WESTERN AUSTRALIA'S JOURNAL OF SYSTEMATIC BOTANY ISSN 0085–4417 Maslin, B.R. Acacia cockertoniana (Leguminosae: Mimosoideae), a new species from banded ironstone ranges of the south-west arid zone, Western Australia Nuytsia 17: 247–252 (2007) A special edition funded by the Western Australian Government’s ‘Saving our Species’ biodiversity conservation initiative. All enquiries and manuscripts should be directed to: The Editor – NUYTSIA Western Australian Herbarium Telephone: +61 8 9334 0500 Dept of Environment and Conservation Facsimile: +61 8 9334 0515 Locked Bag 104 Bentley Delivery Centre Email: [email protected] Western Australia 6983 Web: science.dec.wa.gov.au/nuytsia/ AUSTRALIA All material in this journal is copyright and may not be reproduced except with the written permission of the publishers. © Copyright Department of Environment and Conservation . BN.uRy.t sMiaa 1sl7i:n 2, 4A7c–a2c5ia2 c(o2c0k0e7r)toniana, a new species from banded ironstone ranges 247 Acacia cockertoniana (Leguminosae: Mimosoideae), a new species from banded ironstone ranges of the south-west arid zone, Western Australia Bruce R. Maslin Western Australian Herbarium, Department of Environment and Conservation, Locked Bag 104, Bentley Delivery Centre, Western Australia 6983 Abstract Maslin, B.R. Acacia cockertoniana (Leguminosae: Mimosoideae), a new species from banded ironstone ranges of the south-west arid zone, Western Australia. Nuytsia 17: 247–252 (2007). Acacia cockertoniana Maslin, a new species with a restricted distribution in the south-west arid zone of Western Australia is described. The species is restricted to banded ironstone ranges which accounts for its discontinuous distribution between Mt Jackson (130 km north of Southern Cross) and near Mt Magnet (c. 270 km north-west of Mt Jackson). Sterile specimens from north of Mt Magnet require confirmation as being this species. Acacia cockertoniana is often abundant in the places where it occurs and current evidence suggests that it is most common in the vicinity of the Windarling Range. Acacia cockertoniana appears to be most closely related to A. balsamea Cowan & Maslin. Introduction This new species was first drawn to my attention by Geoff Cockerton, after whom it is named. Botanical surveys in 2003 and 2004 in the Windarling Range (160 km north of Southern Cross) by Cockerton et al. (see Western Botanical 2004) had shown that the species was a conspicuous element of the vegetation in an area covered by a mining lease (an iron ore mine is now operational in this area). Following an inspection of these populations in 2004, I was able to locate additional specimens of the species at the Western Australian (WA) Herbarium (PERTH), mostly filed under Acacia aff. coolgardiensis Maiden. These specimens had mostly been gathered by Hugh Pringle (WA Department of Agriculture) in 1993 from the vicinity of Lake Barlee, about 100 km to the north of the Windarling Range. The species is now known to occur on the Die Hardy Range and Mt Jackson, which are located immediately to the south of the Windarling Range; it also occurs in the Mt Magnet region about 200 km to the north-west. The first collection of the species appears to have been by Alan Payne (WA Department of Agriculture) from Meka Station (about 120 km north-west of Mt Magnet), however, this specimen is sterile and flowering or fruiting material is needed to confirm its identity. The new species is habitat specific, being restricted to areas of Banded Iron Formation (BIF). 