The Transfer of Livistona kingiana (Palmae) to Pholidocarpus

Abstract

Summary. On the basis of floral and vegetative characters Ridley's inclusion of the Malayan species Livistona kingiana Becc. in Pholidocarpus is shown to be correct. Livistona kingiana Becc. and Pholidocarpus macrocarpus Becc. are two large fan palms found growing in lowland swamps of the Malay Peninsula. Without fruit the two taxa appear to be indistinguishable. In fruit, however, there are no problems in naming them: L. kingiana has a very large fruit (for a species of Livistona), at least 6 cm in diameter at maturity, with a smooth, more or less shiny pericarp, whereas in P. macrocarpus the even larger fruit is covered in low corky warts of a dull mid-brown colour. These corky warts arise in a manner similar to those of the fruit ofjohannestei'smannia, Licuala bintulensis Becc., Manicaria, Pelagodoxa and probably other palms with such fruit (Dransfield 1970). Soon after fertilization, the epidermis of the enlarging ovary stops keeping abreast of the expansion of the developing pericarp. The epidermis cracks and dies, while the mesocarp increases considerably and becomes corky. Eventually the remains of the epidermis can be found as small smooth dead patches at the tips of low to high corky warts. In Livistona and Pholidocarpus, apparently slight differences in the patterns of pericarp growth rate account for the striking differences seen in the mature fruits of the two genera. (According to Read (1975) corky warts sometimes found on the fruit of Thrinax parviflora Swartz var. parviflora and previously used to delimit a separate species Th. tessellata Becc. are due to fungal attack, but we have no evidence that this is so in Pholidocarpus.) Doubts as to whether Pholidocarpus is distinct from Livistona arose when certain species of the related genus Licuala (L. bintulensis Becc. and perhaps two other as yet unnamed species) were discovered to have corky-warted rather than smooth fruit. If species of a genus so characteristic as Licuala can have warty rather than smooth fruit, is the possession of corky-warted fruits a character sufficient for separating Pholidocarpus from Livistona? In Pholidocarpus, however, the flowers are subtly but consistently different from those of Livistona (see key below). Furthermore, characters of the leaf are usually but not completely consistently associated with floral differences. On this basis we believe Pholidocarpus should be maintained as a genus distinct from Livistona. Ridley (1907) transferred Beccari's L. kingiana to Pholidocarpus and provided a modified generic description to take account of the smooth rather than corky-warted fruit. Beccari (1933) in his posthumously published monograph of Coryphoid palms, refuted the transfer to Pholidocarpus and included Ridley's combination P. kingianus as a synonym under L. kingiana. Beccari's comments are quite revealing: "The flowers described by Ridley as