Copyright © 2004 by The University of ChicagoA single mummified angiosperm seed is described from a middle Eocene clay lens deposit at the Monier East Yatala Sand Pit, Golden Grove, South Australia. The seed is small (0.7 mm long and 0.45 mm wide), elliptical, black, and shows complex raised reticulate honeycomb sculpturing with deeply excavated cell floors and verrucate sculpturing on the anticlinal ridges. The fossil was compared against extant species of Byblis and the Droseraceae, especially the Drosera indica L. complex, common annual carnivorous plants that grow in seasonally damp environments in northern Australia and that have similarly small sculptured seeds. The combination of deep reticulately honeycombed cells and the verrucate anticlinal walls places the seed close to extant taxa in the Byblis liniflora Salisb. complex. However, in the absence of a larger sample and/or of definitive features to assign the fossil unequivocally to an extant species, as well as nomenclatural restrictions preventing the typification of a fossil by an illustration, the specimen is described as a parataxon and placed in Byblidaceae but without a formal name.Conran, John G., and David C. Christophe

Christophel, D.

Conran, J.

International Journal of Plant Sciences

English

Adelaide Research & Scholarship

A FOSSIL BYBLIDACEAE SEED FROM EOCENE SOUTH AUSTRALIAJohn G. Conran1,* and David C. Christophel*,y*Centre for Evolutionary Biology and Biodiversity, Environmental Biology, School of Earth andEnvironmental Sciences, Darling Building DP418, University of Adelaide, South Australia5005, Australia; and yDepartment of Biological Sciences, University of Denver,2190E Iliff Avenue, Denver, Colorado 80210, U.S.A.A single mummiﬁed angiosperm seed is described from a middle Eocene clay lens deposit at the Monier EastYatala Sand Pit, Golden Grove, South Australia. The seed is small (0.7 mm long and 0.45 mm wide), elliptical,black, and shows complex raised reticulate honeycomb sculpturing with deeply excavated cell ﬂoors andverrucate sculpturing on the anticlinal ridges. The fossil was compared against extant species of Byblis and theDroseraceae, especially the Drosera indica L. complex, common annual carnivorous plants that grow inseasonally damp environments in northern Australia and that have similarly small sculptured seeds. Thecombination of deep reticulately honeycombed cells and the verrucate anticlinal walls places the seed close toextant taxa in the Byblis liniﬂora Salisb. complex. However, in the absence of a larger sample and/or ofdeﬁnitive features to assign the fossil unequivocally to an extant species, as well as nomenclatural restrictionspreventing the typiﬁcation of a fossil by an illustration, the specimen is described as a parataxon and placed inByblidaceae but without a formal name.Keywords: Byblidaceae, fossil, seed, Eocene, South Australia, carnivorous plant.IntroductionThe Eocene ﬂoras of southern Australia have yieldeda wealth of mummiﬁed leaves, ﬂowers, and fruits for numer-ous mostly woody rainforest families (e.g., Christophel andGreenwood 1987, 1988; Christophel et al. 1987, 1992; Hill1982, 1994). Nevertheless, there is evidence at some Eocenesites for the beginnings of xeromorphic adaptation and forpossibly seasonal or monsoonal climates (Greenwood 1996;Hill and Brodribb 2001).In 1986, a middle Eocene fossiliferous clay lens was dis-covered at the Monier East Yatala Sand Pit, Golden Grove,South Australia (138439300E, 34479100S), ca. 25 km north-east of the city of Adelaide. This deposit was rich in leaves,ﬂowers, and fruits of a wide range of