[ Biostratigraphy of a Permian Standard Section ]
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
Folded and overthrust mountain belts of southwestern North America yield classic exposures of a nearly complete sequence of Paleozoic rocks. Exposures consist of uplifted and overthrusted Devonian and Pennsylvanian rocks of the Marathon Fold Belt; and Permian sediments of the Del Norte and Glass Mountains. Sedimentary beds in the Del Norte and Glass Mountains comprise the standard North American type section through rocks of Permian age.
While the invertebrate fauna of the Glass Mountains is well known from detailed studies by Cooper and Grant (1972) and Olszewski and D. H. Erwin (2009); the transitional (deltaic) and marginally marine depositional environments of the Del Norte Mountains, which contain Permian (Leonardian) gigantopterid plant and bellerophontacean gastropod megafossils assignable to Cymatospira or Patellilabia (Mamay et al. 1984), are less well understood.
There are significant similarities of the Permian Del Norte Mountains flora with South American paleofloras of the Permian Palmarito Formation (Ricardi et al. 2004), the Venezuelan Carache Formation (Ricardi-Branco 2008), and Leonardian florules of Mexico (Weber 1997). The Del Norte Mountains Leonardian florule while low in biodiversity and otherwise similar to an older coastal Permian flora from the Abo Formation (DiMichele et al. 2007), is not dominated by walchian conifers and Supaia-like peltaspermaleans.
The late Sergius H. Mamay, Ph.D. of the United States National Museum is pictured above standing on the fossiliferous Upper Member of the Leonardian Cathedral Mountains Formation of the Del Norte Mountains of southwestern North America.
Cretaceous limestones overtopping a 200 meter-thick bed of limestone pebbles, dolomite, quartz, and shales comprising the Bissett Conglomerate (chronostratigraphy in question, younger rocks are eroded away), together with underlying Permian conglomerates, limestones, shales, and siltstones; and Paleogene volcanic intrusions, are prevalent in the rugged Del Norte Mountains of North America, including significant deposits of lead and hematite that have been mined in the last century (Barnes 1982).
Permian rocks of the Del Norte Mountains include marine and transitional, deltaic sediments of the Permian Wolfcampian, Leonardian, Wordian, Guadalupian, and Ochoan Ages (Wardlaw et al. 1990, Rohr et al. 1991, Wardlaw 2000).
Glass and Del Norte Mountains rocks yield gymnospermous fossils in several areas including Units 5 and 6 of Section IV, uppermost Cathedral Mountain Formation (Rohr et al. 1987, Wardlaw et al. 1990), and in several other isolated stations in this mountainous region (C. N. Miller and Brown 1973, Mamay et al. 1988). Dating of the layers is supported by micropaleontological evidence from conodonts (Wardlaw et al. 1990, Wardlaw 2000) and fusulinids (Yang and Yancey 2000).
The image to the left is a slab exfoliating from rock layers of the Upper Member. A private mapping party in 1981 discovered this slab along a wild game trail in the Del Norte Mountains. The in situ slab pictured to the left, which is reproduced by C. A. Hill (Figure 7, page 284, 1999) shows overlapping leaf compressions of Delnortea abbottiae and Taeniopteris. The kodachrome below to the left is of two fossilized seeds, assignable to Cordaicarpus (Mamay et al. 1984), which are virtually identical to platyspermic seeds from the South American Palmarito Formation, also associated with Delnortea leaves (page 82, Figure 6, Ricardi et al. 2004).
Pictured above and to the right are the coalified and compressed foliar remains of the holotype of Delnortea abbottiae (USNM 364416), photographed by the author with Kodachrome ASA 25 film when the fossil was unearthed from beds of the Lower Permian (Leonardian) Cathedral Mountain Formation, Del Norte Mountains, southwestern North America. The color transparency was scanned, restored, and converted to digital format more than 20 years later.
Large leaf compressions and permineralizations of Leonardian plants were described about 20 years ago (Mamay et al. 1986, 1988). A preliminary biostratigraphic study of the fossiliferous layers by Rohr et al. (1987) resulted in mapping of Section IV, Units 5 and 6, which were assigned to the uppermost Cathedral Mountains Formation by Wardlaw et al. (1990) based on detailed conodont and stratigraphic studies of the North American Permian type section.
