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Nuytsia 13(3):471-474(2001) 471 AnewsubspeciesofIsotropiscuneifolia (Fabaceae) G.J.Keighery Department of Conservation and Land Management, Western Australian Wildlife Research Centre, PO Box 51, Wanneroo, Western Australia 6065. Abstract Keighery, G.J. Anew subspeciesofIsotropis cuneifolia (Fabaceae), Nuytsia 13(3): 471—474 (2001). IsotropiscuneifoliasubspeciesglabraKeigheryisdescribedandillustrated.Thesubspecies is consideredendangered, beingconfinedto asmall areaaroundGingin onthe SwanCoastalPlain, WesternAustralia. Introduction During intensive floristic andreserve surveys ofthe Swan Coastal Plain (Gibson etal. 1994) it becameapparentthatanumberoftaxapresentinthearearequiredtaxonomicstudy. Thisisthethird inaseriesofpapersinvestigatingtheseproblems. ThefirstdealtwithanewsubspeciesofLambertia echinata (Keighery 1997) andthe secondwithDiplopeltis huegelii (Keighery 1998). The genusIsotropisBenth. (Fabaceae) iswellknownas theonlyothergroup ofnative legumes producingthepoisonousalkaloides,apartfromthegenusGastrolobiumR.Br. Themostwidespread, and variable member of the genus in southern Western Australia is Isotropis cuneifolia (Sm.) B.D.Jacks.(CommonLambPoison). Thisspeciescontainspopulationsthataren=6, 12and 18and verydistinctivemorphologicalracesthatarecurrentlyunderstudy(Keigheryunpub.obs.). Gardner & Bennetts (1956) distinguished three different “forma” in their treatment ofIsotropis cuneifolia. However,thesewerenotformallynamedaccordingtotheInternationalBotanicalCode,andhavenot beenusedorreferredtointhetaxonomicliteraturesubsequently. Their“formalineata”ms. wasthe only one tested experimentally, and proved toxic to sheep. During surveys ofthe remnant vegetation ofthe eastern side ofthe Swan Coastal Plain, avery distinctive race of Isotropis cuneifolia was recorded in Casuarina obesa and Eucalyptus rudis woodland(Gibsonefa/. 1994). Thistaxoncorresponds with “forma Theauthorconcurs withGardner& Bennetts (1956)thatthisisadistinctivetaxonthatdeservestaxonomic recognition. Itisbeingnamedtofacilitateitslistingasaspeciesofconservationinterest, asitisconfinedtoa fewsmallremnants. ThebiologyandtaxonomyoftherestoftheWesternAustralianmembersofthe genusIsotropisis understudy. 472 Nuytsia Vol. 13, No. 3 (2001) Taxonomictreatment Isotropiscuneifoliasubsp. glabraKeighery,subsp. nov. Differt aIsotropis cuneifoliea subsp. cuneifoliea foliis etramulis omnino glabris. Typus: Gingin business road, 6 km south of Gingin, Western Australia, 16 September 1987, G.J. Keighery9242 (holo: PERTH 02869365;iso:CANB). Aclonalsoft-woodedshrub,to20cmtalland2macross,dyingbacktotheundergroundstemin mm summer, andresproutingin winter. Stemaboveground 2-3 wide,glabrous,basalthirdtinged red, uppershining green. Basalleavessessile (orgradually tapering into apetiole), trident-shaped, mm mm distinctly 2-lobed when mature, 76-88 long, 8-9 across sinus, green, shining, glabrous. mm mm Stipules17-23 long,green,glabrous. Pei/ice/580-98 long,glabrous. Bracieo/e5immediately mm belowcalyx,linear,brown. Ca/yj:brown,glabrous,lobes11-13 long,lowerlobesobovate-acute, mm upperlobestwo-lobed. Standard26-28 wide,eyeyellow,surroundedbyaredcoronathenyellow aroundmargins,reversered. Wing514-17mmlong,red. /(Tee/redtoalmostblack. Gvao'green,densely mm mm hairy.Legumerecurved,cylindrical,23-30 long,narrowedatbaseintoastipe5-8 long,brown, mm withscatteredappressedhairs. Seedsreniform,c. 1 wide,brown,surfacewithanopenreticulate pattern. (Figure 1) Specimens examined. WESTERN AUSTRALIA: Gingin, W.E. Blackall 2962 (PERTH); Gingin, 29Aug. 1924,Came&Gardners.n.(PERTH);45milepeg[72km]onGinginroad,H.Demarz3928 (PERTH, KPBG); Cowalla Rd, 8 miles [13 km] N of Gingin to Guilderton road, 8 Dec. 1965, A.S.Georges.n.(PERTH);YurineSwampNatureReserve,G.J.Keighery14976(PERTH); EofLake BambunReserve,20Nov. 1991,B-d. Keigherys.n. (PERTH). Distribution andhabitat. Knownfromtheeastern sideofthe Swan Coastal Plain, extending about 20km northand southofGingin, whichis 80kmnorthofPerth. Grows underCasuarina obesa or Eucalyptusrudislowwoodlandonwinter-wetflats,usuallyinredclayorironstoneorsandyclayover ironstone. Likeothermembersofthisspecies,plantsdiedowntoapersistentrootstockoversummer. Newstemsareproducedafterthefirstrainsinautumnorwinter. Floweringperiod. AugusttoOctober. Conservationstatus. CALMConservationCodes forWesternAustralianFlora: Priority Two. One smallpopulationisknown withinaconservationreserve. Otherpopulations are also small. Notes. This subspecies differs from all other variants of Isotropis cuneifolia in being completely glabrous, and in the long, thin shining green leaves. It is separated ecologically from the typical subspecieswhichgrowsonwelldrainedsitesontheSwanCoastalPlainandadjacentDarlingRange. Therearethreeotherpotentialsubspecifictaxainthespecies,occurringbetweenGeraldtonandShark Bay, in the southern wheatbelt and along the southcoast. G.J. Keighery, A new subspecies of Isoptropis cuneifolia 473 Figure 1. Flowering branchlet of hotropis cuneifolia subsp. glabra. Scale bar = 20 mm. Drawn from G.J. Keighery 14976 (PERTH). 474 Nuytsia Vol. 13, No. 3 (2001) References Gardner, C.A.G. & Bennetts, H.W. (1956). ‘The Toxic Plants ofWestern Australia.” (Western Australian Newspapers Ltd: Perth.) Gibson, N., Keighery, B.J., Keighery, G.J., Burbidge, A.H. & Lyons, M.N. (1994). A Floristic Survey ofthe southern Swan Coastal Plain. Unpublished Report for the Australian Heritage Commission. Keighery, G.J. (1997). A new subspecies of Lambertia echinata (Proteaceae). Nuytsia 11: 283-284. Keighery, G.J. (1998). Taxonomy of Diplopeltis huegelii (Sapindaceae). Nuytsia 12: 289-291.