Caladenia dienema ListingCaladenia Statement for dienema (windswept spider-orchid)

windswept spider-orchid

T A S M A N I A N T H R E A T E N E D S P E C I E S L I S T I N G S T A T E M E N T

Image by Mark Wapstra

Scientific name: Caladenia dienema D.L. Jones, Austral. Orchid Res . 3: 28 (1998) Common name: windswept spider-orchid (Wapstra et al. 2005) Group: vascular plant, monocotyledon, family Orchidaceae Name history: Calonemorchis dienema (Szlachetko 2001), Arachnorchis dienema (Jones et al. 2001), see Hopper & Brown (2004)

Status: Threatened Species Protection Act 1995 : endangered Environment Protection and Biodiversity Conservation Act 1999 : Critically Endangered

Distribution: Endemic status: Endemic to Tasmania Tasmanian NRM Region: Cradle Coast

Figure 1. Distribution of Caladenia dienema Plate 1. Caladenia dienema (image by Mark Wapstra)

1 Threatened Species Section – Department of Primary Industries, Parks, Water and Environment

Listing Statement for Caladenia dienema (windswept spider-orchid)

IDENTIFICATION AND ECOLOGY appears to respond with prolific flowering in Caladenia dienema is a perennating herb the first few years after the fire event, especially belonging to the large-flowered section of the summer fires. genus Caladenia , sometimes included in the genus Arachnorchis literally meaning “spider- Survey techniques orchid” (Jones et al. 2001). Spider-orchids The flowers are used to identify Caladenia generally have large flowers with long tapered dienema. The flowering period was thought to or filamentous segments. They are often consistently be late October to early November pollinated by male thynnine wasps that attempt (Wapstra et al. 2008), the consistency probably to mate with the labellum. The wasps are due to the relatively consistent west coast attracted by scents resembling pheromones of climate. However, more recent surveys (e.g. the female wasps. These scents are produced in ECO tas 2009) reported flowering in mid glands on the flowers. September suggesting that October may be the All Caladenia species are deciduous and die back most suitable time for survey, depending on after flowering to small subterranean tubers seasonal conditions and time since a enclosed by a fibrous sheath or tunic. Plants disturbance event that promotes flowering. have a single narrow basal leaf that appears above ground in late autumn or early winter Description following rains. The flowers have a labellum Caladenia dienema plants are 5 to 16 cm tall, (lip) which is hinged at the base and bears rows occasionally taller in denser undergrowth. They of conspicuous, variously shaped and coloured have a wiry and densely hairy stem bearing calli on the upper surface. The labellum 1 to 2 flowers. The leaf is narrowly lanceolate, margins often also bear calli or may be deeply densely hairy, with a purple-blotched base, and lobed or toothed. Members of this genus have is 4 to 9 cm long and 3 to 7 mm wide. Flowers hairs on most above-ground organs. are about 60 to 90 mm across. They are variably coloured including shades of yellow (including Caladenia dienema reproduces from seed in almost white forms), red (from pale reds to association with mycorrhizal fungi. Plants may deep reds) and purple, with darker red lines and not flower every year, though when they do, black caudae on all segments. The labellum is they flower for a short period of the year (in the wholly maroon, or white to cream, usually with order of weeks) before being fertilised and a maroon apex, the calli dark reddish purple. withering. Above-ground parts are perhaps The perianth segments are oblong-lanceolate to detectable for 1 to 3 months and may be obovate-lanceolate in the basal quarter to half, destroyed by grazing (by native marsupials, or and then tapered. The sepals are 40 to 60 mm stock, if present), drought-stress (in periods of long and 3.5 mm wide. The dorsal (upper) sepal extreme drought only) and fire (wildfire). Even is held erect and the lateral (lowermost) sepals so, plants can survive into subsequent years are divergent, and stiffly obliquely deflexed to because of the presence of underground tubers drooping. The petals are 35 to 60 mm long and (Jones et al. 1999). However, tubers may wither 4 mm wide, obliquely deflexed to drooping. and die if conditions remain unsuitable for The labellum is ovate-lanceolate, 13 to 20 mm successive years and plants are unable to long and 7 to 11 mm wide, with lateral lobes emerge and replenish their tubers, for example, held erect with 13 to 18 pairs of linear, white- if the vegetation becomes overgrown or during tipped marginal teeth to 2 mm long. The mid- periods of prolonged drought. lobe of the labellum is triangular with very The response of species of Caladenia to fire short, blunt marginal teeth, these becoming varies but most species respond vigorously to fused towards the apex. The lamina calli are in high intensity fires during the preceding 4 to 6 rows extending to the base of the mid- summer (Jones et al. 1999). The habitat of lobe. The column is translucent with reddish Caladenia dienema is fire-prone and subject to markings, 12 to 14 mm long and 6.5 mm wide, relatively frequent fires to which the species with 2 ovoid-obovoid yellow basal glands. 2 Threatened Species Section – Department of Primary Industries, Parks, Water and Environment