248 Nuytsia Vol. 17 (2007) Species description Acacia cockertoniana Maslin, sp. nov. Frutices vel arbores, 3–6(–7) m altae. Phyllodia anguste linearia vel lineari-elliptica vel lineare- oblanceolata, ad basim angustata, 5–15(–17) cm longa, (1–)2.5–5(–6) mm lata, plana, non rigida, resinosa; nervi longitudinali paralleli numerosi, relative lati (0.1–0.2 mm lati); apices curvati vel uncinati, acuti. Capitula globularia vel obloidea, c. 4–5 mm longa (in sicco); gemmae resinosae; pedunculi 4–6 mm longi in statu florenti, usque ad 12 mm in statu fructifero, glabri vel sub-glabri. Flores 5-meri; sepala libra vel ad basim breviter connata, oblonga vel anguste oblonga. Legumina linearia, (4–)6–12 cm longa, 3–5 mm lata, ± plana, plerumque inter semina non constricta, tenuiter crustacea, nervis longitudinalibus paucis, parce anastomosis, inter nervos sericea. Semina in legumine longitudinaliter disposita, 4–4.5 mm longa, 1.5–2 mm lata. Typus: Windarling Range (160 km north of Southern Cross) south of the west end of Portman Iron Ore deposit W3, Western Australia, 14 December 2003, S.A. McNee, G.O’Keefe & J. Lester LCS 8815 (holo: PERTH 07125690; iso: K, MEL). Acacia sp. Diemals (H.J.R. Pringle 3924A), Western Australian Herbarium, in FloraBase, http:// florabase.dec.wa.gov.au [accessed 16 August 2007]. Photographs. WorldWideWattle [online at www.worldwidewattle.com]. Obconic, multi-stemmed or infrequently single-stemmed shrubs or trees 3–6(–7) m tall, main stems 8–10 cm dbh and together with the upper branches typically slightly crooked, young plants rounded and to 4 m across; crowns sub-dense, greyish green (new growth light green) with a silvery sheen. Bark grey, rough, rather deeply longitudinally fissured on main stems, smoother on upper branches. Branchlets terete, reddish brown (often partially covered with a light grey, ± flaking epidermis), angled at extremities due to yellow resin ribs, sericeous between ribs (the hairs short, straight, appressed, silvery and difficult to see without magnification), indumentum sparse to moderate, the ribs not prominent with age. New shoots bright light green (tinged yellowish), resinous, slightly viscid. Phyllodes narrowly linear to linear-elliptic or linear-oblanceolate, narrowed at the base, 5–15(–17) cm long, (1–)2.5–5(–6) mm wide, flat, not rigid, mostly erect but some spreading at wide angles, straight to shallowly incurved, shallow recurved or sometimes shallowly sigmoid, resinous (resin often confined to nerves), with a slight unpleasant musky odour, mid-green to dark greyish green (often drying darkish green tinged yellowish brown), minutely sericeous producing a silvery sheen in sunlight, the hairs mostly confined to between nerves; longitudinal nerves numerous, parallel, of uniform prominence or more commonly 3–5 more pronounced (visible to unaided eye) than the rest, relatively broad (0.1–0.2 mm wide), covered with a discernible layer of translucent shiny resin (observe at ×10 mag. or higher); apices curved to uncinate, acute; pulvinus 0.5–1.5 mm long, not prominent. Gland situated on upper margin on phyllode 0–2 mm above the pulvinus, not prominent, submerged within lamina which is slightly swollen about the gland. Inflorescences simple, 1 or 2 per axil; heads globular (especially in bud) or more commonly obloid, about 4–5 mm long (when dry), light golden, buds resinous; peduncles 4–6 mm long when in flower, up to 12 mm long when in fruit, glabrous to sub-glabrous (hairs minute, straight, appressed and silvery white); single basal peduncular bract persistent to anthesis, c. 1 mm long, brown, resinous. Bracteoles spathulate, 0.6–0.8 mm long, glabrous or sub-glabrous, claws linear, the laminae ovate-elliptic, c. 0.3 mm wide, ± inflexed and brown. Flowers 5-merous, small (1.3–1.5 mm long); sepals free or very shortly united at base, ⅓–½ length of petals, oblong to narrowly oblong but often B.R. Maslin, Acacia cockertoniana, a new species from banded ironstone ranges 249 slightly expanded at apex; petals 1.6–1.8 mm long, glabrous, nerveless or very obscurely 1-nerved. Pods linear, (4–)6–12 cm long, 3–5 mm wide, ± flat (not obviously raised over the seeds), straight- edged or sometimes very slightly constricted between the seeds, pendulous, straight to shallowly curved, thinly crustaceous, light red-brown, marked with few, ± prominent, sparingly