Biodiversity

Species Profile and Threats Database


For information to assist proponents in referral, environmental assessments and compliance issues, refer to the Policy Statements and Guidelines (where available), the Conservation Advice (where available) or the Listing Advice (where available).
 
In addition, proponents and land managers should refer to the Recovery Plan (where available) or the Conservation Advice (where available) for recovery, mitigation and conservation information.

EPBC Act Listing Status Listed as Endangered as Caladenia tensa
Recovery Plan Decision Recovery Plan required, this species had a recovery plan in force at the time the legislation provided for the Minister to decide whether or not to have a recovery plan (19/2/2007).
 
Adopted/Made Recovery Plans Recovery Plan for twelve threatened spider orchids Caladenia R. Br. Taxa of Vic and SA - 2000-2004 (Todd, J.A., 2000) [Recovery Plan] as Caladenia tensa.
 
Policy Statements and Guidelines Draft survey guidelines for Australia's threatened orchids (Department of the Environment, 2013b) [Admin Guideline].
 
Federal Register of
    Legislative Instruments
Declaration under s178, s181, and s183 of the Environment Protection and Biodiversity Conservation Act 1999 - List of threatened species, List of threatened ecological communities and List of threatening processes (Commonwealth of Australia, 2000) [Legislative Instrument] as Caladenia tensa.
 
State Government
    Documents and Websites
VIC:Flora and Fauna Guarantee Action Statement 103 - Twelve threatened Spider-orchids Caladenia species (Todd, J., 2004) [State Recovery Plan].
Non-statutory Listing Status
VIC: Listed as Vulnerable (Advisory List of Rare or Threatened Plants in Victoria: 2005)
Scientific name Caladenia tensa [24390]
Family Orchidaceae:Orchidales:Liliopsida:Magnoliophyta:Plantae
Species author G.W.Carr
Infraspecies author  
Reference Indig. Flora & Fauna Assoc. Misc. Pap. 1: 15 (1991).
Other names Arachnorchis tensa [76206]
Distribution map Species Distribution Map

This is an indicative distribution map of the present distribution of the species based on best available knowledge. See map caveat for more information.

Illustrations Google Images

Scientific Name: Caladenia tensa

Common Name: Greencomb Spider-orchid

Other Names: Rigid Spider-orchid, Common Comb Spider-orchid (Bates 2009).

The Greencomb Spider-orchid has been misapplied to Caladenia interanea by Barker & Bates (2008). In 2001, the genus Caladenia was reviewed (Jones et al. 2001). Caladenia tensa is now known by some botanists as Arachnorchis tensa. This species may be more widespread and common than current records suggest due to the incorrect identification of some specimens as the closely related Caladenia tentaculata (Jeanes 2001 pers. comm.). This species is part of the Caladenia dilatata complex and was previously included under that name (Bates 2009; Todd 2000).

There is some taxonomic confusion in South Australia relating to C. tensa and C. clavula (Peter Lang pers. comm. In Todd 2000). At present, these two taxa are listed as one entity in South Australia, although herbarium records adequately differentiate between the two species on taxonomic and distributional grounds (Bates pers. comm. In Todd 2000).

The Greencomb Spider-orchid is a perennial orchid growing to 30 cm in height when flowering. Its flowers are usually single, 5 cm across and perianth segments are green with crimson median stripes. Sepals of the species are dull yellow in colour with indistinct osmophores and grow to 1 cm in length. The top sepal is erect over the column, and the lateral sepals project forward and down. Petals are shorter and spread behind the flower. The labellum is pale yellowish to white, trilobed, with a maroon tip and 4 rows of uncrowded, stalked, clubbed red calli. The lateral lobes are not extensive, with a long green fringe basally and marginal teeth on the shorter, paler midlobe (Backhouse & Jeanes 1995; Bates 2009). 

Historically, the Greencomb Spider-orchid was widespread on aeolian sand deposits surrounding, and including, the Little Desert in western Victoria and south-east South Australia. The species was found within the areas of the Murray-Darling Depression bioregion and generally associated with 300–400 mm annual rainfall areas (Todd 2000).