Listing Statement for Caladenia dienema (windswept spider-orchid)

[description from Jones 1998, Jones 2006, range of the species is about 104 km, extent of Jones et al. 1999. Note that the original occurrence about 3582 km 2 and area of description of the species indicated that flowers occupancy of less than 10 ha. Excluding the were solitary but recent surveys detected historical sites at Rocky Cape and east of numerous 2-flowered individuals.] Stanley, from where the species has not been recorded for several decades, the linear range is 2 Confusing species 90 km and the extent of occurrence 345 km . Caladenia dienema is part of the confusing Caladenia dienema occurs in windswept low Caladenia patersonii species-complex. It is most heathland among dwarfed shrubs and sedges similar to Caladenia patersonii with which it on moist to well-drained sandy and clay loam allegedly co-occurs and has undoubtedly been (Jones et al. 1999). Rocky outcrops and rocky confused with in the past (Jones 1998). open heathy woodland are strongly associated Caladenia dienema can be distinguished by its with many occurrences of the species (ECO tas short sturdy habit, dark usually reddish flowers, 2009) but it can extend into shrubby forests, drooping perianth segments, and thick, densely usually dominated by Eucalyptus obliqua . glandular blackish tepalline caudae (Jones 1998). The similar Caladenia anthracina has small POPULATION ESTIMATE flowers (45 to 65 mm across) and stiffly spreading segments with slender caudae (Jones The total population of Caladenia dienema is 1998), and occurs in different habitat in a estimated at fewer than 250 mature individuals. different part of the State, being restricted to Most subpopulations are represented by fewer grassy woodland in the Midlands (Jones et al. than 20 mature individuals, which usually occur 1999). The historical records of Caladenia as scattered plants over a relatively small area. caudata from the Arthur-Pieman and Rocky Locally high numbers at some sites in certain Cape areas probably represent Caladenia dienema , years (e.g. over 100 plants in the Rebecca Creek indicative of a similarity between the species. area in 2008) suggests some fluctuations in the total population size, although estimates of the total population in any one year have never exceeded 250.

While the species appears to have a naturally patchy distribution along the State’s west coast, the presence of about 16 subpopulations spread over about 90 km, and its historical recording from the north coast, indicates a potentially much wider distribution including the whole of the northwestern tip of the State. Potential habitat (i.e. coastal heathland within 1 km of the coastline) is widespread on the west coast (Harris & Kitchener 2005), although much of Plate 2. Typical habitat of Caladenia dienema near the coastline remains inaccessible. There is less Rebecca Lagoon, showing rock exposures amongst wind-pruned coastal scrub (image by Mark Wapstra) potential habitat remaining on the north coast primarily due to agricultural clearing and urban development. The record of the species from DISTRIBUTION AND HABITAT the Conical Rocks Point area (about 54 km Caladenia dienema is endemic to northwestern south of the next nearest record), a relatively and western Tasmania, occurring in a near- infrequently visited area, raises the possibility coastal lowland strip from Pieman Heads to that more colonies remain to be found. near Rocky Cape (Jones et al. 1999), although However, despite this possibility, several the core part of its range is in the Temma to targeted surveys have failed to significantly alter Marrawah region (Figure 1, Table 1). The linear the range of the species.

