"gigantopterid" = an English noun describing large leaves with complex reticulate venation resembling the Cathaysian fossil seed plant genus Gigantopteris and North American genus Delnortea of the Permian Period, 260 million years ago"

You are here: Archived Articles

directory bookmark print



[ Archived Articles ]

Popular articles appearing on the gigantopteroid web site in previous years are archived below:

The native Fijian iguana Brachylophus vitiensis pictured above, was photographed by the late John R. H. Gibbons, Ph.D.




[ Living "Fossil" Magnoliids: Degeneriaceae of Fiji ]

JOHN M. MILLER, Ph.D.

University and Jepson Herbaria
Room 1001, Valley Life Sciences Building 2465
University of California, Berkeley
Berkeley, California, USA 94720-2465



Several island groups of the southern Pacific Ocean possess harmonic faunas and floras reminiscent of larger, continental land masses. These include the high islands of the Fiji archipelago, Loyalty Islands, Lord Howe Island, Norfolk Island, Nouvelle Caledonie (New Caledonia), and New Zealand's north and south islands (Carlquist 1974, Green 1994).

The Fiji Islands have long been of interest to biogeographers, biologists, and geologists (Raven and Axelrod 1974, Rodda and Kroenke 1984, Thorne 1986, Kroenke 1996). Three of the largest islands (Viti Levu, Vanua Levu, and Taveuni) support harmonic "continental" floras, including many endemic flowering plant species.



The image above is the northwestern face of the Korombasabasaga Range, Viti Levu Island, Fiji as viewed from the road between Namosi and Wainimakutu villages. The pinnacles in the distance are weathered calc-alkaline Miocene andesites known as the Namosi Volcanics (Rodda and Kroenke 1984).

Endemic tree species of Fiji include several kinds of primitive conifers including Agathis vitiensis, Acmopyle sahniana, Dacrycarpus imbricatus, Dacrydium nausoriense, Dacrydium nidulum, and Decussocarpus vitiensis. A common gnetophyte (Gnetum gnemon) and a narrowly distributed cycad (Cycas rumphii) occur in the archipelago. Tropical forests of the larger islands yield ten genera of monocotyledonous palms including the monotypic Alsmithia longipes, and the enigmatic dicot flowering plant family, Degeneriaceae. All total in this rich flora of some 6,000 species there are 812 endemic angiospermous and gymnospermous species, 12 endemic genera, and one endemic flowering plant family to the archipelago (Ash, 1992, A. C. Smith 1996, Table 1).

Some three-hundred other islands of the archipelago are either composed of uplifted interbedded limestones or coral atolls, and exhibit disharmonic (waif) floras (A. C. Smith 1981).

Little is known of the insect fauna of the Fiji Archipelago (Evenhuis and Bickel 2005).

The family Degeneriaceae was discovered in 1942 by I. W. Bailey and A. C. Smith. Professor Al Smith published additional details of their remarkable discovery in 1949. Degeneriaceae combine a number of primitive features (plesiomorphic traits) that have ignited many debates (A. C. Smith 1981).

Consisting of a single genus and two species Degeneriaceae are endemic to three of the seven "high" islands of the Fiji archipelago (A. C. Smith 1991).

On the left is a picture of a flower of Degeneria roseiflora, and several fragrant flower buds at different stages of maturity. Two of the largest flower buds shown on this kodachrome opened one-by-one on the next two successive nights, releasing a rose-like fragrance (photographed by the author).

Flowering material of Degeneria vitiensis is shown to the right (photographed by Paddy Ryan, Ph.D.). Fragrance of this species resembles Cananga odorata according to Professor Al Smith (A. C. Smith 1981).

Degenerias combine several archetypic morphological traits including polycotyledony, carpels with evaginating stigmatic secretions "plugs" (hairs are absent), microsporophylls and not stamens, and monosulcate pollen. Degeneriaceae are close relatives of the Magnoliaceae and Winteraceae (Dahl and Rowley 1962, A. C. Smith 1981, 1991; Carlquist 1989, Harvey 1984). Despite the presence of ancestral (plesiomorphic) traits of female and male organs and vegetative nodal anatomy, basal Degeneriaceae are not a part of the ANITA or ANA clades.

