomous pattern. Where there was a reasonable distancebetween the flrst and seconddichotomies the interveningportion of the frond often had a strap-shapedappearance (Fig. l4G, H). Lateral pro- liferationsof the bladeswere uncommon except in extremelyold plantsand even then were very small (to 5 mm) and were usually dichotomously divided. Proliferation from the basal disc or from stolons was much more common (Fig. 14B, F, H).Proliferation from the torn or truncatedapices of older plants was zilsoa common occurrenceand a blade with a similar morphology to the parent plant was formed. Subtidal plants growing on rocks or bouldershad a norphology similar to that describedfor intertidal plants but tendedto be slightly larger on average (to 60 mm) and occasionallyhad very long stipes(to 40 mm). In a few plants somelinear elongationof the apiceswas observedbut this was not found to be characteristicof the variety. Plants growing epiphytically on the stipes of Lantinariahyperborea in the subtidal were the largestspecimens examined (to l20mm) and also had the longeststipes (in length and proportionally)(Fig. 14E).The morphology of thesespecimens is otherwisemore or lessthe sameas that found in intertidal sDecimens.

ANATOMY The thallus was composedof a cortex of 2-3 layers of chloroplast-bearing cellsand a medulla of 2 8 layersof more or lesscolourless cells (Figs I5,21). The thallus when first formed (within 2 rnrn of the apices),was usuall1,quite thin and was composedof 2 layersof medullarycells. At I0 mm from the apices the tlrallus was quite thick (100-200pm) and was composedof 2 3layers of medullary cells (Figs 15, 16). At the base of the frond the thallus was 200- 250pm thick and was composedof 6-8 layersof medullarycells (Fig.2l). The cortical cellsappeared widely spacedin optical section 10mm from the apices (Fig. 2) and were slightly axially elongated.These cells measured(in optical section)(3'8) 9'0-13'4(23'2) pm long axiallyand (3.6)8.7-1 I '6 (15.4)pm broad 21 adaxially.Some difficulty was experiencedin measuringthese cells as the next - layer of subcorticalcells was usuallyvisible between the cellsof the uppermost 50p.- layer(Fig. 2). The subcorticallayer was usually composed of cellswith a slightly Frcs l5 22. Canera luuda drawing t ar. p.teudopa lighter colour. The surfacecortical cells,when first formed, had chloroplasts Imala t !anrourourl S ,Frg..f5. R. p^seudopalmata\i.r. pseu which filled the entire cell but as the cells aged (i.e. in the lower parts of the l:g y. Q.Cuiry, TS ar cenrreolr thallus) the chloroplaststended to become more fragmented and parietally .llC. t.). tS ar edge of rhallus t0 m placed. v rer.vrlle-sur-Mer. Calr ados, Franr thallus youngerparts I0 mnt from apex. Fig. l g. C Medullary cells,in the of the thallus,occasionally had a srnall f ron) apjx. Fig. 19.R.pseudopalnar amount of very fragmented,parietally placed chloroplast, the colour of which rr^utry. t5 a1centre of thallus l5 m was easilydestroyed by most preservingfluids. Medullary cellswere large and I5 arjdge o[ rhallus l5 mnr from Lap_ Fagnet, France, nreasured (26)41-51 (61)am periclinally (TS) 9 September in transverse section and thallus l5 rnm frorn base.Fig. 22. r I.5.mnrfronr base.cn: corricil cells (rrldescent)body. The genus Rlntl.t'tnenict 393

50pm

Frcs I5 22. Ccrnteralzrclrla drarvings of transversesections of Rhod.t'nreniopseudLtpulnntu llar. pseudopaln?d/a(Lamouroux) Silva and R. psetrdopalmcttttvar.e1lrsiae (Duby) Guirl trig. 15. R. pseuclopalnrutavar.pseudopalnnto, Treaddur: Bay, Anglesey.l8 August 1974' leg. M. O. Guiry, TS at centre of thallus I0 mln from aper. Fig. 16. Collection data as Ffg. 15, TS at edge of tl'rallus [0 rnm fronr apex. Fig. 17. R. pseudopalmato var. ellisiae, Vierville-sur-Mer, Calvados, France, 2t July 1974,\eg. M. D. Guiry, TS at centre of thallus 10 rnm fronr apex. Fig. 18.Collection data as Fig. J7, TS at edgeof thallus i0 r-nm. fionrapex.Fig. 19.R.pseudopalmatavar.ellisiae,Seaford,Sussex,2Julyl9T3, leg.M.D. Guiry,-TS at Centreof thallus 15 rnr.ufrom base. trig. 20. Collection data as for Fig. 19. TS at edge of thallus l 5 rnm fronr base. Fig. 21 . R. pseudopolmata var. pseLrdopalntata, Cap Fagnet, France, g September 1972,leg. J. H. Price & l. Tittley, TS at centre of thtllus i5 mm fronr base. Fig. 22. Collection data as for trig. 21. TS at edge of thalh"rs l5 mm from base.co: cortical cells; r'l: cuticle; lte: rnedullary cells;/: proteinaceous (iridescent)bod1,. 394 M. D. GUIRY

(65) 102-133(153) axially in longitudinalsection (LS). Thesecells were strongly 1959). Carpogonialbranches coherent and even when soaked in 2N HCI or 2N HNO3 for long periods Thesestructures were mosr er (5 min to t h) would not separateeven when squashedforcibly betweenmicro- supporting ceil (Figs 25_28)" scopeslides, the cell walls breakingrather than separate.In LS the medullary bore. a 3-celled carpogonial cells dovetailedinto one parts another. In the old.er of the thallus (30 40 mm ln..dtameterand was usually from the apicesin mature plar,ts)the thallusthickness wasmore or lessthe sarre ellipticalor oval (Fig.26). Ini at tlre edgeof the thallus as at the centre(Figs 21,22).The medullary area was those with well developedtr aiso nroreextensive, having 7-8 (Figs layersof cells 2l ,22) and seemedto have (Figs 25-28), ofren to 20_25 been added to by growth of the cortical cells which eventuallyformed new branchwas composed of3 cel layers of medullary cells. The anatomy of the stipesand stolons was similar to that of the older parts of the fronds. Someof the medullarycells had a large iridescent body which stained deeply with acetocarmine.Such bodies were particularlycommon in the older cellsof the attachmentdisc.

STRUCTURE AND DEVELOPMENT OF REPRODUCTIVE ORGANS Plants of Rlndymenia pseudopalntatavar. pseudopalntatabearlng carpo- sporophytesand tetrasporangiahave frequentlybeen recorded in the literature (e.-e.Harvey,184l, pl. 134; Newton, 1931,Fig.260; Sparling,1957, pl.55a; Fig. l2h, i, k), but spermatangiaand carpogoniaibranches have been much more rarelyrecorded (Sparling, 1957,p.357, Fig. 11a-g;for SouthAfrican specimens.). Reproductiveorgans were not common on the intertidal plants exarr-rinedfrom the British Islesand northern Franceby the presentauthor but wereoccasionally found on large plants at ELWS (extremelow water of spring tides). Subtidai plants, to judge fror-nthe preservedmaterial examined,are much lrore com- monly fertile.The following descriptionof reproductiveorgans is largelybased on a collectjonmade at Finnavara,Co. Clare, Republic of Ireland (30 August 1,973,|eg.M. D. Guiry) at ELWS on boulders.

GAMETANGIAL PLANTS

In tlris variety spermatangiaand carpogoniawere borne on separateplants. Spermatangiawere formed in ii small, rounded sorus 2-5 (8) mm diam. at the apicesof male plants. The sori were conspicuousas areasof whitish tissue.In all the plants exanrinedthe spenratangiawere fully mature and consequently little can be said of their development.Mature spermatiawere formed singlyin spermatan,eiaborr.re sin-ely or in pairson spermatangialmother cellswhich were probably developedfrom surface cortical cells (Figs 23, 24) (Guiry, 1974b, pl. II, Fig. c). Mature sperrnataneia were rounded or elongate-ovaland measured (3'6)4'5-1'2(9'0)am in diameterand (3.6)5.4-1.2(10'8)pm in length.Sper- matangiawere shed through the cuticle which becantevery thickenedduring spernratangialdevelopment (Fi_es 23, 24).In older sori the cuticletended to be rather irregular with anticlinally orientatedstriations which were probably a Frcs 23-28. Camera lucida drawtl result of spermatialdischarge (Fig. 2q. Spermatialdischarge was rlot observed reproduclt\e.organ> of Rhodymen, Jr.tva. in fresh material.Sperrnertangial plants were, in general,rather rare. Material was collected at , leg.M._D. Cuiry. Carpogonialplants were dilficult to find and carpogonialbranches were only FLryq. Fig.23.i r^alF!t.sol-us Figs 25 28.Carpog observedin plants from the Finnavara collection.The most satisfactorystain A.oDrevrallonsas in Figs l5 22 exi nr : natr for carpogonialbranches in this specieswas iron-alum/acetocarmine(Austin, cell: .\r?c' spermalangialm c: carpogonium; t: trichogyne.

F The genus Rhodyntenru 395

1959).carpogonial brancheswere only found in the first f-ewmm of thallus. Thesestructures were most easily located in TS by rreansof the deeply-staining supportingcell (Figs 25-28).The latter was a nodified subcorticalcell which bore a 3-celledcarpo-eonial branch. The supportingcell rneasuredI5 25 pm in diameterand was usuallyrounded (Figs 25, 21,28) but was occasionally ellipticalor oval (Fig.26). In the proxinrityof carpo_eonialbranches (particularly those with well developedtrichogyrres) the cuticle was very much thickened (Figs 25-28),often to 20 25 trrnr.In all specirrensexaminecr the carpogo'ial branchwas composed of 3 cellswhich werejoinedby largepit connections.The

-.h lr>nfir,' )a il.ct,H#, ,t,I."b { : a a , -V(-r ------=.\.-) o\!-)--:::.J

00

Frc;s 23 2.8. Carnera tucicla drawings of transverse sections of the n-ralc and fentale rcproductive organs of Rltod1,t17sn16,pseLrdopalntattt var. pseudopahrrata(Larrouroux) Silva. Material rvas collectcd at Finnavara, Co. Clare, 30 Augr-rst 1974, boulders: ELWS, leg. M. D. Gr.riry.trig.23. Mature sperrratangial sorr:s.Fig.24. Older spcrma- tangial sorus. trigs 25 28. Carpogonial branches at various stagcs of developrleni. Abbrcviations as in Figs l5 22 crcept: rrr': auxiliary ce11',unu': auriliary rlothcr celll hi'. hair cell: smc: spernratangialmotlrer cell; .rp: spennatangiunt;.it: supporting cell; r: carpogonium; t: trichogyne.

