Lastreopsis abscondita (Dryopteridaceae), a new fern species endemic to New Caledonia

ABSTRACT

The fern genus Lastreopsis has been recently re-circumscribed to include about 19 species. It occurs from southern Asia through the Pacific to the Neotropics, with Australasia having the most species. We here describe a new species endemic to New Caledonia’s Grande Terre, L. abscondita. Morphological comparisons and phylogenetic analyses of chloroplast DNA sequences show that L. abscondita resembles and is closely related to L. vieillardii, also endemic to New Caledonia. From L. vieillardii, L. abscondita differs most noticeably in being much scalier, particularly on its rachis and costae, and in having larger scales, and larger, more-divided fronds. Chloroplast DNA sequences distinguish samples of L. abscondita as a clade, but indicate there is substantial genetic variation within the narrowed circumscription of L. vieillardii such that it is paraphyletic; this should be further investigated. Lastreopsis abscondita is known from only two sites, both at high elevation on non-ultramafic substrates on Grande Terre. We propose an IUCN conservation status of Vulnerable for L. abscondita, particularly because of the small number of sites and limited area of occupancy. The specific epithet alludes to the fact that this large fern, with fronds over 1.5 m long, has been overlooked until now. This is another indication that the ferns of New Caledonia warrant further study, with more discoveries likely to be made.

KEYWORDS:

• Conservation
• DNA sequencing
• Lastreopsis vieillardii
• morphology
• phylogeny
• taxonomy

Acknowledgements

We thank those who have generously helped our fieldwork in New Caledonia, especially Christian Laudereau and Louis Thouvenot. We also particularly acknowledge David Bruy, Jacqueline Tinel, and Vanessa Hequet of NOU herbarium, and the staff of Endemia. Collections were made under permits 1323-2016/ARR/DENV and 3089-2019/ARR/DENV from Province Sud, and 2012 permits from Province Nord and Province Sud to Louis Thouvenot. We thank two reviewers for their comments on a draft manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was funded from Museum of New Zealand Te Papa Tongarewa's Acquisitions and Natural History Research budgets.