Mamay's suggestion that the stratigraphic occurrence of Delnortea in Upper Leonardian rocks of the Cathedral Mountain Formation may lead to a better understanding of Permian floral zones is supported by discovery of Delnortea from the Artinskian of northwestern South America (Ricardi et al. 1999).
A scanning electron micrograph on this page shows the arrangement of permineralized tracheids and ray parenchyma cells of a fragment from the Dadoxylon log (see image to the left) found exfoliating from graded conglomerates in Unit 6. Distribution of rounded chert pebbles up to two centimeters in diameter, sands, and fines in the conglomerate, suggest a much higher energy depositional environment than the fine-grained mudstone comprising Unit 5 (Rohr et al. 1987).
The notion of Delnortea as a widespread and common Pangaean floristic element of the Lower Permian of North America (Mamay et al. 1984) is supported by a startling discovery of Delnortea leaf fragments and other plant fossils in core samples of the Permian, Leonardian, Clear Fork Dolomite recovered from three wells drilled more than 2000 meters deep through the thick sediments of southwestern North America (DiMichele et al. 2000).
Unit 5 of Section IV is shown in the image to the right as it was found in 1982 prior to bulldozing of the Bird Mountain Delnortea beds. The coniferous shrub is Juniperus deppeana (Cupressaceae, Coniferales, Pinidae), which is surrounded by clumps of juvenile Yucca rostrata (Agavaceae, Liliales, Lilianae). A team of Sul Ross State University geology students is shown removing the soil horizon to expose Unit 5 of the weathered rock-section. Shannon Rudine is swinging a pick-axe. The author is studying rock facies exposed down-section.
Tropical, summer wet, terrestrial biomes of the early Permian Period contained innovative and unusual xeromorphic seed plant assemblages (DiMichele et al. 2004). Apparently aridity intensified and spread across the Carboniferous to Permian boundary, but more field work in the region is needed to understand this climatic transition (DiMichele et al. 2010).
Based on research in connection with oil and gas exploration, terrestrial and transitional biomes on either side of the Hovey Channel (or a second embayment draining the Delaware Basin, and connected to the Panthalassa Ocean by the Diablo Strait) just to the north of the Central Pangaean Mountains, were potential sources of bioepigenetic hydrocarbons and sulfur in deltaic and basinal sediments comprising the Cathedral Mountains-, Road Canyon-, Tessey (Castile?) Limestone-, and Word Formation (C. A. Hill 1999).
The widely separated Delnortea-dominated floras reported by Mamay et al. (1984) and Ricardi et al. (1999) are examples of pervasive seed plant associations that might reflect long-term stasis in Permian terrestrial paleoenvironments.
Taphonomic studies of the delnortea beds (Unit 5) and log bed (Unit 6) of Section IV are needed to better understand paleoenvironments of the Cathedral Mountains Formation in relation to western Pangaean subtropical coastal landscapes (DiMichele et al. 2007, Ricardi-Branco 2008) that existed during the Permian Period more than 260 million years ago.
Barnes, V. E. 1982. Geologic Atlas of Texas, Fort Stockton Sheet, Bureau of Economic Geology and The University of Texas.
Cooper, G. A. and R. E. Grant. 1972. Permian Brachiopods of West Texas, Pts. 1-5. Smithsonian Contributions in Paleobiology, 1972-1976.
DiMichele, W. A., A. K. Behrensmeyer, T. D. Olszewski, C. C. Labandeira, J. M. Pandolfi, S. L. Wing, and R. Bobe. 2004. Long-term stasis in ecological assemblages: evidence from the fossil record. Annual Review of Ecology, Evolution, and Systematics 35: 285-322.
DiMichele, W. A., D. S. Chaney, W. H. Dixon, W. J. Nelson, and R. W. Hook. 2000. An early Permian coastal flora from the Central Basin Platform of Gaines County, West Texas. Palaios 15(6): 524-534.
