Myrsine cirrhosa Lorence & K. R. Wood, 2024

Lorence, David H., Wood, Kenneth R., Appelhans, Marc S. & Wagner, Warren L., 2024, Myrsine cirrhosa (Primulaceae), a distinctive new shrub species from Kaua‘i, Hawaiian Islands, PhytoKeys 243, pp. 47-61 : 47-61

Myrsine cirrhosa Lorence & K. R. Wood sp. nov.

Figs 2 , 3 A, B

Diagnosis.

Myrsine cirrhosa is most similar morphologically to both M. helleri and M. fosbergii , from which it differs by its longer petals and leaves with a combination of strongly undulate margins and tendril-like, cirrhose apex.

Type.

USA. Hawaiian Islands: Kaua‘i: Līhu‘e District, Kapalaoa , peak north of Wahiawa drainage, 21.99 N; - 159.50 W, 930 m elev., 15 May 1991, K. R. Wood et al. 835, (holotype: PTBG-barcode 1000096825; isotypes (to be distributed): BISH, MO, NY, UC, US) .

Description.

Moderately branched shrubs 0.7–2 m tall; branches slender, glabrous, erect-spreading, bark brown or with orange- to reddish-brown tinge. Leaves clustered towards branch tips, blades linear-lanceolate to linear-elliptic, 4–8 (– 10.5) cm long, 0.9–1.5 cm wide, glabrous, adaxial surface medium green, yellow-green near base, not or sparsely black punctate, sometimes with longitudinal black streaks, abaxial surface light green, usually with several inconspicuous parallel black streaks 2.5–3.0 cm long on either side of the costa, not or scarcely black punctate, costa scarcely raised above, prominulous below, secondary veins 9–12 on each side, higher order venation conspicuously reticulate, venation prominulous on both surfaces especially below, submarginal vein present, margins entire, revolute and slightly thickened, strongly undulate in distal 2 / 3–3 / 4, apex long-acuminate, curved and hooked, base narrowly cuneate, subsessile, tapering to a winged petiole (1 –) 3–5 mm long. Flowers apparently perfect, 4–7 in bracteate fascicles in leaf axils or occasionally on leafless nodes, bracts broadly ovate-triangular, ca. 1.8 mm long, 1.5 mm wide, margins erose; pedicels 5–7 mm long, glabrous; calyx lobes 1.5–2.0 mm long, 0.9–1.1 mm wide, triangular-ovate, glabrous, black-streaked, margins entire; petals linear-elliptic or linear-lanceolate, 4–5 mm long, 1.3–1.5 mm wide, black-streaked, apex acute, margins slightly incurved, finely glandular ciliate towards apex; anthers 1.5–1.7 mm long, apex with slightly hooked appendage, glabrous; ovary ovoid, 1.0– 1.5 mm long including the capitate stigma 0.6–0.7 mm wide. Drupes longitudinally dark streaked when immature, when ripe purple-black, globose, 7–8 mm in diameter, glabrous; pedicel 5–7 mm long.

Etymology.

Specific epithet refers to the curved or hooked, tendril-like leaf apices. However, the plant is shrubby and non-climbing.

Specimens examined

(paratypes). USA, Hawaiian Islands, Kaua‘i: Hanalei District, Wai‘ale‘ale summit area , 1524 m elev., 2 May 1992, K. R. Wood et al. 1846 ( BISH, PTBG) ; 1524 m elev., 2 May 1992, S. Perlman & K. R. Wood 12747 ( PTBG) ; 1524 m elev., 28 Dec 1994, K. R. Wood 3896 ( BISH, PTBG) ; 1487 m elev., 29 Dec 1994, S. Perlman et al. 14606 ( PTBG, US) ; 1554 m elev., 30 Dec 2005, K. R. Wood 11662 ( PTBG, US) ; 1500 m elev., 30 Dec 2005, K. R. Wood 11683 ( BISH, PTBG) ; 1553 m elev., 6 Dec 2013, A. Williams & V. Caraway AMW 27 ( BISH, PTBG) ; Lihue District, Kamo‘oloa headwater drainage below Kapalaoa , 975 m elev., 4 Oct 1996, K. R. Wood 5692 ( PTBG) ; 905 m elev., 21 Feb 2008, K. R. Wood & M. Query 12804 ( BISH, PTBG) ; 884 m elev., 21 Feb 2008, K. R. Wood & M. Query 12824 ( BISH, PTBG) ; Wai‘ahi, upper central headwaters , 790 m elev., 4 Apr 2019, K. R. Wood et al. 18139 ( NY, PTBG, UC) ; Wai‘ahi, upper northern headwaters , 884 m elev., 25 Nov 2013, K. R. Wood et al. 15744 ( BISH, CAS, PTBG) .

