A REMARKABLE NEW SPECIES FROM THE PAPUAN PENINSULA OF NEW GUINEA

Cyathea lamoureuxii is described from recent exploratory surveys in Papua New Guinea. The new fern is unique among eastern Malesian congeners for its undivided pinnae, and is also the only member of its subgenus with manifestly pinnate leaves. The manner in which the novelty combines diagnostic features across infrageneric lines underscores the difficulties in drawing absolute separations at the subgenus and sectional levels.

Cyathea tree ferns are among the most prominent and photogenic elements in the Papu asian flora.The genus is common at all elevations and provides the defining component for at least one landscape formation (i.e., the subalpine tree fern savannah; Fig. 1).
in the generic circumscription adopted by holttum (1963), 78 species are recog nized for the New Guinea mainland.Tryon's (1970) newer classification increases the difficulties present in Cyathea taxonomy, and has not been followed in this paper.
Pteridology has rarely been a focus of botanical exploration in New Guinea.Except for the activities of a few specialists (e.g., J. croft, J.S. croxall, A.c. Jermy, T. Nakaike, and B.S. Parris) collecting has been primarily inconsequential and opportunistic.Al though floristic documentation has improved in most respects, the historical malaise for ferns has become especially acute in recent years.With Cyathea in particular, the current inactivity can be partly attributed to the large size of most species and the cor responding difficulty in making effective collections.The impediments and disincen tives are comparable to the situation for palms, another group where nonspecialist field workers are understandably reluctant to expend special effort.
Distribution -known only from the type locality.
habitat & Ecology -Understory umbrophile in coastal forest selectively logged during the 1970s.Occurring in remnant stands uncut by the earlier operations.
Etymology -The epithet commemorates the life and contributions of Prof. charles Lamoureux , the late pteridologist and educator from the University of hawaii.
Notes -1. in overall aspect, leaf structure, indument, and venation, the new species is similar to congeners from the moluccana group of section Schizocaena, subgenus Sphaeropteris.The oncepinnate leaves and the position of basal basiscopic nerves (emerging directly from costae) should ordinarily indicate affinity to C. moluccana and its allies (spp. 152-155 in holttum, 1963).however with stipe scales that are obviously flabelloid, C. lamoureuxii is clearly to be placed in section Cyathea, within which it is immediately distinguished by its Schizocaenalike features.in several key respects, the novelty is a composite of character states from otherwise separate sectional facies (Table 1).The absence of sharp infrageneric divisions in Cyathea argues against the reassignments proposed by Tryon (1970) for Malesian taxa.holttum (1981) summarizes some of the difficulties.
2. Within Papuasia, C. lamoureuxii is the only member of the genus with clearly undivided pinnae. in C. klossii and C. ascendens the pinnae are technically simple, but the lamina is so deeply bipinnatisect (divided 1-2 mm from costae) as to appear decompound.Among the dimorphic species in section Gymnosphaera, the sterile leaves of C. biformis are also oncepinnate, but the species is bipinnate when fertile, and has so many other contrasting characters (e.g., a climbing habit, exindusiate sori, vein groups without separately inserted costal nerves) that it could never be mistaken for C. lamoureuxii.(1963) as being more or less diagnostic for infrageneric separations.Cyathea biformis (section Gymnosphaera) is omitted from the tabulation on account of its bipinnate fertile leaves.The stipe-scale terminology (viz., flabelloid, setiferous) is used in the sense established by holttum.For purposes of convenience, 'complete' refers to indusia which initially envelop the sorus as a discrete membrane, later tearing into scalelike fragments upon spore release.Where the applicable character state cannot be determined with certainty from the literature, this is explicitly indicated by '?'.Types have not been examined.
Because of its singular qualities, the novelty can easily be accommodated in holttum (1963: 77) by adding a new fork to the first couplet for section Cyathea: 1a.Lamina pinnate, pinna entire or crenatoserrate . . . . . . . .Cyathea lamoureuxii b.Lamina bipinnatisect or divided to higher orders . . . . . . to the existing couplet 1 3.The new fern is one of the smallest Cyathea in eastern Malesia.Measured from caudex base to the leaf apex, the total length is only 120 cm.
4. The discovery of C. lamoureuxii occurred in conjunction with explorations focused on the Papuan ultrabasic flora (Takeuchi, 2003).Although not part of the ultrabasic series, the Siboma vegetation has numerous floristic elements in common with the serpentine formations across the kuiLababia contact (see geology in Dow & Davies, 1964).Some investigators (e.g., heads, 2003;Polhemus, 1996;Van Welzen, 1997) discount the influence of ultrabasic substrates on floristic patterns, regarding any correlations as coincidental to more fundamental and underlying causes connected to tectonics.irrespective of the real underpinnings for endemic distributions in the Papuan belt, there is no question that the Peninsula comprises a discrete geofloristic unit.This is evident even from casual examination of species distributions within genera such as Aglaia (Pannell, 1992), Myristica (De Wilde, 1995), and Parsonsia (Middleton, 1997).All the rangelimited endemics censused by recent survey at Sibomakamiali fail to cross the tectonic boundary at Salamaua.On the basis of known floristic patterns in south Morobe, C. lamoureuxii is probably a peninsular endemic.Future collections of this unusual fern should occur to the east, further into the Papuan zone, and are very unlikely to be made west of the LaeMarkham subdistrict.

Fig. 1 .
Fig. 1.Cyathea tree fern savannah from the kaijende highlands of Enga Province, Papua New Guinea.Cyathea dicksonioides and C. atrox var.inermis are codominants in the subalpine com munity.Photo by W. Takeuchi.

Table 1 .
Map 1. island of New Guinea.Localities mentioned in the text.a. Siboma; b. kuiLababia boundary; c.Salamaua; d.LaeMarkham subdistrict.comparison of the pinnatelyleaved species of Malesian Cyathea, with respect to characters regarded by holttum