Possible hybrid trees were infrequently observed in mixed stands at Mount Delaikoro and on the Natewa Peninsula of Vanua Levu Island. These trees combined some of the floral traits of both species. Staminodes of possibly hybrid flowers were yellow with pink stripes surrounded by an inner ring of magenta microsporophylls. The slide on the left is a flower from the canopy of a possible hybrid tree. The author placed cut branches side-by-side from two different trees of the Delaikoro stand and photographed them (see right image). The pink-flowered trees were prevalent at Mount Delaikoro, however some individual, possibly hybrid trees had larger flowers.

Detailed, but preliminary field studies of degenerias on Vanua Levu Island at Mount Deliakoro (941 meters), highest point in the Korotini Range ("Deliakoro Study Site"), and tree stands near Mount Naitaradamu (1,153 meters) on Viti Levu Island ("Naitaradamu Study Site"), reveal the extent of seed predation by endemic fruit doves and parrots. The fruits of Degeneria vitiensis at Naitaradamu open in a "butterfly" fashion exposing several bright orange or red seeds that dangle from the fruit casing by funiculi (left-hand image).

The high islands of Fiji are Gau (Mount Delaitho, 738 meters), Kadavu (Mount Buke Levu, 838 meters), Koro, Ovalau (Mount Delaiovalau, 626 meters), Taveuni (Mount Uluingalau, 1,241 meters), Vanua Levu (Mount Manuka, elevation 1,194 meters), and Viti Levu (Mount Tomanivi, elevation 1,323 meters).

Vanua Levu Island is "frying-pan-shaped" more than 200 km in length. It includes low mountains such as Mount Mariko (elevation 881 m), visible in the Valaga Range to the far left on the image shown below. The first picture below is a view from the forested slopes of the central spine of Vanua Levu Island near the head of the Yanawai River. The Natewa Peninsula is to the right of the image in the background. The waterbody in the distance is Savu Savu Bay.

The "high" island of Taveuni shown below, located southeast of the "panhandle" of Vanua Levu, is characterized by a summit volcanic crater and several dormant cinder cones and vents (Rodda and Kroenke 1984). The image below was photographed by the late John R. H. Gibbons, Ph.D. from the summit crater rim.

The Degeneria Image Gallery page contains several scanning electron micrographs of the floral organs of Degeneria vitiensis. The scanning electron micrographs are from flower parts collected in tree canopies of Degeneria at the Naitaradamu and Delaikoro study areas.

Flowering and fruiting trees found on a ridge leading to the summit of Mount Naitaradamu, Viti Levu, Fiji (a tree canopy is illustrated to the left), yielded the samples collected and studied by electron microscopy.

On the Rairaimatuku (Nadrau) Plateau of Viti Levu Island, on the slopes of Mount Naitaradamu, and at Monasavu Reservoir, trees of Degeneria vitiensis (known to foresters as "masiratu") were up to 35 meters tall (and one meter in diameter). Trees were generally scattered in patchy stands. Stands of masiratu were several hundred meters apart on highland volcanic plateaus, ravines, and ridges; or on lowland alluvial terraces (for example, along the Rewa River and tributaries). Masiratu trees had distinct, light-green canopies of shiny Magnolia-like foliage borne on terminal, leafy branchlets.


A Nitidulid Beetle Phytophagous Association with Degeneria vitiensis:

Australasian cucujiform nitidulid beetles are pollen- and staminode exudate-feeding residents of the flowers of Degeneria vitiensis. Haptoncus tahktajanii (Nitidulidae, Coleoptera) was described in 1973 by Medvedev, G. S. and M. Ter-Minasyan. The species is a known nectar and pollen feeder (Britton 1970).