rainforest taxa includ-ing the dicotyledonous families Elaeocarpaceae, Lauraceae,Myrtaceae, Proteaceae, Sterculiaceae, the monocotyledonParacordyline(Laxmanniaceae),thegymnospermfamilyPodo-carpaceae, and a fern in the Lygodiaceae (Christophel andGreenwood 1987; Conran and Christophel 1998). The lenswas dated palynologically as Middle Eocene (Alley 1987),with the original environment considered to be similar toa modern complex notophyll vine forest (Christophel andGreenwood 1987).Examination of the Golden Grove clays for seeds andfruits revealed a number of mostly small ca. 3–5-mm nonde-script ovoid seeds with possible afﬁnities to Lauraceae butwithout any distinctive features that would allow assignmentto any family with certainty (D. C. Christophel, unpublishedobservations). However, a single small, distinctively sculp-tured seed was recovered from the site, bearing close resem-blance to the extant carnivorous plant genus Byblis(Byblidaceae).Byblis Salisb. currently consists of seven species: four an-nual species from northern Australia (Lowrie and Conran1998), with Byblis liniﬂora Salisb. extending to southernNew Guinea (van Steenis 1971), and two perennial speciesfrom southwestern Australia (Conran et al. 2002; Conranand Carolin 2004). Studies of seed morphology in Byblishave shown that seed morphology is a highly useful characterat species level, with a range of useful sculpturing and otherseed coat features helping to deﬁne the different taxa (Lowrieand Conran 1998; Conran et al. 2002).In particular, the annual species form a complex acrossnorthern Australia, growing in seasonally inundated placesand surviving the dry season as soil-buried seed. As such,they might be expected to be ideal candidates for preser-vation in a depositional environment. However, because themajority have seeds less than a millimeter in length, theycould easily be overlooked. Most recent studies of Tertiaryseeds from Australia have dealt with relatively large seededor fruited taxa (Rozefelds 1991, 1995; Rozefelds and Chris-tophel 1996a, 1996b; Greenwood et al. 2000, 2001; Dett-mann and Clifford 2001), but there are currently no seeds orfruits described from the Golden Grove site. Because there isno prior fossil record for the Byblidaceae (micro- or macro-fossil), the seed is described here, and its afﬁnities with extantByblis species are discussed.1 Author for correspondence; e-mail john.conran@adelaide.edu.au.Manuscript received February 2003; revised manuscript received January2004.691Int. J. Plant Sci. 165(4):691–694. 2004. 2004 by The University of Chicago. All rights reserved.1058-5893/2004/16504-0019$15.00Material and MethodsPieces of fossiliferous clay matrix were placed in a 2%–3%aqueous solution of hydrogen peroxide at ca. 60C and al-lowed to disaggregate. After removal of any leaf or otherlarge fragments, the sediment was sieved through a series ofprogressively smaller mesh sizes and then washed with dis-tilled water. The resulting macerate was examined under a dis-secting microscope, and any recognizable seeds were removedand digitally photographed. The samples were then stored atthe University of Adelaide Palaeobotany collection (ADU) invials containing a 1% phenol 50% ethanol mixture. Unfortu-nately, there was a disaster where a tray of extracted small tominute fossil seeds and cuticles (including the fossil) was acci-dentally dropped, smashing them. This happened shortly af-ter the seed had been imaging using light microscopy butbefore SEM or anatomical investigation could occur. As a re-sult, the only extant record of the taxon is the photographpresented