New pteridophyte species and combinations from the Marquesas Islands, French Polynesia

Abstract Intensive botanical exploration of the Marquesas Islands (French Polynesia) for the Vascular Flora of the Marquesas Islands and Flore de la Polynésie française projects has resulted in numerous additional new collections from these islands. Study of these collections has brought to light 11 new species of pteridophytes (ferns and lycophytes) which are described herein: Blechnum pacificum Lorence & A. R. Sm., sp. nov., Cyclosorus castaneus A. R. Sm. & Lorence, sp. nov., Cyclosorus florencei A. R. Sm. & Lorence, sp. nov., Dryopteris macropholis Lorence & W. L. Wagner, sp. nov., Dryopteris sweetorum Lorence & W. L. Wagner, sp. nov., Polystichum kenwoodii Lorence & W. L. Wagner, sp. nov., Polystichum uahukaense Lorence & W. L. Wagner, sp. nov., Pteris hivaoaensis Lorence & K. R. Wood, sp. nov., Pteris marquesensis Lorence & K. R. Wood, sp. nov., Pteris tahuataensis Lorence & K. R. Wood, sp. nov., and Thelypteris marquesensis Lorence & K. R. Wood, sp. nov. One new combination is made: Cyclosorus marquesicus (Holttum) Lorence & A. R. Sm., comb. nov. (based on Plesioneuron marquesicum Holttum). An analysis of the conservation status of these new Marquesas Islands taxa reveals they are in need of inclusion in the IUCN Red List with conservation status ranging from vulnerable (one species), and endangered (four species), to critically endangered (five species).


Introduction
The only recent treatment of the Marquesan pteridophytes (=ferns and lycophytes, used interchangeably herein) is Forrest and Elizabeth Brown's Flora of Southeastern Polynesia (Brown & Brown 1931). This is essentially a report on the plants collected by the Browns on the Bayard Dominick Expedition (1921)(1922), by E. H. Quayle, B. W. Jones, and R. Beck on the Whitney Expedition (1921)(1922), and by the Pacific Entomological Survey (1929)(1930)(1931)(1932) (Lorence and Wagner 1997). The Browns' flora did not include earlier collections not then represented in the Bishop Museum, except as they may have been recorded in the French Polynesian flora of Drake del Castillo (1892). In his Flore de la Polynésie Française Drake del Castillo recognized 142 fern and lycophyte species from the region, three of which were described as new. Brown and Brown (1931) recorded 103 species from southeastern Polynesia, or more specifically 122 taxa including varieties and forms of which 59 (48%) were described as new. Although the Browns' work suffers from a number of shortcomings such as non-parallel descriptions, atypical typifications, and errors in identification, it has remained the only modern pteridophytes flora available for the Marquesas. Copeland (1932) subsequently published a floristic treatment of the Society Islands pteridophytes that included 164 species from this archipelago, but did not include the Marquesas Islands. Most recently, Kato et al. (2008) published an illustrated flora of ferns and lycophytes of the South Pacific islands, encompassing Samoa, Fiji, Vanuatu, and New Caledonia. Revisions of only a few taxonomic groups occurring in French Polynesia and the Marquesas have been published to date, e.g. Elaphoglossum (Rouhan et al. 2008) and Hymenophyllaceae (Ebihara et al. 2006). Useful identification guides include an online key and pictorial checklist of the pteridophytes of Moorea, available at http://ucjeps.berkeley.edu/moorea/pteridophytes.html. A comprehensive published treatment of Marquesan pteridophytes is clearly needed. This paper increases our knowledge of the Marquesan pteridophyte flora by describing 11 new species and proposing one new combination. The present contribution forms part of a series of precursor publications with the goal of producing the first complete Vascular Flora of the Marquesas Islands (Lorence and Wagner 1997). Currently available online as a Web-based flora with a searchable database of descriptions, photos, literature and specimens, it may be accessed at http://botany.si.edu/pacificislandbiodiversity/marquesasflora/index.htm. This project will provide a comprehensive treatment of all Marquesan pteridophytes, for which the essentially completed treatment is now available on the website. A primary goal is to publish the Vascular Flora of the Marquesas Islands as a two volume printed work. A second goal involves collaboration on the Flora of French Polynesia project headed by Jacques Florence under the auspices of the French Institute pour la Recherche et Developpement (IRD, formerly ORSTOM). To date only two volumes of the modern Flore de la Polynésie Française have been published (Florence 1997(Florence , 2004, although Dr. Florence is currently finalizing a field guide to the French Polynesian pteridophytes.

Island Names
Orthographic variation exists for certain of the Marquesas Islands. For the sake of consistency we herein utilize the names accepted by the French Polynesian Government (see website at: www.presidence.pf ) for the islands. In the following list accepted names are in boldface and alternative spellings are listed in parentheses: Fatu Hiva (Fatuhiva, Fatu Iva), Hiva Oa (Hivaoa), Mohotani (Motane), Nuku Hiva (Nukuhiva), Tahuata, Ua Huka (Uahuka), and Ua Pou (Uapou).

