Perrottetia wichmaniorum Lorence & W. L. Wagner, 2019

Lorence, David H. & Wagner, Warren L., 2019, Perrottetia wichmaniorum (Dipentodontaceae), a new species from Kauaʻi, Hawaiian Islands, PhytoKeys 115, pp. 93-103 : 94-97

1. Perrottetia wichmaniorum Lorence & W. L. Wagner sp. nov. Figs 1 , 2 A–C

Diagnosis.

Perrottetia wichmaniorum is similar to P. sandwicensis from which it differs by its larger, thicker, more pubescent and rugose leaves with a smaller length:width ratio [1.5-1.7:1], larger inflorescences with usually four degrees of branching with moderately to densely hirtellous axes, the staminate inflorescences 12.5-14 cm long, 10-13 cm wide, the pistillate inflorescences 9-13 cm long, 6-13 cm wide, and flowers of both sexes with glabrous petals.

Type.

Hawaiian Islands: Kaua‘i: Hanalei District, Nā Pali-Kona Forest Reserve; upper Hanakoa Valley north of Pihea Peak, 3900-4000 ft, 21 Dec. 1988 (pistillate), T. Flynn & D. H. Lorence 3246 (Holotype: PTBG-014949!; Isotypes AD!, F!, MO!, MU!, SING!, US!).

Description.

Sprawling dioecious small tree 1.5-3 m tall with a dense crown or sometimes a shrub; branches when fresh green or sometimes purple or maroon-tinged, densely villous-hirtellous with pale brown hairs 0.2-0.5 mm long. Leaves spirally arranged, dark green except petioles and veins usually purple or maroon-tinged when fresh; blade thickly chartaceous to subcoriaceous, broadly elliptic, broadly ovate, or suborbicular, 7-18.5 cm long, 4.5-10.5 cm wide [length:width 1.5-1.7:1], adaxially glabrous, rugose with secondary, tertiary, and quaternary venation depressed, abaxially with venation prominulous, densely hirtellous-villosulous along costa and on veins, the hairs rufous, 0.2-0.6 mm long, the secondary veins 9-12 on each side, the axils occasionally with hair tufts, the tertiary veins conspicuously anastomosing, base broadly cuneate to obtuse or truncate, apex acute to rounded, the tip short acuminate, margin serrate-dentate, the teeth 0.5-1 mm long, tips indurated; petiole 1.5-5 cm long, brown villosulous or glabrate; stipules linear-oblong, 2-2.4 mm long, glabrous, deciduous. Inflorescences of both sexes axillary or occasionally infrafoliar, paniculate cymes with usually four degrees of branching, pyramidal, purple or maroon-tinged, the staminate 12.5-14 cm long, 10-13 cm wide, the pistillate 9-13 cm long, 6-13 cm wide, both with the peduncle 2-4 cm; axes densely rufous hirtellous, the hairs 0.2-0.3 mm long, bracts glabrous, ovate-elliptic or subulate, those on primary branches 1.8-2.0 mm long, those on secondary branches 1.2-1.5 mm long, those on tertiary branches 1-1.2 mm long, pedicels with 1-3 glabrous linear-oblong to subulate bracts 0.5-1.5 mm long; flowers on glabrous pedicels 0.5-1 mm long, hirtellous below articulation with ultimate axis. Staminate flowers with sepals and petals 5, spreading at anthesis, sepals purplish green, ovate, 1.0-1.2 mm long, apex acute to acuminate, glabrous, margins entire, petals white, ovate, similar to sepals in size but thinner, glabrous, margins entire; stamens on filaments 2-2.5 mm long, anthers transverse-ellipsoid, 0.5-0.6 mm long, 0.6-0.7 mm wide; pistillode 0.8-1.0 mm. Pistillate flowers with sepals and petals 5, glabrous, subequal, not spreading at anthesis, sepals reddish purple, ovate-deltate, 1-1.4 mm long, apex acute, petals white, ovate, similar in size to sepals but thinner; pistil conical, 1.2-1.5 mm long, stigma lobes 2(3), papillose; staminodes 5, 0.3-0.4 mm long. Infructescence 8-14.5 cm long, 6-14 cm wide. Fruit a globose berry 2.5-4 mm in diameter, ripening red or purple tinged, glabrous. Seeds (2-)4, subglobose, tan, 1.2-1.5 mm long, with thin aril, the testa rugose-reticulate.

