All enquiries and manuscripts should be directed to:
Hopper, S.D. & Nicolle, D.
Diamond gum (Eucalyptus
a new threatened species
endemic to the Bremer
Range of the Southwest
Australian Floristic Region.
Nuytsia 17: 185–194 (2007)
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by the Western Australian
our Species’ biodiversity
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WESTERN AUSTRALIA'S JOURNAL OF SYSTEMATIC BOTANY
S.D. Hopper & D. Nicolle, Diamond gum (Eucalyptus rhomboidea: Myrtaceae)
Royal Botanic Gardens, Kew, Richmond, Surrey, United Kingdom TW9 3AB
Currency Creek Arboretum, 15 Rousillion Promenade, Old Reynella, South Australia 5161
Hopper, S.D. & Nicolle, D. Diamond gum (Eucalyptus rhomboidea: Myrtaceae), a new threatened
species endemic to the Bremer Range of the Southwest Australian Floristic Region. Nuytsia 17:
185–194 (2007). Eucalyptus rhomboidea Hopper & D.Nicolle, first collected by the late Ken Newbey
in 1979, is described as new. The species is a member of Eucalyptus ser. Subulatae Blakely allied to
E. transcontinentalis Maiden. It is confined to the Bremer Range, and it is at risk from present and
proposed mining activities.
The Southwest Australian Floristic Region (SWAFR, sensu Hopper & Gioia 2004) is rich in
threat. Until recently, those endemics confined to scattered ironstone and mineralised hills on the semi-
arid margins of the SWAFR were rarely so threatened as to be of significant conservation concern.
However, recent economic circumstances have rendered several such hills and banded ironstone
inselbergs sufficiently attractive to fast-track mining. Almost overnight, ranges rich in localized mineral
prospectivity and exceptionally rich in plant endemics have become seriously threatened because
of the scale of mining proposed or underway (e.g. Bandalup Hill and the Ravensthorpe Range near
Ravensthorpe). The taxonomy of many of these threatened endemics needs further research, with
several undescribed species among them. Here, we describe one such example.
The Bremer Range is a series of mineralised low hills, largely of greenstone with some banded
ironstone, extending for 60 km along the south-eastern side of Lake Johnston and Lake Hope, to the
north of the Norseman – Lake King road. The Range and its highest peak, Mt Gordon, were named for
the naval officer Sir Gordon Bremer by Western Australia’s first Surveyor General John Septimus Roe on
his 1848–49 expedition from Albany to the Russell Range (How et al. 1988). Subsequently, the Bremer
Range was traversed by the explorer Frank Hann in September 1901, who almost circumnavigated
Lake Johnston and named it for the then Surveyor General H.F. Johnston (Donaldson & Elliot 1998).
Because the Range is located off and between the two major east-west roads linking Hyden and Lake
King to Norseman, it escaped detailed floristic survey until the past three decades.
Beard (1976) first described the major structural vegetation formations in the Bremer Range
area but did not complete sufficient field work to document the flora in detail nor collect the species
described as new herein.
Eucalyptus rhomboidea Hopper & D.Nicolle was encountered by one of us (SDH) in 1989 in the
course of a survey commissioned by the Environmental Protection Authority to delineate proposed
conservation reserves in the extensive goldfields eucalypt woodlands between the wheatbelt and
Nullarbor Plain of southern Western Australia (Henry-Hall et al. 1990).
Subsequently, an earlier collection (K.R. Newbey 5603) made in 1979 was located in the Western
Australian Herbarium determined as “Eucalyptus aff. transcontinentalis”. The late Ken Newbey made
the collection when engaged as consultant survey botanist for the Biological Survey of the Eastern
Goldfields, an interagency project from 1977–1983 then involving the Western Australian Museum,
the Department of Fisheries and Wildlife’s Western Australian Wildlife Research Centre, the Western
Australian Herbarium and the National Parks Authority (How et al. 1988).
In the relevant published report, Eucalyptus rhomboidea is mentioned by Newbey and Hnatiuk
(1988) in their Table 4 listing important plant collections as “Eucalyptus sp. (KRN 5603)”. They
indicated that this was the first collection of a taxon considered to be undescribed and endemic to the
Lake Johnston – Hyden study area. Eucalypt taxonomist Ian Brooker is acknowledged by Newbey
and Hnatiuk (1988) for assistance with eucalypt identifications, so it is probable that Brooker was the
first to consider Newbey’s collection as sufficiently distinct to be a possible new taxon not matching
anything then named.