In the early 1990s, the species was considered to be confined to western Victoria: in the Murray Mallee, Lowan Mallee and Wimmera Natural Regions (Conn 1993). The orchid has been recorded at: Little Desert Camping Ground; Little Desert - Tallageira Track; Little Desert - Plains Track; and Little Desert - 800 m east of Chinaman Flat (Cross 1995). Todd (2000) described the Victorian distribution as being widespread in, and surrounding, the Little Desert in western Victoria.

The species is also known from eastern (Bates & Weber 1990) and south-east South Australia (SA) where it is considered widespread but uncommon (Bates pers. comm. cited in Todd 2000). Site examples include Telowie Gorge, Murray Bridge and Mt Boothby Conservation Park (CP). Bates (2009) considers this species to be widespread in SA from the west coast, throughout Eyre Peninsula and adjacent pastoral zone, the Flinders Ranges, rare in the Mt Lofty Ranges and more common in the Murray and upper south-east. However, the species does not extend to high rainfall districts and is absent from the Adelaide Hills.

Collections at the National Herbarium of Melbourne come from Telowie Gorge, Murray Bridge, St Marys Peak Flinders Ranges, Wood Wood, Broughtons Waterhole, Little Desert National Park (NP), West Wail Forest & Forest Reserve, Kiata and Barrabool State Forest (SF) (MEL collection records). In SA, there are at least 25 sites where this species has been recorded in recent years and many of these are in conservation reserves (DEH 2001b).

Monitoring transects were established in the Spring of 1999 for the Greencomb Spider-orchid. Data was collected on species' abundance and distribution, flowering, rates of pollination and fruit production. Additional information on habitat preferences and identified threats was also collected (Todd 2000).

Both Victoria and SA are thought to have thousands of plants (Todd 2000, 2004) with the species being locally abundant in suitable habitat in western Victoria and eastern SA (Todd 2000). The largest known population, containing many hundreds of plants, is in the Kiata Flora Reserve where a monitoring site approximately 100 m x 20 m was set up in 1999. Approximately 150 flowering plants were counted and tagged (Jeanes 2001 pers. comm.).


Approximately 5–10 Greencomb Spider-orchid sites are known to contain plants occurring on a reserve area. However, it is unknown how many sites and plants occur in areas that are not reserved for conservation (Todd 2000, 2004).

The following is a table of key populations for the conservation of Greencomb Spider-orchid (Todd 2000).

Population Land Tenure Land Management Agency
Kiata Flora Reserve, Kiata  Public  Parks Victoria
West Wail Flora and Fauna Reserve, West Wail  Public  Parks Victoria
Barabool Flora and Fauna Reserve, Murtoa  Public  Parks Victoria
Red Gum Walk, Lt. Desert National Park  Public  Parks Victoria
Broken Bucket Campsite, Big Desert National Park  Public  Parks Victoria
Camp Ground, Red Gum Track, Lt Desert National Park  Public  Parks Victoria

 

The Greencomb Spider-orchid has a very high proportion (>75-80%) of its total population represented within conservation reserves (Todd 2000, 2004).

The orchid is reserved in Victoria within Little Desert NP, Kiata Flora Reserve (FR) and the West Wail FR (Todd 2000, 2004).

The species is reserved in SA within Cape Gantheaume CP, Billiat CP and Mt Boothby CP (Todd 2000).

The Greencomb Spider-orchid grows on red-brown sandy loams on rises in open woodland dominated by Yellow Gum (Eucalyptus leucoxylon sens. lat.) and Rottnest Island Pine (Callitris preissii). Its habitat, between the Little Desert and Big Desert, was formerly expansive and extended into SA (Carr 1991). This species has also been recorded from Black Box (Eucalyptus largiflorens)/Yellow Gum woodland and mallee/heathland (MEL collection records).

More recently, the various habitats for the species has been described, including dry Cypress-pine (family Cupressaceae)/Yellow Gum Woodland, Pine/Box woodland, mallee-heath sites, heathy woodland and mallee woodland, generally with rock outcrops (Bates 2009; Todd 2000).