Nitidulid beetles feed on the pollen and exudate of Degeneria vitiensis. Staphylinid beetles inhabit the flowers of Degeneria roseiflora while nitidulids are uncommon. The reader may wish to note that the oldest verifiable fossil nitidulid is from Upper Cretaceous Siberian amber, 80 million year's old (Zherikhin and Sukatsheva 1973). Coupled with possible genetic isolation, the rose-flowered species host might have evolved without Australasian nitidulid beetles (Haptoncus tahktajanii).

To the right is a kodachrome of a portion of a flower of Degeneria vitiensis sampled at night from the canopy of a tree located at Mount Naitaradamu, Viti Levu, Fiji. The flower shown to the right is in the female phase. Flowers of degenerias exhibit nyctinastic, circadian movements.

When the flower first opens in the evening a spongy stigmatic plug of a single, conduplicately-folded central carpel is exposed. The carpel is barely visible at the lower left behind the yellow-colored staminodes.

Staminodes of Degeneria vitiensis are covered with bright-yellow, oily exudate. Note the camouflaged nitidulid beetle, Haptoncus tahktajanii feeding on the exudate in the center of the image to the right. A brown microsporophyll is partially hidden between the staminode and the petal to the upper right near the base of two of the many, spirally-arranged petals.

To the left is part of a flower of Degeneria roseiflora from the canopy of a tree located at Mount Delaikoro on Vanua Levu Island. This is the male phase showing purple staminodes with no visible exudate. An outer ring of magenta microsporophylls, and the edge of one petal is visible. Staphylinid beetles were found in this flower. Nitidulids were not observed in these samples.

Scanning electron micrographs of Haptoncus tahktajanii are available in the Haptoncus Image Gallery. Pictures of the dorsal surface of the head and mandibles reveal pollen of Degeneria vitiensis. The images are from a collection of nitidulids found in male and female-phase flowers of Degeneria vitiensis, Naitaradamu study area, Viti Levu, Fiji.

An enlargement of one insect specimen from the gallery of scanning electron micrographs of Haptoncus tahktajanii is shown below. The image is the anterior end of a beetle that was scanned without intermediate fixation or preparatory washes. Two partially crushed boat-shaped monosulcate pollen grains of Degeneria vitiensis are visible in the insect's feeding apparatus. Possible dried staminode exudate covers the front of the head of the beetle.


Conclusions:

Potentially interesting floral variation is seen in stands of Degeneria roseiflora on the island of Vanua Levu, Fiji. Mixed, potentially variable stands of Degeneria roseiflora on Mount Delaikoro are dominated by trees having pink and magenta flowers (with rare individuals possessing larger flowers resembling Degeneria vitiensis).

The Australasian cucujiform nitidulid beetle, Haptoncus tahktajanii (Nitidulidae, Coleoptera), is a pollen- and staminode exudate-feeding resident of the flowers of Degeneria vitiensis. The nitidulids' contribution to the reproductive ecology of Degeneria vitiensis may be trivial. Haptoncus tahktajanii was not present on the flowers of Degeneria roseiflora studied.

Based on the author's studies of more than 200 trees in several native stands on Vanua Levu Island and Viti Levu Island (Miller 1988, 1989), there is much more to be learned of the ecology and population genetics of degenerias.


Literature Cited:

Ash, J. 1992. Vegetation ecology of Fiji, past, present, and future perspectives. Pacific Science 46: 111-127.

Bailey, I. W. and A. C. Smith. 1942. Degeneriaceae, a new family of flowering plants from Fiji. Journal of the Arnold Arboretum 30: 64-70.

Britton, E. B. 1970. Coleoptera. Page 495-621 In: E. B. Britton (ed.), The Insects of Australia. Melbourne: Melbourne University Press.

Carlquist, S. 1974. Adaptive Radiation: New Caledonia and New Zealand. Pp. 214-252 in: Island Biology. New York: Columbia, 660 pp.

Carlquist, S. 1989. Wood and bark anatomy of Degeneria. Aliso 12(3): 485-495.