Newbey and Hnatiuk (1988: Table 3 and pp. 134–135) used Eucalyptus rhomboidea to characterise
a unique low woodland type (<15 m tall) on undulating greenstone plain country. They indicated that
this low woodland was “very rare” with the average size of individual areas encountered in their survey
being <1 ha. Newbey and Hnatiuk (1988: 33) provided the following brief description of associated
species in the Eucalyptus rhomboidea Low Woodland:
“Low trees of Eucalyptus eremophila occurred in Eucalyptus sp. (KRN 5603) Low
Woodland. Tall shrubs included Melaleuca lanceolata, and low shrubs included Acacia
and Westringia cephalantha.”
Newbey and Hnatiuk (1988: 134–135) also provided a detailed ecological description of one
vegetation site named as a Eucalyptus sp. (KRN 5603) Low Woodland (reproduced herein as
Based on unpublished field notes of SDH, Henry-Hall et al. (1990: 102) provided a brief account
of species associated with E. rhomboidea in their submission for a proposed Bremer Range Nature
endemic Eucalyptus “rhomboidea” (Diamond Gum) ... In the vicinity of Burmeister Hill,
Nicolle and Conran 1999], E. salmonophloia and E. cylindrocarpa over an understorey
of Melaleuca spp. In the Mt Glasse area, Eucalyptus “rhomboidea” was recorded with
E. salubris, E. gracilis. E. eremophila and E. densa subsp. densa over mallees of E. pileata,
E. cylindriflora and E. aff. leptophylla [SDH 7212, = E. olivina].”
a low woodland (from Newbey & Hnatiuk 1988: 134).
Stratum 1: Trees 10–13 m, 3% canopy cover, Eucalyptus sp. (KRN 5603)
Stratum 2: Trees 8–10 m, 5% canopy cover, Eucalyptus eremophila
Stratum 3: Shrubs 2.1–2.7 m, 5% canopy cover, Melaleuca pauperiflora
Stratum 4: Shrubs 1.6–2.0 m, <1% canopy cover, Melaleuca eleuterostachya
Stratum 5: Shrubs 1.1–1.5 m, 0.2% canopy cover, Eremophila pachyphylla, Daviesia sp. (KRN 5598)
[= D. argillacea Crisp], Exocarpos aphyllus
Stratum 6: Shrubs 0.6–1.0 m, 3.6% canopy cover, Melaleuca cardiophylla var. parviflora, Phebalium
Stratum 7a: Shrubs 0.0–0.5 m, 10% canopy cover, Eremophila caerulea, Westringia cephalantha,
Rye], Daviesia aff. colletoides, Glycyrrhiza acanthocarpa, Grevillea acuaria, Olearia muelleri
Stratum 7b: Miscellaneous plants, <1% canopy cover, annuals (sic) Prasophyllum nigricans; parasitic
climbers Cassytha melantha.
UNIT: undulating plain, greenstone
GEOLOGICAL SURFACE: mafic extrusive
rocks, fine to medium-grained
ELEMENT: low rise
NORTHCOTE: A horizon with surface
crust: A2 horizon not bleached; soil reaction
MAIN ORIGIN: in situ weathering
MAIN ATTRIBUTE: stony
PAVEMENT: 30–60% cover of material
4–15 mm long, patchy
LITTER: Logs few; branches few; leaves
broad, deposits 2 cm thick, averaging
6 m apart
GROUP: shallow calcareous earths
A 0–18 cm: dusky red clay loam;
very friable; 30–60% subrounded ironstone
5–15 mm across
B 18–68 cm: weak red medium clay; firm;
inclusions similar to above; slightly calcareous;
pH 9.0, too stony to auger deeper
DISTRIBUTION: only patch seen, 0.8 ha.
PROFILE THICKNESS: 70–100 cm
The proposal for a Bremer Range Nature Reserve by Henry-Hall et al. (1990) was formally
adopted as a proposal by the Department of Conservation and Land Management in its South Coast
Region Regional Management Plan (Anon. 1992). Conservation of endemics such as E. rhomboidea
was included as part of the justification for the proposed nature reserve. Unfortunately, because of
mineral prospectivity, this proposal to create the Bremer Range Nature Reserve has yet to be enacted
In the spring of 1994, a comprehensive floristic survey of the Bremer Range and hills to the north
was undertaken by Gibson and Lyons (1995, 1998) to define plant communities and contribute towards
their conservation. Eucalyptus rhomboidea was recorded in all seven sites clustered as community
type 1, with 40 associates (Table 2). These authors established further support for a low woodland
community characterised by E. rhomboidea (i.e. their Community Type 1).
In April 1998 the junior author traversed the main Bremer Range track and made several more
collections of E. rhomboidea as part of a PhD research program investigating the taxonomy and phylogeny
of Eucalyptus ser. Subulatae Blakely (Nicolle & Conran 1999; Nicolle et al. 2006). Collectively, we have
had the opportunity to conduct comparative herbarium, glasshouse and field studies of E. rhomboidea
and other related taxa, as well as examination of types or their photos of all named taxa in Eucalyptus
ser. Subulatae. It is clear that the species is indeed new. This paper, therefore, formally describes
the seven quadrats clustered as community type 1 by Gibson and Lyons (1988). Note that these data
may, in part, include associates of E. sheathiana from near Round Top Hill, which was misidentified
as E. rhomboidea (cf. N. Gibson & M. Lyons 1975, PERTH 05306957).