Conservation status
As the Marquesan environment is under serious threat from human impacts, feral animals, and weeds (Florence and Lorence 1997) the conservation status was estimated for each new species. When evaluated using the IUCN criteria for endangerment (IUCN 2001, see also www.iucnredlist.org/info/categories_criteria2001), all but one of the new Marquesan pteridophyte species fall into the Endangered (EN) or Critically Endangered (CR) categories, which designates species facing the highest risk of extinction in the wild. One species, Blechnum pacificum which occurs on five Marquesan islands, three Society Islands, and Rapa Iti in the Austral Islands, is considered Vulnerable (VU). The IUCN Endangered (EN) criteria include: B1having known ranges less than 5000 km 2 ; B2 an area of occupancy of less than 500 km 2 ; a, b severely fragmented or known to exist at no more than five locations; c continuing decline in the quality of habitat; or D, a populations size less than 250 mature individuals. The IUCN Critically Endangered (CR) criteria include: B1 having known ranges of less than 100 km 2 and/or B2, an area of occupancy of less than 10 km 2 ; D, population size of less than 50 mature individuals; and estimates including at least two of the following: a, severely fragmented or known to exist at only a single location; b, continuing decline in the extent and/or quality of habitat, extent of occurrence or occupancy, or number of mature individuals.

Methodology
All measurements given herein are taken from dried herbarium specimens, although certain features such as shapes were supplemented with information from field notes and photos. Measurements are presented in the descriptions as follows: length × width, followed by units of measurement (mm or cm). All specimens cited in this paper have been seen by the authors. Specimens from the following herbaria were studied: AD, BISH, BR, K, MO, NY, P, PAP, PTBG, and US. The area of occupancy (distribution) was calculated using herbarium collection data and field observations, and the conservation status is proposed following the IUCN Red List Category criteria (IUCN 2001;www.iucnredlist.org/info/categories_criteria2001).

