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The Tasmanian records of the Short Spider-orchid Caladenia brachy-scapa G.W. Carr and of two closely related specimens.

Introduction

When GW Carr described the Short Spider-orchid Caladenia brachyscapa as a Victorian endemic, he assessed it as possibly extinct' (1988, 442). He was unaware that it had been collected in Tasmania on Clarke Island, in 1979. Next, the species was taken on Cape Barren Island, which is just north of Clarke Island, in 2007. Caladenia sp. aff. brachyscapa has been found at Clarke Island in 1982 and on Cape Barren Island in 2007. The Tasmanian sites are described. The taxons status of endangered', under the Tasmanian Threatened Species Protection Act 1995, is discussed. So is its premature assessment as presumed extinct, or possibly extinct, in Victoria.

Clarke Island

Western Robin Hill

The western part of Clarke Island's northern massif is granite largely overlain by later sand. A track ran from the west to the saddle between Robin Hill, the southern part of the granite, and the main mudstone area known as Steep Hill. This sandy slope has been burnt many times since grazing began on the island in 1846, reducing the dominant Tasmanian Blue Gum Eucalyptus globulus subsp. globulus to scattered, stunted patches amongst often dense scrub. Two plants of a Spider-orchid were collected by the author at the northern edge of the track on 7 November 1979. Jones et al. (1994) identified them as the Short Spider-orchid and illustrated one of the plants collected. There were no local Blue Gums and the taller shrubs of the site were Prickly Moses Acacia verticillata, Smooth Teatree Leptospermum laevigatum, Manuka Leptospermum scoparium, Paperbark Melaleuca ericifolia, South-eastern Broom-heath Monotoca elliptica, and Coast Cherry Exocarpus syrticola. The smaller shrubs were Sticky Boronia Boronia anemonifolia var. variabilis, Golden Pea Pultenaea gunnii and Cranberry Heath Astroloma humifusum. The main ground cover was the Bare Twig-rush Baumea juncea. Also present were Errienallum Drosera auriculata, Potato Vine Billardiera mutabilis and the Small Bearded Greenhood Pterostylis tasmanica.

The vegetation of the slope varied considerably. The extra shrubs beside the track, at 50 m west of the Spider-orchid's site, were Prickly Beauty Pultenaea juniperina, Shrub Everlasting Ozothamnus ferrugineus, Lance Currant-bush Leucopogon affinis, Honeysuckle Banksia marginata and Twiggy Daisy-bush Olearia ramulosa.

Further searches were done in November 1982 but the Short Spider-orchid was not noticed on the western and south-eastern slopes of Robin Hill, nor on the northern slope of Bullock Hill, the island's low north-western rise.

South-east of Sandy Lagoon

The sand of the western slope of Robin Hill continues to the east and is joined, before Sandy Lagoon, by sand that came in over the northern slopes of Steep Hill. It forms an uneven flat in the vicinity of Sandy Lagoon and there are swamps and smaller lagoons in swales and hollows. In late 1982, very little of the flat carried mature vegetation. Instead there were several ages of vegetation as a result of graziers' burning off. Two plants of an orchid approaching the Short Spider-orchid were found amongst re-growth shrubs on a sandy bank near the northwestern corner of a narrow, mapped lagoon. Whip-stick Teatree Leptospermum glaucescens, Manuka Leptospermum scoparium, Native Willow Acacia mucronata, Scented Paperbark Melaleuca squarrosa and Honeysuckle Banksia marginata would become the dominant species. The smaller shrubs were the Spreading Wattle Acacia genistifolia, Golden Pea Aotus ericoides, Mountain Milkwort Comesperma retusum, Sticky Boronia Boronia anemonifolia var. variabilis, Prickly Geebung Persoonia juniperina, Pink Swamp-heath Sprengelia incarnata and Smooth Parrot-pea Dillwynia glaberrima. Also here were Scrambling Coral-fern Gleichenia circinata, Bare Twig-rush Baumea juncea, Love Creeper Comesperma volubile and leaves of the orchid genera Acianthus and Corybas.

