Canariothamnus B. Nord., a new genus of the Compositae-Senecioneae, endemic to the Canary Islands

2006·2.5 MB·

by  Bertil Nordenstam

24 Comp. Newsl. 44, 2006
Canariothamnus B. Nord., a new genus of
the Compositae-Senecioneae, endemic
totheCanary Islands
BertilNordenstam
DepartmentofPhanerogamicBotany,SwedishMuseumofNaturalHistory
P.O.Box50007,S-10405Stocliholm,Sweden
[email protected]
Abstract
CanariothamnusB.Nord.isrecognizedasanewgenusofthetribeSenecioneaefrom
theCanaryIslands.TwospeciesaretransfersfromSenecio(sect.BethencoiirtiiDC.)
and a third new species, C. mpicola B. Nord. is described from the island ofLa
Gomera.
Introduction
The Canary Islands are renowned for their high degree ofendemism at different
taxonomic levelsoffloweringplants. Onthespecies levelabout500speciesoutofa
total of 1200 native flowering plants are endemic, or42% (Davis & al. 1994). The
number ofendemic genera varies with taxonomic opinion, but usually 20 genera
endemictotheCanaryIslandsarerecognized.
The islands are part ofthe Macaronesian Floristic Region, and anumber offurther
genera are Macaronesian endemics, e.g. Pericallis D. Don in Sweet in the tribe
Senecioneae ofthe Compositae, with 14 species, 12 ofwhich are endemic to the
Canary Islands (Bramwell & Bramwell 2001, Swenson & Manns 2003, Swenson
20(H).
AccordingtocurrenttaxonomicopinionfourspeciesotSenecioL.areendemictothe
&
Canary Islands, viz. S. tenerijfae Sch. Bip. ex Bolle, S. bollei Kunk. Sund., S.
palmensis(Nees)Chr.Sm.exLinkinBuch,andS. hermosaePitard.Thefirstmentio-
nedisalliedtothegenerictypeS. vulgarisandaccordinglybelongs insect. Senecio,
whereasS. bolleiisnotassignedtoasection. Thetwolastmentionedspecies, i.e.,S.
palmensis and hermosaetogetherconstitute the sect. Bethencourtii DC. (Candolle
1838,Nordenstam 1978,Jeffrey 1992).
The taxonomic status of sect. Bethencourtii was discussed at some length by
Nordenstam(1978). ItsisolatedandanomalouspositionwithinSeneciowaspointed
Comp. Newsl. 44, 2006 25
out. Especially the caudate anthers and the obtuse style-branches with papilliform
sweeping-hairs servetocharacterizethegroup.
Exceptionally, Kunkel treated this group as a genusunderthenameBethencowtia,
although with some hesitation (Kunkel 1975, 1980), and he made the new
combinationB. hermosae(PrrARo)Kunkel.However,BethencowtiaChoisywasnot
validly published as a genus, since Choisy's generic description appeared in
synonymy of Senecio palmemis (Buch 1825). There is also a homonym, viz.
Betencowtia St.-Hil. (published in 1833, now a synonym ofGalactiaP. Br. inthe
Leguminosae).
Arenewedstudyofsect.Bethencourtiihasledtotheconclusionthatitisbesttreated
asaseparategenus.AlreadyChoisyinBuch(1825)expressedthesameopinionwhen
he introduced the generic name Bethencowtia. As mentioned, this name was not
validly publishedand cannot now be adopted forreasons ofhomonymy. Thegenus
is here described as new and the proposed name Canariothanmus needs no fiirther
explanation.
Discussion
In several morphological features the new genus Canariothanmus is reminiscent of
theMalagasygenusHubertiaBory,suchastheshrubbyhabit,narrowsessileleaves,
numeroussmallandyellow-floweredcapitula,caudateanthers,etc.However,aclose
relationship between thesetwo genera isnot suggested and is also notsupportedby
ongoingmolecularstudies(SenecioneaephylogenyGroup,Pelseretal.inprogress).