systematics BLECHNACEAE Blechnum
Blechnum L. is a cosmopolitan genus of about 180 species especially well represented in the southern hemisphere (Mabberley 2008). Brown and Brown (1931) recorded three species from the Marquesas Islands: the endemic B. nukuhivense E. D. Br., the rather widespread Pacific species B. vulcanicum (Bl.) Kuhn, and B. capense (L.) Schltdl. However, it is apparent that the latter name has been misapplied to Polynesian plants, which we describe below as a new species. The three Marquesan Blechnum can be separated by the following key. Description. Large terrestrial ferns; rhizomes erect or suberect, rarely decumbent and dorsiventral, short, stout, (10-)15-20 mm in diameter (excluding scales), apex covered with scales; scales of rhizome and bases of stipes linear-subulate to oblongovate, 20-30 ×1-3(-5) mm, thin, light brown to brown, concolorous but somewhat  thicker and darker basally and in center, basifixed, base rounded or truncate, apex sinuate, margins entire or subentire, cells linear, arranged in vertical rows. Fronds clustered near apices of rhizomes, usually dimorphic but both fertile and sterile pinnae occasionally occurring on the same blade; stipes 41-102 cm long, 4-10 mm in diameter, stout, light to dark brown when fresh, drying stramineous, densely scaly toward the bases, sparsely so distally, eventually glabrescent, smooth, grooved adaxially. Sterile blades 1-pinnate, oblong-ovate to oblong-elliptic, (35-)50-100 × (20-)30-60 cm, coriaceous to subcoriaceous, stiff, rachises stramineous or sometimes dark brown, proximal pinnae only slightly or not at all reduced, apices acute, each blade with a conform terminal pinna, when young the rachises, costae, costules, and veins scaly with thin, scurfy, brown to pale brown, oblong-ovate to subulate, contorted-sinuate scales to 10 mm long with margins subentire or sometimes lacerate basally; pinnae 19-30 on a side, with a slightly swollen, mammiform aerophore at the base each pinna, basal pinnae opposite and shortly stipitate (to 2 mm), the distal ones becoming subopposite to alternate, sessile with basiscopic base often adnate to rachis, terminal pinna free, conform, medial pinnae 11-30 × 1.5-2.5 cm, linear, margins serrulate, often decidedly undulate, apices acute or acuminate, serrulate, acroscopic bases oblique-cuneate, basiscopic base truncate or rounded, the veins prominulous, simple or 1-forked, free, each ending in a marginal tooth; fertile fronds subequal to or slightly smaller than sterile, with up to 40 pinnae pairs (sometimes the proximal pinnae sterile and distal pinnae fertile on the same frond), fertile pinnae approximately the same length as sterile pinnae but narrower, 2.5-5 mm wide, the margins strongly revolute, the sori covering most of the abaxial surface but usually with some expanded green tissue at the base, adaxially glabrate. Sori linear, abaxial surface of pinnae bordered or partly covered by the reflexed, scarious, erose blade margins except on expanded green bases. Spores subellipsoidal, 67 × 47 µm including a perispore 8-12 µm wide.
Ecology. This new terrestrial species occurs in clearings or shade from 380 to 1500 m elevation in lowland to montane mesic and wet forests, shrubland or fernland, in valleys, on slopes or ridge crests and rocky banks. In the Marquesas associated species include Crossostylis biflora J. R. Forst. & G. Forst., Dicranopteris linearis (Burm. f.) Underw., Freycinetia impavida (Gaudich. ex Hombr.) B. C. Stone, Metrosideros collina (J. R. Forst. & G. Forst.) A. Gray, Pandanus tectorius Parkinson, Santalum insulare Bertero ex A. DC., and other native tree, shrub, and pteridophyte species. Threats include competition from alien plant species and damage from feral ungulates. Although this is the most widely distributed of the new species, it is clearly at risk due to habitat loss and degradation.
Etymology. The epithet refers to the Pacific distribution of this new species. Conservation status. IUCN Red List Category: Vulnerable (VU): B1: total area of occupancy less than 20,000 km 2 (ca. 750 km 2 ); b (i-iii), habitat continuing decline inferred; B2: total area of occupancy less than 2000 km 2 (ca. 750 km 2 ); B2b (i-iii), habitat continuing decline inferred. The suitable habitat for Blechnum pacificum on most islands of occurrence is indicated as a declining or endangered environment, threatened by human activity (deforestation, fire), feral animals, and invasive plants, reducing the extent of the forest.
Specimens examined.  (Brown and Brown 1931;Copeland 1932). The true Blechnum capense is confined to southern Africa and some nearby islands (Burrows 1990;Roux 2001). This southern African species has also been treated under the name B. syl-vaticum Schelpe (Schelpe 1979;Jacobson 1983), on the false assumption that the type of B. capense Burm. f. was a mixed collection of two species (Jacobson 1983). However, there seem to be good reasons for placing B. sylvaticum in synonymy under B. capense (Roux 1982;Schelpe and Anthony 1986;Burrows 1990;Roux 2001).
The name Blechnum procerum G. Forst. has also been incorrectly applied to the Polynesian plants. Quoting Nicholson and Fosberg (2004: 125-126), who stated that the type of Blechnum procerum is from New Zealand: "Tindale (1960b: 254) published a photo (t. 7) of the Goettingen material [Nova Zeelandia, Forster 295, GOET] as 'Type specimen' and referred to BM and K specimens as 'Forster material. ' Chambers and Farrant (1998a: 4), without discussion, said 'T. Noua Zeelandia, Forster; lecto (here chosen): K; isolecto: BM, GOET (photo seen).'" Nicolson and Fosberg (2004: 126) further stated "There is considerable confusion about the names applied to this taxon and the following quotation from Brownsey and Smith-Dodsworth (2001) summarized it well: 'The name Blechnum minus was used incorrectly by Allan (1961) and Crookes (1963) for the plant we call B. procerum. The true B. minus, or swamp kiokio, is only doubtfully distinct from the common kiokio (previously known as B. capense).'" Blechnum procerum has lower pinnae only slightly reduced (not less than half the length of the median pinnae), fertile fronds are up to 50% longer than sterile fronds, and the fertile pinnae show no expanded green tissue at the base in the type as in B. pacificum. Clearly, the name B. procerum does not apply to the Polynesian plants.
In New Zealand, closest relatives appear to be B. novae-zelandiae T. C. Chambers & P. A. Farrant and B. minus (R. Br.) Ettingsh., neither of which is conspecific with our Polynesian plants. Blechnum novae-zelandiae is superficially similar but differs in having reduced proximal pinnae and distinctive "black-spot" rhizome and stipe scales with dark brown or black centers and pale margins (Chambers and Farrant 1998). From evidence presented in a recent paper on the phylogeny of New Zealand Blechnaceae by Shepherd et al. (2007, Fig. 2), it seems likely that if Blechnum pacificum were sampled, it would fall somewhere in the clade containing B. wattsii Tindale and B. novaezelandiae. Several species from New Caledonia, all considered endemic, form a confusing array of species somewhat similar to B. pacificum. These include B. confusum (E. Fourn.) Brownlie, B. chauliodontum Copel., and B. subcordatum (E. Fourn.) Brownlie. Brownlie's (1969) illustration and characterization of B. subcordatum suggests that it differs in having smaller fronds with less scaly stipes and rachises, fewer pinnae pairs (5-15), and sterile pinnae not so undulate at the margins. Blechnum confusum differs in its strongly ascending, more sharply serrulate and less scaly pinnae (sterile blades are nearly glabrous). The closest species in Malesia (excluding Papua New Guinea) appears to be B. vestitum (Blume) Kuhn, nom. cons., non B. vestitum T. Moore (see Chambers and Farrant 2001;Chambers 2004;McNeill et al. 2006: 438). The Papua New Guinea species B. dilatatum (Brause) T. C. Chambers & P. A. Farrant is similar to B. pacificum in having fertile pinnae with an expanded basal sterile region, but in the latter the margins are never revolute and the rhizome scales are thin, concolorous, and pale to medium brown. No names of taxa with types from Fiji apply to the new species, the closest species there being B. milnei (Carruthers) C. Chr. (historically also called B. procerum), which differs in having very large fronds with generally broader, less coriaceous pinnae and a less scaly rachis and costae on the sterile blades, and fertile pinnae lacking expanded green tissue at the base.
Among the Polynesian species of Blechnum, B. pacificum seems most closely related to B. venosum Copel. from Rapa Iti in the Austral Islands. In addition to having copious, shiny, dark brown, almost blackish scales on the stipes as noted in the diagnosis, the veins of B. venosum are very prominent and strongly raised above the surface on the abaxial side of blades, whereas the veins in B. pacificum are visible abaxially but scarcely, if at all, raised. This gives B. venosum a much harsher, more cartilaginous appearance. Also, in B. venosum, there are very short hairs on the veins abaxially and some hairs are even present between the veins on laminar tissue, but B. pacificum lacks such hairs. In B. venosum, some of these hairs on the veins and laminar tissue appear multicellular (septate, but uniseriate), and glandular or gland-tipped. Also, pinna margins in B. pacificum are more crenulate (scalloped) than in B. venosum which has entire margins.

