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| Peperomia kauaiana K.R.Wood & W.L.Wagner, in Wood, Wagner, et Fawcett, 2026. |
Abstract
A new species of Peperomia with alternate leaves from Kaua‘i, Hawaiian Islands, is described and illustrated, with notes on its conservation status, distribution and ecology. We present a dichotomous key to all five Hawaiian Peperomia species with alternate leaves and include notes on two possibly extinct Hawaiian Peperomia species, namely P. degeneri and P. subpetiolata. Peperomia kauaiana sp. nov. differs morphologically from its Hawaiian congeners by its unique combination of diminutive leaves 5–14(–18) mm long, 4–11(–14) mm wide, palmately 5- to 7-nerved, ovate to ovate-orbicular with margins revolute, petioles 2–5 mm long and spikes 11–17(–22) mm long. Plants have been documented in three distinct windward Kaua‘i locations to date, including the southern ridges of Wahiawa, the central ridges of Wai‘ahi and the north-eastern ridges of the Makaleha Mountains. Peperomia kauaiana represents a newly-described wet forest species endemic to the island of Kaua‘i and is currently in need of conservation. Its discovery raises the total number of endemic Hawaiian Peperomia species to 24 and single-island endemic Peperomia on Kaua‘i to three.
Key words: ‘ala‘ala wai nui, endangered species, Hawaiian flora, pepper family, plant extinction prevention, single-island endemism, subgenus Micropiper
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| A–C. Peperomia kauaiana, fertile plants in situ, decumbent to sub-erect habit with terminal spikes, terrestrial in moss; D. View from Kawaikini looking south along the windward ridgeline of eastern Kaua‘i showing buttressed ridges descending to the east (left), which are prime habitat for Peperomia kauaiana. Field photos: A, B Wai‘ahi, 4 Apr 2019, Wood et al. 18149 C Wai‘ahi, 22 Oct 2020, Wood et al. 18580 D photo taken 28 Jan 2022. |
Peperomia kauaiana K.R.Wood & W.L.Wagner, sp. nov.
Diagnosis. Peperomia kauaiana is morphologically most similar to P. degeneri Yunck. from which it differs by the following combination of characteristics: stem internodes 3–5 mm long (vs. 10–15 mm long), leaves 5- to 7-nerved, ovate to ovate-orbicular, 0.5–1.4(–1.8) cm long, margins revolute (vs. leaves 3-nerved, elliptic to oblong-elliptic, 1.5–2(–3.5) cm long, margins flat), petioles 0.2–0.5 cm long (vs. petioles 0.8–1.2 cm long) and spikes 1.1–1.7(–2.2) cm long (vs. spikes 2.5–4.8 cm long).
Etymology. The epithet refers to the island of Kaua‘i, oldest and most floristically rich of all the high Hawaiian Islands and the only known location for Peperomia kauaiana.
Vernacular name. ‘Ala‘ala wai nui is the Hawaiian name for related species. Hawaiians used the ash of their burned leaves and stems as a grey-green dye in kapa making (Krauss 2001).
Kenneth R. Wood, Warren L. Wagner, Susan Fawcett. 2026. Peperomia kauaiana (Piperaceae), A New alternate-leaved Species from Kaua‘i, Hawaiian Islands and Notes on two possibly extinct Hawaiian Peperomia. PhytoKeys. 269: 113-129. DOI: doi.org/10.3897/phytokeys.269.173971