F 396 M. D. GUIRY

carpogonium was always uninucleatebut the secondcell of the carpogonial pl. 134,Figs 2,7). Cystocarl branch was always binucleate.Contrary to the observationof Sparling (1957, was rare. Cystocarps p. 325)that the auxiliary cell was had a easilydistinguished after its formation by the raised. presenceof a proteinaceousbody (: iridescentbody), in the materialexamined it was rather difficult to decide which cells with such bodies representedthe TETRASPORANGIAL PLANTS auxiliary cell branch. In some cases (Fig. 25), a proteinaceousbody was observedin the terminalcell of a filamentbut in others(Ftg. 27)it was observed Tetrasporangiawere form in a subterminalcell. Occasionally an apparently3-celled filament was observed the apicesofthe fronds.The on the supportingcell (Fig. 26).In this particularcase the terminal cell did not opmentalstresses and tetrasl seemto have any proteinaceousbody. Cells other than those involved in re- In the formation of tetraspi production may also have proteinaceousbodies (Fig. 28) and, as remarked I A, B) and were denselysta previously, these seem frequent in medullary cells of this species.Sjostedt a slight elongationand divis (1926,p.32), Kylin (1931,p. 33) and Sparling(1957, p.325) observedthat the expandedin sizeand evenrua auxiliarycell was suffused with "food-material"and consequentlystained deeply. arranged spores.The cleaval This would seem also to be a difficult distinguishingfeature as it has been the longitudinalcleavages. N observedthat many ofthe cellssurrounding the carpogonialbranch are nutritive and measured25-30 gm peri, in function and consequentlyare also full of "food-material". It is however gavedinrensions of 2?'-2Rrtrr possiblethat the stain used in the presentstudy did not differentiatebetween sideredro t.pr.l.'ri,r, "'r,iri cellswith a moderateamount of "food-material" and thosewith a largeamount. TS, sporangia appearingto I In conclusiontherefore it seemsthat the only auxiliary cell branch observedin 1974b,Fig.lC-G). From a s this variety during the present study which correspondswith the classical that thesesporangia had four r conceptis that illustratedas Fig. 25. parallelto the planeof viewi Another featureof carpogonialbranch developmentin this variety deserving sporangiawere observed with t gave specialmention was the disruption of the surroundingcortical cells,many of the appearanceof a spo; which becameanticlinally elongated (Fig. 28) forming what may have beenthe Sporangiain maturesori wr beginningsof hair cells.These cells may possiblyhave been disruptedby the inlerspersedwirh elongare, processofsectioning, as Sparling(1957) observed that hair cell formation fre- cleavageof rhe ,.trurpllun_n quently occurred in the proximity of carpogonialbranches. Fertilization was tetrasporangialmother cells, not observedin any of the many procarpsof this variety observedduring the tetrasporangiaand further div presentstudy. Sparling(1957) reported that a conneclingcell was cut offfrom Tetraspores,when shed, measr (1975, the fertilizedcarpogonium which coalescedwith the auxiliary cell. Boney Table 2) reporte specimensdredged at plymou diametersare more typical of s CYSTOCARP

Three groups of carposporangia at different stages of development were REPRO] invariably present in the mature cystocarp which correspondedto the 3 largest Of the 145collections lobesof the gonimoblast.The most mature gonimolobewas alwaysthe largest of R. I02 were clearly and occupiedtwo-thirds or more of the total volume of the cystocarp.The daredand plants were collected carposporangiaof this lobe were the largestand the most mature. Each con- in June, collectionsin October tained a single carposporeand measured(5.4)7.2-21.6(32.4) pLm maximum through plantsofthis variety diameter and (5'4)7'2-14.4(21.6)pm minimum diameter. Mature carpo- duringthr and tetrasporangialplants sporangiawere usually hexagonalin shape (probably due to crowding) and we indicating that rhis variety ., immature carposporangiawere rounded or angular-rounded.Presumably when is the oldest carposporangiahave been discharged,the second and third lobes expandand filI the resultingspace, the carposporangiamaturing prior to release. Externally cystocarps appeared as irregularly-placedhemisphericaI pro- This variety was found to g tuberances(532-909 pm in diarneter; 500-965pm maximum height) irregularly _ the intertidal,populations wer scatteredat the apicesof the ultimate branchesof the fronds (cf. Harvey, 1847, the subtidal fringe" populatio The genus Rhodynrcnio 397 pl. 134.Figs 2, 7). Cystocarpswere observed half-way down the fronds but this wASrare. Cystocarpshad a small.centrally-placed ostiole which was slightll- raised.

TETRASPORANGIAL PLANTS Tetrasporangiawere formed in smallrounded sori 2 5 (9) mm in diameterat the apicesofthe fronds.The sori were usuallyconcave, apparently due to devel- opu.nentalstresses and tetrasporangiawere formed on both sidesof the thallus. ln the formation of tetrasporangiacortical cells enlarged (.Guiry, I974b, Fig" lA, B) and weredensely staining. The accompanyingcortical cells underwent a slightelon-qatjon and divisionat this stage.The tetrasporangialmother cells expandedin sizeand eventuallydivided forming a sporangiumwith 4 cruciately- arrangedspores. The cleava-eeswere successive,a median cieavagepreceeding the longitudinalcleavages. Mature tetrasporangiawere distinctly elongate-oval and measured25-30 4m periclinallyand l5-22 1tmanticlinally. Sparling ( 1957) ,qavedimensions of 23 28 pm by l3 l51rn.rfor SouthAfrican materialshe con- sideredto represeutthis variety. When tetrasporangialsori were examinedin TS, sporangiaappearing to have two sporeswere frequently observed(Cuiry, 1974b,Fig. lC-G). From a surfaceexamination of suchsori, it was concluded that thesesporangia had four sporesbut the longitudinaldivisions were in a plane parallelto the plane of view in TS. Occasionally(Guiry, 1914b,Fig. lE) tetra- sporangiawere observed with the periclinaldivisions in two differentplanes which gavethe appearanceof a sporangiumwith three spores. Sporangiain maturesori werevery crowded(Guiry, 1974b.Fig. I G) and rvere interspersedwith elongate.sterile filamentstrvo cells long. In this varietl cleava-eeof the tetrasporangjadid not occur synchronouslyand developing tetrasporangialmother cells u'ere alwal-sobserved in rnature sori. Secondarl' tetrasporangiaand furtherdivisions oftetrasporangia in situ werenot observed. Tetraspores.when shed, measured l9'8-28'6 pm diameter(78 spores measured ). Boney(1975, Table 2) reportedtetraspore diameters of (7'5)9'0-12'0 pm from specimensdredged at Plymouth;this would seemunusual, particularly as suclr diametersare more typical of sporesof speciesbelonging to the Phyllophoraceae"

REPRODUCTIVE PHENOLOGY Of the 145collections of R. pseudopalntatavar. p.seudopalmaiaexamined. onl-v 102 were clearly dated and 58 bore discerniblereproductive organs. Most plants were collectedin June, July, August and Septemberwith a scarcityof collectionsin Octoberthrough to March. which may rellectdifficulties in locatin-s plantsof this varietyduring the wintermonths. Spermatangial. carposporangial and.tetrasporangial plants were comnlonest in July, August and. Septernber. indicatingthat this varietyis "summerfertile" in the British Isles.

HABITAT This varietywas found to grow in both intertidaland subtidalhabitats. ln the intertidal,populations were not common and wereinvariably confined to tl-resubtidal fringe. Populationswere commonestin deep pools at MLWS 398 M. D. GUIRY

(mean low water of spring tides) but, in exposedareas, tended to be found in narrow, shallow pools at MLWN (meanlow water of neap tides).Such pools were invariably well-shadedand populations were usually confined to verticatr or near vertical walls well below the water surface.Under certainconditions of shade and humidity populations were capable of surviving emersion. Such populations were common on the west coast of Ireland (Kilkee, Co. Clare), but were invariably associatedwith habitatswhich were not well colonizedby' other algae.At one of the sites examinedin Britain (Elberry Cove, Torbay, South Devon) this variety grew in considerablequantity on vertical open rock at ELWS together with Scltottera nicaeen,sis(Lamouroux ex Duby) Guiry & Hollenberg.ln the subtid.al,plants of this variety were conrmoneston stones. boulders and ledges and epiphytically on the stipes of Laminqria lryperborea to 20 m. .>fr& 'tU DISTRIBUTION g^$I BRITISH ISLES 0\ -o. .'c The distribution records of Rhodymeniapseudopalmata as reported in the literatureunder varioussynonyms are summarized in Fig. 29; someof the litera- v'c ture records cited possibly refer to R. pseudopalmatavar.ellisiae and Schottera , nicaeensis.The records of "Rhodymenia palmette" from the Orkney Isles, all 4 refer,irsfarascanbeascertained,toR.delicatula(seep.4l9).Fig.30illustrates the distribution of R. pseuclopalmatcvar. pseudopalmataaccording to specimens examinedby the autl,or. The data usedto compileFigs 29 and 30 may be found in Guiry (1916).A comparison of Figs 29 and 30 shows that a considerable number of earlierrecords may representmisidentifications and that the variety seemsto be confined to southernand westerncoasts of the British Isles.The Scottish records are in need of confirrnation as they represent,if correct, the nortlrernmost extension of Rhodt,meniapseudopalmata in the Atlantic.

WORLD Rhoclymeniapseudopalmala seems to be confined to the north and south Atlantic. There have been a few records frorn the Pacific (e.g. Setchell & Gardrrer, 1903; Taylor, 1945) but these probably representother speciesof Rhodymeniabelonging to the section Rhodymenia.Moreover, in the Atlantic, many records of Rhodymeniapseudopalmata (often as R. palmetta) possibly are not the type variety but are included here becauseof uncertainty as to the correctnanres which should be appliedto thesespecimens. In the easternnorth Atlantic the specieshas been recorded from the British Ftt,.29 Isles south to Morocco, the Canary Islands and the Azores. In the south Di:rribrrrion in rhc Briri:lrl Atlantic Sparling (1957) tentatively recorded Rhodymeniapseudopalmata from { t.arrronroux) Silva as rccorded i proDabt) corrccl: E doubtful South Africa but her material had a four-celledcarpogonial branch whereasthe r, material describedabove has a three-celledcarpogonial branch. Further investi- gation of materialof this speciesfrom the south Atlantic is needed.Records of this speciesfrom the Mediterranean(e.g. Giaccone, 1969; Gerloff & Geissler, 197l) are probably incorrect. The records may refer to Rltodymeniaardissonei J. Feldnrann or R. ligulata Zanardini, both of which speciesare apparently common in the Mediterranean. 'fhe genus Rhrnl.r'ttteniu 399

210km

Ftc. 29. Dist ribut ion in t he British Islesof Rfiorl,r'nteniupseudopaltnata var. pseudopalnnta (f.amouroux) Silva as rccorcled in the literaturc searched.A' Records which are probably corrcct; E doubtful rccordst I -- incorrect records. 400 M. D. GUIRY

RHODYMENIA

on

, Rhotlyrnenia pseutlopolmata tt long been confused uith a nur confusion arose largely as a resL ntcoeenstsLamouroux ex Dubl H.ollenberglro a variely ol Rhoa !7til!ryenlo nicaeensis ro the gcr both J. Agardh and Monragne-il Scho t t era nicaeensis (phyllo'phor synonymy). Confusion cit ttre pl resuil of a.scarciry ol fertije mat, In Bntatn, Har\ey(1947. p. 13. (^ urler ar Sidmourh as '.Riodyt dupttcale specirnenscollected at specrrnens of Schottera nicaeen. polmetto_var. nicaeensisJ. Agard strrclo. Hoimes ( lgg3) seeme-dp, patmena var. nicaeensis and phyl, ''Ou ing to rhe grearsimilarir. p,tltne.rtoide.s.rhe tuo plants are absent and the fronds art disc and in the former [- Xi prostrate stem."