Dryopteris
Dryopteris Adanson is a large, essentially cosmopolitan genus of around 225 species with its greatest diversity in north temperate regions (Fraser-Jenkins 1986a, 1989Mickel and Smith 2004). Previously only a single species, Dryopteris fatuhivensis E. D. Br., was recorded from the Marquesas (Brown and Brown 1931), where it occurs on Nuku Hiva, Fatu Hiva, and Ua Huka. Dryopteris fatuhivensis was placed in subg. Dryopteris, sect. Hirtipedes by Fraser-Jenkins (1986b) along with related species from Asia, including the widespread D. hirtipes (Blume) Kuntze which includes two subspecies, subsp. hirtipes and subsp. atrata (Kunze) Fraser-Jenk., both in southeast Asia. We follow Fraser-Jenkens (1989) in recognizing D. fatuhivensis as a Marquesan endemic species distinct from D. hirtipes.

Key to Dryopteris in the Marquesas Islands
Distribution. Marquesas Islands, known from Nuku Hiva, Ua Huka, Ua Pou, Hiva Oa, and Tahuata.
Ecology. This new endemic species is apparently rare and localized, known only from the region from Teavapuhiau ridge to Mt. Etymology. We take great pleasure in naming this magnificent new species in honor of Barbara K. and Cyrus B. Sweet, III, who have generously supported scientific research at the National Tropical Botanical Garden and particularly the Vascular Flora of the Marquesas Islands project.
Discussion. This new species differs from D. macropholis by the characters noted in the diagnosis above, notably in the ultimate pinnules segments spaced 5-10 mm distant with serrate margins and acute apices.
Conservation status. Proposed IUCN Red List Category: Critically Endangered (CR): B1ab, B2a,b (i-iii). B1, total extent of occurrence less than 100 km 2 (ca. 85 km 2 ), a,b, known from a single location; B2a, estimated area of occupancy estimated to be less than 10 km 2 [three collections likely representing a single population are known]; B2b (i-iii), habitat continuing decline inferred. The estimated area of occupancy for D. sweetorum on Fatu Hiva (less than 10 km 2 ) is indicated as an endangered environment, threatened by human activity (deforestation and fire), feral animals, and invasive plant species, reducing the extent of the forest.
Etymology. We take pleasure in naming this new species for its collector Kenneth R. Wood (1953-), whose excellent collections have contributed greatly to our knowledge of the Marquesas flora.

Polystichum uahukaense
Distribution. Marquesas Islands, known only from the type locality on Ua Huka in the Hane/Hokatu cliff zone at the head of the valley above Hane village.
Ecology. Polystichum uahukaense is extremely localized and known from a single population on moist, mossy cliff faces in shade of wet forest with Hibiscus tiliaceus and Discussion. Polystichum uahukaense differs from its Marquesas Islands congeners in having uniformly bipinnate blades, a feature it shares with P. rapense from Rapa Iti which differs in having very dark brown, almost black scales 3-4 mm wide on the rhizome and base of stipe and much smaller, bipinnate fronds (stipes 6-1 cm long, blades 11-14 × 8-10 cm). However, based on overall morphology these two species seem closely allied to each other.