anastomosing longitudinal nerves, sericeous between the nerves, marginal nerve scarcely evident. Seeds longitudinal in pods, obloid to narrowly obloid, 4–4.5 mm long, 1.5–2 mm wide, compressed (1 mm thick), mid- brown, shiny; pleurogram ‘u’-shaped, not prominent, open towards the hilum, bordered by a diffuse band of dull yellow tissue; areole 0.4–0.5 mm long, 0.3–0.4 mm wide; funicle filiform, folded below a fleshy, terminal, pale coloured (cream) aril. (Figure 1) Characteristic features. Shrubs or trees 3–6(–7) m tall, main stems and upper branches typically slightly crooked, crowns greyish green (light green when making new growth) with a silvery sheen. Phyllodes narrowly linear to linear-elliptic or linear-oblanceolate, narrowed at the base, 5–15(–17) cm long, (1–)2.5–5(–6) mm wide, flat, not rigid, resinous, mid-green to dark greyish green (often drying darkish green tinged yellowish brown), minutely sericeous (hairs mostly confined to between nerves); parallel longitudinal nerves numerous, relatively broad (0.1–0.2 mm wide), covered with a discernible layer of translucent shiny resin; apices curved to uncinate, acute. Heads globular or obloid, about 4–5 mm long (when dry), buds resinous; peduncles 4–6 mm long when in flower, up to 12 mm long when in fruit, glabrous to sub-glabrous. Flowers 5-merous; sepals free or very shortly united at base, oblong to narrowly oblong. Pods linear, (4–)6–12 cm long, 3–5 mm wide, ± flat, mostly not constricted between seeds, straight to shallowly curved, thinly crustaceous, marked with few, ± prominent, sparingly anastomosing longitudinal nerves, sericeous between the nerves. Seeds longitudinal in pods. Selected specimens examined. WESTERN AUSTRALIA: Mt Magnet, Harmony Gold Minesite, 13 Oct. 2006, S. Kern & D. True 12036 (NSW, PERTH); eastern extremity of Windarling Range (between Southern Cross and Menzies), foothills on N side of Portman Iron Ore deposit, 1 Oct. 2004, B.R. Maslin 8617 (AD, PERTH); Windarling Range (160 km N of Southern Cross) on lower slope of southern side of Portman Iron Ore deposit W2, 14 Dec. 2003, S.A. McNee, G. O’Keefe & J. Lester LCS 8817 (AD, CANB, PERTH); Windarling Range (160 km N of Southern Cross) southern slope of Portman Iron Ore deposit W3, 21 Oct. 2004, S. McNee & G. O’Keefe LCS 9632 (CANB, K, PERTH, NSW); Bulga Downs Station, 7 Jan. 2005, C. Payne s.n. (PERTH 06949347); Cashmere Downs Station, 17 Sep. 1993, H. Pringle 3924A (MEL, PERTH); Coolwater paddock, Lake Barlee, 28 Sep. 1993, H. Pringle 3984 (NSW, PERTH); Mt Elvire Station, 20 Nov. 1993, H. Pringle 30188 (PERTH). Distribution and habitat. Acacia cockertoniana has a disjunct distribution in the south-western extremity of the arid zone in Western Australia (Western Australian Herbarium 1998–). It occurs in the vicinity of Lake Barlee (e.g. Bulga Downs Station, Cashmere Downs Station, Diemals Station and Mount Elvire Station) and on the Die Hardy Range, Windarling Range and Mt Jackson, immediately to the south. It also occurs near Mt Magnet township (c. 270 km north-west of Mt Jackson); two sterile specimens from c.120 km north-west of Mt Magnet (Hitchcock SH718-08 from Weld Range and Payne 36 from Meka Station; both at PERTH) are provisionally referred to A. cockertoniana but flowering or fruiting material is needed to confirm these identifications. A variant from the Jack Hills (c. 200 km north of Mt Magnet) is discussed below under Variation; this variant is currently not included within the circumscription of A. cockertoniana. Acacia cockertoniana is often abundant in the places where it occurs and current evidence suggests that it is most common in the vicinity of the Windarling Range. The discontinuous nature of the distribution of this species relates to its habitat specificity. Acacia cockertoniana is restricted to BIF hills and ranges and grows in iron-rich, red-brown sandy loam or silty clay. It grows in dense Acacia shrubland with scattered eucalypts. 