Pteris marquesensis Lorence & K. R. Wood, 2011

Lorence, David H., Wagner, Warren L., Wood, Kenneth R. & Smith, Alan R., 2011, New pteridophyte species and combinations from the Marquesas Islands, French Polynesia, PhytoKeys 4, pp. 5-51 : 19-20

7. Pteris marquesensis Lorence & K. R. Wood sp. nov. Figs 9 15C, D.

Latin.

Ab aliis Marquesas speciebus laminis 1-pinnatis usque ad 1-pinnato-pinnatifidis, stipitibus dense vestitis cum squamis persistentibus, rigidibus, setiformibus rubro-castaneis differt.

Type.

Marquesas Islands: Tahuata, summit ridge near Haaiputeomo, satellite dish region NE of Vaitahu, 2500-2700 ft, 9°57.19'S, 139°5.74'W, 17-19 July 1997, K. R. Wood 6565(Holotype PTBG 038520!, 038521!, 038522!, 038523!, 038524! [5 sheets]; Isotypes BISH!, NY!, P!, PAP!, UC!, US!).

Description.

Terrestrial ferns; rhizomes dorsiventral, short creeping to suberect, up to 2 cm in diameter (to 15 × 15 cm including stipe bases), scaly at apex, scales of rhizome and base of stipe concolorous, reddish brown, lustrous, linear, sinuate distally, 15-30 × 0.5-0.7 mm, margins subentire or rarely with scattered short teeth, intermixed with smaller narrower scales. Fronds 4-7 per rhizome, clustered at rhizome apex; stipes 60-134 cm long, 4-6 mm in diameter medially, adaxially grooved, stramineous, densely scaly especially in lower ca. 1/3, above with scales spreading and less dense, acicular, bases dark brown, persistent, thickened, distally sinuate, apex filiform, margins subentire; lamina chartaceous, 1-pinnate-pinnatifid or in smaller fronds 1-pinnate, 66-90 × 35-64 cm, ovate-triangular, base obtuse or truncate, apex acute, pinnatifid and not conform; pinnae 6-10 pairs, basal 1-5 pinnae pairs rarely entire or more c ommonly irregularly pinnatifid or lobed at least toward base, or occasionally to apex in sterile fronds, basal pair of pinnae on stalks 2-6 mm long, largest basal pinnae 22-36 × 11-18 cm, basiscopic lobes to 13 × 2.5 cm, linear-oblong, slightly falcate, nearly twice as long as acroscopic lobes, acroscopic base often auriculate, apex acute to acuminate, occasionally obtuse in shorter lobes, middle and upper pinnae sessile, basiscopic base decurrent on rachis, acroscopic base free and nearly parallel to rachis, margins entire or finely serrate towards lobe apices, rachis stramineous, grooved adaxially, with scattered dark brown, acicular scales to 2 mm long, glabrescent or scales sometimes persisting in pinnae axes; veins netted with 2-5 rows of areoles in larger pinnules. Sori with indusia 1 mm wide, entire, continuous along margins except at serrate apices; sporangia mixed with paraphyses. Spores medium brown.

Distribution.

Known from Tahuata and Hiva Oa, Marquesas Islands.

Ecology.

Pteris marquesensis occurs in wet forest and shrubland with Crossostylis biflora , Freycinetia sp., Metrosideros collina , and Weinmannia marquesana var. marquesana, dominant. Other associates include Cyrtandra spp., Morinda citrifolia , Psychotria spp., Vaccinium cereum var. adenandrum, numerous pteridophytes including Asplenium spp., Doodia marquesensis E. D. Br., and Tmesipteris gracilis Chinnock, and diverse bryophytes.

Etymology.

This new species is named for the Marquesas Islands, where it is known from three islands.

Conservation status.

Proposed IUCN Red List Category Endangered (EN): B2a, B2b ( i–iii), D): B2: total area of occupancy less than 500 km2 (ca. 10 km2); b ( i–iii), habitat continuing decline inferred; D, population size estimated to number fewer than 250 mature individuals. The suitable habitat for Pteris marquesensis on Hiva Oa (ca. 315 km2) and Tahuata (ca. 61 km2) is indicatedas an endangered environment, threatened by human activity (deforestation, fire), feral animals, and invasive plants, reducing the extent of the forest.

Discussion.

This striking, large new species is distinctive among all other Polynesian and Micronesian members of the genus. It resembles Pteris warburgii Christ from Papua New Guinea which also has reticulate veins and pinnatifid blades, but that species differs in having only a single pair of lateral pinnae and a terminal pinna, and very few, inconspicuous rhizome and stipe scales. Pteris marquesensis also somewhat resembles Polystichum umbrosa R. Br. from Australia, but that species has fronds with free dichotomous veins and narrower pinnae adnate to the winged rachis, with the lowermost pair of pinnae pinnate-pinnatifid.

Specimens examined.

Marquesas Islands: Hiva Oa: Temetiu region, drainages to the SE of Vaimete and Vaiumioi, headwaters of Hanamenu, UTM 0710665-8916125, 1067 m, Wood 10046 (P, PAP, PTBG, US); Ootua, W side of summit area above road, 9°46'S, 138°58'W, 777 m, Wood 10871 (PTBG, 3 sheets), Wood 10072 (P, PAP, PTBG, US). Tahuata: Haaoiputeomo near satellite dish, NE from Vaitahu to summit ridge, 2000-2500ft (610-762 m), Wood 4461 (BISH, NY, P, PAP, PTBG, UC, US); satellite dish region NE of Vaitahu, 2500-2700 ft (762-823 m), 9°57.19'S, 139°5.74'W, Wood 6556 (BISH, NY, P, PAP, PTBG, US).

Figures

Figure 9. Pteris marquesensis Lorence & K. R. Wood. A rhizome and stipe bases B fertile blade C lower sterile pinna D lower surface of fertile pinnule showing marginal sori E rhizome scale F part of rhizome scale, detail of cells G detail of stipe scales. Drawn from the type collection (Wood 6565) and field images.

Figure 15. A Polystichum uahukaense, frond (Ua Huka, Wood 10518) B Pteris hivaoaensis (Hiva Oa, Wood 4374) C, D Pteris marquesensis C frond D rhizome and stipe bases (both Hiva Oa, Wood 10871) E Pteris tahuataensis (Tahuata, Wood 10083) F Thelypteris marquesensis, habit, colony on wet rock face (Hiva Oa, Wood 4408).