The Greencomb Spider-orchid's non-biological habitat has been described as Quaternary loamy dunes of Aeolian origin (Carr 1991), sands and sandy loams derived from Aeolian sand deposits (Todd 2000), clay loam or sandy loam soils (MEL collection records) and rock outcrops (Bates 2009).

Flowering in the species is reported to occur from late August–October (Bates 2009), September–November (Backhouse & Jeanes 1995) and September–October (Todd 2000). The Greencomb Spider-orchid has one flower (rarely two) and fruits in October–November (Todd 2000).

Reproduction is entirely from seed (usually ripe and dispersed 4–8 weeks after pollination). Plants produce a single replacement tuber each year, and may be capable of maintaining themselves in this way for many years. Seed capsules, resulting from natural pollination, have been observed in the wild (Jeanes 2001 pers. comm.). Currently, little is known about the effects of fire on this species or its mycorrhizal relationships.

The exact vector of the species has not yet been determined, however most forms so far studied have been pollinated by the Slender Black Thynnid (Thynnoides sp. aff. gracilis) with yellow mandibles. Kangaroo Island plants are pollinated by a similar wasp without the yellow mandibles and may represent a separate taxon (Bates 2009).

Similar Victorian taxa include C. dilatata and C. tentaculata. The Greencomb Spider-orchid can be identified by means of its moderately large flower on a short, thick scape; rigid perianth segments; short sepaline osmophores on sepals; and sparse laminar calli on the labellum (Backhouse & Jeanes 1995).

The Greencomb Spider-orchid is separated from other taxa by a combination of its dull green colour; not very hairy leaf; rigid, straight segments with dull osmophores on sepals only; and a broad, white based labellum with long marginal fringe restricted to lower portion and uncrowded calli. Similar species include C. parva, C. phaeoclavia, C. verrucosa, C. tentaculata and C. interanea. Hybrids have been recorded with many members of the Caladenia patersonii complex i.e. C. colorata, C. brumalis, C. woolcockiorum, C. verrucosa and C. toxochila (Bates 2009).

Habitat destruction is the major threat to the species as it occupies broad riverine plains habitats (of central and western Victoria) on reasonably fertile soils. These habitats have been cleared for agricultural production over large parts of the species' range. Extant populations tend to occupy fragmented forests and woodlands within predominantly agricultural landscapes. It is this fragmentation, and the associated degradation, that represent the greatest threat to the long-term conservation of this species (Todd 2004).

The remaining populations are threatened by weed invasions, browsing by introduced and native herbivores (for example kangaroos (Macropus spp.) and the Rabbit (Oryctolagus cuniculus)) and human interference (Backhouse & Jeanes 1995). One site is threatened by the invasion of Perennial Veldt Grass (Ehrharta calycina) (Jeanes 2001 pers. comm.; Todd 2000).

Recommended recovery actions (Todd 2000, 2004) include:

  • Identify and survey potential habitat in the Murray Darling Depression Bioregion for new populations and accurately determine plant numbers within known populations.
  • Identify key populations in Victoria and SA.
  • Control high-priority weed species at key population sites through use of broad-scale habitat management techniques and targeted control of high-risk species (eg. Perennial Veldt Grass).
  • Control animal pests and predators at key populations sites using suitably designed fences or targeted pest animal control techniques.
  • Collect Vital Attribute Data following planned fires to determine appropriate fire regimes for the species' habitat and prepare a fire management plan for key populations. Ensure that protection of key populations forms an integral part of park management plans.
  • Conduct annual censusing of populations.
  • Identify pollinator and determine natural pollination levels.
  • Determine genetic relationship of Victorian and South Australian populations.
  • Isolate and culture the mycorrhizal fungus.
  • Prepare education material and undertake community extension.
  • Establish a regional Caladenia tensa Recovery Team.
  • Prepare Victorian Flora and Fauna Guarantee Act 1988 (FFG) Action Statement for the Greencomb Spider-orchid.