250 Nuytsia Vol. 17 (2007) Figure 1. Holotype of Acacia cockertonia Maslin (S.A. McNee, G.O’Keefe & J. Lester LCS 8815), scale = 5cm. B.R. Maslin, Acacia cockertoniana, a new species from banded ironstone ranges 251 Flowering and fruiting periods. Flowers have been collected from October to December and judging from these specimens it is likely that the flowering period would extend to January. Pods with mature seed have been collected from late October to late November and judging from these specimens it is likely that mature seed would also occur in December and possibly January. Although the flowering and fruiting periods coincide it is rare to find specimens with both flowers and mature pods (most specimens are either in flower or in fruit). From available information it is possible that it takes about a year from flowering for seed to mature, however, such a lengthy seed maturation period would be unusual for Acacia. The possibility also exists that an as-yet unrecorded flowering event occurs around mid-year (associated with winter rainfall), in which case the seed maturation time would be reduced to a few months. There are many arid zone Acacia species that flower opportunistically in response to both summer and winter rains. Conservation status. Acacia cockertoniana was formerly included on the Department of Environment and Conservation’s Declared Rare and Priority Flora List as a Priority Three species (Atkins 2006), however, it has recently been removed from the List because it is now known to be more common than first thought. Etymology. This new species is named for Geoff Cockerton (Managing Director, Landcare Holdings Pty Ltd) who first brought it to my attention and who facilitated my October 2004 visit to the Windarling Range to inspect plants in the field. Over the past decade Geoff and his staff have made a valuable contribution to science, and to the collections of the Western Australian Herbarium, by the information and specimens they have provided, especially of rangeland species of Acacia. Affinities. Because the heads of A. cockertoniana vary from globular to obloid it does not fit well into either Acacia sect. Juliflorae (Benth.) Maiden & Betche (phyllodes plurinerved, flowers in cylindrical spikes) or Acacia sect. Plurinerves (Benth.) Maiden & Betche (phyllodes plurinerved, flowers in globular heads). The new species appears to be most closely related to A. balsamea Cowan & Maslin (1999) on the basis of phyllode nervature and general floral and carpological features. Like A. cockertonia, A. balsamea has obloid heads, thus is not robustly placed in either Acacia sect. Juliflorae or Acacia sect. Plurinerves. Acacia balsamea is normally readily distinguished from A. cockertoniana by having terete phyllodes, however, a rare flat phyllode variant occurs in the Gibson Desert (Clutterbuck Hills, S.D. Hopper 2833, PERTH; specimen sterile) and Little Sandy Desert (Rudall River, R.P. Hort 993, PERTH; specimen in flower); over 1000 km to the north of where A. cockertoniana occurs. These plants are shrubs 1–3 m tall and while their phyllodes and branchlets are very similar to those of A. cockertoniana the flowering peduncles are 8–10 mm long and the sepals are linear-spathulate. Better material of this variant is needed to further investigate its relationship to A. cockertoniana. The closest known populations of typical A. balsamea to those of A. cockertoniana are at Leinster, c. 150 km due north-east of Lake Barlee. Acacia thoma Maslin (Western Australian Herbarium 1998–; Maslin & van Leeuwen in press) appears to have some affinities with A. cockertoniana but is readily distinguished by its cylindrical inflorescence spikes (10–25 mm long), sub-moniliform pods (i.e. clearly raised over and constricted between the seeds) and by its phyllode nerves, which are more numerous, narrower and not covered by an obvious, translucent layer of resin. Furthermore, A. thoma is a smaller shrub (mostly 2–3.5 m tall), its phyllodes normally dry a pale greyish green colour (dark green often with a yellowish brown tinge in A. cockertoniana) and it is distributed to the north and east of the geographic range of A. cockertoniana (Western Australian Herbarium 1998–; Maslin & van Leeuwen in press). In the Windarling Range area A. cockertoniana is sympatric with A. ramulosa W.V. Fitzg. 