Mt. Dzumac

Mt. Dzumac

© RBGE
Mt. Dzumac

Mt. Dzumac

© RBGE
Mt. Dzumac

Mt. Dzumac

© RBGE

Podocarpaceae

Parasitaxus usta (Vieill.) de Laub.

This, the only known parasitic conifer species is endemic to New Caledonia where it's host is the conifer Falcatifolium taxoides.

Description

Habit

Small, erect monoecious shrub 1–1.5m tall, usually multistemmed. Bark thin, with large lenticels, Branches many, spreading and ascending, contorted, upper covered with reddish scale leaves.

Foliage

Leaves scale-like, spirally arranged, overlapping, 2–3 x 1–2mm, broadly lanceolate, apex appressed or free, obtuse or acute. Stomata on both sides of the leaves.

Cones

Male pollen-cones occur on same branches as female seed-cones, terminal, solitary, 3–3.5 x 1.5–2mm. Female seed-cones mainly terminal consisting of 3–6 spreading red bracts, fertile scales with a single termianl inverted ovule. Seeds surrounded by a globose, hard glaucous white epimatium, 3–4mm across.

Notes

The parasitic on the endemic species Falcatifolium taxoides. This is the only known parasitic conifer species

Distribution

Endemic to New Caledonia in isolated localities on Grand Terre. It occurs in the mountains of the southern part of Province Sud on Mt. Dzumac and Montagne des Sources; the central west on Paéoua and Tchingou and in the far north of Province Nord on Mt. Colnett and Mt. Panie. It only occurs in association with some of the stands of its widely distributed host Falcatifolium taxoides. The subpopulations are small, highly localized and severely fragmented. The total population size is estimated to be less than 10,000 with no subpopulation containing more than 100 individuals.

Habitat and Ecology

A small shrub which parasitises the roots of Falcatifolium taxoides in cloud forest on both acidic and ultramafic substrates. Found at altitudes of 600 to 1,200m.

Conservation Status

Global assessment

Vulnerable B1ab(iii,v)+2ab(iii,v);C2a(i)

Global rationale

The subpopulations are severely fragmented and there is a continuing decline projected in the quality of habitat. Its extent of occurrence is estimated to be 6,035km² and the area of occupancy is 76 km², but this may be an under-estimate, but it is certainly less than 2,000km². Therefore this species meets the criteria for listing as Vulnerable under criterion B. The total population size is estimated to be less than 10,000 mature individuals with no subpopulation estimated to contain more than 100 mature individuals and a projected continuing decline in mature individuals. On this basis it is also within the thresholds for criterion C2a(i) under the Vulnerable category.

Global threats

There are direct threats from mining and its associated activities at Mt Paéoua. In other parts of its range it is threatened by an increase in fires and an overall loss of suitable habitat. It requires primary forest and is not known to survive or establish in secondary forests. It is also very sensitive to disturbance caused by tourists and others visiting the areas where it occurs.

Conservation Actions

This species is known from several proteceted areas such as Montagne des Sources, Rivière Bleue Provincial Park and Mont Panie.

References and further reading

  1. Cherrier, J. F. (1981). Le Parasitaxus ustus (Vieillard) de Laubenfels. Rev. Forest. Fr. 33: 445–448.
  2. Cherrier, J. F., Giraud, M., Ghiglione, C. & Woltz, P. (1990). Parasitisme interspécifique chez les Gymnospermes. Étude comparative des acides aminés. Rev. Cytol. Biol. Vég. Botaniste 13: 191–197.
  3. Cherrier, J. F., Gondran, M., Woltz, P. & Vogt, G. (1992). Parasitisme interspécifique chez les Gymnospermes. Données inédites chez deux Podocarpaceae endémiques Néo-Calédoniennes. Rev. Cytol. Biol. Vég. Botaniste 15: 65–87.
  4. Field, T.S, & Brodribb, T.J. (2005). A unique mode of parasitism in the conifer coral tree Parasitaxus ustus (Podocarpaceae). Pl. Cell Environm. 28: 1316-1325
  5. Jaffré, T., Munzinger, J. & Lowry, P.P. (2010). Threats to the conifer species found on New Caledonia's ultramafic massifs and proposals for urgently needed measures to improve their protection. Biodiversity & Conservation 19(5):1485-1502.
  6. Köpke, E., L. J. Musselman, & D. J. De Laubenfels. (‘1981’ publ. 1983). Studies on the anatomy of Parasitaxus ustus and its root connections. Phytomorphology 31(1–2): 85–92
  7. Seyfullah, L.J., Beimforde, C., Perrichot, V., Rikkinen, J. & Schmidt, A.R. (2017) Parasitaxus parasitized: novel infestation of Parasitaxus usta (Podocarpaceae). Arthropod-Plant Interactions 11:507–514
  8. Sinclair, W. T., Mill, R. R., Möller, M., Gardner, M.F., Woltz, P., JaffréT., Preston, J., Hollingsworth, M. & Ponge, A. (2002). Evolutionary relationships of the New Caledonian heterotrophic conifer, Parasitaxus usta (Podocarpaceae), inferred from chloroplast trnL-F intron / spacer and nuclear rDNA ITS2 sequences. Plant Syst. Evol. 233: 79-104.
  9. Stockey, RA, Ko H & Woltz P. (1995). Cuticle micromorphology of Parasitaxus de Laubenfels (Podocarpaceae). Int. J. Pl. Sci. 156(5): 723–730.
  10. Thomas, P. (2010). Parasitaxus usta. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.1. www.iucnredlist.org. Downloaded on 29 June 2012.