Holmes exanr_inedcysrocarprc sf and*concludedthat the structure0 olr_hyuophora.and cited rhe opir ol Phyll.ophorawhich bore cysroci f d6)) rrrough.l phyllophora uas . Uurry & L. lrvinel. Desplterhei Agardh (l 842) represenreda phyl ".nicaeensis" for his material (a itr the mistaken impression thai hi sensu Holmcs raasinvalidared b1 (Monragne. 1846.pp.68 69;. The earliest valid name which c: ated.by.Batters, 1902)to be Halym cited Chauvin's specimenno. l6 c basrr lor his description.althou Lam_ouroux with the name. Dubl valid accoynt of this entity. Nin were found by the presentauthor i de Strasbourg(STR); 6ns 6i thq56 J4: thc cenlt.espccimen) is selecte Duby. All specimens la.belledSpi are represenlariveofa spcciesof Ri pseudopalmatavar.pseudopalmata Frc. 30. Distribution in the British Isles of Rftodymenia Frg. J: as Khodymeniapolmetta tt (Lamouroux) Silva according to specinrensexamined during the present study. l: as R. tricaeensis)ensu Holmes) : an Specimenswith clear locality citations; I specirnenwith doubtful locality citation. Calvados region of northern Fran )ussex are preserved in the British

* Tllo orthographic iariants ol "ellisiae" and "clisiae". The form (in accordance with recent practic footnote). The genus Rfu;d1'ntenia 401

RHO D YX,,I I.:N I A PSEU DOPA LII,TAT'A V AR. ELI,ISIAI.

ORIGINAL DESCRIPTION

Ilhorll'nenia p.seudopulmarovar. ellisiae (Duby) Guiry in Guiry & Hollenberg (1975) has long bcen confused with a nunrbcr of other algae, particularly S(holtera nitaeensis.This coniusion arose largely as a rcsult of.l. Agardh's (1842, p. 153 154) reduction of Hulynreniu rtitaeensisLamourtjux ex Dr-rby I Sc/totteranicaeensis (Lamouroux er Duby) Guiry & Hollenbergl to a variety ol Rhocl_y'neniupolmetto and Montagne's (18.{6,p.68-69) transl'erof Htrltrtrcniti tticaeen.si.sto the genus Rhod.ymeniaas l?hodyntenio nicaeensis The materials of both J. Agardh and Montagne (BM; PC) undoubtedly representthe alga presentlyknown as S(lrcttero nitaeensis(Phyllophoraceae; see Guiry & Hollenberg, 1975,for a nlore complete synonynry). Confusion of the Phyllophoraceanalga with Rlutdynteniupalntettct was largell-a result of a scarcity of fertile material. In Britain, Harvey (1847,p. 134, Fig. 3) describedplants collectedby Mrs Grilithsand Miss Cutlcr at Sidmouth as "Rhodl,ntenia polnletta var. nicaeettsisJ. Agardh". [t is clear 1'ront duplicare specimenscollected at Sidmouth by Griffiths (BM) that Harvey (1847) confuserl sr-rccirlens of St hottera nicaeensis fror.n the Mediterranean (then known as Rhod.vnteniu palmetta var. nicoeensisJ. Agardh) with British specinrcnsofa speciesol Rhoclynrcniosensu stricto. Holnres (1883) seenlcdprinrarily concerncd with the confusion between Rhodymeniu lolnrcl10 var. nitaeensis and Ph;,llophot'ttpalntettoide.s J. Agardh stating that:

"Owing to the greatsimilarity in t he shapeand strLlctureof the frond lctIhat of Ph;,llopl.tortt pulnettoides, the two plants often pass thc one lor the other when the terminal cirrlrl are absenrand tl-refronds are collecied rvithout thc root, which in the lattcr is a spreading discandinthefornterl: Rhoclrntenictpolnettovar.nitueen.si.slisacreepingstolonittrous proslrate stem."

Holmes exanrined cystocarpic specimensof "Hul1'nteniu rticaeen,si.sDubyl ft'or.ttMarseille. and concludedthat the structure ofthe frond showed tl-ratthese specintens reprcsented a spccie: of Phyllophora,and cited the opinion of Hauck that in the Mediterrancan there was a species of Phyttophorawhich bore c)\toca|ps, Ler|asporangiaand spermatangiawhich he (sce Hauck. f 885)' thought yvas Pht,llophora pilnettoide.i [now known as Ph.vllophoru .rlcrrla (Kirtzing) Guiry & L. Irvinel. Despite tl-reieindications that the Mediterranean alga dcscribed by J. Agardh (1842) repftsenteda Phyllophoraceanalga, Holr.nes(1883) chose to retain the epithet "nitaeensis" for his nraterial (a speCiesof Rhod)'nteniasensu stricto), apparently being under thc nristakcn inrpression that he was rnaking a new cotnbination. Rhotl.vnieiliLIItitlern.\i.\ sensrrHolmes was invalidatc

* T*o orthographic variants of the varietal epithet have been r.rsedby- vartous autllors: "elli.siae" and:elisiae". The fornrer was used in the original description (DLrby, 1830)and (in accordancc vi,ith reccnt pracrice) is here rctained (see Guiry & Hollenberg, 1975,p. lzl9 foo t note). 102 M. D. GUIRY

ppn Rlnldy ia psetdLryolnat o \ ar. el, Basfon) nt: Halyntenit puliltettuva Synonyms: Sphaerococ(uspalmett( Rhodyntenia palmetta r Rhodynte n ia n icaeens i s non Rhoctynenia nic I Schottera nicuee, p.1531. Rhodymenia (?) holntes tltc gpl1spy61.(,((u.\ . , .As nant.e lrrt rrr,dz/. no. tO).rr: usageb1 Kiirzing( t_tte $1 _corrrbinationol Rh,rl.rnrctriti, (t892, p.285). Ardissone-(1893)i 31 ttit'treensi.sand the Mediterranean p proposed the new nante Rhotlyrie Holnres. As the earliestvalid ^ ancllegitinra R,.,.f.\erdt)lnlt I talzl ( | atnourou\) Sil (ttrs:kte(Duby) Gui11.in Cuirl & Ht te /t).

-e STRUCTUREAND t- rl "tr O cl e LXI II{NAL MOR]]HOLOG\, EI rf'l Plrrrrts ol Rlrotl.r.ntetriult.rct, -l lionds fronr stolonswl.rich wer I slvelyjn soft rock or sponges. completelyembedded ancl wel clurrpsof erectblades (Fig.35r 32 red colourand wereoften spira appearanceof the erectblade growillg se:rson.Epiphytic spec ln the intertidal - plantstend, Sussex(27 March I974)stolor rock ar)d lorrrringshort. trprig April. 1883by E. M. HolmJr Fig. c, d; BM) were l0 35mn front narrow stolons.These pla erect.blades had probablyrege fronds (Holmes,t883, p1. 240, l (2 July 1973)were to 35mm ir frorrds with two or three narr( {$,*r"rp*d[ ,|r'{td,.s'{. feature 34 o&... Wr_ *, of suchfroncls was the s was found to be causedby the Frcs 3l-34. Herbarium material.o.f Rhodynt_eniapseudopalmata var. ellisiae (Duby) starchi11 the medullarycells in I Guiry. Fig-s 31,.32, Jype nta-terialof Rhod),rnenianit:ieensis sensu Holmes'(BMl; Mer, Calvados,France illustrated as tab.240c and 240a,.respectively,in Hoh-ncs (1gg3). The cystocarprc nearthe specimen.in trig.3J is selectedas. the lectoiype. trig. 33. Materiai witir long apical in height (average50 mm) with pro_Jifcrations, Baie de Morlaix, Brittany, Franie, l0 August 1966,leg. M.-th. LlUardy_ dichotomies(Fig. 358).These pl HaJos (MDG^)-rfig. 34. Material_of H-alymeniapalmetta var. eilisiae-Duby from Duby-'s (STR), graduallyexpanding to form herbarium annolated "M. chauvin" in Duby's handwriting llower right). a I The centre specimenis chosen as the lectotype. same width (lesstlian 5 rnm) fo Thc genus Rhotll'meniu 403

SYNONYMY

RhptlylteniapseLtrloltalntutu .var. elli.siue (Duby) Guiry, in Guiry & Hollenberg, I975, p. l'19' Basionym: i7al1'miniapolnetto var. p ellisiaeDuby-, 18,19,p' 943,^-^ Synonyrr-rs:Sphaerocot'ir.rsp.tlmettovar.ellisiue (Duby)Kiitzing, l8!8rp.3-+. 1ah.99Fig-a. p 286 Rhodl,neniu polnetta var. eli.siue[sic] (Dubl ) B-o-rnet.l^89^1. , pl Rhotil'ntenia'nitaeensissensu Holrnes' 1883,p.289, l40. Fig 1.^9't'd' no^ Rln(!)'nenicr rtit'tteensis(Lanrourour ex Duby) Montagne,-18'{6. pp 68 69' 1975. l. Sclntieru rtirtreen-sis( Larrouroux ex Duby) Guiry & Hollenberg, p. |531. Rliodt,neniu('l) holnesii Arclisson:, 1893,p. 682 As thc name SphuerototlLrspulnetta var. elisiae was not validly publishecl by C-hauvin 0827,no. l6),itsusagebyKirtzing(1868,p.34,Tablc99,Fig.a)constitutedanervcot.ubination. TIre icrrrbiniiion of- Ritttl)'ntenii pulnteitrt var. ellisiae was probably first nrade by Bornel (1892. p.285). Ardissone (1893) iecognizing tlre confusion between Holnres's Rhtttlvrttettitr iicneen'si.talcl the Mediterranean phyllophoraceanalga then known as Plt.t'llophoru/11('(r(t'/r.\i\. rricneerl.slssensu 1rr-oposedthe nerl name R/iorl,r,lreniuholnesii Ardissone fttr Rluttt.y'ntentrt Holmes. As thc carliest valid and Iegitilnate natrc for Rltod1.ntenia pu\nrctlo (Lanrouroux) Grei'iIlc is R. pseutlopaln'tt1rl (Lalrouroux) Silva the new corrrbinalion Rltod\'tttenitrpseudoPoltltolu \tar' a,ilr.riae(Dr,rby) Cuiry. in Guiry & Hoilcnberg hasbeennloposed (Guiry, in Cuily & I-lollenberg. r975).