here. Nevertheless, there is sufﬁcient detail in theimage to indicate its afﬁnities to Byblidaceae.The difﬁculty with formally naming the fossil is the lossof the type other than as a photograph. Under the St.Louis version of international code of botanical nomencla-ture, Article 8.5 states that the type of ‘‘the name of a fossilplant of the rank of species or below is always a specimen’’(Greuter et al. 2000, p. 11). Similarly, Article 9.13 states:‘‘the holotype or lectotype of a name of a species or infra-taxon of fossil plants is the specimen (or one of the speci-mens) on which the validating illustrations are based’’(p. 15). Because the designation of a formal name for thefossil would result in a nomen invalidum under the currentcode, the specimen is hereby assigned to Byblidaceae butdescribed as a parataxon.Seeds of wild collected populations of Byblis aquaticaLowrie & Conran from the Northern Territory, Byblis ﬁlifo-lia from the Kimberley or Western Australia, Byblis liniﬂorafrom northern Queensland and Byblis rorida Conran &Lowrie from the Kimberley (voucher details listed in Conranet al. 2002) were examined under SEM and stereo dissectingmicroscope for size and sculpturing comparisons. DescriptionFig. 1 Golden Grove Byblidaceae fossil and seeds of similar extant Byblis species for comparison. A, Golden Grove Byblidaceae seed Molenaars.n. (ADU, destroyed; represented by the photograph); scale bar ¼ 200 mm. B, Byblis ﬁlifolia A. Lowrie 2041 (PERTH). C, Byblis liniﬂora A.Lowrie 1320 (PERTH). D, Byblis rorida R.L. Barrett 595 (PERTH). B–D all to indicated scales.692 INTERNATIONAL JOURNAL OF PLANT SCIENCESand comparisons of the seed follow the features used byLowrie and Conran (1998) and Conran et al. (2002).SystematicsOrder—LamialesFamily—Byblidaceae (Engler & Gilg.) K. Domin.Parataxon. Golden Grove Byblidaceae seed.Locality. East Yatala Sand Pit, Golden Grove, South Aus-tralia (138439300E, 34479100S).Stratum. Base of the Proteacidites pachypolis Zone of theTertiary southern Australian palynological zone (Alley 1987).Age. Middle Eocene.Description. Seed small (0.7 mm long and 0.45 mmwide), black, elliptical, ends rounded, micropylar end slightlymore acute. Testal cells 7–9 along the long axis and 4–6across; cells 90–140 mm long and 80–120 mm wide (mean110 390 mm). Testa reticulately honeycombed; longitudinalridges minutely denticulate-crenulate; transverse ridges shal-low. Periclinal walls deeply concave; anticlinal wall ridgesverrucate (ﬁg. 1A).DiscussionComparison of the fossil with extant Byblis taxa immedi-ately rules out the perennial temperate species because theirseeds have prominent ribbed lamellar or muricate processes(Conran et al. 2002). Among the tropical annual species, By-blis aquatica has conspicuous longitudinal furrows and ridgesand is very different from the Golden Grove fossil (table 1),which more closely resembles seed of Byblis ﬁlifolia (ﬁg. 1B),Byblis liniﬂora (ﬁg. 1C), and Byblis rorida (ﬁg. 1D). The ver-rucate anticlinal ridges resemble those of B. liniﬂora and B.rorida (the ridges in B. ﬁlifolia are smooth), and the size ofthe fossil seed and lack of obvious irregular anticlinal rough-ening places it closest to B. liniﬂora (table 1). Nevertheless,in the absence of a number of representative seeds of the fos-sil to allow sculpturing and size variability to be assessed,care must be taken in placing it with an extant taxon. Simi-larly, because the extant species are differentiated on anther,gland, and chromosomal characters in addition to seed sizeand testal sculpturing, the fossil can be placed only into theB. liniﬂora complex.Byblis