Distribution.

Hawaiian Islands, northern Kaua‘i, known only from the Hanalei District, growing along streams or on windward upper valley slopes and summit areas above the valleys at c. 740-1280 m (Fig. 3 ). Collections are known from the upper Waioli Valley in the east and along the Nā Pali Coast to Awa‘awapuhi Valley in the west, although they likely also occur in intervening areas with suitable habitat.

Habitat and ecology.

This new species grows in diverse wet forest with species of Metrosideros Banks ex Gaertn. dominant, associated with species of Cheirodendron Nutt. ex Seemann, Syzygium Gaertn., Psychotria L., Melicope J. R. Forst. & G. Forst., Broussaisia Gaud., Dubautia Gaud., Smilax Tourn. ex L., Astelia Banks & Sol. ex R. Br., and diverse ferns including Dicranopteris linearis (Burm. f.) Underw., Cibotium Kaulf., Sadleria Kaulf., and Diplazium Sw. Flowering was observed from November to June and fruiting from January to August.

Threats.

Threats to this species include invasive alien plant species, primarily Axonopus fissifolius (Raddi) Kuhlm., Buddleja asiatica Lour., Clidemia hirta (L.) D. Don var. hirta , Erigeron karvinskianus DC., Hedychium gardnerianum Sheppard ex Ker Gawl., Juncus planifolius R. Br., Rubus argutus Link, and R. rosifolius Sm. Habitat modification by introduced pigs ( Sus scrofa ), blacktail deer ( Odocoileus hemionus ), and goats ( Capra hircus ) also negatively impact this species. Although recorded as first naturalized on Kaua‘i as recently as 2004, Buddleja asiatica is rapidly becoming a very serious invasive species in the same wet drainages and riparian zones in which Perrottetia wichmaniorum occurs.

Conservation status.

When evaluated using the World Conservation Union‘s IUCN Red List criteria for endangerment ( IUCN 2012), Perrottetia wichmaniorum falls into the Endangered (EN) category, a designation recommended for taxa facing a very high risk of extinction in the wild. The species merits this designation by having a very small Extent of Occurrence (EOO) of ca. 35 km2, along with a small Area of Occupancy (AOO) of ca. 10 km2, and an estimated population of ca. 7200 individuals (K. R. Wood, pers. comm.). The formal IUCN coding system for our evaluation is EN, B1ab(i,ii,iii,v)+2ab(i,ii,iii,v), which indicates that P. wichmaniorum is subject to an inferred decline in its area of occupancy, in addition to a decline in the extent and quality of its habitat and number of mature individuals.

Etymology.

We take pleasure in naming this new species for Charles R. “Chipper” Wichman, Jr., who has served as Director and CEO of the National Tropical Botanical Garden (NTBG) since 2005, and his wife Hau‘oli Wichman, who has served alongside Chipper throughout his directorship, for both their service on behalf of the Garden and especially for their efforts to conserve the Hawaiian Flora. Chipper has also served as Director of NTBG‘s Kahanu Garden on Maui and Limahuli Garden on Kaua‘i, where the new species occurs in the Upper Limahuli Preserve.

Specimens examined (paratypes).

