Pelliciera

Abstract: SUMMARY (1) Cohorts of seedlings of Avicennia bicolor+A. germinans, Laguncularia racemosa, Pelliciera rhizophorae and Rhizophora mangle were studied for 1 year, the Avicennia and Pelliciera on the Pacific side of the Isthmus of Panama, and the Laguncularia and Rhizophora on the Caribbean side. The seedlings were in almost pure stands of the mangroves concerned. (2) There was an exponential decay of numbers in three species, the half-lives being 85, 338 and 604 days in Avicennia, Rhizophora and Pelliciera respectively. (3) The rate of decay of the Laguncularia cohort increased with time; 50% were lost in

Abstract: The geological record of mangrove plants is based on comparablemorphological characteristics of pollen, fruits and wood, of fossil andmodern species. But this record relies on the assumption that the ecologicaland habitat preferences of ancestral taxa have remained similar throughages. A reexamination of fossil evidence of Avicennia, Pelliciera,Sonneratia, Rhizophora, Bruguiera, Ceriops, etc.reveals that the modern mangrove flora was pantropic by the Eocene, andappears to have originated during Paleocene times. Earlier Paleozoic andMesozoic candidates for a mangrove ecology lack conclusive evidence oftheir exclusive association with tidal environments. It is therefore clear thatcontinental drift had a limited role in the dispersal and development ofmodern mangrove floras. The Eocene/Oligocene boundary crisis appears toherald a beginning of the biogeographic split between the current-dayeastern and western provinces of mangrove plants. But, while the climaticorigins of this major disjunction is not clearly understood, our reassessmentof Tertiary paleoclimates suggests that the major cooling events of themiddle Paleocene, the end of the Eocene and the middle Pliocene were themost likely influences on the evolution of mangrove floras. The associatedinvertebrates, especially molluscs, further support our assertion that amodern mangrove ecosystem was established only during the earliestEocene times. We summarize our interpretation in a set of 9 palinspasticmaps of fossil mangrove genera through their evolution ending with thecurrent, bipartite distribution of present day taxa.

Abstract: The mangrove Pelliciera rhizophorae had a wide distribution in the Caribbean area until at least the beginning of the Miocene. By the early Pliocene its distribution had been reduced drastically. This reduction in range and its present distribution appears to be related to the influence of past and present climates on soil salinity regimes within the mangrove ecosystems. Intolerance of the species to soil salinities higher than 37%oo may explain its absence in the dry areas of the eastern Pacific coast. Abundant runoff from more humid uplands and localized areas of high rainfall have allowed the survival of small P. rhizophorae populations on the Caribbean coasts of Central and South America. PELLICIERA IS A MONOTYPIC NEOTROPICAL MANGROVE GENUS which has been of great paleobotanical and phytogeographic interest because of its wide representation in the Tertiary record and current restricted distribution. The only species, Pelliciera rhizophorae Tr. & P1., grows exdusively in mangroves of tropical America (Kobuski 1951). Although the provenance of the species is unknown, Fuchs (1970) has suggested an African origin because of pelliceroid pollen found in Oligo-Miocene sediments of the Niger delta. PAST AND PRESENT DISTRIBUTION Pelliciera rhizophorae had a wide distribution in the Caribbean area during the Tertiary. Hammen and Wijmstra (1964) reported the presence of P. rhizophorae (described as Psilatricolporites crassus) in Oligocene-Miocene sediments in Guyana. The species also has been found in Oligocene-Miocene sediments of Chiapas, Mexico (Langenheim et al. 1967), in Eocene sediments of Jamaica and Panama (Graham 1977), in Eocene-Miocene sediments of Colombia (Wijmstra 1968) and in Miocene sediments of Brazil (Boer et al. 1965), Venezuela (Fuchs 1970) and Trinidad (Fuchs 1970). It is clear that P. rhizophorae was present throughout the Caribbean and northern South America until at least the beginning of the Miocene. Reduction in this range appears to have started in the early Miocene. Pelliciera rhizophorae has not been reported from the late Miocene sediments in the northern Caribbean, although it was present in isolated areas of northern South America throughout the Miocene (Graham 1977). Presently, significant stands of the species exist only from the Gulf of Nicoya, Costa Rica to the Esmeraldas River, Ecuador (Graham 1977). In addition, some isolated individuals grow dose to the tidal channels north of the Gulf of Nicoya and south of the Esmeraldas River (Horna et al. 1980, Jimenez 1981). Although the distribution of this species has been traditionally described as restricted to the Pacific coast of America, several small populations have been recently reported on the Caribbean coasts of Central and South America (Fig. 1). About 1000 individuals have been found in the Cartagena and Barbacoas bays, Colombia (Calderon 1983). Two other small populations have been reported in the estuary of the Prinzapolca River, Nicaragua (D. Neill, pers. comm.) and Chiriqui Lagoon, Panama (Ballou and Getter, in prep.). The reasons for the drastic reduction in the Tertiarian distribution of the species and for its current restricted range are still not clear. Fuchs (1970) suggested that poor propagative power and special edaphic demands of the species are responsible for its extremely restricted distribution. Graham (1977) proposed that the range reduction most likely involved the interaction of sea-level fluctuations, interspecific competition, and cooler climates by late Miocene. Gentry (1981) noted that the species seems to occur only in dimatically wetter areas and suggested that it might have been eliminated from the Caribbean by Pleistocene dry periods. A HYPOTHESIS FOR THE PRESENT DISTRIBUTION Recent observations of P. rhizophorae communities on the Pacific coast of Costa Rica (Jimenez 1981) reveal special ecological requirements that could explain its present restricted distribution. These observations suggest that Pelliciera is more sensitive to high soil salinities than other more widespread neotropical mangroves (Table 1). I Received 29 March 1983; revised 16 July 1983; accepted 1 August 1983. 304 BIOTROPICA 16(4): 304-308 1984 This content downloaded from 157.55.39.133 on Fri, 17 Jun 2016 05:37:47 UTC All use subject to http://about.jstor.org/terms