STRUCTURE AND DEVELOPMENT OF THE THALLUS

| \ ll R\AL \'lr )l{l'H()1.()c\

PIants of Rhod)'nteniul.\'eLrdopulntutd var. clli.siaetbrrued efect. f'latterled frond.sflonr stolonswhich wereLlsuallv tcrete and \\'erefoLillcl to ranlif-ve.rten- sivell,-i1 soft rocl(or spon-ses.Stolons \\'ere colourless or lightly coloureclwhen coutplctelventbedclecl liltd \\'erebranched irrcgularly. oltctl reslrltingin large- clunlpsol'efect bladcs (Fi-s. 35C). Erect fior.rcls had a dark crinlsollor pLlfplish- redcoloLlr and wcreoftert spirallv trvisted (Fig. 35A).Sonle slight charlges irl the apperiranceof the erect bladeswere observedto take place thrtlughoutthe growillgseilsolt. Epiphltic \pecinlell\\\ere not observed ln thc intertidalplants tended to grotv gregariousl).ln March at SelLlbrcl. Sussex(27 March I974) stolonsof this variet,v-were lbultd ranriiyillgin sol't rock anclforniing short. r-rpright.slightly'flattened fronds. Plantscollected in April. lE83 by E. M. Holnresat Hastings.SLrssex (Hoinres. 1883.pl.240. Fig. c, cl: BN,l)were l0-35 rrm in height rvith elongatecllinear bladesarising frot'nniLrrow stolons. These plants had. at nlost.olle dichotor.nr-.Several of the erect bladeshad probablv re-selleratedfrom the basesof the previoLl\\crlr \ l}onds (Holmes,1883. pl. 240, pig. c [lefl]).Pla6ts collectecl ip July at Scafbrd (2 July 1973)were to 35 mnr i1 height arld oflerl had wcakly spirallytn'isted fronds witli two or three narrow dichotonlies(Fig. 35E.F). A charlcteli:tic featureo1'such fronds wasthe sli-uhtl1'nlottled appearance of the thalluswhich rversfouncl to be causedby the accumulatjonof largequantities of lloridean starchiu the nredullarycells in localizedareas. Plants collected at Vierville-sur- Mer. Calvados,France near the type locality(21-23 July 1974)were to 80 nlnr in height(average 50 ntm) with long. narrow fronds (to 5 ntm broad)and,2-4 clichotonlies(Fi-e. 358). These plants had shortci'lindrical stipes to l0 nrm long' gracluallvexpanding to form a lirrearfrond whiclr mailltainedmore or lessthe samewidth (lessthan 5 ntm) for most of its length.Sucl'r specimens gre\l or1 M. D. GUIRY

the vertical walls of soft roc on the prorrudingtips of fi growlng erectwith short,s( plant seemedto be confined plants describedabove we bladesborne on short later, locality were found to have frond.apex had becomeero, in length.Holmes (1883, pl. a specimenfrom Hastings Specimensfrom Brittany (Ba Halos) with long apicalpro blanceto someplants of Scfu 1975,Fig. 74c,d, e). Suchp and Septemberand haveoc(

STOLONS

Stolon productionjn Rho in its intensity.whole stands matureplants the basesof thr forming lateralproliferarion: geotrophic(or perhapsnegati 15mm: ABCEF and presumablyforming stor

ANATOMY

The thalluswas composec cellsand a medullaof 2-6 la of the thallusthe frondswere posedof two layersof medu spacedin optical section(Fi cortical cells measured(5.a) (10.8)pm wide adaxially.A subcorticalcells appeared ver. The chloroplasrshad a simili describedfor rhe rype varier measured (24) 4I-53 g7) pm axially in LS. Thesecells wer Flc. 35A F. Range of variation in external morphology and appearance of tetra- for the type variety.ln thelov sporangial and carposporangial plants of north Atlantic material of Rhodymenia pseudopalntata var. ellisiae (Duby) Guiry. Fig. 35A. Cap Fagnet, France, 9 September in extentbut thecortex remai 1972,1e9.J. H. Price & I. Tittley; tetrasporangial plant, note the apical sorus (rs). Fig. was very much narrower thr 35B. Vierville-sur-Mer, Calvados, France, 21 July 7974, vertical walls: MLWN, leg. wjth R. pseudopalmata M. D. Guiry, cystocarpic plant (cy). Fig.35C. Collection data as for Fig.35B, but var.pr growing on sandy ledgesat MLWS, note the shorter fronds. Fig. 35D as Fig. 35C, show- lessthe samethickness as th ing the basal position of the cystocarps. Fig. 35E. Seaford, Sussex, U.K., 2 luly 1973, ellisiae the thallus was ll6_l rocks: MLWS, leg. M. D. Guiry, sterileplant, showing the developmentof stoloniferous more from growth. Fig. 35F as Fig. 35E, but collected as drift, note the basal and median position the apex, increas of the cystocarps (cy) and stoloniferous growth (st). flattenedportion. The genus Rhodymenia 405 the verticalwalls of soft rocks at M LWN-ELWS. At the samelocality, growing on the protrudingtips of flat sandyrocks at ELWS, small plantswere found growingerect with short.sometimes simple, fronds (Fig. 35C,D). This type of plant seemedto be confinedto suchwave-washed plateaux. However. the larger plants describedabove were occasionallyfound to have such short simple bladesborne on short lateralstolons (Fig. 35B).Sorre plantscollected at this locality were found to have small apicnl proliferations,particul:rrly where the frond apexhad becomeeroded (Fig. 35C) but theserarely exceeded a few mm in length.Holmes (1883, pI.240, Fig. a; Fig.32 of the presentwork)illustrated a specimenfrom Hastingswith cirrose apical proliferationsto l0 mm long. Specimensfrom Brittany(Baie de Morlaix, l0 August1966, leg. M.-Th. L'Hardy- Halos) with long apical proliferationsto 20 mm bore an extraordinaryresem- blarrceto someplants of Sclotteranicaeensrs (cf. Fig. 33 and Guiry & Hollenberg. 1975.Fig. 14c.d, e').Such plantswere common in collectionsmade in August and Septemberand haveoccasionally' been found in April.

STOLONS Stolon production in Rhod.ynteniapseudopalnlata var. ellisiaeis remarkable in its intensitir.whole standsof plantsoften havinga conrntonorigin. In more matureplants the basesofthe flattenedportion ofthe frondsrvere often observed forminglateral proliferations (Fig. 35A) which. on occasion.seemed positivelr.' geotrophic(or perhapsnegatively phototrophic) curvin-e towards the substratuni and presumablyforniing stolons.

ANATOMY The thallus was composedof a cortex of 2-3 layersof chloroplast-bearing cellsand a rnedullaof 2-6 layersof colourlesscells. Within 2 nrm of the apex of the thallusthe frondswere usually thin (to 381im thick in TS) and werecom- posedof two layersof medullarycells. The corticalcells appeared fairly widely spacedin optical section(Flg. 3) and were sliglitlyaxially elongated. Surface cortical cells measured(5'4)9'0-14'4 (19'8)gm long axially and (3.6)4.5-7.2 (10'8)pm wide adaxially.A characteristicfeature of this varietywas that the subcorticalcells appeared very regularlyarranged when viewed frorn the surface" The chloroplastshad a similar rrorphologyand developmentalpattern to that describedfor the type variety. Medullarycells, when mature,were large and. measured(24) 41 53 (57)trrrr periclinally in TS and (98) 102-133(137)lnr axiallyin LS. Thesecells were very stronglycoherent in the mannerdescribed for the type variety.In the lowerparts of thethallus the medullawas to sixlayers in extentbut the cortexremained quite thin (Fig. l9). The marginof the thallus was very much narrower than the centre(Figs 19,20) which contrastswell with R. pseudopalmatavar. pseudopalmala,where the thallus edgehad more or lesstlre sarrletl.rickness as the centre (Figs 21,22). ht R. pseuclopalmatavar. elli.siaethe thallus was ll6 1451tm thick in the flattenedfronds at l0mm or more from the apex, increasin_qto 188tr.rm thick at the extreme base of the flqttpnorl n,r"ti^. Pvr rrvri. 406 M. D. GUIRY

STRUCTURE AND DEVELOPMENT OF REPRODUCTIVE ORGANS as such a frond would prot in which As far as can be ascertained,the descriptionand illustrationsgiven by Holmes casethe cystocarp (1883,pl. snlgtecilse. 240 as R. nicaeensissensu Hoimes) are the only pubilshedrecords of in a specimenco reproductive 23 Augusr organs in this variety. He illustratedtetrasporangia occurring in 1889,collecror r aprces. a smaliapical soruson terminalfiliform proliferationruni occurring Otherwisethe cysro, at "yrtJ.urps structure the apicesof'short, erect,terete fronds, but statedthat cystocarpswere also as that described generations found near the baseof tlre fronds. which is more tvoical. of carposporang

amc GAMETANGIAL PLANTS

Spermatangiawere not found on any of the pra.ts collected.The description Buffham- of (1894,pp. 294-295,pr. l3: Figs is-t7) of the spermatangia-of a specimenof "Rhotlvnteniapahnetta" collectedby J. T. Neeveat Deal, kent in August, 1892may in lact representthe spermatangiaof this variety.Tliere is a specimenin the ulster Museum (BEL) Iabelled"',Rhodymenianicaeenslr,, by E. M. Holmeswhich was collected,at Deal by Neevewhiih bearsspermarangra. This specinrenwas howevercollected. in November Ig9g. I have not beenable to locatethe n-raterjalcited by Buffham (1994). carpogonial branches were f,ound in one colrectio' (vierville-sur-Mer, 2l July 1974)at the apices of srnallplantswhich had simple'carpogoniablades (Figs 35C, D) and which also bore basal cystocarps.Most of these were in an advancedstate of post-lertilizationd.evelopment and all cirpogonial branches observed(Fig. 38) werewithout tricl-iogynesbut seemedto be coirposedof three 6r\ cells. The supporti'g cells were large and stained.deeply with Acetocarmine C\V .ool and Harris's Haematoxylin.Figs 36 and 37 show somepost-fertilization stages which were not observedin the type variety. Fig. 36 showswhat seemedto be a very young fertilizedauxiliary cell with the carpogonialbranch deterior:ating. As observedby sjostedt [1926; for Rhodymeniapertusa (postels & Ruprecht) J. Agardh], the auxiliary cell stainedvery deeply and the proteinaceousbocly was very largeand obvious,however, as in the type variety a number of nearby cells.alsostained deeply. A connectingcell betweenthe iarpogonium and the auxiliarycell wasnot observed.Fig. 37 showsa similar stagebui in this casethe secondcell of tl-recarpogonial branch seemedto have fused..Several further stagesir.r the developmeniof the gonimoblastwere observedbut a satisfactory account of these cannot be given. The procarps and young gonimoblastsof speciesof the Rhodymenialessensu stricto can only be observedafter sectioning. All the generastudied by the presentauthor show a remarkablereslstance to any form of squashpreparation (such as tirat usedby Norris, 1957on members of tlre Kallynreniacae;see Sparling , lg5J, pp. 3214:22).