is not the only tropical Australian marsh plant pro-ducing abundant small black reticulately sculptured seeds. Inparticular, many of the carnivorous Drosera L. and Utricu-laria L. (Lentibulariaceae) with which Byblis grows also havesmall sculptured seeds (Dwyer 1983; Taylor 1989). In partic-ular, Drosera indica L. (Droseraceae), which, like the tropicalByblis species with which it grows, is an annual carnivorousplant from ephemeral soaks, pond, and creek margins, alsoshows considerable variation in seed morphology and sculp-turing across northern Australia (Susandarini 2001; Susan-darini et al. 2002). However, although D. indica mostlyshows reticulate honeycombing, the seeds are ovoid-elliptical,tapering at the micropylar end, and the periclinal sculpturingand anticlinal concavities are very different from the fossil(see illustrations in Susandarini et al. 2002), ruling it out asa possible candidate for afﬁnities with the fossil. Similarly,the seed coat patterns seen in other Australian carnivorousplants do not match those of the Byblidaceae (Dwyer 1983;Taylor 1989).The clay lens at Golden Grove possibly represents an ox-bow lake and is thought to have been surrounded by com-plex notophyll vine forest similar to that seen in extantrainforests in north Queensland (Christophel and Greenwood1987). Providing there is good light, Byblis is often a commontaxon around such pondages and along creeks, especiallywhere drawdown during the dry season exposes the mud forcolonization by herbaceous annuals (Lavarack 1981; Lowrie1998). Thus, if there was a dry season resulting in drawdownat the Golden Grove site (which occurs even in the wettropics of present-day north Queensland), the palaeoenviron-ment would have been ideal for Byblidaceae species, furthersupporting the identiﬁcation of the seed.AcknowledgmentsMonier Ltd. are thanked for access to the Monier EastYatala Sand Pit, Golden Grove, South Australia. Trudy Mo-lenaar is thanked for the maceration and sorting of theTable 1Seed Character Data for the Golden Grove Byblidaceae Fossil and the Extant Annual NorthernAustralian Species Byblis aquatica, Byblis ﬁlifolia, Byblis liniﬂora, and Byblis rorida(modiﬁed from Conran et al. 2002)CharacterGolden GroveByblidaceae B. liniﬂora B. ﬁlifolia B. aquatica B. roridaLength (mm) 0.7 0.5–0.9 (0.7) 0.4–1.1 (0.7) 0.9–1.3 (1.0) 0.5–0.8 (0.6)Width (mm) 0.45 0.4–0.6 (0.5) 0.3–0.8 (0.5) 0.4–0.7 (0.6) 0.4–0.6 (0.5)Longitudinal ridges Denticulate Minutely denticulate Denticulate Smooth, prominent Minutely denticulateTransverse ridges Shallow Shallow Deep Absent ShallowAnticlinal wallsculpturing Verrucate Tuberculate-verrucateSmooth Smooth IrregularlyroughenedCell length (mm) 90–140 (110) 73–165 (119) 57–178 (120) 114–150 (130) 54–74 (66)Cell width (mm) 80–120 (90) 68–104 (88) 42–132 (82) 10–78 (66) 52–65 (60)Periclinal walls Unclear Foveolate Foveolate Smooth SmoothNote. Numbers in parentheses represent mean values.693 CONRAN & CHRISTOPHEL—FOSSIL BYBLIDACEAE SEEDspecimens as part of studies toward an honors degree in thethen Department of Botany (now Environmental Biology) atthe University of Adelaide. Professor Dr. Werner Greuter(Botanic Garden and Botanical Museum Berlin-Dahlem) isthanked for his extremely helpful advice regarding the no-menclatural issues raised by the loss of the type specimen.Literature CitedAlley NF 1987 Middle Eocene age of the megafossil ﬂora atGolden Grove, South Australia: preliminary report and com-parison with the Maslin Bay ﬂora. Trans R Soc S Aust 111:211–212.Christophel DC, DR Greenwood 1987 A megafossil ﬂora from theEocene of Golden Grove, South Australia. Trans R Soc S Aust 111:155–162.