Key to Pteris in the Marquesas Islands
Distribution. Known only from Hiva Oa, Marquesas Islands. Ecology. This rare species is known only from the type location at 930 m on wet stream walls adjacent to wet forest dominated by Cheirodendron bastardianum, Cros-  Conservation status. Proposed IUCN Red List Category Critically Endangered (CR): B2a, B2b (i-iii), D); B2: total area of occupancy less than 10 km 2 (ca. 5 km 2 ). B2a, a single population known; b (i-iii), habitat continuing decline inferred; D, population estimated to number fewer than 250 mature individuals. The suitable habitat for Pteris hivaoaensis on Hiva Oa (ca. 315 km 2 ) is indicated as an endangered environment, threatened by human activity (deforestation, fire), feral animals, and invasive plants, reducing the extent of the forest. D, the rarity of this species is supported by the lack of collections and the small extant area within a commonly collected island, i.e. with a single collection.

Pteris marquesensis
Conservation status. Proposed IUCN Red List Category Endangered (EN): B2a, B2b (i-iii), D): B2: total area of occupancy less than 500 km 2 (ca. 10 km 2 ); 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 km 2 ) and Tahuata (ca. 61 km 2 ) is indicatedas an endangered environment, threatened by human activity (deforestation, fire), feral animals, and invasive plants, reducing the extent of the forest.

Pteris tahuataensis
Distribution. Known only from Tahuata, Marquesas Islands. danus tectorius, and Xylosma suaveolens subsp. pubigerum, Sapindus saponaria. The main threats to this species include competition from invasive alien plant species and habitat destruction by feral goats and fire at lower elevations. Known only from three collections, the one population at 418 m having an estimated 50-70 plants (Wood 10085), the others were isolated plants.

Ecology. This new terrestrial or lithophytic species occurs in wet forests
Conservation status. Proposed IUCN Red List Category Critically Endangered (CR): B2a, B2b i-iii; D): B2: total area of occupancy less than 10 km 2 (ca. 5 km 2 ); B2a, three populations known; b (i-iii), habitat continuing decline inferred; D, population estimated to number fewer than 250 mature individuals. The suitable habitat for Pteris tahuataensis on Tahuata (ca. 61 km 2 ) is indicated as an endangered environment, threatened by human activity (deforestation, fire), feral animals, and invasive plants, reducing the extent of the forest. D, the rarity of this species is supported by the lack of collections and the small extant area, i.e. with only three known collections and an estimated total population size of fewer than 250 plants.
Etymology. This new species is named for its only known island of occurrence.

THELYPTERIDACEAE
With approximately 950 species (Smith et al. 2006) the Thelypteridaceae are one of the largest and most diverse fern families in the Marquesas and the tropics in general. Holttum recognized 15 genera in the Pacific and Australasia (Holttum 1976(Holttum , 1977. However, delimitation of Holttum's genera is often not clear-cut, and some of the most important characters he used for circumscribing them involve chromosome numbers and spore characters visible only at high magnification (e.g., under the scanning electron microscope). Furthermore, although many of Holttum's genera seem monophyletic, a combination of characters is usually needed to circumscribe them. For these reasons, many authors now recognize only about five genera of Thelypteridaceae (Kramer and Green 1990;Smith and Cranfill 2002;Smith et al. 2006). For the purposes of the Marquesas Vascular Flora project we prefer to adopt this broader generic circumscription of Thelypteris Schmidel. and Cyclosorus Link, but follow Kramer and Green (1990) in recognizing the subgenera as natural groups. Two new species of Cyclosorus (subg. Plesioneuron) and one new species of Thelypteris (subg. Coryphopteris) have come to light among specimens collected in the Marquesas and are described below. One new combination is required, bringing the total number of Thelypteridaceae species in the Marquesas to nine. The genera may be separated using the characters in the following key.