CYSTOCARP Ftcs 36 40. Contertt lucidt drawtr ot Rhr.rjy111pni4pseu(lopolntuto val cystocarps DranLttes were found to be commoneston the smallerplants (Frg. at various slaAesof de _Mature .ur-Mer. 35c, D) and wereusually present only at Calvados. Fraice, 2l J the basesof trreblades. on the larger r-tg. J9. I rans\ersesection of mat plants cystocarpswere rarer but when present were ls,snoun. ( usually confined to the ap Fagnet. France,g i basesof the flattened (Fig. section fronds 358, F). Holmes (18g3,pr. 240,Fig.c ]l?ft_r,.rrg ofa nrarurccys [left]) rle^_t3rge. illustrateda plant lo,lc, cenrral. srerile.-g of thrs variety from Hastings which boie cystocarpsat the t Juty 1973,leg. M. D. Cuiry. A-h apicesof a seeminglyterete, erect frond. sporangtun): This does not seemuncharaiteristic, cb: carpogonial br tetrasporangiunt. Tlte gr'ntts Rlrul.trttertiu 401 as sucha lroncl would probablyhave grown on and formed a flattenedblade' i11which casethe cystocarpswould haveeventually been basally placed' In a siltglecilse. in a specirllencollected at Bulverhytlre,(near St Leonitrd's'Sussex' 23 AugLrst1u89. collector unknown. BM) the cystocarpswere borne at the at)ices.otherwise the cystocarpslrad n]ore or lessthe samedirlterrsions arld siructureas thilt clescribedfor the type varietyand. whell lnature.had three gencratiousof carposporangia(Fig. 401.

20 !m,36-38

30 pm,39 qQ o roffi,ao

sotltelcprodu!-ti\e organs Frc;s36 40. Ctrnreru1lcill drawings of transversesection\ of of Rlutdt'nteniup.seutloytltnita vari ellisiae(DLrbv) Guirv,,Fi*t.19: post-lcrtilizatron,--Vierville-llt 1Y;-!ot1ll*oniul branches at vanous stages of cieveloprllent,pr-obabll all ;;;-M;;: iuru"Joi,praice,2l .lulvlou+, iunav.lqdses: M!|l'.-l'-Y.,^Y^Pi-G''i''t' nlaturetetrasporangialsoru\;onl) alloltlonoTtlresorus Fig.3g.Transversesectionof Fig.40' i.r'i1',;;r;r;t"ij e"-g"i], p,'ance.9Septer.lbei 1972, leg. J. H. Pricc& l. Tittlel', f ,oniu"ii" r.ition-of a n.,"tui"'.-uttocurpshowing'thice generations of carposp-orangia' steiile,-goninbblast filinrcnts,-Scaford,Sussex, U.K.' drift, ,i,rt.'if*'-i"rg.,ientral, (?: iSii,T.g. Hl. o.'Cuity- Albreriationsas in F,igs15 28,except for: carpo- zirry pertcarp:le: sporangium;r:b: carpogonialbranch; .ry1:goninroblast filamcnt' /'e: tetl'asporanglum. M. D. GUIRY

TETRASPORANGIAL PLANTS WORLD only a few tetrasporangialplants have been examined.plants collectedat Most specimensexamined Cap Fagnet, France (9 September 1912,leg. J. H. Price & I. Tittley) bore the Caen-Calvadosarea whe tetrasporangiain a small apical sorus (2 3 rnrn diam., Fig. 35A). These sori by Chauvin (Fig. 4t). As on were concavein a similar fashion to that describedfor the type variety. other varlety seemedcommonest ot tetrasporangialplants examinedhad slightly elongatesori (to 5-6 mm long). Specimenshave beenexam Tetrasporangiawere borne on both sid.esof the thallus and mature sori variety doesnot seemto have measured100-1404m in thickness.The sporeswere cruciatelyarranged and Atlantic France(28 August I the sporangiameasured (14)23 25(29)4m long and (tl) 14-18(20)irm broad Atlantic Spain (16 September (Fig. 39). The developnrentof tetrasporangiawas exactly as describedfor the The materialcited by Borr type variety. Holmes (1883)illustrated tetrasporangia as occurringin terminal Rltodymeniapalmetta var. ellit filiform proliferationsbut a similar specimenfrom the Baiede Morlaix, France to judge from specimens(Bn ( Fig. 33) did not have tetrasporangiain the apical proliferations" variety from Atlantic Morocc

REPRODUCTIVE PHENOLOGY The scanty phenological data available suggestedrhat Rhodynteniapseuclo- palntata var. ellisiaebears reproductive organs in April, June-september,which is nrore or lessthe sameperiod of fertility as the type variety.

HABITAT

Plants of R. p.seudopalmatavar. ellisiae seemedto be commonest on shores wheresoft rocks suchas chalk and limestonepredominated. Most of the British records are from Sussexand Kent, where such rock dominates the shore formations. At Vierville-sur-Mer,Calvados, France (which is near the type locality)zones of this variety werepresent on soft chalky limestonesat MLWS- ELWS. The enormouscapacity for stolon productionseemed to give the plants a cornpetitiveadvantage on such soft rocks. In Britain the specieswas less common on the shoresexamined but was frequentat ELWS in similar situations at Seaford,Sussex. Many of the specimensexamined were collectedas drift (particularlyin Kent, Sussexand Norfolk) but the frequentoccurrence of such fresh drift material suggeststhat there are considerablepopulations in sublittoral habitats.

DISTRIBUTION BRITISH ISLES

Specimenshave been recorded for most of the countiesbordering the English Channel(Fig. al). Recordsoutside this areaare rare (Lundy, North Devon and Saundersfoot,Pembrokeshire). N. A. Jephson& S. Hainsworth (pers.comrn.) found this variety growing subtidally at Sherkin Island, Co. Cork, south-west lreland in August 1975.The specimenswere sterileand were growing on open rock below the kelp forest (c. l5 m) in a stand of typical R. pseudopalmatayar. pseudopalmata.This record constitutes the first for the Irish coastline and Frc.4l. Distributionof Rhodymen and_north considerablyextends the known range (Fig. France as known ro r of this variety al). study; | literaturerecords^ The genus Rhctdynrenia

WORLD Most specimensexamined from the northerncoast of Franceoriginated in the Caen-Calvad.osarea where the type nraterialof this varietl, was collected by Chauvin(Fig.4lt. As on the southerncoast of Englandpopulations of this varietyseemed commonest on the easternshores. Specimenshave beenexamined from the followinglocalities from wherethe varietydoes not seemto have beenrecorded previously: Biarritz, COteBasqr-re. Atlantic France(28 August 1854,herb. Thuret no.869, PC); Gijon, northern Atlantic Spain(16 Septemberto l5 November1895, leg. Sauvageau. PC). The materialcited by Bornet (1892.p.285) from Tangiersunder the name Rhodl'nteniapalmetta var. ellisiaeare probably not representativeof this variety to judge from specimens(BM). Dangeard(1949) record.ed specimens of this variety fronr Atlantjc Morocco but his n.raterialhas not beenexamined"

ENGLANO

FRANCE

Frc.4l. Distribution of Rhodynteniapseudcpalnntttvar.elli.siae(Duby)Guiryin Britain and north France as known to date. ,l Specin.rensexanrined during the present study; I - literature records. 410 M. D. GUIRY

COMPARISON OF RHODYMENTA PSEUDOPALMATA VAR. fendto be thinnerin TS but tb PSEUDOPALMATA AND R. PSEUDOPALMATA VAP.. ELLISIAE fonned (at 10 mrn from the similar in appearancein TS (, Rhodymeniapseudopalmata var. ellisiae(hereafter referred to as "var. ellisiae") of the thallus hasmore or les and R. pseuclopalmatayar. pseudopalmala(hereafter referred to as "var. psettclo- var. ellisiae. At tl"re palntata") differ in sevefal morphological and leproductive characters. Tl-re baseof different in TS (Figs grossmorphology of the thallus is probably the most distinctivefeature. The l9t2). very thick (200 250 with re-eularlydichotomous, elongated-linear fronds of var. ellisiaecontrast strongly 4m) thallus has r.noreor lessthe s with the broad, irregular fronds of var. pseudopalmafa.Spiral twisting of the tlre tl-rallusof var. ellisiae(a fronds, which is common in the larger specimensof var. ellisiae,has not been with 4 5 layersof medullary< observedin var.pseudopalmata. The frequencyof stolonformation i1 specimens thick, appearsto taper of var. ellisiaealso distinguishesthis variety from var. pseuclopalmalawhere, _eradu of medullary cells.This char although stolons are formed, tlr.e intensity of production observedin var. for the seeminglyrnore delici ellisiaeis never matched. The apical cirrose proliferations of vzrr.ellisiae seem cortical erndmedullary cells c also to characterizethe variety; such proliferationsare extremelyuncommon (Table I). in var. pseud1palmataand when they occur in the latter they always seen to be The position of the repror merelyflattened extensions of the apexwhereas those of var. ellisieeare invariabiy providesa meansof distingui terete. havebeen observed to occurc or medianposition on the me Trnrn I. A comparison of the principal morphological features of Rhodymenia pseuclopalnata var. pseudopolnnta and R pseudopalmata var. ellisiae Cystocarpshave neverbeer palmata. However, in one sp of var. ellisiee (Bulverhythe, ps Rlto dy men i a p se udop a Inat a Rhody m en itr euttopa/ nata just var, pseuctopaIntotct var. ellisiae scatteredfrom below tl thallus.This has only beenot small subapicalsori in both vz To 80 ml-n Height To 120mm to occur also on apicalprolil Width of fronds To 10 mn-r To 5 mnr Thickness of fronds (60) 100-200(250) pm (58)ll6 145(188) r,m var. ellisiae(Table I) but the r Stolons Sometimesformed Commonly forrned As many of the characters Cortical cells (axially at clearcut in some l0 mn fron-r apex) (3'8)9'0-13'4 (23'2) pn (s'4)9'0 l4'4 (19'8)pm specimensI Cortical cells (adaxiallYat thallus is very similar in botl (3'6) l0 mrn from apex) (3 6) 8'7 I l'6 (15'4)pm 4's-7'2(10 8) pm yar. ellisiaeas a variety.There Medullary cells periclinallYin transverse sectlon (20)41-51 (61) pm (24)4t 53 (63) pm recognizingthe entity as a spe Medullary cells axially in longitudinal section (65)102 133(153) pm (98)102 133(137) r,nt Position of cystocarps Apical,rarely median Basal,occasionally medtan RHOD Position of tetrasporangia Smallapical sorus Smallapical sorus Size of tetrasporangia (length by breadth) 25-30x 15-22pn 23-25x 14 18pnr ORI(