——— 1988 A comparison of Australian tropical rainforest andTertiary fossil leaf-beds. Proc Ecol Soc Aust 15:139–148.Christophel DC, WK Harris, AK Syber 1987 The Eocene ﬂora of theAnglesea locality, Victoria. Alcheringa 11:303–323.Christophel DC, LJ Scriven, DR Greenwood 1992 An Eocenemegafossil ﬂora from Nelly Creek, South Australia. Trans R Soc SAust 116:65–76.Conran JG, RC Carolin 2004 Byblidaceae. Pages 45–49 in JKadereit, ed. The families and genera of vascular plants. Vol 7.Dicotyledons: Lamiales. Springer, Berlin.Conran JG, DC Christophel 1998 Paracordyline aureonemoralis(Lomandraceae): an Eocene monocotyledon from South Australia.Alcheringa 22:351–359.Conran JG, A Lowrie, J Moyle-Croft 2002 A revision of Byblis(Byblidaceae) in south-western Australia. Nuytsia 15:11–20.Dettmann ME, HT Clifford 2001 The fossil record of Elaeocarpus L.fruits. Mem Queensl Mus 46:461–497.Dwyer TP 1983 Seed structure in carnivorous plants. Carniv PlantNewsl 12:8–22, 33–38, 45–50.Greenwood DR 1996 Eocene monsoon rainforests in central Aus-tralia? Aust Syst Bot 9:95–112.Greenwood DR, PW Haines, DC Steart 2001 New species ofBanksieaeformis and a Banksia ‘‘cone’’ (Proteaceae) from theTertiary of central Australia. Aust Syst Bot 14:871–890.Greenwood DR, AJ Vadala, JG Douglas 2000 Victorian Paleogeneand Neogene macroﬂoras: a conspectus. Proc R Soc Vic 112:65–92.Greuter W, J McNeill, FR Barrie, H-M Burdet, V Demoulin, TSFilgueiras, DH Nicolson, et al, eds 2000 International code ofbotanical nomenclature (Saint Louis code) adopted by the SixteenthInternational Botanical Congress, St. Louis. July–August 1999.Koeltz Scientiﬁc, Ko ¨nigstein. 474 pp.Hill RS 1982 The Eocene megafossil ﬂora of Nerriga, New SouthWales, Australia. Palaeontogr B 181:44–77.———, ed 1994 History of the Australian vegetation: Cretaceous torecent. Cambridge University Press, Cambridge. 433 pp.Hill RS, T Brodribb 2001 Macrofossil evidence for the onset ofxeromorphy in Australian Casuarinaceae and tribe Banksieae(Proteaceae). J Mediterr Ecol 2:127–136.Lavarack PS 1981 The northern rainbow plant Byblis liniﬂora.Carniv Plant Newsl 10:102–103.Lowrie A 1998 Carnivorous plants of Australia. Vol 3. University ofWestern Australia Press, Perth. 288 pp.Lowrie A, JG Conran 1998 A taxonomic revision the genus Byblis(Byblidaceae) in northern Australia. Nuytsia 12:59–74.Rozefelds AC 1991 Mid-Tertiary Sacropetalum (Menispermaceae)from Glencoe, mid-eastern Queensland. Alcheringa 15:145–150.——— 1995 Miocene Wilkinsonia fruits (Hicksbeachiinae, Protea-ceae) from the base of the Yallourn Formation, Latrobe Valley,Victoria. Pap Proc R Soc Tasman 129:59–62.Rozefelds AC, DC Christophel 1996a Elaeocarpus (Elaeocarpaceae)endocarps from the Early to Middle Miocene Yallourn formation ofEastern Australia. Muelleria 9:229–237.——— 1996b Elaeocarpus (Elaeocarpaceae) endocarps from theOligo-Miocene of Eastern Australia. Pap Proc R Soc Tasman 130:41–48.Susandarini R 2001 Investigation of the population variation ofDrosera indica L. complex using combined morphological andmolecular techniques. MS diss. Adelaide University.Susandarini R, GG Collins, A Lowrie, JG Conran 2002 Morpho-logical variation within the Drosera indica (Droseraceae) complexin northern Australia. Aust J Bot 50:207–214.Taylor P 1989 The genus Utricularia: a taxonomic monograph.HMSO, London. 724 pp.van Steenis CGGJ 1971 Byblidaceae. Flora Malesiana Bull Suppl SerI 7:135–137.694 INTERNATIONAL JOURNAL OF PLANT SCIENCES

A fossil byblidaceae seed from eocene South Australia

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