Cape Barren Island

Near Ariel Gully

Mount Munro is the summit of Cape Barren Island and Big Hill is its north-western knoll. Ariel Gully drains the latter's western side and it was all burnt on 24 October 2006. The first record was made on 29 September 2007 in the shallow gully of an unnamed minor tributary of Ariel Gully. Blue Gum Eucalyptus globulus subsp. globulus and Smithton Peppermint Eucalyptus nitida formed the dominant layer. Drooping Sheoak Allocasuarina verticillata was the under-storey when the site was burnt in 2006. These shrubs have tillered to a cover of about 10%. About 80% of the c. 15 gravelly slope derived from granite is bare. Tall Cutting-rush Lepi-dosperma elatius (regrown to a c.15% cover), Common bracken Pteridium esculentum, Everlasting Argentipallium dealbatum and Errienallum form the sparse lower cover. There were 14 plants of a Spider-orchid in about 25 [m.sup.2]. Several of them grew in the runnel of the seasonal stream. The specimen, which seemed to the author to be a mixture of several species--including the Short Spider-orchid--was determined at the Australian National Herbarium by Dr Mark Clements as Caladenia sp. aff. brachyscapa (Jo Palmer, pers. comm., 22 November 2012). Dr Clements has since decided that the specimen matches the description of the Short Spider-orchid (Jo Palmer, pers. comm., 20 February 2018). This makes it the second Tasmanian specimen of the taxon.

Gully of Big Hill Run

Big Hill Run rises on the western slope of Mount Munro and flows northward to the sea. The middle part of its gully is steep-sided and it was all burnt on 24 October 2006. The site of a patch of Spider-orchids was stony with about 15% granite. The dominant layer of Blue Gum and Smithton Peppermint has been opened by several fires. The site had, when burnt in 2006, a main understorey of Drooping Sheoak and Spreading Wattle. There was also one Needle-wood Hakea decurrens var. platytaenia. The lower shrubs were Dwarf Cherry Exocarpos strictus and Shrubby Velvet-bush Lasiopetalum macrophyllum. The other species now are Tall Cutting-rush, Sand-hill Cutting-rush Lepidosperma concavum, Coarse Raspwort Gonocarpus teucrioides, Variable Stinkwood Opercularia varia, Mayfly Orchid Acianthus caudatus, Potato Vine and a single leaf of a Sun-orchid Thelymitra sp. Three of the 15 spider-orchid plants of the locality were collected. Two were Tailed Spider-orchids Caladenia caudata and the other a Spider-orchid Caladenia sp. aff. brachyscapa. The identity of the remaining plants is not known.

The Victorian status of the Short Spider-orchid

Carr (1988, 442) noted that 'Caladenia brachyscapa, apparently a narrow [Victorian] endemic, is possibly extinct.' According to Backhouse and Jeanes (1995, 57), the species is known 'with certainty only from the type locality and now presumed extinct there, having been collected last in 1959.' Jeanes and Backhouse (2006, 48) repeated that the orchid is 'Presumed extinct in Victoria, where not seen since 1959.' However the specimen collected in south-western Victoria in 1992 is held at the Australian National Herbarium under the name of Caladenia brachyscapa (CBG9702469). This specimen contradicts the assessments of the species as possibly or presumed extinct in Victoria.

The identity of the Short Spider-orchid

Backhouse and Jeanes (1996:57) asserted that the species was 'Apparently related to both Caladenia patersonii and Caladenia reticulata... Now considered to be most closely related to Caladenia caudata from Tasmania, due to the structure of the osmophores.' By contrast Dr Mark Clements, of the Australian National Herbarium, considered that 'C. reticulata, C. australis and C. brachyscapa are all extremely close if not the same taxon and work is currently underway to decide what the correct name should be' (Jo Palmer, pers. comm., 22 November 2012). Jeffrey Jeanes (13 December 1995) assessed the author's specimen of 1982 from Clarke Island as Approaching Caladenia brachyscapa G.W. Carr but marginal labellum calli longer and leaf smaller and narrower David Jones confirmed this assessment on 20 January 1986. These details come from a determinavit slip lodged with the specimen at the National Herbarium of Victoria. Had the first Tasmanian specimen close to the Short Spider-orchid been available when the species was described, it seems likely that the description would have been broadened somewhat from the features of the limited number of plants drawn on by Carr in 1988.

The current note is based on the assumption that the Short Spider-orchid is a distinct species and that the two Tasmanian specimens represent the taxon.

Discussion

The Victorian habitats of the Short Spider-orchid differ from the Tasmanian ones. Jeanes and Backhouse (2006: 48) noted that the species is Apparently restricted to a small area east of Warrnambool, where it grew in Messmate Stringybark (Eucalyptus obliqua) lowland forest, on grey sandy loam.' The final Victorian record, of November 1992, by Gellibrand River Road, occurred in 'Heath.' There are no other details.

It is possible, in the field, to distinguish Spider-orchid leaves found on the three main Furneaux Group islands from those of the Pink Fairies Caladenia latifolia and the Hare's Ears Leptoceras menziesii. On Cape Barren Island, in late 2007, there were flowering plants at all but one of the sites of Spider-orchid leaves. The flowerless site was at an altitude of about 270 m and this is close to the elevations of the two highest sites of the Mount Munro massif, both of which carried the Green-comb Spider-orchid Caladenia dilatata (Whinray 2012). So its leaves were likely to have been those of the same species.