Rhodymenia delicatulaP. J. L. Da paramctersof these 10N, O, P) fron-r the Atlantic coas TableI showsa comparisotlof someof the rnorphological located in the Dengeard herariurn two varieties of R. pseudopalmata.ln var. ellisiaespecimens were ralely found Bordeaux at Talence. One specimen to exceed80 mm in heightwhile var. pseudopalmalaattained heights of 120mm. collected by P. J. L. Dangeard at A yar. second specimen was collected at tl As irlready noted, however, p.teudopalmataonly reachedits maxinrurll specimensare sterile (Figs 42, 43). potential height in subtidal habitats and most intertidal plants were lessthan original description, this plant (Fig, 60 mnl in lreight,so that in more or lessequivalent habitats, vat. ellisiaemay be longer. The width of the fronds is also an importelntfeature: var. ellisiae nevermore than 5 mm broad at the centreof the bladewhile var.2seuclopolmotq is possible, The fronds of var. ellisiae It is as will be discusse frequently attains 10 mm, even in intertidal habitats. should be included in the synonym, G 'The genus Rhod.tlnenio ,+ll tendto bethinrrerin TS but thereis considerableoverlap (see Tablc l). Whenfirsr formed (at l0 nm fronr the apices)the thalli of thesetwo varictiesirre ver\ similarin appearancein TS (Figs l5- l8). At this stageof devclopmentthe edge of the thallusltas rnoreor lessthe samethickness as the centreof the biadein var. ellisiae.At the baseo1'the fronds. however.the two varietiesare qulre differentirr TS (Figs 19-22).trn var. p.teuclopalntala(Figs 21.22t thc trrallLrsi: very thick (200 2501rm) with 7-8 layersof medullarycells and the edgeo1 tlre thallushas rnoreor lessthe sau.rethickness as the centre(Fi-s.22). In contrast the tlrallusof var. cllisiue(at the samelevel) is relativelythin (130.145trrrr). witli4 5layersol'medullarycells,buttheedgeofthethallusisonly80 100lrnr thicl<,appears to tapergradually to a point in TS (Fig.20) and has 2 4lai'ers of medullari,cells. This characteris remarkablyconsistent and nray accounr for the seemingll,'more delicatethallus of var. elli.siae.The climensiolsof the coriicaland medullarycells of both varietiesare, however,renrarktrbly similar (TabieI). The position of the reproductiveorgans, particularly the cvstocarps,ulscr providesa treansof distinguishingthese two er-rtities.In var. elli.sictecysrocarps havebeen observed to occllron snrallsimple blades (Fig. i5C, Dj and irra basal or rnedianposition on the maturefronds (Fig 35B, C, D, F). cystocarpshave neverbeen found to occur in such positionsin var. p.st'uclo- palmata. However. in one specimenwhich was thought to be representative of var. ellisiae(Bulverhythe, Sussex, 23 March 1889,BM) cystocarpswere scatteredfrom .just below the apices to approximatelyhalf-way down the thallus.This has only beenobserved on one occasion.Tetrasporangia occur in smallsubapicalsoriinbothvarietiesbutinvar. eIIi,ciaetheyhavebeenreported to occur also on apical proliferations.Tetrasporangia tended. to be smallerin var. ellisiae(Table l) but the differencesare slight. As many of the charactersdistinguishing these two varietiesare not quite clearcutin some specimensand as the anatomy arrd basic structureof the tlrallus is very similar in both, it has seemedbest to retain R. pseuclopalmata var. ellisiaeas a variety.There would seemto be insufficier.rtevidence to consicjer recognizirrgthe entity as a speciesdistinct from Rhoclyrneniapseutlopalmala.

RHODYMENIA DELICATULA

ORIGINAL DESCRIPTION

Rhodymeniadelic,atula l. J..L. Dangeard was describedby Dangeard (1949,pp. 172-173,Fig. 10N, O, P) from the Atlantic coast of Morocco. Two specirnensof this species have-bejn located in the Dangeard herariurr at the Laboratoire de Botanique, Facultd des Sciencesde Bordeaux at Talence.one specimenis that illustrated by Dangeard (1949,Fig. l0 N) and was collectedby P. J. L. Dan_geard.atAgadir, Morocco on 28 June 1938(Dangeaid 1177 bis). The second specimen was collecte-dal-the same locality on 5 July 1948 (DangCard 5543 bis). Both specimensare sterile (Figs 42, 43). As Dangeard 1177 bis is the specimenillustrated in rhe original description, this plant (Fie. a4 has been selected as the lectotype of the specres.

SYNONYMY

. It is possible,.as will be discussed later, that Rhodymenio phyllotde.r L'Hardy-Halos (1970) should be included in the synonvrny of R. delicatula.

G 1t2 M. D. GUIRY

30mm

A n I i)\,'/ ) i '\ ,/ /

42

30mm :f5!,?V )/ 30mm iil 30mm inl

t*''/ ){/ .;l i.s( _ srS q 5mm ,ft .45 s Ftc. 46,4 U. Rangeof morph material of Rhodymeniaclelicatt qqgcimenswith simplefronds, Ftcs 42 45. Hcrbariunr material of Rhctd;,nteniadelicutultt P. J. L. Dangcard. Fig. .12. yLWS. leg.M. D. Cuiry.Fip Lectotypespecimen ol R. delicotula,Agadir, M orocco,2 I June I 938 (DangeardI 177bis), fronds.nore rhe differing-lengr leg. P. Dangcard. Fig.43. Agadir, Morocco, 5 July 1943 (Dangeerd 5543 bis), leg. P" Variation of summerspeiimens Dangeard.Fig.4.{.Kirkwall Bay,Orkneylslands, l83T,dredged,exherb.J.H.Pollexfen, Penmon.Anglesey, Norrh Wal (BM). Fig. 45. Probably collccted at Beaumaris, Anglesey, Nortlr Wales, 30 Augusl Guiry.Fig.4bT-U. Variarion in 1882,lcg. J. E. Crilith, (BM). strpesand the elongationof the The genus Rhodyntenict 413

5mm

FIc. 46A U. Range of rlorphological variation in sterile specimensof British lsles nraterial of Rhody.nreniadelicatula P. J. L. Dangeard. Fig. 46A-I. Varjation of spring 1p9ci1en; with sir-nplefronds, Penrnon, Anglesey, North Wales,3 Apr:il 1973,pools: MLWS, leg. M. D. Guiry. Fig. 46J-P. Variation cf spring specimeni witlr branched fronds, note the differing length of the stipes,collection data as for A I. Fig. l2e-S. Variation of sumnrer specimenswith simple fronds, note the peg-like attachntentorgan, !e1mon, Anglesey, North Wales, pools: MLWS ELWS, l9 August 1974, leg. M. D. Guiry. Fig. 46T-U. Variation in sumnter specimenswith branchedfronds, note thc Iong stipcs and the elongation of the ultin-ratedicl-roton-ries, collection data as for e S. 414 M. D. GUIRY

STRUCTUREAND DEVELOPMENT OF THE THALLUS

EXTERNAL MORPHOLOGY Plantswere delicateor flaccid to slightly cartilaginousand had a light rose- red colour which was often obscuredby epibionts.There was considerableform variation within the populations examined. The maximum length of plants collectedwas 22 mm (Fig. 45) but most plants were considerablysmaller (Fig. 46) and the averageheight was about l5 mm. In December(Penmon, Anglesey l2 December1973) plants were little more than simple oval bladeletsnot more than 5mm in height borne on short stipes.In April (Penmon 3 April 1973; Porrh Trecastell,2 April 1973)small oval bladeletswere still to be found (Fig. I 46A-D) bur elongated,elliptical bladeson both short and long stipeswere also & present(Fig. 46F I). In addition fronds with one or occasionallytwo dichot- t'1 -omies g were also found, usually with long thin terete stipes (to 330pm diam.) t most of which gradually expanded to form a flattened frond with a basally 5mm, ABCDEFG q cuneateappearance (Fig. a6J-P).Some ofthese fronds arosefrom short stolons, presumablyof a previousyear's growth. The apicesof the frondswere occasion- illy curled in one direction (Fig. a6O). Plants collectedin July and August (Vierville-sur-Mer,Normandy,2l July 1914l'Penmon, l9 August 1974)wete eithersimple elongated blades arising from peg-likediscs (Fig. a6Q-s) or stolons (Fig. 47F), or irregularly dichotomously divided plants with long or short stipes(Fig. 46T,IJ). At this stageof developmentthe dichotomousfronds were often elongatedand strap-shapedwith rounded apices. Someregeneration was apparentamongst the plantsexamined but seemedto be largely from the stipes of the previous year's growth or from the apices of truncated,flattened fronds. Plantswith torn apiceswere also common amongst the populationsexamined (Fig. 60C). In one population examined (Penmon, l9 August 1974) lightly coloured orotuberances wele found on the surface of the fronds of some of the plants (Fig. 604). These structures were a much lighter whitish-red colour than the nearby frond and usually had the appearanceof a collapsedballool when mature. These measuredto 3 mm long and 0'77 mm broad and often had one or two dichotomies.When preservedmaterial was examinedwith a binocularmicroscope these structures were often brownish,greenish or yellow- brown. other irregularities were also observed in the frond shape (Fig. 608) which may have been developmental stages in the formation of these pro- tuberancesor may havebeen gal1s. L'Hardy-Halos (1970)found suchstructures on the surface of the fronds of Rhodymeniaphylloides and suggestedthat these vegetativereproductive organs. Frc. 47A-H. Plantsof Rhodvm might represent organs.Fig. 47A D. Terraspo;a Stolo1s,as alreadydiscussed, were rarely found, but were well developedin sori. PorthTrecastell. Anglesey. a few collections. Fig. 47F shows such a specimen from Vierville-sur-Mer, Fig.47E.Terrasporangial Ilanr r Bay. (21 1974)(from a sandypool) wherea stolon was formed high Anglesey,U.K.,5 April I9 Normandy July sporangialplants with basalcy up on the primary stipe of the plant. This stolon formed several irregular Vierville-sur-Mer,Calvados, Fr organs along its length which often had grains of sand firmly em- Guiry. Fig.47G. Carposporangii attachment lrond, usually formed terminally and sub- Penmon.Anglesev. Nortl bedded in them. Flattened fronds were Guiry. Fig.47H. Enlargimenro terminally on such stolons.Stoloniferous plants were mainly found in silty or Figs l5 28 and 36-40.except fo soft sand areas. The genus Rhodltnsniq 415

A

\ I,,(

5MM ' ABCDEFG

Fr<;. .{7A H. Plants of Rhod),nenitt delitatula P. J. L. Dangeard bearing reploductive organs. Fig. 47A-D. Tetrasporangial plants with tetrasporangia.in-media,n:elolsaleO soii, PortliTr.castell, Anglesey, U.K.,2 April 1973, pools: MLWN, leg. M D.Guirv. Fig. .{7E.Tetrasporangial plant with tetrasporangiain a median, rounded sorus,Cemlyn Ba-y,Anglesey, U.K.,5 April 1973,pools: MLWN, leg. M. D. Guiry. Fig.47F. Carpo- snoraneial piants r.rith besal cystocarps,note the stolon with terminal, erect blades' Viervili-e-sui-Mer,Calvados, France,2l July 1974, sandy pools: MLWS, leg. M. D' Guiry. Fig.47G. Carposporangialplant with a cystocalPaj-the baseof a_short,flattened frond, Peimon, Angiesey,Norlh Wales, U.K.,3 April 1973,po-o1s:MLWS, leg. M. D. trig. 47H. Enlargenient of rhe basal cystocarp in Fig.47F. Abbrcviations as in Guiry.-l Figs 5-28 and 36-40, except 1or: .): ostiole; /.t: tetraspo.rangialsorus. 416 M. D. CUIRY