3 Threatened Species Section – Department of Primary Industries, Parks, Water and Environment

Listing Statement for Caladenia dienema (windswept spider-orchid)

Table 1. Population summary for Caladenia dienema

Subpopulation Tenure NRM 1:25 000 Year last Area of Number of region mapsheet (first) occupancy plants seen (ha) 1 Green Point private property Cradle Marrawah 2001 unknown “locally Coast frequent” 2 Nettley Bay West Point State Cradle Marrawah 1994 unknown unknown Reserve Coast 3 West Point Road West Point State Cradle Marrawah 2008 each patch 30–50 Reserve, Coast (1988) about 0.1 ha Arthur-Pieman (over 25 ha) Conservation Area 4 South Downs Arthur-Pieman Cradle Marrawah 1995 unknown unknown Conservation Area, Coast Crown land 5 Black Bull Scrub Arthur-Pieman Cradle Marrawah 1997 0.01 (1994) 2 (1994) Conservation Area, Coast (1982) Crown land 6 Near Callaghans Arthur-Pieman Cradle Bluff 2009 each patch “several” Scrub, Bluff Hill Road Conservation Area, Coast (1997) about 0.1 ha (2009) junction Crown land (over 11 ha) 2 (2008) 7 Bluff Hill, 1 km east Arthur-Pieman Cradle Bluff 2008 each patch 3 Conservation Area Coast <0.001 ha (over 0.5 ha) 8 Temma Road near Arthur-Pieman Cradle Bluff 2008 7 Alert Creek Conservation Area Coast 9 Bottle Creek – Bottle Arthur-Pieman Cradle Sundown 2008 6 sites over c. <10 Flat – Little Sundown Conservation Area Coast (1988) 72 ha but River each patch <0.1 ha 10 Nelson River area Arthur-Pieman Cradle Sundown 2008 4 sites <20 Conservation Area Coast (1989) 0.02 11 Temma Road near Arthur-Pieman Cradle Temma 2010 3 sites 15 Heemskirk and Couta Conservation Area Coast (2007) Rocks Road 12 Heemskirk Road Arthur-Pieman Cradle Temma 1994 unknown unknown Conservation Area Coast (1990) 13 Rebecca Creek area Arthur-Pieman Cradle Temma 2009 35 records 100+ (2008) Conservation Area Coast (1988) over 36 ha, each patch <0.1 ha 14 Temma unallocated Crown Cradle Temma 1982 unknown unknown land Coast 15 Behind Conical Rocks unallocated Crown Cradle Hardwicke 1983 unknown unknown Point land Coast 16 Between Detention unknown Cradle Rocky 1841 unknown unknown and Black River Coast Cape 17 1 Rocky Cape unknown Cradle Rocky 1974 unknown unknown Coast Cape

1 This subpopulation was originally recorded as Caladenia caudata but has been re-determined as more likely to be Caladenia dienema , based on the distribution of the two species

4 Threatened Species Section – Department of Primary Industries, Parks, Water and Environment

Listing Statement for Caladenia dienema (windswept spider-orchid)

RESERVATION STATUS the Arthur-Pieman Conservation Area. A Caladenia dienema occurs within the West Point management plan for the conservation area State Reserve, the Arthur-Pieman Conservation (PWS 2002) identifies the potential for various Area, and on parcels of Crown land commercial and recreational activities to either recommended as reserves (CLAC 2005). The continue or be further developed. These unconfirmed Rocky Cape record is possibly include wind electricity generation, mineral from within Rocky Cape National Park. prospecting and camping. Similar commercial activities are also likely to be undertaken in the vicinity of subpopulations outside the Arthur- CONSERVATION STATUS Pieman Conservation Area. Without Caladenia dienema was originally listed in 2001 as appropriate mitigation measures, any of these vulnerable on schedules of the Tasmanian activities have the potential to impact on Threatened Species Protection Act 1995 . It was up- subpopulations at a localised scale. listed to endangered in early 2008, meeting the Inappropriate fire regime: Most sites following criteria: (C) total population supporting the species have been subject to estimated to number fewer than 2,500 mature summer wildfires and/or controlled fuel individuals with no subpopulation with more reduction burns suggesting that Caladenia than 250 individuals, and a continuing decline dienema responds to fire and the species appears inferred in the area, extent and/or quality of to flower in greater abundance at sites subject habitat; and (D) total population estimated to to higher intensity summer fires (ECO tas 2009). number fewer than 250 mature individuals. The often low subpopulation numbers (generally scattered individuals) may be THREATS, LIMITING FACTORS AND indicative of an inappropriate fire regime, MANAGEMENT ISSUES which may become a problem within the Historically, the key threat to Caladenia dienema Arthur-Pieman Conservation Area as fire is has probably been clearance of habitat in the being used less frequently as a management near-coastal parts of the west and northwest tool. The more controlled broadscale ecological coasts. More recently, the key threat is likely to burns conducted in autumn may be unsuitable be an inappropriate disturbance regime, in for maintaining ideal conditions for Caladenia particular an inappropriate fire regime, resulting dienema . The species does occur in sites that are in changes to vegetation supporting the species. long unburnt suggesting that fire is not critical Specific threats to some sites cannot be for the species, though in less exposed sites, the ascertained due to imprecise locality details. species may become extinct due to atrophy of the tubers if the vegetation is allowed to thicken Land clearance: Much of the coastal and remain undisturbed for many years. heathland habitat of Caladenia dienema on the Recreational activities: Many subpopulations north coast of mainland Tasmania has been lie within the Arthur-Pieman Conservation destroyed or degraded by agricultural and Area. A management plan for the conservation coastal development. Land clearing for pasture area (PWS 2002) identifies the potential for development on private property in the various recreational activities to either continue northwest, where undiscovered subpopulations or be further developed. These include may occur, is an ongoing threat. Few sites on camping, horse riding, recreational driving, private property are known, possibly reflecting hunting, angling and bushwalking. Similar survey bias rather than genuine absence. The recreational activities are also likely to be Temma subpopulation, now possibly extinct, is undertaken in the vicinity of subpopulations known from a single imprecise 1982 record that outside the Arthur-Pieman Conservation Area. falls within an area now excluded from the If not appropriately managed, any of these Arthur-Pieman Conservation Area because of activities have the potential to impact on the presence of private shacks (PWS 2002). subpopulations at a localised scale. Development on public land: Many Cattle agistment: The Arthur-Pieman subpopulations of Caladenia dienema are within Conservation Area is subject to cattle grazing 5 Threatened Species Section – Department of Primary Industries, Parks, Water and Environment

