Table Of ContentNuytsia 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
