A New Species of Metroxylon (Arecaceae) from Western Samoa

Abstract

Metroxylon paulcoxii sp. nov., from the islands of 'Upolu and Savai'i in Western Samoa, is described, illustrated, and compared to M. warburgii (F. Heim) Beccari, which is also present in Samoa. Metroxylon paulcoxii is differentiated from M. warburgii by the presence of three autapomorphic characters: shorter mid-rachis leaflets, pendulous or variable rachillae, and terminal (distal) rachillae more than twice as long as lateral (proximal) rachillae. In addition, the ambiguous name M. upoluense Beccari is discussed. While surveying the palms of Samoa in 1996 with Scott Zona of Fairchild Tropical Garden, Miami, specimens of Metroxylon warburgii (F. Heim) Beccari were collected from the islands of 'Upolu and Savai'i in Western Samoa. During the course of collecting, Samoan colleagues and guides indicated that two entities existed. Further discussions with elderly Samoans confirmed that two ethnovarieties (culturally recognized taxa) of Metroxylon traditionally were recognized and collectively called niu Lotuma. Although recognized by some informants, the two ethnovarieties do not appear to have separate Samoan names. The leaves of the trees are used by Samoans as leaf thatch, and recently some individuals have learned that the stem pith can be used as a source of edible starch. Some informants indicated that the leaves of one of the two ethnovarieties were not useful for thatch. Throughout both islands, we encountered and collected herbarium specimens from isolated and mixed stands of both ethnovarieties, which appear to be sympatrically and sym-ecologically distributed. Detailed taxonomic studies, as outlined below, support the conclusion that the two entities are specifically distinct, one representing the widely distributed Metroxylon warburgii, and the other a Samoan endemic, here described as Metroxylon paulcoxii. Morphological variation in the species ofMetroxylon sect. Coelococcus has been previously considered (McClatchey, 1996), with recognition of wide variation in many vegetative and fruit characters. Much less infrataxon variation has been observed in floral and inflorescence characters. Characters observed in the field varied much more widely than those observed on herbarium specimens; therefore this research has relied more heavily upon field observations of living trees than only upon preserved materials. Previous analysis of morphological variation among populations of species of section Coelococcus (McClatchey, 1996) has supported the phenetic distinction of each species. These phenetic species were then used in a morphological cladistic analysis that provided a hypothesis that M. paulcoxii is more closely related to M. warburgii than to the other species of section Coelococcus (M. amicarum (H. Wendland) Beccari, M. salomonense, and M. vitiense). Only characters that consistently differentiate M. paulcoxii and M. warburgii (Table 1) have been selected for this discussion, although many more have been used in historical descriptions of the species of Metroxylon (Beccari, 1918). A brief synopsis of the historical record of taxonomic studies of Metroxylon in Samoa is provided below. METROXYLON UPOLUENSE BECCARI, NOMEN DUBIUM In 1905, the German botanist Rechinger sent sp cimens of apparently immature Metroxylon f uits from the island of 'Upolu, in Samoa, to Beccari in Italy, which were subsequently named M. upoluense Beccari. The author located these fruits in FI still in the original envelope that was used to mail them from Samoa. These fruits are pyriform in shape, as are fruits of M. warburgii and M. paulcoxii, as well as some fruits of M. amicarum. Beccari's (1918) description of M. upoluense is simply a description of immature pyriform Metroxylon fruits, which are unassignable to species. These m y represent either M. warburgii, which had previously been described, or M. paulcoxii, which is ein described. It is also possible that the immature fruits represent M. amicarum, but this is improbable because this species is found in Micronesia, far to the northwest of Samoa. Thus the name M. upoluense Beccari, which has a type and description that cannot with confidence be determined [WESTERN SAMOA. 'Upolu Island: 1905, Rechinger s.n. (FI), Asiatic Palms-Lepidocaryeae Ann. Roy. Bot. Gard. (Calcutta) 12(2): 156-195. 1918] is considered to be a nomen ambiguum. NovoN 8: 252-258. 1998. This content downloaded from 157.55.39.58 on Wed, 16 Nov 2016 04:33:15 UTC All use subject to http://about.jstor.org/terms Volume 8, Number 3 McClatchey 253 1998 Metroxylon paulcoxii from Western Samoa