Tmesipteris horomaka
Common names
Banks Peninsula fork fern
Biostatus
Native – Endemic taxon
Category
Vascular
Structural class
Ferns
Detailed description
Epiphytic or rarely terrestrial plants. Aerial stems pendulous, 70–510 mm long, not known to branch within the leafy part of the stem. Leaves spirally arranged, narrowly oblong to narrowly ovate, linear to falcate(-sigmoid), 10–25 × 2.5–6.5 mm; apex emarginate, truncate or cuspidate, with mucro 1–2 mm long. Synangia 2.5–6 × 1–2 mm, rounded to slightly biconic, with the lower surface of the sporangia appressed along all or most of their length to the subtending leaf margin, and points where present projecting laterally. Spores 71–83 × 35–39 μm. (Description adapted from Perrie et al. (2010)).
Similar taxa
Tmesipteris horomaka is distinguished from T. elongata by its emarginate to truncate leaf apices and from T. tannensis by its more rounded synangia that do not project upwards from their subtending leaf. Tmesipteris horomaka is also distinguished from both these species by its octoploid chromosome number and generally larger spore size.
Distribution
Endemic. New Zealand: South Island (Banks Peninsula).
Habitat
An epiphyte mostly found on the trunks of the tree ferns ponga (Alsophila tricolor), Smith’s tree fern (A. smithii) and wheki (Dicksonia squarrosa) within enclosed forest. It has also been collected once within the rich peaty soil produced by a species of harakeke/flax (Phormium sp.) growing on a cliff face.
Current conservation status
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2022-2023 using the New Zealand Threat Classification System (NZTCS) – more information about this can be found on the NZTCS website. This report includes replaces all previous NZTCS lists for vascular plants. Previous assessments can be found here.
- Conservation status of vascular plants in Aotearoa New Zealand, 2023. 2024. Peter J. de Lange, Jane Gosden, Shannel P. Courtney, Alexander J. Fergus, John W. Barkla, Sarah M. Beadel, Paul D. Champion, Rowan Hindmarsh-Walls, Troy Makan and Pascale Michel Department of Conservation. Source: NZTCS and licensed by DOC for reuse under the Creative Commons Attribution 4.0 International licence.
2023 | Threatened – Nationally Endangered | Qualifiers: DPR, RR
Threats
Initially known from 11 sites and an estimated c. 75 plants, based on the eight populations visited by Perrie et al. (2010), led to Tmesipteris horomaka being assessed as Threatened – Nationally Critical. However, better knowledge of the population size, resulted in the conservation status being revised to Threatened – Nationally Endangered in the 2017 assessment (de Lange et al. 2018). The population is presumed to be stable.
Detailed taxonomy
Family
Synonyms
None (first described in 2010)
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Ecology
Propagation technique
Difficult—should not be removed from the wild.
Other information
Etymology
tmesipteris: From the Greek tmesis (cutting) and pteris (fern), alluding to the forked appendages on fertile fronds
Chromosome number
2n = c.416
Previous conservation statuses
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2022-2023 using the New Zealand Threat Classification System (NZTCS) – more information about this can be found on the NZTCS website. This report includes replaces all previous NZTCS lists for vascular plants. Previous assessments can be found here.
- Conservation status of vascular plants in Aotearoa New Zealand, 2023. 2024. Peter J. de Lange, Jane Gosden, Shannel P. Courtney, Alexander J. Fergus, John W. Barkla, Sarah M. Beadel, Paul D. Champion, Rowan Hindmarsh-Walls, Troy Makan and Pascale Michel Department of Conservation. Source: NZTCS and licensed by DOC for reuse under the Creative Commons Attribution 4.0 International licence.
2017 | Threatened – Nationally Endangered | Qualifiers: RR
2012 | Threatened – Nationally Critical | Qualifiers: RR
2009 | Threatened – Nationally Critical | Qualifiers: DP, OL
2004 | Threatened – Nationally Critical
Referencing and citations
References and further reading
de Lange PJ, Rolfe JR, Barkla JW, Courtney SP, Champion PD, Perrie LR, Beadel SM, Ford KA, Breitwieser I, Schonberger I, Hindmarsh-Walls R, Heenan PB, Ladley K. 2018. Conservation status of New Zealand indigenous vascular plants, 2017. New Zealand Threat Classification Series 22. Department of Conservation, Wellington, NZ. 82 p. https://www.doc.govt.nz/globalassets/documents/science-and-technical/nztcs22entire.pdf
Perrie LR, Brownsey PJ, Lovis JD. 2010. Tmesipteris horomaka, a new octoploid species from Banks Peninsula. New Zealand Journal of Botany 48(1): 15–29. https://doi.org/10.1080/00288251003640010.
Townsend AJ, de Lange PJ, Norton DA, Molloy J, Miskelly C, Duffy C. 2008. New Zealand Threat Classification manual. Department of Conservation, Wellington, NZ. 35 p. https://www.doc.govt.nz/globalassets/documents/science-and-technical/sap244.pdf
Attribution
Fact sheet prepared for the NZPCN by P.J. de Lange (5 May 2010).
NZPCN Fact Sheet citation
Please cite as: de Lange, P.J. (Year at time of access): Tmesipteris horomaka Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/tmesipteris-horomaka/ (Date website was queried)