DiMichele, W. A., D. S. Chaney, H. Kerp, and S. G. Lucas. 2010. Late Pennsylvanian floras in western equatorial Pangea, Cañon del Cobre, New Mexico. Pp. 75-113 In: S. G. Lucas, J. W. Schneider, and J. A. Spielmann (eds.), Carboniferous-Permian Transition in Cañon del Cobre, Northern New Mexico, Bulletin 49, New Mexico Museum of Natural History and Science, A Division of the Department of Cultural Affairs. Albuquerque: New Mexico Museum of Natural History and Science, 229 pp.
DiMichele, W. A., D. S. Chaney, W. J. Nelson, S. G. Lucas, C. V. Looy, K. Quick, and W. Jun. 2007. A low diversity, seasonal tropical landscape dominated by conifers and peltasperms: early Permian Abo Formation, New Mexico. Review of Palaeobotany and Palynology 145(3-4): 249-273.
Hill, C. A. 1999. Reevaluation of the Hovey Channel in the Delaware Basin, West Texas. American Association of Petroleum Geologists Bulletin 83(2): 277-294.
Mamay, S. H., J. M. Miller, and D. M. Rohr. 1984. Late Leonardian plants from West Texas: the youngest Paleozoic plant megafossils in North America. Science 223: 279-281.
Mamay, S. H., J. M. Miller, D. M. Rohr, and W. E. Stein, Jr. 1986. Delnortea, a new genus of Permian plants from West Texas. Phytologia 60: 345-346.
Mamay, S. H., J. M. Miller, D. M. Rohr, and W. E. Stein, Jr. 1988. Foliar morphology and anatomy of the gigantopterid plant Delnortea abbottiae from the Lower Permian of West Texas. American Journal of Botany 75(9): 1409-1433.
Miller, C. N. and J. T. Brown. 1973. A new voltzialean cone bearing seeds with embryos from the Permian of Texas. American Journal of Botany 60: 561-569.
Olszewski, T. D. and D. H. Erwin. 2009. Change and stability in Permian brachiopod communities from west Texas. Palaios 24(1): 27-40.
Ricardi, F., O. Rösler, and O. Odreman. 1999. Delnortea taphoflora (Gigantopteridaceae) of Loma de San Juan (Palmarito Formation, NW of Venezuela) and its palaeophytogeographical relationships in the Artinskian (Neopaleozoic). Plantula 2(1-2): 73-86.
Ricardi-Branco, F. 2008. Venezuelan paleoflora of the Pennsylvanian-early Permian: paleobiogeographical relationships to central and western equatorial Pangaea. Gondwana Research 14(3): 297-305.
Rohr, D. M., R. A. Davis, S. H. Mamay, and J. M. Miller. 1987. Leonardian plant-bearing beds from the Del Norte Mountains, west Texas. Pp. 67-68 In: D. W. Cromwell, Jr. and L. J. Mazzullo (eds.), The Leonardian Facies in W. Texas and S.E. New Mexico and Guidebook to the Glass Mountains, West Texas, Society of Economic Paleontologists and Mineralogists (SEPM) Guidebook 87-27. Midland: Permian Basin Section, SEPM, 111 pp.
Rohr, D. M., B. R. Wardlaw, S. F. Rudine, A. J. Hall, R. E. Grant, and M. Haneef. 1991. Guidebook to the Guadalupian symposium. Pp. 18-111 In: B. R. Wardlaw, R. E. Grant, and D. M. Rohr, (eds.), Proceedings of the Guadalupian Symposium. Alpine: Sul Ross State University, 111 pp.
Taylor, T. N., E. L. Taylor, and M. Krings. 2009. 19. Gymnosperms with obscure affinities. Pp. 757-785 In: T. N. Taylor et al., Paleobotany: The Biology and Evolution of Fossil Plants, Second Edition. Burlington: Elsevier Academic Press, 1230 pages.
Wardlaw, B. R. 2000. Guadalupian conodont biostratigraphy of the Glass and Del Norte Mountains. Pp. 37-88 In: B. R. Wardlaw, R. E. Grant, and D. M. Rohr, (eds.), The Guadalupian Symposium, Smithsonian Contributions to the Earth Sciences 32. Washington D. C.: Smithsonian Institution Press, 415 pp.
Wardlaw, B. R., R. A. Davis, D. M. Rohr, and R. E. Grant. 1990. Chapter A, Leonardian-Wordian (Permian) Deposition in the Northern Del Norte Mountains, West Texas. U. S. Geological Survey Bulletin 1881, Washington, D. C., 14 pp.