ANATOMY and nreasured16.4,22.5 pm1 Plants were multiaxial, growth and differentiation taking place over a broad not crowded and wereintersl long, areaat the apices.Cortical cells of the uppermost part of the fronds were widely derived from surface formed spaced(Figs 4, 55) with the cells of the subcortex showing through the "gaps". from surfacecortical The cortical cells at 10 mm from the apex measured(a'0) 8'0-14'2 (20'5) pm long cessivelyforming sporangia v axially and (4'0) l'2-10'8 (21'6)pm broad adaxially and had many discoid Thesetetrasporangia often ha chloroplasts which seemed parietally concentrated in preserved material. In but, as in R. pseudopelmara,r TS the cortical cells were slightly elongated anticlinally and only the first two layers of cells had distinct chloroplasts. The medulla was composed of 2-3 layers of strongly coherent, axially elongated cells which appeared entirely colourlessin preservedmaterial but have parietally-placed chloroplasts which are easily destroyed by preservingfluids. Medullary cells measured(15) 25-58 (73)pm periclinallyin TS and (48) 67- 100(108) pm axially ir, LS. An iridescentbody (probably proteinaceous)was presentin someof thesecells. The thalluswas (30) 58 87 (102)irm in thickness. ln the lower part of the flattened fronds and in the stipes the cortical cells were arranged much more closely together (Fig. 57). Such a pattern was also observedin older or more mature fronds (Fig. 58).In the protuberancesdescribed above the surface cells were also more regularly-sizedthan those of the frond 48- JUPM and measured6'3-10'3 lm in diameter^

STRUCTURE AND DEVELOPMENT OF THE REPRODUCTIVE ORGANS

GAMETANGIAL PLANTS Plants bearing spermatangiaor carpogonial brancheswere not observed.Two collections examined contained plants bearing cystocarps; these were formed only at the base of the flattened portion of the thallus (Fig. 41F' G) and were rounded, hemispherical and slightly flask-shaped (Fig. 47H) with a small centrally-placedostiole and with a relatively thick pericarp. Mature cystocarps measured 400-500 1rm broad when mature and the gonimoblast was rounded and 300-4004m broad. The gonimoblast was composed of two lobes (Fig. 53) in the material examined, one of which was always considerably smaller than the other. The gonimoblast was nourished by a basalplacenta of deeply-staining cells with many secondary pit connectionsfrom which arose large sterile cells which were irregularly branched with very large pit connections. The sterile gonimoblast cells formed large clusters of hexagonal-roundedcarposporangia each of which formed a single carpospore. Carposporangia' when mature, measured 16.4J0.5 pm in maximum diameter, but the carposporangia of the secondlobe were considerablysmaller (Fig. 53). Releaseof carposporeswas not observed.

Ftcs 48 53. Camera lucida draw TETRASPORANGIAL PLANTS of Rhodymenia delicatula P. J. L were collected in April. Tetrasporangia both sides of the thallus.Port ! All tetrasporangial plants examined pools: MLWN, leg.M. D. Guiry were formed.in a small sorus at the base of the flattened portion of the frond sporangia. Collection data as fo (Fig. 47A-E). The sori were rounded, elliptical or elliptical elongate and were pericarp and the two generatio: Abbreviations a: in Fies I5 28. 1.0-1.5mm broad and 1'0-3'5mm long. Tetrasporangiawere small, rounded cell; I sreritenlanieni] Thc genus Rhtxlvtrcniu :ll7 and meilsuredl6'4-22'5 l.m broad and 24'6-34.8/,rr long. The sporangiawere not crowdedzind were interspersed with short,blunt, sterilefilaments l-2 cells long, derived fronr surface cortical cells {Figs 48 52). Tetrasporan-r{lawere lbrnred frorn surfacecortical cells (Fig.49) which enlargedancl divjded suc- cessivelyfornring sporangia which alwayshad four cruciatelyarranged spores. Thesetetraspo rangia often had.the appearance of hav in g only two or threespores but, as in R. p.saud.palmata,this wouid seemto be a result of orreor two of tire

48- 50um

Ftcs.{8 53. Cttttteru lucidu drawings of transvelse scctions of sor.nereproductive organs ol Rltodyttteniadelit'atula P. J. L. Dangeard. Fig.48. Development of letrasporangia on both sidcs of the thallus. Port Trecastell, Anglescy, Nortlr Wales, U.K.,2 April 1973, pools:MLWN, lcg.M.D.Cuiry.Figs49 52.Variousstagesinthedeveloprnentoftetla- sporangia.Collection data as fol Fig.48. trig. 5-j. Cystocarp; note the relatively thick pericarp and the two generations of carposporangia. Collcction data as for Ftg. 48. Abbrcviations as in Figs I5-28, 36-,40and 47 except for'. rmt.'.tetrasporangial nrotlrcr cell; .y': sterilefilament. 418 M. D. GUIRY cleavagesbeing in the plane ofsectioning (Figs 50-52).Further divisionsofthe (Lirrnaeus)Dixon and Cordy sporangiain situ were not observedand releaseof sporesin culture was not R. delicatulabecame more lt achieved. occasionallybeen found in situationsand were generai REPRODUCTIVE PHENOLOGY paltttatu,various Delesseril Kiitzing. In the British Isies plants of this speciesform reproductiveorgans in early In subtidalsituatior.rs in B spring; the period of reproductionseems to be from Decemberto April or May. usuallyon the uppersideofs

HABITAT BRITISH ISLES In Britain R. clelicatulahas been collected from intertidaland subtidalhabitats. The intertidal populationswere found mainly in the sublittoralfringe: in pools There are no literature rec at MLWN-ELWS and on open rock in sandyareas at ELWS. Pool populations that in Parke& Dixon (197( vilri()us were typically presenton vertical or near-verticalwalls in very deep, shaded localitiesduring the pools in exposedsituations. Plants were jnvariably well below the water surface There are many early li1 and seemedparticularly common (at leaston Anglesey,North Wales)in the type ltseudopalmata(as R. palnte, of pool which is encrustedwith very line silt and where few other algaegrow. 1838;Harvey, 1847, pl. 134; At Penmon, Anglesey,plants were repeatedlyfound on gently sloping rocks tr Rltodymenia-likethallus d at MLWS ELWS, scattered amongst stands of Plocamium cartilaginetrnr malor Briiish herbariaare tl Pollexfen(BM) and are annc also sterile but probablyrt Fig. 58 showsthe surfacecort specimensand therecan be l iliffitr8# the type specimen(Fig. 59). 'oq.Ub#fr'n%t the specirnensalso suggestr shows the distribution of ,R [W8ffffi exanri ned. WORLD 30Pm Rlrodyntenia delicatula wa: Cape Agadir, Atlantic Mor i&dffioeil%9& Saint-Vincent(PC) collected structure of Rhodymeniadeli ffi##,ffi specimensfrom Portugalas r Thesehave beenexan-rined (F ffi% COMPARISON OF RHODI Rltodymsnlq phylloides Frcs 54-59. Cantera lucida drawings of the surface cell morpl-rology of specimens of wa:. Rhodtmenitt delicatula P. J. L. Dangeard and R. phylloides L'Hardy-Halos preserved in growir.rgin the sublittoralto I different ways and fron-r different parts of the thallus. Fig. 54. Portion of the thallus in that plantswere less than 2 of the lectotype specimen ol R. delicatula taken 10 mm from the apex of dried material. Fig. 55. Portion of the thallus of a young plant of R. delicatulcr(Porth Trecastell, 50 90 gm in thickness(L'Har Anglesey, U.K., 2 April 1973), 5 mm from the apex of a liquid-preserved spectmen. had a thin cortexand 2-3 (4)lt Fig. 56. Portion of the thallus of an isotype specimen of R. phylloides, 5 mm from the thin stipes500 to 3 mm 1r apex of a liquid-preserved specirnen. Fig. 57. Portion of the thallus of a rnature plant of 4m R. delicatula (Penmon, Anglesey, U.K., 19 August 1974), 7'5 mn-r from the apex of a lanceolateblades which were fiquid-preserved specimen. Fig. 58. Portion of the thallus of R. delicatula (Kirkwall playeda considerablecapacit Bay, Orkney Islands, 1837, dredged, BM) l0mm from the apex of a dried specimen. or fronds (L'Hardy-Halos, Fig. 59. Portion of the thallus of the lectotype specimen of R. delicatula, 5 nrm from the 19 anex of dried. mature material. to the substratumby a flesh1 Tlre genr"rsRhodYnenia 419

(Linnaeus)Dixon ar.rdCortb,lec'ladia erectq (Creville) J. Agardh. At this locality R. delicatulabecame more luxuriantand, comlrron towards ELWS. Plantslrave occasionallybeen founcl. in long guilliesat MLWN but seemedrare it.tsuch situationsand were generallyassociated with R. p.seudopalntatav&r. p,seudo' palntata. vnrious Delesseriaccousalgae and Cladophorapellucida (Hudson) Kiitzing. In subtidalsituatious in Britain this specieshas beencollected dolvn to 5 m' r-rsuallyon the uppersideof stonesand bouldersembedded. in sandor silt.

DISTRIBUTION I}RITISH ISLES Theretrre no literaturerecofd.s of this speciesfronl the Britishlsles prior tt' that irr Parke& Dixon (1976)but specinrensof the entity werecollected frorn variouslocalities during the pastcentury but misidentified' There irre frrany early literature ref-erencesto specimensof Rltod.t'nretriu psetrtlopolntala(as R. palrtretta\dred.ged at Kirkwall, Orkr.reyIsles (W.H.C ' 1838;ilarvey. 1847,pl. 134;Traitl. 1890,p.327 etc.).The only specirrenswith a Rltodl,rnem'a-likerhallus dredgedat Kirl

WORLI) Rhodt.meniudelir:cttultt was qriginally describedby Dangeard (19491fronr Ca;le Agadir. Atlantic Morocco. Specintensin the herbariunrof Bory de Saint-Vincent(PC) collectedat Cadiz, Spail show the size,morphoiogy and srructureof Rltctrltttrenioclelicatttla. Ard16 (1969.pp. 132-133footnote) listed specirrensfiorrr Portugal as resemblingRhodt'ntenia pltl'lloides L'Hardy-Halos Thesehave beenexarnined (PC) and seemedto be referableto R. delicatula.

