ynology 139 (2006) 41–52www.elsevier.com/locate/revpalbo

Review of Palaeobotany and Pal

Late Cambrian acritarchs from the “Túnel Ordovícico del Fabar”,Cantabrian Zone, N Spain

Roberto Albani a,⁎, Gabriella Bagnoli a, Enrique Bernárdez b,Juan Carlos Gutíerrez-Marco b, Cristiana Ribecai a

a Dipartimento di Scienze della Terra, Università di Pisa, Via S. Maria, 53-56126 Pisa, Italyb Instituto de Geología Económica (CSIC-UCM), Facultad de Ciencias Geológicas, 28040 Madrid, Spain

Received 29 October 2004; received in revised form 10 March 2005; accepted 25 July 2005Available online 14 March 2006

Abstract

A single sample from the La Matosa Member of the Barrios Formation, exposed during the excavation of the El Fabar Tunnel inAsturias, N Spain, yielded a rich and well-preserved Late Cambrian acritarch assemblage. The Middle? to Upper Cambrian LaMatosa Member consists mainly of quartz sandstone and includes locally a thick fossiliferous intercalation of dark shale (“El Fabarbeds”) from which the acritarch sample was collected. The latter shale levels yielded also some linguliform brachiopods, olenidtrilobites and phyllocarid crustaceans.

Characteristic genera of the study sample are Acanthodiacrodium, Lusatia and Cristallinium. Other significant components areCymatiogalea, Timofeevia and Vulcanisphaera.

Lusatia dendroidea Burmann 1970, recorded for the first time in Spain, is a characteristic element of this assemblage. In thestudy sample, the latter species is abundant, well-preserved and exhibits appreciable morphological variability.

This acritarch assemblage is correlated with the lower part of microflora RA5 of Parsons and Anderson [Parsons, M.G.,Anderson, M.M., 2000. Acritarch microfloral succession from the Late Cambrian and Ordovician (early Tremadoc) of RandomIsland, eastern Newfoundland, and its comparison to coeval microfloras, particularly those of the East European Platform. AASPContr. Ser. 38, 129 pp.] corresponding to the Protopeltura praecursor trilobite Zone.© 2006 Elsevier B.V. All rights reserved.

Keywords: acritarchs; Late Cambrian; biostratigraphy; Cantabrian Zone; Spain

1. Introduction

The excavation of the El Fabar tunnel of theCantabrian superhighway in the Asturias, northernSpain (Fig. 1), provided the opportunity to investigatecontinuous Cambrian to Ordovician successions of theLaviana and Rioseco nappes (Gutiérrez-Marco et al.,

⁎ Corresponding author. Fax: +39 050 2215800.E-mail address: albani@dst.unipi.it (R. Albani).

0034-6667/$ - see front matter © 2006 Elsevier B.V. All rights reserved.doi:10.1016/j.revpalbo.2005.07.005

2003) with a rich and diverse fossiliferous content. TheCambrian to Ordovician exposure in the CantabrianZone (NW Spain) is otherwise discontinuous andsparsely fossiliferous (see Aramburu and Garcìa-Ramos, 1993; Liñán et al., 2002; Aramburu et al.,2004, for a more accurate regional stratigraphical settingand previous references).

In the tunnel section, the Cambrian to OrdovicianBarrios Formation consists of ca. 800 m of white quartzsandstone with some interbedded micaceous shale, andconformably overlies Middle Cambrian glauconitic

Fig. 1. Geological sketch map of the area between Caravia and Ribadesella (Asturias, N Spain) showing the northeastern ends of the Laviana (W) andRioseco nappes and the location of the El Fabar tunnel section (1) (modified after Gutiérrez-Marco et al., 2003).

42 R. Albani et al. / Review of Palaeobotany and Palynology 139 (2006) 41–52

sandstone and green shale of the Oville Formation (Fig.2). In the lower part of the Barrios Formation,corresponding to La Matosa Member, a ca. 40 m.thick intercalation of dark shale, named as “El Fabarbeds”, occurs. These beds represent a deeper marinefacies, as testified also by the presence of somephyllocarids, obolid brachiopods and olenid trilobitesof the Parabolina (Neoparabolina) assemblage, whichunconformably overlies tidal delta sandstone (Gutiérrez-Marco and Bernárdez, 2003; Gutiérrez-Marco et al.,2003).

The Middle Ordovician (upper Oretanian to lowerDobrotivian) Sueve Formation is mainly composed byshale and unconformably overlies the BarriosFormation.

The rich Late Cambrian acritarch assemblagedescribed in this study is from a single sample collectedin the La Matosa Member during the excavation of thetunnel. This sample comes from the lowermost part ofthe El Fabar beds, being derived from an horizon of darkshale directly above a 25 cm thick conglomeratic layer,

that is the basal transgressive lag which unconformablyoverlies the lower part of the La Matosa Member of theBarrios Formation. This unconformity represents a thirdor second order sequence boundary within the localCambrian–Ordovician succession.