AllthreetaxaofCanariothamnusareincludedinabroadstudyofthewholetribeand
theyfonnacloselyknitgroup,whichisonlyremotelyrelatedtoSenecio.Averyclose
relationship between Canariothanmus and Hubertia is not indicated by the
molecular data, but Senecio s.str. (including ofcourse the type S. vulgaris) is even
more distantly positioned in ourphylogenetic tree. Canariothanmus belongs with a
fewAfricanelements(namedSenecio,butstillunassignedtogenera)inacladewhich
appears as sisterto aJacobaeaclade. The circumscription ofmonophyletic generic
concepts such as Senecio s. str., Jacobaea, and other presently ill-defined or
unrecognisedtaxawillbediscussedinforthcomingpapers,togetherwithapresenta-
tionofthecompletephylogenetictree.
Thebalusterfonnfilamentcollars,distinctanthertails,andsmallprismatichexagonal
ovary wall crystals in taxa now referred to Canariothamntis were illustrated in
NoRDENSTAM(1978:Figs.7B, 10E&33).
The two known species of Senecio sect. Bethencourtii, viz. S. palmensis and
26 Comp. Newsl. 44,2006
hermosae, are here transferred to the new genus Camiriothammis. During the field
workwithinthepresentstudyitbecameapparentthatathirdtaxonexistsonthesmall
islandofLaGomera. Itisheredescribedasanewspecies,Canariothamnusrupicola
B.NORD.
Taxonomy
CanariothamnusB.Nord.,gen.nov.
Syn.:BethencourtiaChoisyexLinkinBuch,nom.illeg.,Phys.Beschr.Canar.Ins. 148
(1825),insyn.,non5efe«cowr//aST.-HiL.,Voy.Inter.Bresil. 1:376(1833);Sewec/'osect.
BethencourtiiDC,Prodr.6:411 (1838).
Fruticuliglabriramosierectivelascendentes. Foliaaltemasessilialineari-lanceolata
Integra vel sparse dentata vel lobata vel pinnatipartita. Capitula parva corymbosa
ecalyculataheterogamaradiataflaviflora.Involucribracteaeuniseriataepaucae(4-5).
Flosculi radii feminei 1-3 brevi. Flosculi disci 3-5 hermaphroditi; corolla 5-lobata..
Antherae caudatae; endothecium radiale. Styli rami apice obtusi vel subtruncati
papillati; areis stigmaticis fere confluentibus. Cypselae oblongae brevihirsutae vel
papillosae5-costatae.Pappisetaenumerosaealbaeminutebarbellataesemipersisten-
tes.
Typus: C.palmemis(Nees)B.Nord.
Small glabrous shrubs, repeatedly and densely branching. Leaves alternate, sessile,
lineartooblanceolate,entire,ortoothedorfew-lobedtopinnatipartite.Capitulasmall,
corymbose in rather dense bracteate terminal synflorescences, radiate, yellow-
flowered.Involucrenarrowlycampanulatetoturbinate,ecalyculate,butsubinvolucral
bractspresent,small,subulate;involucralbractsuniseriate,few(4-7).Ray-floretsfem-
ale, fertile, few (1-3). Disc-florets hermaphrodite, few (3-5); corolla 5-lobed; lobes
narrowly ovate-lanceolate, midveined. Anthers tailed; endothecial tissue mainly
radial; filament collars balusterfonn; apical appendage ovate-oblong, flat, obtuse.
Style branches obtuse to subtruncate, apically with few and short papilliform
sweeping-hairs, inside stigmatic area continuous or nearly so. Cypselas terete,
narrowlyoblong, shortlyhirsuteorpapillosewithobtuseduplexhairs, 5-veinedor-
ribbed; carpopodium distinct of several cell layers. Pappus bristles numerous,
minutelybarbellate,white,semi-persistent,basallyconnate.
Species3,CanaryIslands.
Chromosomeno.:n=l (C.palmensis,Ortega&Navarro 1977).