Weber, R. 1997. How old is the Triassic flora of Sonora and Tamaulipas, and news on Leonardian floras in Puebla and Hidalgo, Mexico. Revista Mexicana de Ciencias Geológicas 14(2): 225-243.
Yang, Z. and T. E. Yancey. 2000. Fusulinid biostratigraphy and paleontology of the Middle Permian (Guadalupian) strata of the Glass Mountains and Del Norte Mountains, West Texas. Pp. 185-259 In: B. R. Wardlaw, R. E. Grant, and D. M. Rohr, (eds.), The Guadalupian Symposium. Smithsonian Contributions to Earth Sciences Number 32. Washington D. C.: Smithsonian Institution Press.
The image above is a slab containing the impression of Delnortea abbottiae, which was unearthed from Unit 5 of Section IV of fossiliferous exposures in the Del Norte Mountains and separated from the holotype specimen (shown at the top of the page, USNM 364416). A colleague, Dave Rohr, Ph.D., photographed this impression in the early 1980s. I introduced the false-color variations of the matrix on these two images using ADOBE PHOTOSHOP. The mudstone matrix true-color of USNM 364416 is dull beige-gray.
A concluding note from the field. I was the scientist responsible for unearthing, selecting, and packing specimens for shipment to the Department of Paleobiology, USNM. Hundreds of pieces from fossilized leaves estimated to be 20 to 30 cm long were left behind in the tailings at the dig. Limonite mineralizations of fossilized leaves were more abundant lower in the section.
Students of Permian seed plant paleobotany should take into account the phrase on Page 760 of T. N. Taylor et al. (2009), "most specimens of D. abbottiae are 3-5 cm long, but some may have been up to 30 cm," is imprecise. Fossil delnorteas left-behind in bedding planes were typically much larger than "3-5 cm," which was a fact not widely known until now, begging future field work to include georeferencing, stratigraphic, and taphonomic studies of Unit 5.
Morphometric data and scaling studies of the foliar remains illustrated above and below are needed. Future field work should employ more sophisticated bed- and depositional layer-specific sampling methods, which are necessary to overcome field problems of "what to count" (Materials and Methods, page 77, DiMichele et al. 2010), or to answer the following question.
Do the detached "leaves" shown above and below belong to the same mother plant or two different sympatric seed plant species?
This fossilized fragment of Taeniopteris sp. photographed by Dave Rohr, Ph.D., is one of hundreds of weathered rocks left behind in the tailings of the Bird Mountain Delnortea beds. While unusable for taphonomic studies, rock fragments in the bulldozed tailings are important reminders of fossilized remains in intact slabs and sedimentary layers yet to be surveyed in Section IV of the uppermost Member of the Cathedral Mountains Formation.
[ 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, Morley 2001). 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 magnoliid 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 (J. 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 1979).
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, Kubitzki 1993).
Floral biology of degenerias. A study of floral phenology and biology was conducted by the author in the 1980s. Flowers in the canopies of trees in the Naitaradamu stand, specifically spirally-arranged foliar organs of the perianth, exhibit peculiar rhythmic circadian movements, which are indicative of a proterogynous breeding system, probably enforcing outcrossing and creating habitat for phytophagous insects and pollinators (J. M. Miller 1989).
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).
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.
The stage-specific movements of floral organs, including scent emissions of degenerias, are remarkably similar to those observed in other Magnoliales (Endress 1984, Bernhardt and Thien 1987; page 97, Figure 1, C.-C. Pang and Saunders 2014; page 337, Figure 2, C.-C. Pang and Saunders 2015).
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 (D. E. Soltis et al. 2011).
Detailed, but preliminary field studies of degenerias were conducted on the upper slopes of Mount Deliakoro (941 meters) on Vanua Levu Island, which is the highest point in the Korotini Range ("Deliakoro Study Site") and eastern rim of the Deliakoro Caldera.