Previous published data on Late Cambrian acritarchsfrom the Cantabrian Zone are by Fombella (1978,1979), Fombella Blanco (1986, 1987) and FombellaBlanco et al. (1993), from the inferred diachronousOville Formation (Fombella Blanco, 1986; Aramburu etal., 1992; Aramburu and Garcìa-Ramos, 1993). Thediachronous character of the Oville Formation and itsstratigraphic relationships with the Barrios Formationare not discussed in this paper. The acritarch assem-blages from the Oville Formation, reportedly of LateCambrian age (Fombella, 1978, 1979; Fombella Blanco,1986, 1987; Fombella Blanco et al., 1993), cannot bedirectly compared with our assemblage because onlyfew long-ranging taxa are shared.

The only previous record of acritarchs from theBarrios Formation is in an abstract by Vanguestaine and

Fig. 2. Stratigraphic section of the El Fabar tunnel with significant bedsand fossils from the Barrios Formation (from Gutiérrez-Marco et al.,2003). Asterisk indicates the study level.

43R. Albani et al. / Review of Palaeobotany and Palynology 139 (2006) 41–52

Aramburu (1988) that reported acritarchs of Middle toLate Cambrian age from La Matosa Member in theBarrios de Luna section (NW Spain).

Among the remaining Spanish Palaeozoic areas, LateCambrian acritarchs are known from the IberianCordillera (Aragonese Branch), where Wolf (1980)reported a small assemblage, recorded in a single samplefrom near the base of the Borrachón Formation. Thiswas considered to be of basal Tremadocian age at thattime (Wolf, 1980), but after the formal designation of theglobal standard for the Cambrian/Ordovician boundaryin 1999, the corresponding beds are unambiguously ofterminal Late Cambrian age. Moreover, the olenid–asaphid trilobite assemblage (Parabolina Fauna)recorded at higher levels within the Borrachón Forma-

tion may be also coeval with the latest CambrianCordylodus proavus conodont Biozone (Gutiérrez-Marco et al., 2002 and references therein).

In the same area (Borovia locality), Palacios (1997)re-examined some acritarch assemblages from theTorcas Fm. (Acón Group), previously studied byGámez et al. (1991). On the presence of characteristicacritarch species (i.e. Eliasum llaniscum Fombella inFombella Blanco, 1977), the latter authors assignedthese samples to the Middle Cambrian Paradoxidesparadoxissimus Trilobite Superzone. According toPalacios (1997), the new record, in the same samples,of specimens referred to Cristallinium randomenseMartin in Martin and Dean, 1981 emend. Martin inMartin and Dean, 1988, and Polygonium martinaeMoczydłowska and Crimes, 1995, suggested a LateCambrian age.

Nevertheless in a recent paper Gozalo et al. (2004)revised data on Cambrian successions of IberianCordillera and assigned the entire Torcas Fm to theMiddle Cambrian, thus supporting the previous (Gámezet al., 1991) dating.

Late Cambrian acritarchs have also been recorded inthe Ossa Morena Zone, in an assemblage comprising,among others, Dasydiacrodium obsonum Martin inMartin and Dean, 1988 and Trunculumarium revinium(Vanguestaine, 1973) Loeblich and Tappan, 1976, fromthe upper “El Playón Beds” of the Alconera basin(Palacios, 1993). The acritarch assemblage reported byMette (1989) from the Umbría–Pipeta Fm cropping-outfarther south, in the Barrancos–Hinojales area, wasconsidered by Palacios (1997) to be also of LateCambrian age, but comparison with the original illustra-tions by Mette (1989) of the most important taxa wasinconclusive and the assemblage seems to fit better in theMiddle Cambrian, as stated originally by Mette.

2. Materials and methods

Forty-five grams of shale were processed usingstandard palynological methods. After treatment withhydrochloric acid (33%) and hydrofluoric acid (40%),the residue was sieved in absolute ethanol, and thenconcentrated by treatment with zinc bromide solution(S.G. 2.5). Neither oxidative nor alkali treatments wereapplied. The residue was studied using light microscopyand scanning electron microscopy. The acritarchs areabundant, well preserved and light brown in colour (TAI3−–3+, Traverse, 1988, pl. 1). The figured specimens arehoused at the Museo Geominero of Madrid of the IGME(Instituto Geológico y Minero de España); repositoryMGM 1050K–MGM 1079K.

Fig. 3. Histogram showing the relative abundance (percent) ofacritarch genera of sampled level.

44 R. Albani et al. / Review of Palaeobotany and Palynology 139 (2006) 41–52

3. Composition and stratigraphic significance of theacritarch association

Twelve taxa have been identified at species level, and7 more are left in open nomenclature, comprising 16genera (Appendix 1). Acanthodiacrodium Timofeev,1958, emend. Deflandre and Deflandre-Rigaud, 1962,Lusatia Burmann, 1970 and Cristallinium Vangues-taine, 1978 (Fig. 3) are especially abundant.