By contrast, at Clarke Island in 1979 and 1982 there were seven sites with flowering Spider-orchids and five others that lacked any flowers. As Spider-orchids could not be determined at the latter localities, the flora is not known fully. Just the northern slopes of Bullock Hill, with granite outcrops, were inspected. Only a small part, less than 2% of the northern strip, formed from aeolian sand, was visited. Green Hill Gully was checked from the often-burnt tussockgrass of its head down to its mouth. It is a very unusual area with the western slope to the bed all sand from ancient dunes blown in from the west and its eastern slope weathered from granite. No Spider-orchid leaves were noticed in the gully or on the crest southwards from Green Hill to the tussocks of South Head. If Bullock Hill and the northern sandy areas could be searched thoroughly, especially after they were burnt by a major bushfire, the range of the five Spider-orchid species recorded for the island could be better ascertained.

The status of the Short Spider-orchid

The Victorian site where the Short spider-orchid was first collected has been cleared and the species has been found just once since then, in 1992. So it is inappropriate for it still to be assessed as possibly extinct' or extinct' in that State. There, it might be classed more appropriately as critically endangered'. The two Tasmanian sites of the taxon are unlikely ever to be cleared As well, the species may occur at some of the Clarke Island sites where only Spider-orchid leaves were found in 1979 and 1982. The taxon is scheduled, under the Tasmanian Threatened Species Protection Act 1995, as endangered The total number of plants at the two Tasmanian sites was just 19. It is not known whether any of the other 12 plants of the locality in Big Hill Run's gully were Short Spider-orchids rather than Tailed Spider-orchids. It could be appropriate to add the classification critically endangered' to the Tasmanian Threatened Species Protection Act 1995. If so, this more serious category would be suitable for the Short Spider-orchid.

The specimens

Caladenia brachyscapa G.W. Carr, J.S. Whinray C2390, 7.xi.1979, Robin Hill, Clarke Island, CANB 522013; approaching Caladenia brachyscapa G.W. Carr, J.S. Whinray s.n. 5.xi.1982, near Sandy Lagoon, Clarke Island, MEL 2380340; Caladenia brachyscapa, J.S. Whinray 13,159, 27.ix.2007, western slope of Big Hill, Cape Barren Island, CANB 834066; Caladenia sp. aff. brachyscapa J.S. Whinray 13,172A, 4.x.2007, eastern side of Big Hill Run's gully, CANB 499452; Caladenia brachyscapa G.W Carr, P. Barnett DLJ 10602, 11.xi.1992, by Gellibrand River Road, 7-8 km south of Carlisle River, Victoria, CBG9702469.

Acknowledgements

The 1979 visit to Clarke Island was made possible by the generous loan of GWG Goode's small boat. Jeffrey Jeanes, of MEL, determined the specimen of 1982 from Clarke Island as close to Caladenia brachyscapa. David Jones, of CANB, confirmed Jeanes' assessment of that specimen. Jill Thurlow of the library at MEL supplied several very useful photocopies. Catherine Gallagher, also of MEL, provided prints of labels of orchid specimens from Clarke Island. Jo Palmer answered questions about specimens held at CANB. In December 2005 Sue Summers, of the Cape Barren Island Aboriginal Association, kindly arranged for continued access after much of the island became Aboriginal Land earlier that year.

References

Backhouse GN and Jeanes J (1995) The Orchids of Victoria. (The Miegunyah Press: Carlton, Victoria)

Carr GW (1988) New species of Caladenia R. Br. (Orchi-daceae) from Victoria and New South Wales, Australia. Muelleria 6, 439-447.

Jeanes J and Backhouse G (2006) Wild Orchids of Victoria Australia. (Aquatic Photographics: Seaford, Victoria)

Jones D, Wapstra H, Tonelli P and Harris S (1999) The Orchids of Tasmania. (Miegunyah Press: Carlton, Victoria)

Whinray JS (2012) The Tasmanian records of the Fertile Caladenia Caladenia prolata D.L. Jones. The Victorian Naturalist, 129, 144-146.

John Whinray

Flinders Island, Tasmania, 7255

Received 12 July 2018; accepted 25 October 2018
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Title Annotation:Contribution
Author:Whinray, John
Publication:The Victorian Naturalist
Article Type:Report
Geographic Code:8AUST
Date:Feb 1, 2019
Words:2149
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