Affinis Eucalypto transcontinetali Maiden sed characteribus sequentibus distinguitur: foliis adultis
crassioribus et latioribus; alabastris fructibusque non-pendulis; pedunculis et pedicellis brevioribus;
alabastris rhombeis; operculis conicis; fructibus obconicis vel pyriformis differt.
21 April 1998, D. Nicolle 2274 (holo: PERTH 07618743; iso: AD, CANB).
Cat. p. 381 (2000), nom. inval.
to orange-brown or yellow-brown, decorticating in strips and short ribbons. Branchlets pruinose, pith
glands absent. Cotyledons bisected. Seedling leaves opposite for >20 pairs, linear at first, soon becoming
sessile and strongly decurrent, ovate to elliptic, undulate, to 40 mm long × 32 mm wide, more or less
concolorous, dull, blue-green, glaucous, especially on new growth. Adult leaves disjunct, pendulous,
petioles 23–30 mm long; lamina lanceolate, 110–155 mm long × 18–35 mm wide, concolorous, dull,
blue-green; reticulation moderately dense, oil glands abundant, mostly at intersections of veinlets.
Inflorescences axillary, unbranched, held erect, 7-flowered; peduncles somewhat angular, 7–12 mm
long; pedicels stout, 1.5–3.5 mm long. Buds pruinose, rhomboid (diamond-shaped), 9–11.5 mm long;
operculum conical, 6–7 mm long, smooth, scar present. Stamens irregularly flexed, all fertile; anthers
basifixed, ovoid, opening by slits. Flowers creamy-yellow. Ovules in 4 vertical rows. Fruits held
erect, usually pruinose, especially when young, shortly pedicellate, obconical although often slightly
contracted at rim, 7.5–8.5 mm long × 7.5–9 mm diam., smooth; disc ± level and often prominent,
1–2 mm wide; valves (3)4; style tips exserted. Seed angular-ovoid, dull to slightly glossy, grey-brown,
finely reticulate. (Figures 1, 2)
17 Mar. 2005, G.F. Craig 6381 (PERTH 07218605); 21 Apr. 1998, M. French 452 (PERTH 05202396);
10 May 1989, S.D. Hopper 7208 (PERTH 05229499); 10 May 1989, S.D. Hopper 7209 (PERTH
05229502); 10 May 1989, S.D. Hopper 7210 (PERTH 05229510); 10 May 1989, S.D. Hopper 7216
(PERTH 05229588); 11 May 1989, S.D. Hopper 7230 (PERTH 05229677); 12 May 1989, S.D. Hopper
7233 (PERTH 05231876); 11 May 1989, S.D. Hopper 7234 (PERTH 05231884); 13 Sep. 1994, N. Gibson
13 Sep. 1994, N. Gibson & M. Lyons 1725 (PERTH 05295130); 14 Sep. 1994, N. Gibson & M. Lyons
1833 (PERTH 05306914); 14 Sep. 1994, N. Gibson & M. Lyons 1918 (PERTH 05306922); 15 Sep. 1994,
N. Gibson & M. Lyons 1761 (PERTH 05307007); 16 Sep. 1994, N. Gibson & M. Lyons 1561 (PERTH
05306930, 05307090); 16 Sep. 1994, N. Gibson & M. Lyons 1586 (PERTH 05306949);16 Sep. 1994,
05307082, 05306981); 16 Aug. 1979, K.R. Newbey 5603 (PERTH 1448196, 2520621); 21 Apr. 1998,
CANB, PERTH); 30 Oct. 2000, A.V. Slee & J. Connors AVS 4310 (PERTH 05998336); 30 Oct. 2000,
Figure 1. Holotype of Eucalyptus rhomboidea (D. Nicolle 2274), scale = 3cm.
Figure 2. Eucalyptus rhomboidea (S.D. Hopper 7209, PERTH 05229502). A – habit and habitat;
B – base of trunk; C – buds. Photographs: S.D. Hopper.
Glasse area of the Bremer Range between Lake King and Norseman, over a linear range of approximately
15 km (Figure 3). It occurs in low open woodland or tall shrubland vegetation on red clay-loams.