Phenology.

Myrsine cirrhosa has been collected with flowers from December to April, and with fruit in May and December.

Distribution and ecology.

Myrsine cirrhosa has only been documented along the central windward summit ridges and peaks of Kaua‘i, preferring lowland to predominantly montane wet ecosystems at 784–1554 m (2572–5098 ft) elevation (Fig. 4 ). The two plant communities where the new species has been observed include open montane bogs and also exposed windswept ridges dominated by low statured shrubs and ferns. To date, only 45 plants of M. cirrhosa have been documented, including ca. 20 plants within the summit bogs of Wai‘ale‘ale, renowned for being one of the wettest places on earth; ca. 20 plants in the general area of Kapalaoa peak and the very northern reaches of Wahiawa (ca. 9 km to the south of Wai‘ale‘ale); and ca. five plants found midway between those peaks along the windswept ridges of Wai‘ahi.

The open montane bog vegetation around the Wai‘ale‘ale population of Myrsine cirrhosa is characterised by gently contoured wet slopes dominated by a mixed composition of native sedges, grasses, herbs, shrubs and ferns. Generally, lichens and mosses are prevalent wherever pig disturbance is minimal. The low-stature vegetation (ca. <1 m) of these open bogs is occasionally interspersed with small islands of taller (1–5 m) shrubs and trees or dissected with headwater streams of riparian vegetation bordered with forest dominated by species of Metrosideros Banks ex Gaertn. and Cheirodendron Nutt. ex Seem. In addition to the small stunted trees of Metrosideros and Cheirodendron , these remote bogs are typically composed of endemic taxa, including grass and sedge genera such as Carex L., Deschampsia P. Beauv. , Dichanthelium (Hitchc. & Chase) Gould , Gahnia J. R. Forst. & G. Forst. , Machaerina Vahl , Oreobolus R. Br. and Rhynchospora Vahl. Genera of herbs and shrubs include Astelia Banks & Sol. ex R. Br. , Bidens L., Coprosma J. R. Forst. & G. Forst. , Drosera L., Dubautia Gaudich. , Geniostoma J. R. Forst. & G. Forst. , Geranium Juss. , Kadua Cham. & Schltdl. , Keysseria Lauterb. , Melicope J. R. Forst. & G. Forst. , Myrsine , Nertera Banks ex Gaertn. , Peperomia Ruiz & Pav. , Perrottetia Kunth , Plantago L., Stenogyne Benth. , Vaccinium L. and Viola L. Fern genera typically include Adenophorus Gaudich. , Asplenium L., Cibotium Kaulf. , Dryopteris Adans. , Elaphoglossum Schott ex J. Sm. , Odontosoria (C. Presl) Fée , Huperzia Bernh. and Sadleria Kaulf.

Exposed windswept ridges where individuals of Myrsine cirrhosa have been observed at the Kapalaoa, Wahiawa and Wai‘ahi sites are also dominated by endemic tree species of Metrosideros and Cheirodendron along with other shrub and tree genera, such as Dubautia , Hydrangea Gronov. ex L., Ilex Tourn. ex L., Kadua , Leptecophylla C. M. Weiller , Lobelia Plum. ex L., Melicope , Polyscias J. R. Forst. & G. Forst. , Pritchardia Seem. & H. Wendl. , Psychotria L., Vaccinium ; sedges including Machaerina ; and scrambling ferns Dicranopteris Bernh. and Diplopterygium (Diels) Nakai.

Figures

Figure 2. Myrsine cirrhosa Lorence & K. R. Wood A habit, fruiting branch B leaf showing cirrhose apex and detail of intramarginal venation C inflorescence in bud D inflorescence, flowers at anthesis E flower at anthesis, view from apex F flower at anthesis, view from base G pistil H mature drupe. A, B drawn from Wood et al. 835 (PTBG), C drawn from Wood & Query 12824 (PTBG), D – G drawn from Wood et al. 18139 (PTBG), H drawn from Perlman & Wood 12747 (PTBG). Illustration by Robin Jess.

Figure 3. Myrsine cirrhosa A habit showing leaves with characteristic undulate margins and cirrhose apex (from Kamo‘oloa headwater below Kapalaoa Kaua‘i, Wood & Query 12824) B twig with leaves and flowers (from Wai‘ahi, Kaua‘i Wood 18139) C open exposed wind-swept summit ridges of Wai‘ale‘ale, Kaua‘i representing the habitat for Myrsine cirrhosa. All photos by K. R. Wood.

Figure 4. Distribution map with dots representing known locations for three Myrsine species on Kaua‘i, Hawaiian Islands.