252 Nuytsia Vol. 17 (2007) var. ramulosa and grows in close proximity to A. coolgardiensis subsp. effusa R.S. Cowan & Maslin (but is not sympatric with it). Narrow phyllode forms of A. cockertoniana may superficially resemble either of these two taxa, which are distinguished by their terete pods (thick in A. ramulosa var. ramulosa and very narrow in A. coolgardiensis subsp. effusa) and their phyllode nerves, which are not covered with a translucent layer or resin. Acacia ramulosa is further recognized by its cylindrical flower spikes and A. coolgardiensis subsp. effusa by its normally sessile, obloid heads. Variation. The phyllode width varies to some extent. For example, on plants at Windarling Range the phyllodes are mostly 2–5 mm wide (only occasionally do a few reach 6 mm) but scattered throughout the populations are some plants with consistently very narrow phyllodes (1 mm wide). The reason for this variation is unknown. Also, judging from the relatively few collections at hand, the phyllodes on plants from the western extremity of the geographic range (i.e. Mt Magnet and northwards) are consistently narrower (2–3 mm wide) than elsewhere. An entity of uncertain taxonomic status, and known from only a few flowering specimens, occurs on banded ironstone ranges at Jack Hills, c. 200 km north of Mt Magnet. This entity appears to be related to A. cockertoniana on account of the general features of its phyllodes (especially nervature and colour) and flowers (especially the sepals), but it differs significantly from the new species in having elongated flowering spikes (1–2 cm long) and less resinous phyllodes. Fruiting material is needed to further investigate the taxonomic status of this entity. This entity has been provided with the informal name A. sp. Jack Hills (R. Meissner & Y. Caruso 4) and is represented at PERTH by the following specimens: A. Capobianco AC 658-11; R. Meissner & Y. Caruso 4, 5, 6 and 141. Acknowledgements Shapelle McNee (Landcare Holdings Pty Ltd) is thanked for her good company and sharing her knowledge of A. cockertoniana and other species during my October 2004 visit to Windarling Range. Portman Iron Ore Ltd is thanked for the provision of distribution data on the species, and for travel and accommodation associated with this field review at Windarling Range. Rachel Meissner and Yvette Caruso (Department of Environment and Conservation) are thanked for providing specimens and information regarding the Jack Hills variant. Paul Wilson is gratefully acknowledged for providing the Latin description and Carrie Buscumb for technical assistance. References Cowan, R.S. & Maslin, B.R. (1999). Acacia miscellany 17. Miscellaneous new taxa and lectotypifications in Western Australian Acacia, mostly section Plurinerves (Leguminosae: Mimosoideae). Nuytsia 12(3): 413–452. Maslin, B.R. & van Leeuwen, S. (in press). New taxa of Acacia (Leguminosae: Mimosoideae) and notes on other species from the Pilbara and adjacent desert regions of Western Australia. Nuytsia. Western Australian Herbarium (1998–). FloraBase – The Western Australian Flora. Department of Environment and Conservation. http://florabase.dec.wa.gov.au/ [accessed 16 August 2007] Western Botanical (2004). Flora and vegetation assessments, baseline data collection. (Consultants Report (WB 238) to Portman Iron Ore Ltd: Mundaring.) [This unpublished Report by Western Botanical involved flora and vegetation assessments at Windarling Range and Mt Jackson]