Detailed ecological data and a list of associated taxa are included in Tables 1 and 2. Associated eucalypt
species include E. cylindriflora Maiden & Blakely, E. eremophila (Diels) Maiden, E. densa Brooker &
Hopper subsp. densa, E. olivina Brooker & Hopper, E. pileata Blakely, E. salmonophloia F. Muell.,
fruits present, (no collections from June, July or August), numerous specimens with both buds and
fruits in September, two specimens with buds, flowers and fruits collected on September 16
two specimens with buds, flowers and fruits collected on October 30
by the Conservation Codes for Western Australian Flora (Atkins 2006; Western Australian Herbarium
1998–). The species is at risk from present and future mining activity in the Bremer Range and requires
and unique within E. ser. Subulatae and unique in the E. transcontinentalis complex.
by the combination of deeply bisected cotyledons, lack of pith glands in the branchlets, 7
Within the series, E. rhomboidea is part of the E. flocktoniae (Maiden) Maiden – E. transcontinentalis
Maiden complex (E. subser. Decurrentes Brooker on the basis of the strongly decurrent and opposite
juvenile leaves (Brooker 2000)). Eucalyptus rhomboidea is most closely related to E. transcontinentalis
(especially subsp. transcontinentalis), differing from that species by the broader, thicker adult leaves;
the erect inflorescences (± pendulous in E. transcontinentalis) on short peduncles and pedicels;
the diamond-shaped buds with a conical operculum (elongated buds due to a long, horn-shaped
operculum in E. transcontinentalis); and the obconical to pyriform fruit (urceolate to barrel-shaped
in E. transcontinentalis).
Eucalyptus rhomboidea occurs within the distribution of E. transcontinentalis, although the two
species are not sympatric. Eucalyptus transcontinentalis has not been recorded for the southern part
of the Bremer Range, but occurs to the north (south of the Hyden – Norseman road) and to the south
(Peak Charles area) of E. rhomboidea without apparent hybrids or intergrades.
are the only non-sprouter species known in the series (Nicolle et al. 2006), regenerating from fire by
Figure 3. Distribution of Eucalyptus rhomboidea (
) in the Southwest Australian Floristic Region.
habit, bark, leaf and fruit morphology and branchlet glaucescence. However, it belongs to a different
section (E. sect. Dumaria
L.D.Pryor & L.A.S.Johnson ex Brooker). Eucalyptus rhomboidea can be
pith glands, diamond-shaped buds and dull, grey seeds.
We are grateful to Nick Henry-Hall and Malcolm French for assistance in the field, to Rhian Smith,
Justin Moat, Susana Baena and Roger Joiner for assistance with figures, and to Ryonen Butcher and Kelly
Shepherd (‘Saving our Species’ biodiversity conservation initiative) for facilitating publication.
Anon. (1992). “South Coast Region Regional Management Plan 1992–2002. Management Plan 24.” (Department of Conservation
and Land Management: Perth.)
Atkins, K.J. (2006). “Declared Rare and Priority Flora list for Western Australia.” (Department of Environment and Conservation:
Kensington, Western Australia.)
Beard, J.S. (1976). “The vegetation of the Boorabbin and Lake Johnston areas, Western Australia.” (Vegmap: Perth.)
Brooker, M.I.H. (2000). A new classification of the genus Eucalyptus L’Her. (Myrtaceae). Australian Systematic Botany 13(1):
Australia 1895–1908.” (Hesperian Press: Carlisle, Western Australia.)
Gibson, N. & Lyons, M.N. (1995). “Floristic Survey of the Bremer and Parker Ranges of the Eastern Goldfields of Western Australia.
Report for the Australian Heritage Commission.” (Department of Conservation and Land Management: Perth.)
Gibson, N. & Lyons, M.N. (1998). Flora and vegetation of the Eastern Goldfields Ranges: Part 2 – Bremer Range. Journal of
the Royal Society of Western Australia 81(2): 107–117.
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in the Eastern Goldfields, Western Australia.” Report to the EPA Red Book Task Force, pp. 264.
Hopper, S.D. & Gioia, P. (2004). The southwest Australian floristic region: evolution and conservation of a global hot spot of
biodiversity. Annual Review of Ecology, Evolution and Systematics 35: 623–650.
How, R.A., Newbey, K.R., Dell, J., Muir, B.G. & Hnatiuk, R.J. (1988). “The Biological Survey of the Eastern Goldfields of
Western Australia. Part 4. Lake Johnston – Hyden Study Area.” Records of the Western Australian Museum Supplement
(Eds). The Biological Survey of the Eastern Goldfields of Western Australia. Part 4. Lake Johnston – Hyden Study Area.
Nicolle, D., & Conran, J.G. (1999). Variation in the Eucalyptus flocktoniae complex (Myrtaceae) and the description of four
new taxa from southern Australia. Australian Systematic Botany 12(2): 207–239.
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series Subulatae (Myrtaceae) of southern Australia. Australian Systematic Botany 19(1): 59–86.
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