KeytothespeciesofCanariothamnus:
1. Mostleaveslanceolate-oblongoroblanceolate,upto 10mmbroad,shortly3-5-
;
Comp. Newsl. 44, 2006 27
mm
dentateor-lobedwithovate-oblonglobes 1-5 long 1. C.palmemis
mm
Leavesentireor2-5-lobedwithlinear-filiformlobes5-20 long 2
2. Leaves2-3cmlong,3-5-lobed;lobes5-10mmlong 2. C. rupicola
Leaves3-7cmlong,entireormostly3-lobed;lobes 10-25mmlong
3.C.hermosae
1.Canariothamnuspalmensk(Nees)B.Nord.,comb.nov.
Basionym: CinerariapalmensisNees,Horaephys.Berol.Tab.24(1820).
Syn.:Bethencourliapalmensis(Nees)ChoisyexLinkinBuch,Phys. Beschr. Canar.
Ins., 148(1825),nom.illeg.;Seneciopalmensis(Nees)Chr.Sm.exLinkinBuch,I.e.
Leaves 2-3.5 cm long, 2-10 mm broad, oblanceolate to narrowly oblong-obovate,
mostly 3-5(-7)-lobed, some entire or bilobed, flattened, coriaceous; lobes ovate to
triangular-oblong, 1-3 mm long, mucronate. Involucral bracts 4—5. No distinct
calyculus, but small peduncular and subinvolucral bracts present. Ray-florets 1-3;
tube equalling lamina in length; lamina 4-veined, with additional incomplete veins
apically.Disc-florets3-5.Stylebranchesshort,notexserted,apicallyobtusewithfew
short papillifonn pili. Anther tails long, about the length ofthe balusterform collar.
mm
Cvpsela narrowly oblong, 2.5-3 long, straw-coloured, with 5 impressed veins,
shortlypuberulouswithwhitepapillifonnobtuseduplexhairsmainlyalongtheveins.
mm
Pappusbristlesnumerous,2.5-3 long,minutelybarbellate,white,semi-persistent.
C.palmensisisfairlycommonintheCalderaregionofLaPalmaupto2400ms.m.,also
occurringinbarrancosatloweraltitudes (450m,Bramwell&Bramwell 1974,2001
165 m. Lid 1967). OnTenerife it is morerare, foundinahandful oflocalities in Las
Caiiadasaround2000m(e.g. at RoquedelAlmendroAmargo,nearBocedelTauce,
NoRDENSTAM 9326 in S) and lower down in the Barranco del Rio (on steep cliffs at
1400m,NoRDENSTAM9328 inS).Thereisasinglerecordfromamuchloweraltitude
(<400m)inAricoineastemTenerife.
In spite ofthe small flowerheads the plants may be rather showy when the densely
corymbose synflorescences are in full flower(cf photo in Bramwell & Bramwell
2001:353).
Thelocalnameis'Turgayte'(Schenck 1907,Bramwell&Bramwell 1974,2001).
2.CanariothamnusrupicolaB.Nord.,sp.nov.
Type:CanaryIslands,LaGomera,ParqueNacionaldeGarajonay,RoquedelaZarcita,
1020 m, steep phonolithic rocks, E-NE aspect, 28.11.2002, Nordenstam 9333 (S
holotype; K,MA, O isotypes ).
Fruticulusramosusglaberc.0.5-1 maltusetlatus.Foliaaltema2-3.5cmlongalinearia
mm
Integra vel plerumque 3-5-lobatacoriacea; lobis linearis usque ad 10 longis et
28 Comp. Newsl. 44,2006
2 mm latis. Capitula parva numerosa subcorymbosa heterogama ecalyculata.
Involucrum anguste campanulato-cylindraceum; involucri bracteae 5-6
lineari-oblongae. Flosculi radii feminei 2-3 flavi. Flosculi disci 3-5 hermaphroditi;
corollaflava5-lobata. Cypselaeangusteoblongaepuberulae. Pappi setaenumerosae
barbellataealbae.