The tree on the left is a young specimen of Degeneria roseiflora, which is Tree No. 63 in one of the several stands I discovered on the south coast of Vanua Levu Island in 1987. This was the specimen (J. M. Miller 1189-63), which was trimmed to provide the Y. L. Qiu Gen Bank tissue DNA isolate. A neighboring tree (No. 68) was cut-down to yield bark and wood samples studied by Sherwin Carlquist in 1989. Bark of mature Degeneria roseiflora is often "cinnamon-brown or light gray" [especially in immature trees] (J. M. Miller 1988, Key to Species on page 587, A. C. Smith 1991). Kini Vosarara is standing next to the tree.
According to A. C. Smith (1979) 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, 1241 meters), Vanua Levu (Mount Manuka, elevation 1194 meters), and Viti Levu (Mount Tomanivi, elevation 1323 meters).
Vanua Levu Island is "frying-pan-shaped" more than 200 km in length. It includes low mountains such as Mount Mariko (elevation 881 meters), 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 is located southeast of the "panhandle" of Vanua Levu (A. C. Smith 1979).
Focused studies of Degeneria on Viti Levu Island were conducted near Mount Naitaradamu (1153 meters). Flowering and fruiting trees found at the "Naitaradamu Study Site," yielded many of the samples collected and studied by electron microscopy.
Near Naitaradamu in the catchment of the Wainikoroiluva River, degenerias (a tree canopy is illustrated to the left) were marked with numbered aluminum tags, which were affixed to the gray bark of each study tree. Peni Bulivakarua is pictured on the right while marking a large Degeneria specimen in 1986. The bark of mature Degeneria vitiensis is "dark gray to black" (J. M. Miller 1988, Key to Species on page 587, A. C. Smith 1991).
Masiratu stands here 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).
On the Rairaimatuku (Nadrau) Plateau of Viti Levu Island, on the slopes of Mount Naitaradamu, and at Monasavu Reservoir, trees of Degeneria vitiensis were up to 35 meters tall and one meter in diameter.
Trees of Degeneriaceae 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 of the Rewa River and tributaries.
Masiratu trees possess distinct, light-green canopies with shiny foliage. Liriodendron- or Magnolia-like flowers are borne on terminal, leafy branchlets, hence another common name, "Fiji Magnolia," coined on millennial Republic of Fiji documents.
The above image is a flowering branch of a Degeneria vitiensis tree, which is indigenous to the Colo-I-Suva Forest Reserve on Viti Levu Island. Colo-I-Suva is located in the upper reaches of a catchment feeding a southwesterly-flowing minor tributary of the mighty Rewa, which is the largest river on the island. The image was captured by Professor Hervé Sauquet, Laboratoire Ecologie Systématique et Evolution, Equipe Evolution des Angiospermes, Université Paris-Sud, France, and is posted here with his written permission.
Classical literature on Degeneriaceae suggests that pollen-bearing floral organs are microsporophylls and not stamens (Canright 1952).
Yet, some paleobotanists depart from this view without backing-up their homology assessments with biochemical evidence from the development of magnoliid reproductive SAMs.
The image on the left is a scanning electron micrograph of a detached Degeneria vitiensis microsporophyll, ×5. To the right is a close-up scan of Degeneria pollen lodged in a furrow of this same microsporophyll. The pollen-bearing organ was hand-collected from a flowering tree in the Naitaradamu stand.
How could future tool kit studies clarify homologies of Degeneria microsporophylls with foliar organs?
Developmental genetics of magnoliids. Great gaps exist in an understanding of the evolutionary-development (evo-devo) of magnoliids as only a few model species are amenable for biochemical studies. Avocado (Persea americana) is the best-known model organism but other candidate species are the subject of ongoing laboratory research (Chanderbali et al. 2010). Molecular tool kits of degenerias are unstudied from this research perspective. Cultivation of either species of Degeneria is difficult.
A solitary carpel of a flower of Degeneria vitiensis is depicted in the right-hand scanning electron micrograph, ×15.
An image gallery contains more scanning electron micrographs of the floral organs of Degeneria. The scanning electron micrographs are from flower parts collected in tree canopies of Degeneria at the Naitaradamu and Delaikoro study areas ... LINK
Important reviews of floral evo-devo include Baum and Hileman (2006), P. S. Soltis et al. (2009), Specht and Bartlett (2009), Chanderbali et al. (2010), Melzer et al. 2010, Mathews and Kramer (2012), Glover (2014), Melzer et al. 2014, and Specht and Howarth (2015), among others.