Hawaiian Islands. Kaua‘i: Hanalei District. Nā Pali-Kona Forest Reserve, upper Hanakoa Valley north of Pihea peak, T. Flynn et al. 2937 (AD, F, PTBG), T. Flynn & D. H. Lorence 3247 (BISH, PTBG, US); Kōke‘e State Park, Hwy 550 at mile 19 [southern rim of Kalalau Valley], along north side of road, T. Flynn et al. 3257 (PTBG); Kōke‘e State Park, Awa‘awapuhi Valley west and below Hwy 550, T. Flynn & D. H. Lorence 3260 (PTBG); Kōke‘e State Park, along Hwy 550 near mile 19 on edge of Kalalau Valley, T. Flynn & L. Hume 3292 (PTBG); upper Hanakoa Valley just E of Kalalau Valley rim, D. H. Lorence et al. 6312 (BISH, PTBG, US); upper Waioli Stream Valley, main waterfall, hanging valley between upper and lower falls on N face of Nāmolokama Mt., D. H. Lorence et al. 7295 (PTBG); Kalalau rim, north, below Pu‘u o Kila, K. R. Wood 1047 (PTBG); Kalalau rim, NW facing aspect, below Pihea Peak, K. R. Wood 1132 (BISH, PTBG, US); upper Hanakoa valley from Pihea peak, southwest facing cliffs, K. R. Wood et al. 2218 (PTBG); upper Hanakāpī‘ai drainage and the North Bog area along Wainiha Rim (ridge to Hono o nā pali), below in Hanakāpī‘ai head-water, east drainage, K. R. Wood 5272 (PTBG); upper Hanakoa drainage north of Pihea peak, west of Moa‘alele, K. R. Wood & S. Perlman 7453-A (PTBG, US); Limahuli, upper south-east corner below Pali Ele‘ele, K. R.Wood 7508 (PTBG); below Pihea Peak in Upper Hanakoa Valley, W. L. Wagner et al. 6265 (PTBG, US).

Discussion.

This new species sometimes grows sympatrically with P. sandwicensis with which it occasionally hybridizes. Two examples of putative hybrids were recognizable by their intermediate leaf morphology and inflorescence structure, if fertile.

Putative hybrids.

Hawaiian Islands. Kaua‘i: Hanalei District. Kōke‘e State Park, mile 19 of Highway 550 just below Pu‘u o Kila lookout on southern rim of Kalalau Valey, D. H. Lorence et al. 6001 (BISH, MO, NY, PTBG, US), Highway 550, mile 19 [southern rim of Kalalau Valley], T. Flynn et al. 3256 (PTBG).

Figures

Figure 1. Perrottetia wichmaniorum Lorence & W. L. Wagner A Habit, branch with pistillate inflorescences B Staminate flower C Pistillate flower. A, C drawn from holotype T. Flynn & D. H. Lorence 3246 (PTBG), B from T. Flynn & L. Hume 3292 (PTBG).

Figure 2. Perrottetia wichmaniorum (A-C) A Abaxial leaf surface B Adaxial leaf surface C inset of abaxial leaf surface. Drawn from isotype and field images of T. Flynn & D. H. Lorence 3246 (US), and W. L. Wagner et al. 6265 (US). Perrottetia sandwicensis A. Gray (D-F) D Abaxial leaf surface E Adaxial leaf surface F inset of abaxial leaf surface. Drawn from D. Herbst 871 (US). Field images from Forest and Kim Starr [http: // www. starrenvironmental. com / resources /] were used to augment illustration, especially colors: Ko'olau Gap, Maui [ 110713 - 7251 (25006081321 _ ac 9 bdd 7 fdb _ o), 110713 - 7252 (24731716429 _ d 7 c 44 c 451 a _ o), and 110713 - 7253 (25006085211 _ f 687 c 67 af 8 _ o)]; Road to Lower Kula Pipeline Haiku Uka, Maui [ 170520 - 0692 (34385766464 _ bb 0 d 9 bc 7 d 0 _ o), 170520 - 0693 (34385767704 _ f 28 a 1 b 34 d 7 _ o)].

Figure 3. Distribution map showing known locations of Perrottetia wichmaniorum on Kaua'i.