Dahl, A. O. and J. E. Rowley. 1965. Pollen of Degeneria vitiensis. Journal of the Arnold Arboretum 46: 303-343.

Evenhuis, N. L. and D. J. Bickel. 2005. The NSF-Fiji terrestrial arthropod survey: overview. Pp. 3-25 In: N. L. Evenhuis and D. J. Bickel (eds.), Fiji Arthropods I. Bishop Museum Occasional Papers 82.

Green, P. S. 1994. Norfolk Island and Lord Howe Island. Pp. 1-26 in: Flora of Australia 49, Oceanic Islands 1. Canberra: Australian Government Publishing Service, 681 pp.

Harvey, W. 1985. Notes on the epidermal features of Degeneria vitiensis (Degeneriaceae). Botanical Journal of the Linnaean Society 90: 201-208.

Kroenke, L. W. 1996. Plate tectonic development of the western and southwestern Pacific: Mesozoic to the present. Pp. 19-34, In: A. Keast and S. E. Miller (eds.), The Origin and Evolution of Pacific Islands Biotas, New Guinea to Eastern Polynesia: Patterns and Processes. Amsterdam: SPB Academic Publishing.

Medvedev, G. S. and M. Ter-Minasyan. 1973. A new species of beetle of the genus Haptoncus (Coleoptera, Nitidulidae) from the Fiji Islands. Entomologiceskoe Obozrenie 52: 151-153.

Miller, J. M. 1988. A new species of Degeneria (Degeneriaceae) from Fiji Archipelago. Journal of the Arnold Arboretum 69: 275-280.

Miller, J. M. 1989. The archaic flowering plant family Degeneriaceae: its bearing on an old enigma. National Geographic Research 5(2): 218-231.

Raven, P. H. and D. I. Axelrod. 1974. Angiosperm biogeography and past continental movements. Annals of the Missouri Botanical Garden 61: 539-673.

Rodda, P. and L. W. Kroenke. 1984. Fiji: A Fragment Arc. Pp. 87-107 In: Cenozoic Tectonic Development of the Southwest Pacific. United Nations ESCAP, CCOP/SOPAC Technical Bulletin No. 6.

Smith, A. C. 1949. Additional notes on Degeneria vitiensis. Journal of the Arnold Arboretum 30: 1-9.

Smith, A. C. 1981. Degeneriaceae Pp. 7-13 In: A. C. Smith, Flora Vitiensis Nova, Volume 2. Lawai: Pacific Tropical Botanical Garden, 810 pp.

Smith, A. C. 1991. Degeneriaceae Pp. 587-588 In: A. C. Smith, Flora Vitiensis Nova, Volume 5. Lawai: National Tropical Botanical Garden, 626 pp.

Smith, A. C. 1996. Comprehensive Indices, Flora Vitiensis Nova, Volume 6. Lawai: National Tropical Botanical Garden.

Thorne, R. F. 1986. Antarctic elements in Australasian rainforests. Telopea 2(6): 611-617.

Zherikhin, V. V. and I. D. Sukatsheva. 1973. One the Cretaceous insect-bearing "ambers" (retinites) from north Siberia. Pp. 3-48, In: E. P. Narchuk (ed.), Problems in Insect Paleontology. Leningrad (St. Petersburg): Nauka.


Acknowledgments:

Field work on Degeneriaceae of the Fiji Islands was sponsored by a grant from the National Geographic Society.


A set of four postage stamps commemorating the native flora of Fiji were issued at the close of the 1980s by the Republic of Fiji as first day covers and numbered blocks.

Dr. Miller with the help of University of the South Pacific School of Pure and Applied Sciences staff artist Raj, designed these stamps for the Fiji Posts and Telecommunications Philatelic Bureau.

Fijians and philatelists celebrated the first day covers in those happy years, but unfortunately the stamps are out of print.

The other two postage stamps of the set commemorated two species of native epiphytic Dendrobium orchids. Raj used watercolor technique and materials to create the four original paintings used by the lithographer to produce the stamps.



[ top ]


INTERNET SERVICES
by
runadun.com