Listing Statement for Caladenia dienema (windswept spider-orchid)

(through agistment licences). This activity has assessed in November 2007 with 7 new sites the potential to impact on subpopulations at a detected. Potential habitat in the southern part local scale through direct grazing, trampling, of the Arthur-Pieman Conservation Area to the damage to the soil and plants from vehicles, mouth of the Pieman River was assessed (when enrichment of the soil from cow pats assessing 4 wheel drive tracks) during (disrupting mycorrhizal fungal associations) and November 2006, though no plants were possible shifting of the understorey to include detected. The species has also been surveyed competitive weeds and pasture grasses. This is informally by orchid enthusiasts, resulting in especially prevalent in the subpopulation minor range extensions, infillings and a better immediately south of Rebecca Creek bridge understanding of the impact of controlled near a cattle loading yard where there has been burning. damage by trampling and tractors. Management planning: The management Phytophthora cinnamomi : No plan for the Arthur-Pieman Conservation Area subpopulations of Caladenia dienema are (PWS 2002) specifically identified the need for currently affected by Phytophthora cinnamomi and ecological burning to manage biological values. there are no records of directs effects of the A subsequent fire management plan (PWS pathogen on orchids. However, activities at 2003) identifies several ecological burn units, some sites, especially recreational activities such several of which include subpopulations of as 4 wheel driving within the Arthur-Pieman Caladenia dienema . Conservation Area, have the potential to introduce and/or spread the pathogen further Management objectives through the conservation area (PWS 2000). The main objectives for the management of This may affect the species indirectly through Caladenia dienema are to maintain the viability of modification of habitat, especially the known subpopulations, to promote conditions understorey. for its successful recruitment and to increase Stochastic risk: With fewer than 250 mature the known distribution and population size individuals from fewer than 20 subpopulations through survey. and most individuals in 3 subpopulations, as well as a naturally patchy distribution, the What is needed? species is in consequence considered to be at risk from extinction due to chance events. • undertake extension surveys, especially in the 54 km gap in contemporary distribution MANAGEMENT STRATEGY between Conical Rocks Point and Temma, and the historical distribution area from What has been done? Marrawah to the Rocky Cape area; Recovery planning: Caladenia dienema was • monitor selected subpopulations to included in the Flora Recovery Plan: Tasmanian determine the response of the species to Threatened Orchids 2006–2010 (TSU 2006) with a ecological burns and unplanned wildfires; high priority for further survey effort, baseline • implement the fire management plan for surveys for important subpopulations and site the Arthur-Pieman Conservation Area management guidelines noted. (PWS 2003) and use the results from Targeted surveys and monitoring: Extension demographic monitoring to inform any surveys were undertaken in October/ revision of the plan; November 2008 between Marrawah and • support the Private Land Conservation Temma, mainly on public land (ECO tas 2009), Program (DPIPWE) with the establishment resulting in minor range infillings. The area of conservation covenants for private land around the Conical Rocks Point subpopulation supporting Caladenia dienema , and ensure was assessed in November 2008, with no plants that current priorities for the species are detected. Potential habitat in the northern part incorporated into the program’s reservation of the Arthur-Pieman Conservation Area was strategies; 6 Threatened Species Section – Department of Primary Industries, Parks, Water and Environment