"... by studying the underlying developmental processes that give rise to particular morphologies, investigations of convergence in phenotype [e.g. Degeneria microsporophylls and laminar stamens] can help us to understand the correlations among GRNs [gene-regulatory networks], developmental processes [i.e. 'process homology'] and derived phenotypes" (page 87, VIII. Conclusion, Specht and Howarth 2015 [phrases in brackets are mine]).
Viti Levu Island is the largest landmass of the Fiji Archipelago. The Rairaimatuku (Nadrau) Plateau of the island is visible in the background of the image below. This photograph was taken from the main road to Nadarivatu and the Tomanivi trailhead at a high point east of Monasavu. There are numerous canopies of Degeneria vitiensis visible in this image including several trees accessible from the track by utility vehicles.
Molecular systematics of magnoliids. Despite many published field and laboratory studies on the basic biology and evolution of magnoliid basal angiosperms (A. C. Smith 1981, 1991, J. M. Miller 1988 [two papers], Carlquist 1989, J. M. Miller 1989, J. A. Doyle and Endress 2000, among others), the molecular phylogenetic relationships among the component families and genera are unclear. Possibly critical families such as Annonaceae, Degeneriaceae, Magnoliaceae, and Winteraceae are incompletely studied from this research perspective (Sauquet et al. 2003, P. S. Soltis et al. 2009, D. E. Soltis et al. 2011, Massoni et al. 2014, Massoni et al. 2015, S. Müller et al. 2015).
Molecular phylogenetic studies of magnoliids by Hervé Sauquet and others (Massoni et al. 2014) reveal unexpected relationships of Degeneria with Myristicaceae. In fact, the Gen Bank sample at the heart of these perplexing results is from a tree in a known stand (J. M. Miller 1189) bearing one of my numbered aluminum tags. This tree is Degeneria roseiflora and not "Degeneria vitiensis," which is imprecisely stated in one published molecular study. As of the date of this writing it is not known whether Sanger- or pyro-sequencing methodology will resolve the two species of Degeneria, or their potential natural hybrids.
Notes from the field. The Gen Bank sample was shipped by air to Y. L. Qiu at the Missouri Botanical Garden late in October 1987, and is from a tree bearing the aluminum tag No. 63. Tree 63 is from a documented stand (J. M. Miller 1189, SUVA [DA 22253, fruits were obtained on 27 June 1987 as a voucher specimen]).
My field book states, "Degeneria roseiflora, Fiji, Vanua Levu Island, Cakaudrove Province, 35.5 km W of the Trans-insular Highway and a km or so N of the Wailevu Coast Road on the logging spur that leads to Keka Village," 23 October 1987.
Uluitana, a signature volcanic plug of Vanua Levu Island, and pristine Fijian tropical forest, is pictured above and to the right. Much of the forest in the area surrounding the Dreketi Forestry Station has been logged and replanted with nawanawa (Cordia subcordata, Boraginaceae, Asteranae) and Mexican mahogany (Swietenia macrophylla, Meliaceae, Rosanae), among other species.
Bioinventories in the Nakauvadra Range published by Conservation International in 2013, report additional stands of Degeneria roseiflora. These United Nations sponsored inventories of Fijian forests continue.
Interestingly, the Nakauvadra Range of Viti Levu Island is directly across the strait from the western tip of Vanua Levu Island.
The northern side of the charismatic Korombasabasaga Range of Viti Levu Island as viewed from the slopes of Mount Naitaradamu, which is one of two 1986-1988 Degeneria study sites proposed on page 4 of a letter to Harm J. de Blij, editor, National Geographic Research, Volume 4 (1988) and outlined by J. M. Miller in 1989, is pictured above and to the left.
The image above on the right is the southwestern face of the Korombasabasaga Range above Namosi Village. The cliffs in the distance constitute the Namosi Andesite according to Rodda and Kroenke (Appendix 7.1, page 100, 1984).
Much of the past molecular phylogenetic work suggests a close relationship between Degeneriaceae and Himantandraceae (page 89, Figure 3, Massoni et al. 2014). A 26S rDNA isolate from the only Gen Bank sample of Degeneria available, when subjected to phylogenetic analyses, reveals "surprising" results (page 90, Figure 4, Massoni et al. 2014).
