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Nuytsia 12(3):495-496(1999) 495 Acaciahopperianasp. nov. (Leguminosae: Mimosoideae) mm Ab Acacia isoneura Maslin et A.R. Chapman phyllodiis 10-ncrvibus, glande 10-60 supra pulvinum posita, legumine griseo-brunneo, et seminibus obloideo-cilipsoidalibus vel discoideo, differt. Typus: 44kmnorthofMurchisonRiveronNorthWestCoastalHighway,WesternAustralia,3August 1974,B.R.Maslin3650{holo:PERTH00658340;iso:CANB,K,MEL-alldistributedasA. isoneura subsp.nimia). Dense,domedorobconicshrub I-3mtalland 1-4macross,occasionallyatreeto4mtall,single- ormulti-stemmedatgroundlevel;crownrounded. Barklongitudinallyfissured,fibrousanddarkgrey atbaseofmainstemsonoldestplantsotherwisesmoothanddarkgreyorreddishgrey. Branchletscreci, straight,red-brown(yellow-orangeatextremities),teretebutmarkedwithfine,yelloworreddishribs, silvery sericeous between ribs (hairs short, straight,closely appressed) butnormally soon glabrous. Stipules inconspicuous, 0.5-1 mm long, scarious, red-brown. Phyllodes terete, 6-14 cm long, 0.7-1 mm wide, sub-rigid, straightto shallowly incurved, ascendingtoerect, lightgreen,appressed- puberulous when young, glabrous or with hairs confined to furrows between nerves when mature; longitudinalneives 10,ofuniformwidth(0.2-0.3mmwide)andprominence,llat-toppedorshallowly convex, each separated by avery narrow, shallow, dark longitudinal furrow; apexacute, innocuous tocoarsely pungent, darkbrown;pulvinus 1-2 mm long, often indistinctbeingencrustedwithresin, yellow tolightorange, densely appressed-hairy on uppersurface. Glandinconspicuous, sometimes absent,onuppersurfaceofphyllode 10-60mmabovepulvinus. Inflorescencesimple, 1 or2peraxil; peduncles -2mmlong,oftenobscuredbystamensatanthesissothatspikeappearssessile,appressed- hairy;basal1 peduncularbractscaducous, c. 1 mm long. Spikes 10-20(25)mm long,4-7 mm wide, sub-densclyOowered,golden;hracteolespersistent,spathulate,0.6-0.8mmlong. Flowers4-memus- calyxgamoscpalous, 1/4-1/2 length ofcorolla,darkbrown, sub-glabrous tomoderately puberulous, mm dissected for 1/4-1/2 its length into triangular lobes; corolla 1.4-2 long, glabrous; petals obscurely I-nerved. Pot/.?5-9cmlong,2-3mmwide,pendulous,Hat,moderatelytodeeplyconstricted between seeds and scarcely raised over them, thinly coriaccous-crustaceous to firmly chartaceous, straight to shallowly curved, greyish brown, glabrous or minutely antrorsely strigulose; margins narrow, thickened, yellow to light brown. Seeds longitudinal m pod, obloid/ellipsoid or discoid, 2-3mmlong, 1.5-2mmwide,compressed(c. 1 mmthick),glossy,lightbrownorgrey-brownmottled pale yellow, orgreyish mottled dark brown; pleurogram fine, U- orV-shaped with a wide opening towardshilarend; arcolcsmall, ().3-0.5 mm long, c. 0.2mm wide;funicle filiformexpanded intoan obvious, ±conical, folded, white aril which commonly readily detachesfromseed. Selectedspecimensexamined. WESTERNAUSTRALIA;22.8kmSolBillabongRoadhouse,North WestCoastalHighway,.W,E. Ballingall 1894(PERTH);Winchesterarea, 19Aug. 1972,C Chapman s.n. (PERTH00656836);70kmNofNorthajnpton,R. Hnutiuk760473 (PERTH);Coorow,lateNov. 1979, B. Jacks.n. (PERTH00657255);45 km N ofMurchison River, NorthWestCoastal Highway, B.R.Maslin3345(CANB.G,K,NY,PERTH);BuntineRock.NNWofWubin,fi./?.Maslinl605(CANB, K,MEL,PERTH)andS.D. Hopper8337(BRI,NSW). Distribution. South-west Western Australia where it occurs between Carnamah and Watheroo, at BuntineRock(about20kmnorthofWubin),andnorthofGeraldtonfromNerrenNerrenStationsouth to about 10 km north ofthe Murchison River. 496 Nuyt.sia Vol. 12, No. 3 (1999) Habitat. North oftheMurchison River/4. hopperianagrows in yellow orreddish sandon plains or intheswalesbetweensanddunes;aroundCoorowitoccursinyellowsand,andatBuntineRockitgrows in gritty loam on the soil apron that fringes the rock. Phenology. FloweringspecimenshavebeencollectedfromlateJulytoSeptember. Podswithmature seeds havebeencollected from mid-Novembertomid-December. Conservation status. Not under threat. Etymology. Thisattractivenew species is named forStephen D. Hopper,ChiefExecutiveOfficerof Kings Park and Botanic Garden and, more importantly, my respected colleague whose scientific researchoverthepastmorethan20yearshascontributedsomuchtotheunderstandingoftheWestern Australiaflora. Affinities. Acacia hopperiana is a member ofAcacia section Juliflorae. It is closely related to A. isoneuraMaslin&A.R.Chapman(Maslin&Chapman 1999)andcareisneedednottoconfusethe two. Characters shared by these two species include their sericeous, finely ribbed branchlets; long, terete,multi-nervedphyllodes(nerves±broadandofuniformwidthandprominence);axillaryspikes onveryshortpeduncles;4-mcrousllowerswithagamosepalouscalyx;andlong,narrow,thin-textured pods with ± obscurely mottled seeds. Acacia isoneura is most reliably distinguished from A. hopperianabyits8-ncrvcdphyllodeswiththe(obscure)glandsituated0-3mmabovethepulvinus, reddishbrownpodsandellipsoidtoobloid-ellipsoidseeds(neverdiscoid). Themostreliablewayof countingnervenumbersaccurately istosection thephyllodeandobservethecutendsatxlOmag.or higher. Inbothspeciestheglandsareveryobscurebuttheirpositionisgenerallyindicatedbyaslight swelling ofthe phyllode lamina about the gland. BothA. hopperiana andA. isoneura subsp. nimia occur near Buntine, but they appear not to be sympatric; in addition to the characters noted above subsp. nimia is distinguished from A. hopperiana by its essentially epulvinate phyllodes. Variation. On plants occurring north ofGeraldton the seeds are clearly discoid with the aril readily detaching from theseed. On plants south ofGeraldton, however, the seeds areobloid-ellipsoid and the aril does notso readily detach. Note. Most duplicates of this species were dispatched by PERTH some years ago, identified as A. isoneura subsp. nimiaMaslin &A.R. Chapman. Acknowledgement Alex GeorgeisthankedforprovidingtheLatindiagnosisandforeditorialassistanceinpreparing this description. Reference Maslin, B.R. & Chapman, A.R. (1999). Acacia miscellany 19. The taxonomy ofsome Western Australian species of Acacia section Juliflorae with 4-merous llowers (Legiiminosae: Mimosoideae). Nuytsia 12: 469^86. B.R.Maslin Department of Conservation and Land Management, Locked Bag 104, Bentley Delivery Centre, Western Australia6983