Conservation actions undertaken (Todd 2000, 2004) include:

  • Population monitoring.
  • Preliminary surveys of potential habitat in Victoria.
  • Hand pollinating of plants at West Wail in 1994.

Responsible agencies/organisations (Todd 2000, 2004) include:

Department of Natural Resources and Environment, Victoria - Parks Flora and Fauna, Department of National Resources and Environment - Port Phillip Region; Mornington Peninsula Shire Council; Friends Group; Royal Botanic Gardens, Melbourne; Department of Environment and Heritage, South Australia

On-ground works (Todd 2000) include:

Populations of the Greencomb Spider-orchid within the Kiata Flora Reserve have benefited from activities by the Gerang Landcare Group (Friends of Kiata Flora Reserve) which has erected rabbit-proof guards for C. lowanensis, removed woody weeds, repaired an existing internal fence and removed hard rubbish from the area. They have also been involved in a joint exercise with Parks Victoria to control Rabbits in the reserve through warren identification and fumigation. The Friends group has received funding from Parks Victoria to construct a rabbit-proof boundary fence around the reserve and this is expected to be completed by mid-2000. This does not appear to have been completed.

On-ground works at sites containing populations of Greencomb Spider-orchid include:

Population On-ground works Start date
Kiata Caging, monitoring 1998
West Wail Hand-pollination, seed collection, fencing 1994–1998

 

Threat abatement documents for the Greencomb Spider-orchid include:

  • Flora and Fauna Guarantee Action Statement 103 - Twelve threatened Spider-orchids Caladenia species (Todd 2004).
  • National Recovery Plan for twelve threatened spider orchids Caladenia R. Br. Taxa of Vic and SA - 2000-2004 (Todd 2000).

The following table lists known and perceived threats to this species. Threats are based on the International Union for Conservation of Nature and Natural Resources (IUCN) threat classification version 1.1.

Threat Class Threatening Species References
Biological Resource Use:Logging and Wood Harvesting:Habitat loss, modification and degradation due to firewood collection Recovery Plan for twelve threatened spider orchids Caladenia R. Br. Taxa of Vic and SA - 2000-2004 (Todd, J.A., 2000) [Recovery Plan].
Human Intrusions and Disturbance:Recreational Activities:Habitat disturbance from recreational vehicle use Recovery Plan for twelve threatened spider orchids Caladenia R. Br. Taxa of Vic and SA - 2000-2004 (Todd, J.A., 2000) [Recovery Plan].
Invasive and Other Problematic Species and Genes:Invasive Non-Native/Alien Species:Competition and/or habitat degradation Oryctolagus cuniculus (Rabbit, European Rabbit) Recovery Plan for twelve threatened spider orchids Caladenia R. Br. Taxa of Vic and SA - 2000-2004 (Todd, J.A., 2000) [Recovery Plan].
Invasive and Other Problematic Species and Genes:Invasive Non-Native/Alien Species:Competition and/or habitat degradation Ehrharta erecta (Panic Veldtgrass) Recovery Plan for twelve threatened spider orchids Caladenia R. Br. Taxa of Vic and SA - 2000-2004 (Todd, J.A., 2000) [Recovery Plan].
Invasive and Other Problematic Species and Genes:Invasive Non-Native/Alien Species:Competition and/or habitat degradation caused by marine invertebrates Recovery Plan for twelve threatened spider orchids Caladenia R. Br. Taxa of Vic and SA - 2000-2004 (Todd, J.A., 2000) [Recovery Plan].
Invasive and Other Problematic Species and Genes:Problematic Native Species:Competition, predation and/or habitat degradation by kangaroos and wallabies Recovery Plan for twelve threatened spider orchids Caladenia R. Br. Taxa of Vic and SA - 2000-2004 (Todd, J.A., 2000) [Recovery Plan].
Natural System Modifications:Fire and Fire Suppression:Inappropriate and/or changed fire regimes (frequency, timing, intensity) Recovery Plan for twelve threatened spider orchids Caladenia R. Br. Taxa of Vic and SA - 2000-2004 (Todd, J.A., 2000) [Recovery Plan].
Species Stresses:Indirect Species Effects:Low numbers of individuals Recovery Plan for twelve threatened spider orchids Caladenia R. Br. Taxa of Vic and SA - 2000-2004 (Todd, J.A., 2000) [Recovery Plan].

