On the discovery of a new endemic Cynanchum (Apocynaceae) on Gunner's Quoin, Mauritius

On the discovery of a new endemic Cynanchum (Apocynaceae) on Gunner's Quoin, Mauritius
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  On the discovery of a new endemic Cynanchum  (Apocynaceae) on Gunner’s Quoin, Mauritius .. INCENT   LORENS   LAUDIA   AIDER  2  Department o Boscences, Unversty o Maurtus, Rut, AURITIUS v. orenuom.ac.mu   Maurtus Herarum, Maurtus Sugar Inustry Researc Insttute, Rut, AURITIUS  stract - Cynancum scopuosum  Bosser Apocynaceae, a new Maurtus enemc speces was scovere in 2003 on Gunners Quoin Nature Reserve, a highly degraded offshore islet north of Mauritius. he plant’s basic ecology is described and threats to its persistence are discussed. The species is Critically Endangered. Recommendations to secure its future are given. The discovery adds further conservation value to Gunners Quoin.  Key wors -  ynanchum scopulosum , islet restoration, invasive species, IUCN conservation status.  NTRODUCTION Te ora o Maurtus starte to e ocumente urng te ate 18 th  cenury, an wtn two centures most o ts speces a een escre (B OSSER  t a . 1976-onwars). However, espte avng ony aout 5% o ts orgna natve vegetaton et, new recors o natve pant speces contnue to e mae. Recent exampes ncue a new enemc Myrtaceae, Syzygium gueoi  Bosser & Forens ( OSSER   & LORENS  2000), scovere n 1989, or te orc aeniopyum coxii  (Summer.) Summer., an apyous eppyte o we struton rst recore n Maurtus n 2000 ( OBERTS e a.  2004). Here we report on te atest suc scovery, mae n 2003, o a  ynancum speces (Apocynaceae) enemc to Gunner’s Quon set, nort o Maurtus.Te Apocynaceae s a arge many tropca amy o some 415 genera an 4,555 speces ( TEVENS  2001-onwars) o wc some 200 eong to te genus Cynancum  (M ABBERLEY  1997). In Maurtus, te Ascepaoeae s represente y sx natve genera an 11 natve speces ( OSSER    ARAIS  2005). Te rst menton o  ynancum  n Maurtus, o wc te speces cannot e ascertane, was mae y  OJER   (1837) uner Sarcostemma mauritianum . t as recore on g mountans on Maurtus, a atat type toay occupe y .  gomeratum . Later, B AKER   (1877) mentone a secon speces,  Decanema ojerianum Decne (= . utei uens  (Jum. & H. Perrer) Desc.)), wc appears to e te same as Boer’s taxon ( OSSER    ARAIS  2005). ater reerences to Cynancum  n Maurtus are uner Sarcostemma viminae  (ex. V AUGHAN  1937, G UÉHO  1988). It s now estase owever tat Rorgues as one an Maurtus tree enemc speces o  ynancum (B OSSER   & M ARAIS  2005). No natve Cynancum  s nown rom Reunon san. 1 In the lore de Mascareignes   ynanchum is treated under Asclepiadaceae  Phelsuma 14 ; 7-12  ETHODS Stuy site  Gunner’s Quon, a 76a osore vocanc set 4 m nort o Maurtus, conssts o roc a own 0.7-0.025M years ago ( ONTAGGIONI   ATTIVEL  988) an cumnates at 162m a.m.s.. Most o te set conssts o rae vocanc tut we te eastern se as an overyng asat ayer. Inerrng rom C AMOIN et a.  (2004), te set ou ave een cut o rom manan Maurtus y rsng sea eve some 10,000 years . AUGHAN  an IEHE  (1937) eeve tat te set supporte a pam savanna n ts  prstne conton eore eng muc atere y uman actvty snce te 18 h  cenury. Te most recent puse otanca surveys prevous to our vst reveae an ecosystem argey overrun y aen pants wc mae up 48 o te 72 ger pant speces ( ULLOO 1994). Despte ts avance egraaton state, were arge parts o te set are omnate y nvasve pants, Gunner’s Quon st arours some vauae natve rects e te argest popuaton o te Maurtus enemc  Lomatopyumormentor  . Te natve verterate auna ncues many tropc rs (  Paeton ruricaua  an  P. epturus )an Wege-tae searwater(  Pu nus paci cus  as we as our speces o reptes. Te eracaton o Norway rats ( attus norvegicu  , ac-nape are (  Lepus nigricoi  ) an omestc rat ( Oryctoagu  sp.) n te 1990’s ( ELL  2002), greaty enance te conservaton vaue o te set partcuary as a ste or eventua rentroucton o reptes rom Roun Isan. Surveys  Te autors oun te new  ynancum  speces urng a our-ays oversty survey o te set n Decemer 2003 uner a Government o Maurtus proect commssone or te creaton o te Isets Natona Par. Te survey was carre out n a erent areas sae te naccesse western cs wc were examne were  posse wt nocuars. Ecoogca notes, e eve o treats pose to te atat y aen speces, were taen to aow or an assessment o te treat category o te speces usng IUCN Crtera (IUCN 2001). Sampes were eposte at te Maurtus Herarum an upcates sent to te Herarum o te Museum Natona ’Hstore Naturee, Pars. ESULTS  We oun 77 ger pant speces ncung te new Cynancum o wc a coony o an estmate two ozens ntermnge nvuas was oun. A sampe as eposte at te Maurtus Herarum (Hootype MAU 23772). Oter voucers coecte on a secon vst n 2004 are: MAU 24070, 24071, 24072, 24073 an 24074. . scopuosum  was growng rom te upper scarp ownwars on a near vertca sea acng c an ts eges n te sout west o te set etween 20-50 m ams (Fg. 1). Te speces s a rater procument ana wt rances reacng one cm n ameter. It as marey constrcte noes an a svery green tnge tat stnguses t vegetatvey rom a oter Maurtan Cynancum . Its rancng stems reac severa metres ong an creeps over expose rocs an ow c vegetaton. Towars ter extremtes, te stems are usuay erect sometmes reacng one meter g. Te coony spans a maxmum  o aout 40 m ateray an 30 m vertcay an vares rom ense monospec c areas towars ts core to more use growt towars te eges were t grows togeter t severa oter natve speces ncung  yopora coriacea  (Apocynaceae),  Lomatopyum tormentorii  (Aspoeaceae), Scaevoa taccaa  (Gooenaceae), an more rarey wt  Latania oigesi  (Arecaceae) an  Diciptera acata  (Acantaceae). Tere s, owever, a numer o nvasve aen pants tat appear to e encroacng on te Cynancum ’s atat, ncung te re prone grass  Heteropogon contortus  an oter aggressve wees e  Facourtia inica  (Sacaceae) an  puntia vugaris  (Cactaceae) tat ave areay eveope nto ense stans or tcets esewere on te set. ISCUSSION  Te ora o Gunner’s Quon was torougy surveye at east tree tmes ( ULLOCK  t a.  , ULLOO  1994, MWF 2003) snce ts escrpton n te 1930’s ( AUGHAN   IEHE  1937). It tus appears surprsng tat te new  ynancum  speces coverng a patc o severa ozen metres across was scovere ony n Decemer 2003. However, we some surveys genuney msse te pant (V AUGHAN  & W IEHE  1937, MWF 2003), oters appeare to ave ocate ut msent e t. Tus Buoc t a. (1983) recore an aen tree wee,  Euporia tirucai  (Euporaceae) were we scovere . scopuosum . Anoter survey y ELL t a.  (1994) mentone a cump o . tirucai  were we ater oun te Cynancum  coony. In act, C. scopuosum super cay resemes  E. tirucai  rom a stance. Inerte erarum sampes o te two speces can aso e very smar. We oun no . tirucai  on te set. g .  Dstruton o Cynancumscopuosum  on Gunner’s Quon Iset Nature Reserve, nort o Maurtus.  t s ortunate tat tere was no attempt to eracate te msent e  ynancum urng restoraton o te set e was successuy one wt rats, ares an rats ( ELL  2002). But t s worryng tat a pant oun on neary Serpent Isan n 2003 an ent e as a wee y te expeton memers, wc comprse no experence otanst, as een estroye an tat no sampe was ept (T ATAYAH  & C OLE  2004). Tere exsts aso te unortunate at on Maurtus to wee Cynancum  spp. rom areas manage or conservaton ecause t s a toxc pant. Weeng o  ynancum  as een reporte rom Ie aux Agrettes Nature Reserve (A. HEDUN  pers. comm. 2004), Perrer Nature Reserve an Monran Prvate Reserve (. A RGENT , . . 