Abstract: New discoveries of fossil pollen of Pelliceria in Tertiary deposits of the Caribbean extend both the stratigraphic and geographic range of the genus in the Antilles and Central America. The new records include specimens from the Eocene of Jamaica, Eocene of Panama, and Oligo-Miocene of Panama. Factors suggested for explaining the range restriction of Pelliceria, from once widespread throughout the Caribbean, to presently from Pacific Costa Rica to northwestern Colombia, include sea-level fluctuations, climatic trends toward cooler conditions, and competition from extensive communities of Rhizophora which first developed in the Caribbean region during the Oligocene. THE GENUS Pelliceria' is a monotypic member of the Theaceae (Pelliceriaceae fide Airy Shaw 1966) presently restricted to lowland coastal areas from Puntarenas in Costa Rica, through Panama and northwestern Colombia, to the Esmeraldas Province of Ecuador (Holdridge, pers. comm. 1976). The single species, P. rhizophorae Planchon and Triana (the 'palo de sal' in Panama), is a mangrove but lacks the characteristic prop-roots (cf. Kobuski, 1951: 258). It frequently occupies sites where rivers empty into the Pacific (Genuty, pers. comm. 1976), or slightly brackish water zones behind the mesoto euryhaline strand of Rhizophora-Laguncularia-Avicennia. In the mangrove region of the Osa Peninsula of Costa Rica, however, it is associated with Rhizophora in areas of highest salinity. At Main Beach and Playa Grande, Panama, "It develops best along the main drainage channels of the swamp in constantly wet soils that are very shallowly inundated at high tide, usually in company with Rhizophora and Laguncularia" (Johnston 1949: 207). Pelliceria is a small tree, usually between 5-10 m in height but occasionally reaching 20 m. In the Golfo Duke region it has . . . "a very straight, unbranched trunk and narrow crown. The trees have a very strongly developed, deeply fluted pyramidal buttress at the base, even in young specimens, and are unique in this character in the mangrove association" (Allen 1956: 287). Kobuski (1951) and Cuatrecasas (1958) provide further taxonomic and ecological information on the genus. In 1964 van der Hammen and Wijmstra described a fossil pollen type, Psilatricolporites crassus, from the Tertiary of the Guiana Basin. Subsequently Langenheim et al (1967) reported "Pelliciera-type pollen" from the Oligo-Miocene Simojovel Group of Chiapas, Mexico (plate XLII: 315). Wijmstra (1968) recognized the Chiapas specimens as similar to Psilatricolporites, and the biological affinities of the latter were established. Later pollen of Pelliceria was also described from the Oligocene of Puerto Rico (Graham and Jarzen 1969, figs 66-68). Germeraad et al. ( 1968) summarize its stratigraphic range in the Caribbean as basal Eocene to Recent. Thus with the recognition of fossil pollen of P. ctasus as belonging to Pelliceria, the latter, presently restricted to Pacific Central and northern South America, is revealed as a once widely distributed mangrove extending from northern South America to south-central Mexico and the Antilles (fig. 1). Recently, new occurrences of Pelliceria have been discovered in the Caribbean Tertiary establishing the genus as even more abundant and widespread. The pollen of Pelliceria is variable both in size and ornamentation. Some specimens have conspicuous mound-like scabrae with a fine sub-reticulum evident at lower focal levels (fig. 2A insert, fig. 2B). In others the scabrae are less conspicuous, and the grains are distinctly reticulate (e.g., figs. 2G, H). Size ranges from ca. 40,u to 90u in modern pollen, with moderate percentages of smaller abortative grains present in some preparations. Germeraad et al. (1968) noted these variations and suggested they may represent various states of preservation (viz., erosion of the scabrae). However, comparable range in size and ornamentation is also evident on modern reference slides prepared from a single flower. The pollen of Pelliceria is distinct, and similar ranges in size and ornamentation are present in both modern pollen and fossil specimens from the Caribbean.