Cyclosorus
Viewed in the broad sense, Cyclosorus is the largest genus of Thelypteridaceae, comprising about 600 species in the tropics of both hemispheres. The seven indigenous or endemic and one naturalized species in the Marquesas may be separated by the following key. Blade with basal pinnae narrowed or not on both sides, but rudimentary basal pinnae lacking or several pairs regularly present; blades lacking sessile spherical yellow glands abaxially, or these spread ± evenly on laminar tissue; scales present or absent along costae abaxially, costal hairs 0. Discussion. Cyclosorus subpectinatus (Copel.) Ching, from the Marquesas and Society Islands, is extremely variable and possibly represents more than a single species, but the material at hand seems to intergrade. Specimens from different islands are all slightly different in various indument, venation, indusial, and size characteristics. Specimens with the largest indusia (to nearly 1 mm in diameter) and longest costal hairs are from Ua Huka (e.g., Dunn 340, BISH; Lorence 9307, PTBG, UC). The type of C. subpectinatus, from Tahiti, also has rather long, dense costal hairs, but has smaller indusia only ca. 0.3 mm in diameter The sole collection seen from Tahuata (Wood 10270, P, PAP, PTBG, US) has exceptionally large fronds, with pinnae to 28 × 3.5 cm. Most specimens seen from both the Society Islands (Huahine, Moorea, Raiatea, and Tahiti), and the Marquesas Islands have relatively short, uniform costal hairs ca. 0.1 mm long and small indusia ca. 0.3 mm in diameter. Two specimens from Fatu Hiva (Chapin 789, BISH, cited by Holttum, 1977, as the sole specimen of the species from the Marquesas; and Florence 9509, BISH, P, US) seem to be nearly or quite exindusiate. All specimens seen of C. subpectinatus have rather numerous to moderate, tan, adpressed, lanceolate costal scales abaxially, as well as dense, spherical, yellowish to orange-red sessile glands between the veins abaxially, but lack laminar glands adaxially.  Description. Terrestrial ferns; rhizomes erect, caudices 15-60 cm long; fronds clustered, 7-10 per rhizome; base of stipes to first large pinnae 40-50 cm, distal part of stipes bearing 7-10 pairs of reduced pinnae 3-5 cm apart, 1-7(-35) mm long, the largest ones sometimes trifid; rachises reddish brown, bearing numerous reddish, often curved hairs; proximal large pinnae narrowed at their bases; blades, excluding reduced proximal pinnae, 50-70 cm long; largest pinnae 11-16 × 1.5-2 cm, at their bases each with a swollen, tuberculiform aerophore (most developed and scalelike, to 4 mm long in young fronds), pinnae bases not auricled, apices caudate-acuminate, lobed 2/3-3/4 toward the costae (2-3 mm from costae), lobes slightly falcate, rounded at tips; costules ca. 3-5 mm apart; veins to ca. 8-9 pairs per segment, the basal pair from adjacent segments anastomosing and producing an excurrent vein 1-1.5 mm long to the sinus, the next acroscopic vein to sinus-membrane; abaxial surface of costae with very short, hyaline, spreading to distally curved hairs 0.1 mm long and much longer and stouter falcate hairs to 0.3-1.5 mm on costae, scales lacking or costae with a few adpressed, tan, amorphous scales to 2 × 0.1 mm; yellowish sessile glands borne on abaxial laminar surfaces, often dense, absent or very sparse on adaxial laminar surfaces; stout reddish, falcate hairs adaxially on costae and costules to 1 mm long, with short, falcate hairs ca. 0.2-0.3 mm long sometimes on veins and between veins, especially below sinuses. Sori medial; indusia reddish brown to tan, ca. 0.4-0.6 mm in diameter, glabrous or with a few short hairs 0.1-0.2 mm long; sporangia with sessile, yellow glands on the capsules.