"... we argue that this result is due to an artifact of attraction between the well-known long stem branch of Myristicaceae [Sauquet et al. 2003] and the unusually long branch of Degeneria for 26S rDNA" (page 91, Discussion, 4.5, 26S rDNA Isolate of Degeneria Leads to Long Branch Attraction, Massoni et al. 2014).
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.
The scanning electron micrograph (right-hand image) is the anterior front part of the head of Haptoncus tahktajanii, the cucujiform phytophagous associate of the primitive magnoliid flowering plant Degeneria vitiensis.
Some of the gustatory, olfactory, and visual sensory organs of the nitidulid beetle are visible including antennae, sensillae, compound eyes, mandibles, maxillae, and labia.
Several additional 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.
At the Delaikoro Study Area on Vanua Levu Island, staphylinid beetles inhabited flowers of Degeneria roseiflora while nitidulids were uncommon in the flowers sampled there. More field work will be necessary in order to confirm these observations.
The oldest verifiable fossil nitidulid is from Upper Cretaceous Siberian amber from tree resins exuded more than 80 MYA (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.
Above and 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.
An insect specimen from the gallery of scanning electron micrographs of Haptoncus tahktajanii is shown on either side of this text. The left-hand image is the posterior (anus) of the invertebrate. The anterior (mouth) of the same beetle appears on the right. The preparation 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, which is visible in the scanning electron micrograph shown to the right.
Professor Roger A. Beaver of the Department of Biology, The University of the South Pacific, identified the nitidulid beetles. Al Soeldner of the Oregon State University Electron Microscope Facility prepared and photographed the specimens on this page.
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).
Jack A. Wolfe, Ph.D. visited Vanua Levu Island in 1988 to select possible study sites for his angiosperm leaf margin analyses. His image was captured by the author during our field trip to view stands of Degeneria.
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.
Degenerias are indigenous to three islands Miocene or younger in age (J. M. Miller 1989). Yet, preliminary estimates on the nodal age of the Degeneria stem lineage, based on molecular-phylogenetic inference (the only Gen Bank sample is from a single tree of D. roseiflora growing on an island 7.5 million years old) ranges from 101 to 134 million years old (Figure 1 and Table 1, Massoni et al. 2015). More DNA sampling, including both species of Degeneria (D. vitiensis has not been studied to date), should be sequenced and analyzed, in my opinion.
There has been considerable speculation on the origin and dispersal of magnoliids on the southern continents and island archipelagoes by Carlquist (1974), Raven and Axelrod (1974), Thorne (1986), J. A. Doyle (2000), Poole and Francis (2000), and R. J. Morley (2001), among others.
Biogeographic studies of basal flowering plants and magnoliids cloud some of these ideas, including conclusive evidence drawn from modern molecular-phylogenetic studies of magnoliid clades (Massoni et al. 2015). Based on Professor David Greenwood's unpublished field studies, and my collection of palm fruit casts sent to Professor Emeritus David Dilcher (the specimen was in sedimentary float found in a ravine on the eastern tip of Vanua Levu Island in 1987), there is a potentially rich and unstudied paleoflora of the two largest islands of the Fiji archipelago to be added to this line of scientific inquiry.
Studies of more than 200 trees in numerous native stands of Degeneria from Vanua Levu and Viti Levu islands by J. M. Miller (1988, 1989), underscore a need to learn more on the paleobiogeography, ecology, and population genetics of these endemic relict magnoliids of the tectonically complex Fiji archipelago, South Pacific Ocean.
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Field work on Degeneriaceae of the Fiji Islands was sponsored by a grant from the National Geographic Society. Scanning electron micrographs were prepared by Al Soeldner, Director, Oregon State University Electron Microscopy Laboratory. I thank Hervé Sauquet, Ph.D., Laboratoire Ecologie Systématique et Evolution, Equipe Evolution des Angiospermes, Université Paris-Sud, France, for contributing an image of Degeneria vitiensis. David Greenwood, Ph.D., University of Manitoba, Canada, was also kind to share his field experiences on the unstudied Fijian paleoflora. This article is dedicated posthumously to paleobotanist Jack A. Wolfe, Ph.D.
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.
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