Backhouse, G.N. & J.A. Jeanes (1995). The Orchids of Victoria. Carlton: Miegunyah Press, Melbourne University Press.

Barker, R.M. & R.J. Bates (2008). New combinations in Pterostylis and Caladenia and other name changes in the Orchidaceae of South Australia. Journal of the Adelaide Botanic Gardens. 22:102.

Bates, R. (2009). South Australian Native Orchids. Compact Disc. Adelaide: Native Orchid Society of South Australia.

Bates, R.J. & J.Z. Weber (1990). Orchids of South Australia. Adelaide: Flora and Fauna of South Australia Handbooks Committee.

Carr, G.W. (1991). New taxa in Caladenia R.Br., Chiloglottis R.Br. and Gastrodia R.Br. (Orchidaceae) from south eastern Australia. Indigenous Flora & Fauna Association Miscellaneous Papers. 1. Melbourne: Indigenous Flora & Fauna Association.

Conn, B.J. (1993). Natural Regions and Vegetation of Victoria. In: Foreman, D.B. and N.G. Walsh, eds. Flora of Victoria: Volume One. Page(s) 79-153. Melbourne: Inkata Press.

Cross, R. (1995). Caladenia Sect. Calonema survey and ex situ conservation. Canberra, Australian Nature Conservation Agency.

DEH (2001b). Biological Survey Database. [Online]. Available from: http://www.environment.sa.gov.au/Knowledge_Bank/Information_and_data/Biological_Survey_of_South_Australia.

Jeanes, J. (2001). Personal communication.

Jones, D.L., M.A. Clements, I.K. Sharma & A.M. McKenzie (2001). A new classification of Caladenia R.Br. (Orchidaceae). The Orchadian. 13(9):389-417.

MEL (collection records) (undated). National Herbarium of Victoria Specimens. [Online]. Available from: http://www.rbg.vic.gov.au/research_and_conservation/herbarium.

Todd, J. (2004). Flora and Fauna Guarantee Action Statement 103 - Twelve threatened Spider-orchids Caladenia species. [Online]. Victorian Department of Sustainability and Environment, Melbourne. Available from: http://www.dse.vic.gov.au/plants-and-animals/flora-and-fauna-guarantee-act-action-statements-index-of-approved-action-statements.

Todd, J.A. (2000). Recovery Plan for twelve threatened spider orchids Caladenia R. Br. Taxa of Vic and SA - 2000-2004. [Online]. VIC DNRE. Available from: http://www.environment.gov.au/biodiversity/threatened/publications/recovery/12-orchid/index.html.

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This database is designed to provide statutory, biological and ecological information on species and ecological communities, migratory species, marine species, and species and species products subject to international trade and commercial use protected under the Environment Protection and Biodiversity Conservation Act 1999 (the EPBC Act). It has been compiled from a range of sources including listing advice, recovery plans, published literature and individual experts. While reasonable efforts have been made to ensure the accuracy of the information, no guarantee is given, nor responsibility taken, by the Commonwealth for its accuracy, currency or completeness. The Commonwealth does not accept any responsibility for any loss or damage that may be occasioned directly or indirectly through the use of, or reliance on, the information contained in this database. The information contained in this database does not necessarily represent the views of the Commonwealth. This database is not intended to be a complete source of information on the matters it deals with. Individuals and organisations should consider all the available information, including that available from other sources, in deciding whether there is a need to make a referral or apply for a permit or exemption under the EPBC Act.

Citation: Department of the Environment (2014). Caladenia tensa in Species Profile and Threats Database, Department of the Environment, Canberra. Available from: http://www.environment.gov.au/sprat. Accessed Tue, 29 Jul 2014 01:30:06 +1000.