2004). Cynancum  seems now eracate rom te atter two stes. Conservation status  C. scopuosum  s nown ony rom Gunner’s Quon. A secon expeton tere n August 2004, reveae a tny secon cump o two pants on a rge 100m rom te rst coony rngng te tota area occupe y te speces to ess tan 0.1a n two separate paces (Fg. 1). Te speces tus as one o te most restrcte range or an enemc pant on Maurtus. Ts act aone exposes t to a g treat o extncton n te w. Te coony may tus easy e estroye y re, te more so tat muc o te set s toay nvae y re prone eteropogononorus , an aso receve ega vstors reguary gtng camp res. Inee, evastaton y re as een recore n te past ( ULLOO  1994) an  proay expans party at east ot wy te set s so poor n natve pants an wy te Cynancum  tse as suc a restrcte an margna struton. g. . Cynancum scopuosum  on Gunner’s Quon - young pant an owers.  estructon o te coony y a anse appears ey as ts s a common eature on te san as ncate y numerous roc a scars on te sea acng cs. Te ste were Cynancum  grows s aso grauay eng nvae y aen pants. Tus, te speces sou e regare as Crtcay Enangere (CR B1a() + 2a(); D). Gven tese rss, we recommen tat te pant e propagate to severa ocatons o sutae ecoogy on te set tse, ncung we nan. Aso te proxmty an smar cmate an geoogy o Roun an Fat Isans, an ter ongong restoraton  programmes mae tem ea stes to receve transocate . scopuosum . Estasng tese popuatons wou greaty reuce te pant’s extncton rss n te w. It s qute concevae tat . scopuosum  mgt ave once grown on tese two sets gven te  pant’s e centy wn-sperse sees an te act tat many natve speces are nown not to ave survve te uman-nuce ecoogca evastaton o ot sets. xtncton rss w aso e mnmse y mantanng te pant n ex-stu actes. C. scopuosum  s easy to propagate. A 12 cuttngs taen roote wtout rootng ormones wtn 5-6 wees. Tese are eng grown n te aroreta o te  Natona Pars an Conservaton Servce an o te Maurtus Herarum (MSIRI). Propagaton y sees, atoug avsae, seems ess easy or te moment ue to te currenty rater rare expetons to te set an snce te pants appear to set very ew ruts at a tme.A CKNOWLEDGEMENTS  We are grateu to Mr Yousou Mungroo an Mr Kevn Ruomaun o te  Natona Pars an Conservaton Servce, or avng organse te trp to te set. C.B. tans J-C. Autrey or revewng te rat. EFERENCES B AKER  , J.G. 1877. Fora o Maurtus an te Seycees. L. Reeve & Co, Lonon. ELL , B.D. 2002. Te eracaton o aen mammas rom ve osore san o Maurtus, Inan Ocean. In: EITCH  .. LOUT , .. (es). urning te ie: te eraication o invasive species . Occasona Paper o te IUCN Speces Survva Commsson, No. 27. p. 40-45.B ELL , B.D., D ULLOO , E. & B ELL , M. 1994. auritius osore isans survey report an management pan . We Management Internatona Lt. Wengton, New Zeaan.  pp. OJER  , . . ortus auritianus . Imprmere ’Am Mamarot et Compagne, Port Lous, Maurce.B OSSER  , J. & M ARAIS , W. 2005. 122. Ascepaaces.  Fore es Mascareignes . IRDMSIRIKew. Pars. OSSER  , ., ADET , H ., UEHO , . ARAIS , . 1976-onwars.  Fore es Mascareignes  La Reunion, Maurice, Rorigues . MSIRIORSTOM-IRD Kew. B OSSER  , J. & F LORENS , D. 2000.  yzygium gueoi  (Myrtaceae), nouvee espce e ’e Maurce. ansonia 22 (2): 183-186. ULLOCK  , .; ORTH , . REIG , . .  Roun Isan Expeition 1982 Fina Report. Unpuse Report.
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