Key to the species of Cyclosorus in the Marquesas Islands
Distribution. Known only from Nuku Hiva, Marquesas Islands. Ecology. This new species occurs in montane rain forest with fern understory. All three specimens seen were collected on Nuku Hiva on or near Ooumu Peak in the Toovii area and probably represent a single population.
Conservation status. Proposed IUCN Red List Category Endangered (EN): B2a, B2b i-iii): B2: total area of occupancy less than 500 km 2 (ca. 50 km 2 ). B2a, a single population known; b (i-iii), habitat continuing decline inferred. The suitable habitat for Cyclosorus castaneus on Nuku Huka (ca. 340 km 2 ) is indicated as an endangered environment, threatened by human activity (deforestation), feral animals, and invasive plants, reducing the extent of the forest. Discussion. The three known specimens were previously determined as Sphaerostephanos (Cyclosorus)heterocarpus (Blume) Holttum, a related species known from Southeast Asia, Malesia, Australia (Queensland), Melanesia (Fiji, Vanuatu), and Samoa. From that species C. castaneus differs in the numerous shiny, castaneous, falcate hairs 0.3-1.5 mm long, on the rachises, costae, and costules abaxially. These hairs vary in length, but are frequently longer than 0.5 mm on the costae. Cyclosorus heterocarpus shows considerable variation in indument (both length and disposition of hairs); however, the hairs in C. heterocarpus are always hyaline, not so decidedly curved, and are generally much shorter than those in C. castaneus. Holttum (1982) recognized many unnamed forms of C. heterocarpus and produced a key to them based primarily on the depth of pinna lobing, presence/absence of sessile glands on the laminae adaxially, width of fertile pinnae, and presence/absence of hairs on the laminae adaxially. Cyclosorus heterocarpus also has larger indusia than C. castaneus, often 1 mm in diameter or more, and the indusia envelop the sporangia when young. Some variants of C. heterocarpus have sessile glands adaxially (rare in C. castaneous) and less deeply incised pinnae (Holttum 1982). Aerophores in C. heterocarpus appear to be much less developed, only a lunate, slightly raised area, or mammiform hump. In C. castaneus, the aerophores are tuberculiform, peglike, or even scalelike, to 4 mm long. A single specimen from Ua Pou (Anakooma river valley just ESE of Oave peak, 470 m, Lorence 9117, PTBG) resembles C. castaneus in having reddish hairs on the costae abaxially, but the hairs are less deeply colored and spreading, not falcate. Most sporangia seem empty, and what spores are formed are irregular, so it is possible this is a hybrid involving C. castaneus and C. florencei. However, neither parental species has been found on Ua Pou. Further study is clearly needed.  Description. Terrestrial ferns; rhizomes creeping, to 10 mm in diameter; fronds spaced, base of stipes sparsely scaly, scales brown, lanceolate; stipes to ca. 70 cm long below first large pinnae, distal part of stipes to 9 mm in diameter at base, bearing ca. 10 pairs of greatly reduced pinnae 2.5-4 cm apart, these 1-10 mm long; proximal large pinnae narrowed at their bases; blades subcoriaceous, excluding reduced, glanduliform proximal pinnae, to ca. 60 cm long, gradually reduced distally to a pinnatifid apex; rachises tan to stramineous, glabrous; large developed pinnae to ca. 30 lateral pairs, to ca. 12 × 1.7 cm, at their bases each with a swollen, conical aerophore to ca. 0.5 mm long, pinnae bases not auricled, apices caudate-acuminate, lobed 2/5-1/2 toward the costae (3-4 mm from costae), lobes oblique and slightly falcate, subacute to rounded at tip; costules ca. 4 mm apart; veins to ca. 8-9 pairs per segment, prominent (especially abaxially) on both sides of laminae, the basal pair from adjacent segments generally obtusely united and producing an excurrent vein 2.5-3 mm long to the sinus, the next 1-1 1/2 pairs merging with this excurrent vein or running to a cartilaginous, raised, sinus membrane; abaxial surface of rachis, costae, costules, and veins nearly lacking hairs or with scattered, minute hairs less than 0.1 mm, costae bearing adpressed to slightly spreading, tan, amorphous (cell walls not readily discernible at 30×) scales to 2 × 0.2 mm; yellowish sessile glands absent on both laminar surfaces, pustules also lacking; hairs absent adaxially on costae, costules, and veins. Sori medial to supramedial; indusia absent; sporangia bearing yellowish capsular glands ca. 0.1 mm, lacking acicular hairs on sporangia and from receptacles.

Cyclosorus
Distribution. Hiva Oa, Marquesas Islands, known only from the type collection made along the trail from Atuona to Hanamenu.
Etymology. We take pleasure in naming this new species for Jacques Florence (1951-) who has done so much to advance our knowledge of the flora of the Marquesas Islands and that of French Polynesia in general.
Conservation status. Proposed IUCN Red List Category Critically Endangered (CR); B2a, B2b i-iii; D): B1, extent of occurrence estimated to be less than 100 km 2 ; B2, area of occupancy estimated to be less than 10 km 2 (ca. 9 km 2 ), and B2a, a single population known; b (i-iii), habitat continuing decline inferred; D, population estimated to number fewer than 250 mature individuals. The suitable habitat for Cyclosorus florencei on Hiva Oa (ca. 315 km 2 ) is indicated as an endangered environment, threatened by human activity (deforestation and fire), feral animals, and invasive plants, reducing the extent of the forest; and D, the rarity of this species is supported by the lack of collections and the small extant area within a commonly collected island, i.e. with a single collection.
Discussion. This new species is perhaps most closely related to Cyclosorus glanduliferus (Brack.) Copel., from Rarotonga (Cook Islands), Samoa, Solomon Islands, and New Hebrides, and to C. stokesii (E. D. Br.) Ching, known only from Rapa Iti in the Austral Islands (Holttum 1977). The three species are similar in rhizome habit, blade dissection, and blade size. However, C. glanduliferus differs from C. stokesii in having more numerous glanduliform pinnae along the stipes (to about 20 pairs), longer aerophores at bases of costae, presence of small aerophores at costule bases, fewer and shorter costal scales, presence of numerous acicular, falcate hairs on the costae adaxially, and hairs borne on the sporangial stalks and receptacles. From C. stokesii, C. florencei differs in having less scaly stipe bases (scales numerous and ovate in C. stokesii), fewer pairs of glanduliform proximal pinnae (to 20 pairs of glanduliform pinnae in C. stokesii), lacking aerophores at bases of costules, more numerous, longer costal scales, 4-5 pairs of veins uniting below sinus or connivent at the sinuses, and lacking hairs from the sporangial stalks. Spore differences mentioned by Holttum (1977) between C. glanduliferus and C. stokesii cannot be evaluated for C. florencei because the sporangia in the type of C. florencei are immature. The label with the type indicates the presence of small pustules abaxially, but we fail to see any pustules of the kind often found in species of subg. Pneumatopteris; we do see numerous, slightly more reflective stomates (guard cells) at 30 times magnification. Until now no species of subg. Pneumatopteris has been recorded from the Marquesas Islands.
The following new combination in Thelypteridaceae is also required. ( Holttum (1976Holttum ( , 1977 circumscribed Coryphopteris Holttum as a genus of about 50 species with its greatest diversity in New Guinea and the Malesian region. However, we prefer to consider Coryphopteris as a subgeneric segregate of a more broadly circumscribed Thelypteris following the concepts of Kramer and Green (1990), Smith and Cranfill (2002), and Smith et al. (2006). For the purposes of the Marquesas Vascular Flora project we prefer to adopt two genera, Thelypteris and Cyclosorus in their broader sense, but follow Kramer and Green (1990) in recognizing the subgenera as natural groups.