Branchingglabrousshrubletca.0.5-1 mhighandwide.Leaves2-3.5cmlong,mostly
3-5-lobed,somebilobedorsimple,flattened,subcoriaceous,greyish-green;leaflobes
mm mm
linear, 5-10 long, 1.5-2 wide,apicallymucronatewithbrownish-blacktips.
Capitula several to numerous in corymbose bracteolate synflorescences, small,
mm
heterogamous; peduncularand subinvolucral bracts small, ca. 1 long, subulate.
Involucrenarrowlycampanulateto subcylindrical; involucral bracts 5-6, uniseriate,
mm mm
narrowlyoblong-lanceolate,3.5-4 longand0.7-1.2 wide,green, 1-3-veined,
acuteorsomewhatacuminate, somewith narrow scariousmargins.Ray-florets2-3,
mm mm
female,fertile,lightyellow;tubecylindrical,2-3 long;laminaoblong,2.5-3
mm mm
long, 1-1.5 wide,4-veined,apically3-toothed.Stylebrancheslinear,0.7-0.8
long, with continuous stigmatic area, apex obtuse. Disc-florets 3-5, hermaphrodite.
Corolla yellow, tubular below, gradually widening above, 5-lobed; lobes narrowly
mm mm
ovate, 1-1.2 long,distinctlymidveined,acute.Anthers 1.7-1.8 longincluding
appendage and tails; distinctly caudate; tails ca. Vi the length offilament collar or
longer; apical appendage narrowly ovate-oblong, obtuse; endothecial tissue mainly
radialwithsmallthickenings;collarelongated,balusterform.Discstylebrancheslin-
earwithconfluentstigmaticareas,apicallyobtusetosubtruncatewithonlyshortand
mm
few papilliform hairs outside laterally. Cypselas narrowly oblong, ca. 2 long,
5-ribbedor-veined,shortlyvillouswithwhitepapilliformduplexhairsmainlyalongthe
veins;carpopodiumdistinctof10-12cellrows;ovarywallcrystalshexa-tooctagonal,
flat. Pappus bristles numerous, white, minutely barbellate, semi-persistent, basally
connate into an annulus.
ThisrarespeciesisonlyknownfromthreesmallpopulationsathigheraltitudesofLa
Gomera. In the type locality 1 counted to only five plants, growing in partly
inaccessible rockcrevices ofthe sheerphonolithic precipiceofRoquede laZarcita.
Thesespecimenswerealllargeandhealthy.Thespeciesisalsofoundintwoplacesat
RoquedeAgando, with a fewand somewhatdepauperate specimens. Mycolleague
UlfSwensoninStockholm(S)inspectedoneofthesepopulationsin 1993(Roquede
Agando,NEslope, 1150m,20.111.2003,Swenson580,photoinS)andheconfirmsthat
it is dwindling and that its fliture is precarious. C rupicola must be classified as a
highly endangered species.
3.Canariothamnushermosae(Pitard)B.Nord.,comb.nov.
Basionym: SeneciohermosaePitard in Pitard& Proust, lies Canaries239 (1908).
Comp. Newsl. 44, 2006 29
Syn.:Bethencourfiahermosae(Pijard)Kunkel,Cuad.Bot.Canar.25:28(1975),nom.
illeg.
Illustr.:Lid 1967Plate3;Bramwell&Bramwell 1974,Fig. 100;Nordenstam1978,Fig.
33C,F,G
Leavessimpleor2-3-lobed,mostleaves3-lobed, 3-7cmlong; lobeslinear-filiform,
flattened, 1-2.5cmlong.Involucralbracts6-7,lanceolate,4.5-5mmlong.Cypselas
mm
terete,narrowlyoblong-cylindrical,2.5-2.8 long,greenishtobrownish,5-striate,
denselypuberulous with white papilliform duplex trichomes. Pappus bristles semi-
mm
persistent,minutelybarbellate,2.5-3 long,white.