COMPARISON OF RHODYMEIV]A DELICATUL,4 AND R, PHYLLO|DES Rltodl'nteniapltl'lloi:de.s was describedfrom the Baie de Morlaix, Blittanl' grcrn,ingin the sublittoralto 20 m;this specieswiIS very similarto R. delicatulct in that plantswere less than 20 mr.t.tin height.with fronds0'1-0'3 t.nrr rvide and 50 90 1rmin thickness(L'Hardy-Halos, 1970, Figs l, 2). Plantsof this species had a thin cortexand 2-3 (4)layers of medullarycells. Specimens often had lon-s. tl.rinstipes 500 trrnt to 3 mut lorig wliich expandedgradually, forming rout.rded- lanceolateblades which were simple or had one dichotolry. This speciesdis- played a coltsiderablecapacity for regeneratingnew bladesfrom erodedstipes or fronds(L'Hardy-Halos, 1970, Fig lA, B, D, F, H, K).Plants wereattached to the substratumby a fleshypeg-like disc which was irregular in shape.The 420 M. D. GUIRY reproductive organs were reported to be formed in winter and spring (L'Hardy- Tnsrp II. Comparisonof Rhodyr, Halos, 1970,pp. 26-27) and were borne at the apicesof the fronds on very material examined.Details from examinationof the type smallplants(300-700pm long: L'Hardy-Halos,1970: Fig. ID, F, G, H, I, J). Lightly-colouredprotuberances were also reported to occur on some fronds with a frequency which led L'Hardy-Halos (1970, p.23) to consider them characteristicof R. phylloides. Rho ph) There are severalpoints of close similarity betweenthe collections examined and L'Hardy-Halos's description. A comparison of these specimenswith R. phylloidesand R. delicatulais given in Table iL The main points of difference Height (mm) To 20 Width of fronds(n.rm) 0.1,3 are the position of the reproductive organs, the shape and mode of branching Thickness of of the blades and the reported absenceof stolons in R. phvlloides. fronds (pm) 50-90 Stolons Not repor Callosities Present Stipes Often lon Fronds Simple or dichoto branche Peg-like attachment Present disc Tetrasporangia In apical I Sizeof tetrasporangia (pm) 16-18x28 Cystocarps Al apices

Size of cortical 10-12lonl cells (pm) 3 6 bror Medullary cells 2-3 (4) la1

c

2'5mm 2mm 2.5mm FIc. 60,4' C. Unusual morphological features of British specimens of Rhodymenia deli- t'tttLtla P. Dangeard. Fig. 604. Specimen with mature, dichotomously-branched, lightly-coloured protuberances on the surface of the thallus, note the collapsed appearance of these, Penmon, Anglesey, U.K., 19 August 1974, sandy ledges: MLWS, leg. M. D. Guiry. Fig. 608. Specin-renswith irregular protuberances, Penmon, Anglesey, U.K., pools: MLWS, 3 April 1973,leg. M. D. Guiry. Fig. 60C. Specimenwith truncated frond and subsequent (?) irregular development; collection data as for Fig. 608.

Although tetrasporangialsori and cystocarpsof Rltodymeniapltylloide.r were described.as occurring at the apices of the fronds and the material described above under the name R. delicatulahad tetrasporangiain sori in the middle of the frond and cystocarps at the base of the frond, it seemsprobable that the preciselocation of theseis variable in a winter/spring fertile entity where most of the growth of the frond takesplace after the formation of reproductive organs. 5mm,A-E For example,in Schotteranicaeensi,t where tetrasporangialsori are also formed Frc. 6lA-F. Morpholoev of Rhody men i a p hy ttoi de.s L' iardy - in winter and early spring (Schotter,i952; Guiry & Hollenberg, 1975)on very I967. leg. M.-Th. L'Hardy-Halo small plants, the thallus continuesto grow and what were initially more or rhalli. note rhe long sripesand r less apical sori in January (Guiry & Hollenberg, 1975,Fig. 11A, F) may, by truncated stipes.Fig. 60D,F. C1 carps on an unflattened stipe. Ft Tlre genus Rhodl'nteniu 421

TAerr lI. Corlparison ol Rltoct_t,nteniapltylloide,s and R. delietula with British and Flcnch rraterial examined. Dotails fronr L'Hardy-Halos (1970) and Dangeard (19'19)and fronr an eranrination of the type r.nalerialof the speciesdescribed by these authors

Rhod.y tt rc n iu specirlt.ns Illrcdytttettiu Rhoct.t,nten iu fronr the British lslcs pht.lloide.s delicrtt r.rltr and Northern Frarrce

Herghl (nrnr) To 20 To 12 fo 22 Width of fronds (nrm) 0. I 3 0.5 3 0.5.,3 Thickness of fronds (prr) 50 90 .+0 70 (30) 58 87 (102) Stolons Not reported Present Prcsent Callosities Present Not reported Present Sti pes Often long and thin Often long and thin Often long and thin Froncis Sinrplc or Sirlple or Sinrple or d ichotorrousl)' d ichotorlously d ichotor.rror-rsly branched brancl-red brancltcd Peg-likeattachnlent Present Not reported Present ciisc -I etraspo rangia In apical sorus Unknou,n In waisted s0rlls alt centre of thc flontl Size of tetrasporangia (i.tr1 l6 l8'28 30 Unknown t6 22 .25 35 Cystocarps At apices of plants LJnknown At base of flattened portiol-l of plants Size of cortical l0 I 2 long, (..1)9 l6 long (4) 8 l4 (20'5) long cells (pnr) 3 6 broad (4)7 ll (21.6)broad Medullary cells 2 3 (4) layers 2 3la1,ers 2 3 laycrs

h i'/ T l\t I l

5mm,A-E Frr;.61A-F. Morphology of fcrtile and sterrle specirltensof isotypc tllaterial ol Rhod)'nreniuplt) lloiilesI-'Har-dy-Halos. Baie dc Mor-laix,Blittanl', France' l9 Deccrrlbel 1967,leg. M.-Th. L'Hardl'-Halos no. R 2233. Fig. 6lA C. Rangc of variation in steri|: rhalli. note the long stipcs ancl the beginningsof regenerationofffattened bladesfrorrt truncated stipes. Fig. 60D,F. Cy'stocar-picplant. note thc apical position of the cysto- cafps on an unflalteneclstiLre. Fig.6lE. as Fig.60A C. 122 M. D. GUIRY

placed (Guiry April, due to growth of the frond, be at the base of the frond & similar to thoseof young B Hollenberg,1975,Fig.72B,D, E). Speciesof Rhodymenicseem to havesimilarly cortical cellsof an olderBri apical persistentreproductive organs and it is conceivablethat what was an from the apex)and theseshr plants December(L'Hardy-Halos, sorus or apical cystocarpon very small in catula (which.was also colle phylloides) cystocarp by April (cf. Fig. 1970,as R. may become a basal sorus or In the latterillustration, hov phylloides (Baie de 6lD, F and Fig. 47A-E). The type material of Rhodltmenia 56 are not clearlyvisible. A from Morlaix, Brittany, 19 December 1961, PC, and liquid-preservedmaterial of R. delicatula taken at 5 ml the same collection,courtesy of Mme L'Hardy-Halos: Frg. 61A-F) has been with theR. ph.vlloidesmarerii gradual examined.The long stipesand the expansionofthese to form a flattened, specirnenssuch as the typen The thin bladeare very similarto what hasbeen described above. surfacecortical thallus cells to regain their phylloides cells of a representativespecimen of R. 5 mm from the apex are very layers;Fig. 58,which illustr from the Orkney Isles also layers. The chief points of simila Franceand the Moroccann branching ofthe fronds (cf. J in both, the thinnessof thr ' 210 km morphological parameterssr It would thus appearthat R. phylloides,as describedb1 position and occurrenceof t the grossmorphology of intt The occurrenceof specimens sizeand a lack ofreproducti of Atlantic Morocco, Atlan suggeststhat but one widely,

AC

I am indebtedto Dr D. E. G. Irr ment and critical observations;to manuscript; to Mme M.-Th. L'H and herbarium material; and to D Irvine, N. A. Jephson,J. H. Pri observations. I would Iike to thank the Go Etherington for making financial : ship. Grateful acknou ledgementi tioned in the text and to Professo Bordeaux at Talence for permiss Dangeard. The completion of the John West and the author.

Acnnou, C. A., 1822.Species A| descr ip t ioni bus succ int i s. Y o7. AcARDH, J. G., 1841.ln historian AcnRoH, J. G.. 1842.Algae maris et dispositionemgenerum.Pp. t Ac,tnon, J. G.,1851.Species gener Lund. AcnnoH, J. G., 1876.Species gent Frc. 62. Distribution in the British Isles of Rhodynteniadelicatula P. J. L. Dangeard generum et ordinum, quibus r known to date. Floridearun. Pp. viii*724. T. The genus Rhod.lnpniu 123 similar to thoseof your.rgBritish specimens(cf. Figs 55 arrd 56). The surface corticalcells o1'an older Britishspecimen are also illustrated(Fig. 57: 7'5 mm fronr tlreapex) and thesesliow a closesinrilarity to the t1'pematerial of R. deli- lalrrln (which was also collectedin summer: Fig. 54. l0 mrrrfronl the apex). Irrthe latterillustration. however. the largesubcortical cells seen in Figs55 and 56 are not clearlyvisible. A similar portion of the thallusof the typc specirnen LtfR. delicurtLlataken at 5 mm from the arpex(Fig. 59) showsil greatersinrilarity' u'ithtlie R.phrlloitle,r nraterial and.the British specimens (Figs 56.57). ln pressecl specirrenssuch as the type ntaterialof R. delicatulait is often dif'ficultto get the thirlluscells to regain their former dimensions.particularly the sirbcortical lavers:Fig. 58. which illustratesa portion of the thallusof a pressedspecinlen frtlnr the orkner' Islesalso showsa sinlilar lack of claritit ol'the subcortical layer:. The chief pointsof similaritybetween specinrens frorrr Britain lrnd northeru Franceald the Moroccannraterial of R. tlelicatulaare the shapeand mode of branchirrgofthefronds(cf. Figs 42.43and46,47,60).thefbrnrationof stolotrs irr both. the thinnessof the thallus and the srnallsize of the frond.s.C)ther morphologicalparameters seem also ttl corrcspondwell (TableIl). Ir rvor"rlclthus appearthat further investigationof the Frerrchpopulations o1' R.pht,lloidt',s. asdescribed by L'Hardy-Halos(1970) is requiredto deternlinethe positionand. occurrence o1'the reproductive organs in springand sut.tlnler,ancl the grossntorphology of intertidalspecinlens at the peakof vegetativegrowth. The occurrenceof specintensof a speciesof Rhotl)'tncnialvith thin fronds,snrull sizean

ACKNOWLEDGEM ENTS

I ant indebted to Dr D. E. G. lrvine, M rs L. M. lrvinc and Dr P. C. Silva for their cncouragc- ltent and critical observationsi to ProfessorP. S. Dixon for his advice and rcflectionson the 6tanuscript; to Mnte M.-Th. L'Hardy-Halos and Dr P. R. Newroth for valuablc discussion and herbariunr matcrialiand to Dr G. T. Boalch, W. F Farnlram, S Hainsworth, Mrs L. M lrvinc. N. A. Jephson..l. H. Price and I. Tittley for pernrission to u\c sontc unputrlislred observat i ons. I rvou[l like to thank thc Covernors of the Polyteclrnic of North London antl Mr D. Ethcrington fbr ntaking financial suplrort available during the tenure of a ResearchAssistant- shiLr.Giateful acknowledgentcntis urade to the Directors and Cut'atorsof the herbalia nlerr- tioned in the text and to Professor Eynrc. Laboratoire de Botanique, Facult6 des Scicncescle Bordeaur at Talence for perrlrissionto eratrrine sltecinlensfronr the herbal-it-tmof P J' L' l)ange:rrd. The cornpletion of the manr:script was facilitated by N.A.T.O. grant no. ll30 tcr .lolrrr\\ e\t irnd lhc aulhor.

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