Cyclosorus marquesicum
Species belonging to Thelypteris subgenus Coryphopteris are small to medium-sized terrestrial ferns (rarely epiphytic) resembling miniature tree ferns with an erect or sometimes decumbent rhizome topped by a cluster of 1-pinnate fronds with the basal pinnae pairs deflexed in most species. Additional distinguishing characters include relatively large, sessile glands especially dense on the lower surface of the lamina, often abundant scales on the lower surface, and septate acicular hairs on the upper surface of the rachis and costa of some species. Most species belonging to subgenus Coryphopteris are restricted to low wet forest or mossy cloud forest habitat on high mountain ridge slopes and crests, often above 1,000 m elevation, where they grow in leached, nutrient poor soils (Holttum 1976).
Two species of Thelypteris subgenus Coryphopteris are known from the Marquesas, T. quaylei (E. D. Br.) Ching [Coryphopteris quaylei (E. D. Br.) Holttum], and a diminutive new species described below, T. marquesensis. Thelypteris quaylei is a larger, more robust species known from Nuku Hiva, Ua Pou, Ua Huka, Hiva Oa, and Fatu Hiva, generally at lower elevations (580-884 m). Certain collections of T. quaylei from the summit region of Ua Huka (700-884 m) tend to be relatively small, precociously fertile plants. However, the appearance and habitats of the two species are quite different and they can be separated morphologically by the characters in the following key.
Distribution. Known only on Hiva Oa, Marquesas Islands, from a single population in the vicinity of Mt. Temetiu, on the island's central summit crest.
Ecology. Thelypteris marquesensis occurs at 1000-1200 m elevation in low, windswept, montane wet forests and shrublands with Alsophila tahitensis, Cheirodendron bastardianum, Crossostylis biflora, Cyrtandra spp., Freycinetia spp., Leptochloa marquisensis, Melicope spp., Metrosideros collina, Psychotria spp., Weinmannia marquesana var. marquesana, and abundant pteridophytes in the understory. This new species is rare and localized, although in one area it occurs in dense colonies of hundreds of plants that completely cover wet banks and rock faces in and around shallow depressions or grottos, with fronds often appressed to the rock face (K. Wood, pers. obs.). Threats to this species include rooting by feral pigs and invasion by aggressive alien plant species, notably Elephantopus mollis, Psidium guajava, and Syzygium cumini.
Etymology. This new species is named for the Marquesas Islands, where it is known currently known only from Hiva Oa.
Conservation status. Proposed IUCN Red List Category Critically Endangered (CR): B2a, B2b i-iii): B1, extent of occurrence estimated to be less than 100 km 2 ; B2, area of occupancy estimated to be less than 10 km 2 (ca. 9 km 2 ), and B2a, a single population known; b (i-iii), habitat continuing decline inferred. The suitable habitat for Thelypteris marquesensis on Hiva Oa (ca. 315 km 2 ), confined to Mt. Temetiu and vicinity, is indicated as an endangered environment, threatened by human activity (deforestation and fire), feral animals (pigs), and invasive plants, reducing the extent of the forest.
Discussion. This new species differs from Thelypteris quaylei in its much smaller habit (although some specimens of T. quaylei from the Ua Huka summit are atypically small), fronds with 1-3, gradually reduced basal pairs of pinnae, and lack of sessile glands on the lamina surfaces (but present on indusial margins), a feature it shares with T. fasciculata Ching from New Caledonia, New Guinea, and the Celebes (Holttum 1977). Although T. marquesensis may occur in the vicinity of T. quaylei (Lorence et al. 8942,PTBG), the latter species tends to grow in wet forest understory either terres-trially or on mossy boulders, although it is sometimes found in shady depressions on steep ridge slopes either as individuals or forming small colonies.