Parapolystichum kermadecense
Common name
Raoul Island shield fern
Synonyms
Lastreopsis kermadecensis Perrie et Brownsey
Family
Dryopteridaceae
Flora category
Vascular – Native
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Structural class
Ferns
Chromosome number
2n = 164
Current conservation status
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2017 using the New Zealand Threat Classification System (NZTCS) – more information about this can be found on the NZTCS website. This report includes a statistical summary and brief notes on changes since 2012 and replaces all previous NZTCS lists for vascular plants.
Please note, threat classifications are often suggested by authors when publications fall between NZTCS assessment periods – an interim threat classification status has not been assessed by the NZTCS panel.
- Conservation status of New Zealand indigenous vascular plants, 2017 . 2018. Peter J. de Lange, Jeremy R. Rolfe, John W. Barkla, Shannel P. Courtney, Paul D. Champion, Leon R. Perrie, Sarah M. Beadel, Kerry A. Ford, Ilse Breitwieser, Ines Schönberger, Rowan Hindmarsh-Walls, Peter B. Heenan and Kate Ladley. Department of Conservation. Source: NZTCS and licensed by DOC for reuse under the Creative Commons Attribution 4.0 International licence.
2017 | At Risk – Naturally Uncommon | Qualifiers: IE, OL
Previous conservation statuses
2012 | At Risk – Naturally Uncommon | Qualifiers: IE, OL
2009 | At Risk – Naturally Uncommon | Qualifiers: IE, OL
Distribution
Endemic. Kermadec Islands: Raoul Island.
Habitat
Common in the ‘wet’ forest of Raoul Island where it is a frequent ground cover fern, it also extends into the ‘dry’ forest of that island, though there it is much less common. Within its habitat range it commonly associates with the ferns Pteris carsei, Doodia australis, D. milnei, Zealandia pustulata subsp. pustulata and, less commonly, Arachniodes aristata, the sedge Carex kermadecensis and seedlings of common forest trees, most especially the palm Rhopalostylis baueri (Perrie & Brownsey 2012).
Detailed description
Terrestrial fern. Rhizomes erect or short creeping with fronds clustered at apex. Rhizome scales similar to, but narrower than, those on stipe, non-clathrate, margins entire to abundantly ciliate, cilia apices sometimes globular. Stipes stramineous to castaneous, darker towards the rhizome, 100–500 × 1–4 mm diameter, lacking hairs or with scattered hairs 250–700 mm long, scaly proximally. Stipe scales brown to dark-brown, the more distal clathrate, narrowly-triangular or narrowly ovate, 5.0–12.0 × 0.8–2.1 mm, margins entire to repand (or ciliate). Laminae green, paler abaxially, 3-pinnate to 3-pinnate-pinnatifid, with 8–13 pairs of primary pinnae of which 0–1–(2) catadromous, angular-ovate to pentagonal, 145–450 × 100–330 mm wide, apex acuminate. Rachises 140–420 mm long, adaxial sulcus densely set with erect ctenitoid hairs, the hairs 80–180 mm long, reddish-clear to red or orange; abaxially glabrous or proximally nearly so, or with scattered hairs, often clustered at junctions with primary pinnae and sometimes many distally, the hairs clear with red transverse cell walls, mostly 170–350 mm long, occasionally or commonly interspersed with longer hairs up to 700 mm. Proximal pair of primary pinnae 75–250 × 50–210 mm, with proximal basiscopic secondary pinna enlarged, 35–150 × 11–45 mm. Primary pinnae in apical third of lamina pinnate-pinnatifid, very occasionally 2-pinnate with ½–1 pair of secondary pinnae. Ultimate segments sparsely serrate-crenate, the apex obtuse to acute but with several teeth. Costa of primary pinnae adaxially with hairs similar to those of adaxial rachis, but paler and up to 270 mm long, thinning distally so that minor veins and lamina usually glabrous or nearly so; abaxially glabrous or densely hairy, especially proximally, the hairs usually inconspicuous, clear or reddish clear, predominantly ctenitoid, 170–270 mm long, thinning distally so that minor veins and lamina almost glabrous, sinuses between secondary pinnae with no or few hairs. Glands inconspicuous, absent or few on abaxial rachis, few to many on abaxial lamina, yellow to orange, often pale, 70–140 mm. Sori circular, 0.9–2.1 mm in diameter. Indusia persistent, round to ovate, cordate with a narrow to broad sinus, brown to reddish-brown, 0.7–1.3 mm diameter, only partially covering mature sori, glands absent or present on the dorsal surface or margin. Spores monolete 29–34 × 22–27 µm.
Similar taxa
Parapolystichum kermadecense is the only species present on the Kermadec Islands group (where it is found only on Raoul Island). As such, in the field it is unlikely to be confused with any other terrestrial fern on that island, or any other Parapolystichum. However, from other Parapolystichum species it can be distinguished by the short hairs in the sulcus on the adaxial rachis; by the abaxial rachis being sparsely hairy; by the abaxial lamina having inconspicuous sparse glands and by its tetraploid chromosome number.
Propagation technique
Can be grown from spores and transplanted but difficult to maintain. Needs room to spread and cold sensitive. Does best in a warm, sheltered, shaded site, planted in a free draining, moist, fertile soil.
Threats
Widespread and common on Raoul Island. This species is listed only because on a global scale, as an island endemic it occupies a small area. Beyond natural threats, such as volcanic activity and earthquakes, there are no known, human-induced threats affecting this species. For this reason it has previously been listed, appropriately as “At Risk/Naturally Uncommon” under the informal name of ‘Lastreopsis aff. glabella (AK 242151; Raoul Island)’ by de Lange et al. (2009). Despite its formal elevation to species rank there is no need to change this threat status (see comments by Perrie & Brownsey 2012).
TAXONOMIC NOTES
In 2017 Lastreopsis kermadecensis was transferred to Parapolystichum, as P. kermadecense (Gardner et al. 2017). See also Labiak et al. (2015).
Attribution
Fact Sheet prepared for NZPCN by P.J. de Lange (8 March 2012). Description adapted from Perrie & Brownsey (2012).
References and further reading
de Lange PJ, Norton DA, Courtney SP, Heenan PB, Barkla JW, Cameron EK, Hitchmough RA, Townsend AJ. 2009. Threatened and uncommon plants of New Zealand (2008 revision). New Zealand Journal of Botany 47(1): 61–96. https://doi.org/10.1080/00288250909509794.
Gardner JJS, Perrie L, Shepherd L, Nagalingum NS. 2017. Taxonomic Placement of Unassigned Species of Lastreopsid Ferns (Dryopteridaceae) Using Phylogeny. Systematic Botany 42(3): 385–391. https://doi.org/10.1600/036364417X695952.
Labiak PH, Sundue M, Rouhan G, Moran RC. 2015. New combinations in Lastreopsis and Parapolystichum (Dryopteridaceae). Brittonia 67: 79–86. https://link.springer.com/article/10.1007/s12228-014-9351-3
Perrie LR, Brownsey PJ. 2012. Lastreopsis kermadecensis, a new fern species from Raoul Island in the Kermadec Islands, New Zealand, with notes on L. pacifica. New Zealand Journal of Botany 50(1): 29–36. https://doi.org/10.1080/0028825X.2011.640336.
NZPCN Fact Sheet citation
Please cite as: de Lange, P.J. (Year at time of access): Parapolystichum kermadecense Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/parapolystichum-kermadecense/ (Date website was queried)