The threatened edible yams of the Dioscorea sambiranensis R.Knuth species complex (Dioscoreaceae): a new species and subspecies

[摘要] TheDioscoreasambiranensisspeciescomplexisendemictoNorthernandNorth-WesternMadagascar.Itstaxahavebroad,cordateleaveswithpetiolesroughlyequalinlengthtotheblade,laxmaleinflorescenceswithflowersonlongpedicelsarrangedincymulesofusuallyfiveormoreflowersandflatdiscoidfloraltori.Followingstudyofitsmorphologicalvariation,twonewtaxainthecomplexaredescribedandillustrated.DioscoreabuckleyanaWilkinwaspartofamixedtaxonomicconceptundertheinvalidnameD.sambiranensisR.Knuthsubsp.ambrensisH.Perrier.ItisglabrouslikeD.pteropodaH.Perrier,butdiffersinpetioleandleafblademorphology(especiallybladetexture),pedicellengthandcapsulemorphology.ClarificationofthelimitsofD.sambiranensisR.Knuthrevealedanundescribedsubspecies,subsp.bardotiaeWilkin,whichdiffersinleafbladeandpetioledimensions,andlacksthesurfaceornamentationoftheovaryandcapsulefoundinsubsp.sambiranensis.TherelationshipofD.sambiranensiswithD.namorokensisWilkinisrevealed.Keys,descriptionsandadistributionmapareprovidedforallthetaxacovered,andconservationstatusassessmentsgiven.Thelattershowthatallofthetaxaofthecomplexare,orarelikelytobe,threatened.

[学科分类] 植物学

[关键词] Dioscoreaceae;Dioscorea;yams;Madagascar;endemic;edible;conservation;new species;new subspecies;Dioscoreaceae;Dioscorea;ignames;Madagascar;endémique;comestible;conservation;espèce nouvelle;sous-espèce nouvelle