C hermosae is readily distinguished from its congeners by the longer and more
dissected leaves. The leaves often havethree narrow segments, which are flattened
(notcylindrical,assometimesstatedinliterature),butasintheothertaxasomeleaves
maybeentireor4-5-lobed.
C. hermosaeisendemictoLaGomera,whereitisrareandlocal,foundinafewsmall
populationsintheVallehermosoregion,e.g.onthesteepwallsofRoqueCano,andon
m
cliffsatPresadelEncantadoraat340 s.m.(Nordenstam9332inS).
Acknowledgements
1 wishtothankCecilioMassanetAcostaand RicardoMesaCoello(Tenerife)and
JacintoLeralta (LaGomera) forexcellentcompany inthe field, theCuratorofthe
GarajonayNationalPark,Dr.AngelFernandez,forsupportandpermissiontocollect
samples for studies, and Dr. Ulf Swenson for personal observations on one ofthe
populations ofC. rupicola.
Financial support from the Royal Physiographic Society in Lund is gratefully
acknowledged.
30 Comp. Newsl. 44,2006
References
Bramwell, D. & Z. Bramwell 1974. WildFlowersofthe CanaryIslands. Excmo.
CabildoInsulardeTenerife.
Bramwell, D. & Z. Bramwell 2001. WildFlowers ofthe CanaryIslands, 2"'' ed.
EditorialRueda,Madrid.
BucH, L. VON 1825. PhysicalischeBeschreibungder CanarischenInseln. Koenigl.
Akad.Wissensch.,Berlin.
Candolle,a. p. de 1838. Prodromus systematis naturalis regni vegetabilis, vol.6.
&
Treuttel Wiirtz,Paris.
Davis, S. D., Hevwood,V. H. &A. C. Hamilton 1994. CentresofPlantDiversity.
A Guide andStrategyfor their Conservation. I. Europe, Africa, South West
AsiaandtheMiddleEast. WWF/IUCN.Cambridge,U.K.
Jeffrey,C. 1992.ThetribeSenecioneae(Compositae)intheMascareneIslandswith
anannotatedworldcheck-listofthegeneraofthetribe.KewBull.47:49-109.
KuNKEL.G. 1975.NovedadesytaxonescriticosenlafloradeLaGomera. Cuad. Sot.
Canar.25: \1-49.
KuNKEL, G. 1980. Die Kanarischen Inseln undihre Pflanzenwelt. Gustav Fischer,
Stuttgart,NewYork.
Lid,J. 1967.ContributionstothefloraoftheCanaryIslands.Sh:Norske Videnskaps-
Akad. Oslo I. Mat.-Naturvet. Klasse,n.s.23.Univ.forl.,Oslo.
NoRDENSTAM, B. 1978. Taxonomic studies in the tribe Senecioneae (Compositae).
OperaBot.44: \-S3.
&
Ortega,J. B.Navarro 1977.EstudiosenlafloraMacaronesica:algunosnumeros
decromosomas111.Bot. Macaron.3:73-80.
ScHENCK, H. 1907. Beitrdge zur Kenntnis der Vegetation der Canarischen Inseln.
DeutscheTiefsee-Expedition 1898-1899.Bd.II. 1.Teil.G.Fischer,Jena.
SwENSON,U.2004.Pericallis-ettfargstarktslaktemedrotteriMakaronesien.Sv.Bot.
ridskr.9S: \93-206.
SwENsoN,U.&U.Manns2003.PhylogenyofPericallis(Asteraceae):Atotalevidence
approachreappraisingthedoubleoriginofwoodiness. Taxon52: 533-546.
Comp. Newsl. 44, 2006 31
B
Fig. 1.Leafoutlinesin Canariothamnus.
AC. hermosae.
B C. rupicola.
C C.palmensis.
(ANoRDENSTAM9332,BNoRDENSTAM9333,CNoRDENSTAM9326,allinS).X Vi.
Del.B.NoRDENSTAM.