Listing Statement for Caladenia dienema (windswept spider-orchid)

• provide information and extension support PWS (Parks and Wildlife Service) (2002). to relevant Natural Resource Management Arthur-Pieman Conservation Area: Management committees, local councils, government Plan . Parks and Wildlife Service, Hobart. agencies, the local community and PWS (Parks and Wildlife Service) (2003). development proponents on the locality, Arthur-Pieman Conservation Area: Fire significance and management of known Management Plan . Parks and Wildlife Service, subpopulations and potential habitat; Hobart. • implement the threatened orchid recovery Szlachetko, D.L. (2001). Nomenclatural plan (TSU 2006) and include the species in adjustments in the Thelymitroideae any revision of the plan. (Orchidaceae). Polish Botanical Journal 46(2): 137 −144. BIBLIOGRAPHY TSU (Threatened Species Unit) (2006). Flora CLAC (CLAC Project Team) (2005). Crown Recovery Plan: Threatened Tasmanian Orchids Land Assessment and Classification Project 2006–2010. Department of Primary Consultation Report and Recommended Allocations Industries and Water, Hobart. for the Municipality of West Coast . Department Wapstra, M., Roberts, N., Wapstra, H. & of Primary Industries, Water and Wapstra, A. (2008). Flowering Times of Environment, Hobart. Tasmanian Orchids: A Practical Guide for Field ECO tas (Environmental Consulting Options Botanists . Self-published by the authors (April Tasmania) (2009). Extension Surveys for 2008 version). Threatened Flora in the Arthur-Pieman Wapstra, H., Wapstra, A., Wapstra, M. & Conservation Area. A Report to the Gilfedder, L. (2005). The Little Book of Threatened Species Section (Department of Common Names for Tasmanian Plants . Primary Industries & Water). Department of Primary Industries, Water Harris, S. & Kitchener, A. (editors) (2005). From and Environment, Hobart. Forest to Fjaeldmark: Descriptions of Tasmania’s Vegetation . Department of Primary Prepared in 2001 under the provisions of the Industries, Water and Environment, Hobart. Tasmanian Threatened Species Protection Act 1995. Hopper, S.D. & Brown, A.P. (2004). Robert This revision prepared in June 2010 and Brown’s Caladenia revisited, including a published in November 2010. revision of its sister genera Cyanicula , Cite as: Threatened Species Section (2010). Ericksonella and Pheladenia (Caladeniiae: Listing Statement for Caladenia dienema (windswept Orchidaceae). Australian Systematic Botany 17: spider-orchid). Department of Primary Industries, 171 −240. Parks, Water and Environment, Tasmania. Jones, D.L. (1998). A taxonomic review of View: Caladenia in Tasmania. Australian Orchid www.dpipwe.tas.gov.au/threatenedspecieslists Research 3: 16 −60. Contact details: Threatened Species Section, Jones, D. (2006). A Complete Guide to Native Department of Primary Industries, Parks, Orchids of Australia including the Island Water and Environment, GPO Box 44, Hobart, Territories. New Holland Publishers Tasmania, Australia, 7001. Phone (03) 6233 (Australia), Sydney. 6556; fax (03) 6233 3477. Jones, D.L., Clements, M.A., Sharma, I.K. & Permit: It is an offence to collect, disturb, Mackenzie, A.M. (2001). A new damage or destroy this species unless under classification of Caladenia R.Br. permit. (Orchidaceae). The Orchadian 13(9): 389 −419. Jones, D., Wapstra, H., Tonelli, P. & Harris, S. (1999). The Orchids of Tasmania . Melbourne University Press, Carlton South, Victoria. 7 Threatened Species Section – Department of Primary Industries, Parks, Water and Environment