Upper Cambrian acritarch successions from RandomIsland, eastern Newfoundland have been recentlyinvestigated and compared with coeval microflorasfrom different areas by Parsons and Anderson (2000).Based on their biostratigraphic scheme, it is possible tocorrelate the studied assemblage with microflora RA5,Orthosphaeridium? extensum–Acanthodiacrodium sp.B, even though microflora RA5 of Parsons andAnderson (2000, table 1) includes several species thatare not present in the El Fabar sample. Of the two keytaxa, Acanthodiacrodium sp. B was not recorded in thisstudy, and some specimens of O.? extensum asillustrated by Parsons and Anderson (2000) are heretentatively included in the range of variability of Lusatiadendroidea Burmann, 1970 (see taxonomical remarks).However, these problems notwithstanding, the acritarchassociation from the El Fabar beds can be correlatedwith microflora RA5 considering that Cymatiogaleavirgulta Martin in Martin and Dean, 1988 and Vulcani-sphaera turbataMartin in Martin and Dean, 1981 do notextend higher than microflora RA5; Poikilofusa sp. A ofParsons and Anderson (2000) and Impluviculus multi-angularis Umnova in Umnova and Vanderflit, 1971make their appearance in microflora RA5; and Vulcani-sphaera spinulifera (Volkova, 1990) Parsons andAnderson, 2000 is restricted to this interval. Ortho-

Plate I. For each illustrated specimen the following information is given:coordinate. Scale bars: 10 μm, except where otherwise indicated.

1–2a. Acanthodiacrodium achrasi Martin, 1973.1. Tun-Filocar, slide II/1, MGM-1050K, P28.2. Tun-Filocar, stub4, MGM-1051K, S44.2a. Enlargement of the same specimen, showing detail of spines.3, 4. Acanthodiacrodium sp.3. Tun-Filocar, slide>10/1, P50-2, MGM-1052K, N29/3.4. Tun-Filocar, stub 6, K37-3, paratype; MGM-1053K, K44.5. Cristallinium cambriense (Slavíková, 1968; Vanguestaine, 1978)6–8. Cymatiogalea virgulta Martin in Martin and Dean, 1988.6. Tun-Filocar, slide II/sn, MGM-1055K, P35/3.7. Tun-Filocar, slide II/sn, MGM-1056K, P29/1.8. Tun-Filocar, stub 2, MGM-1057K, R46.9,10. Dasydiacrodium obsonum Martin in Martin and Dean, 1988.9. Tun-Filocar, stub 2, MGM-1058K, Q44.10. Tun-Filocar, slide II/1, MGM-1059K, Q47/3.11. Impluviculus multiangularis (Umnova, 1971) Volkova, 1990. Tu

sphaeridium? triangulare (Umnova, 1975) Parsons andAnderson, 2000, here tentatively assigned to Lusatiadendroidea, is also confined to the same interval.Known stratigraphic ranges of the other identified taxaare consistent with this interpretation.

Parsons and Anderson (2000) correlated theirMicroflora RA5 with the Protopeltura praecursor andPeltura minor trilobite Zones, and compared it with theMicroflora A5 of Martin and Dean (1981, 1988) fromRandom Island, eastern Newfoundland. Parsons andAnderson (2000) included in their Microflora RA5 twosamples (C-98021 and C-98022) that Martin (in Martinand Dean, 1988) assigned to the upper part of herMicroflora A4. This was because Trunculumariumrevinium (Vanguestaine, 1973) Loeblich and Tappan,

sample label, slide number, repository number and England Finder

Tun-Filocar, slide>10/1, MGM-1054K, Y28.

n-Filocar, slide II/1, MGM-1060K, Q44/2.

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46 R. Albani et al. / Review of Palaeobotany and Palynology 139 (2006) 41–52

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1976, whose abundance characterizes Microflora A4, isonly present as a single specimen in one sample.Leiofusa stoumonensis Vanguestaine, 1973, anothercharacteristic component of Microflora A4, is rare orabsent in RA5. Therefore, the upper part of MicrofloraA4 of Martin (in Martin and Dean, 1988) is similar incomposition to the lower part of Microflora RA5 ofParsons and Anderson (2000), thus corresponding tothe P. praecursor Zone. The acritarch distributionreported by the latter authors in table 2 (sectionextending from north of Weybridge to north of Elliot'sCove) and table 3 (Section 1, from south of BoundsMead to north of the causeway) indicates that in thisinterval Dasydiacrodium caudatum Vanguestaine,1973 and L. stoumonensis are not present, and thatT. revinium is present only in one sample, andAcanthodiacrodium sp. B, the index species ofMicroflora RA5, makes its appearance only in the P.minor Zone. Therefore, the composition of the studyassemblage, where D. caudatum, L. stoumonensis, T.revinium and Acanthodiacrodium sp. B are notpresent, is more likely to correlate with the lowerpart of microflora RA5. On the other hand, in oursample, Poikilofusa sp. A of Parsons and Anderson(2000), Impluviculus multiangularis, Vulcanisphaeraspinulifera, and Orthosphaeridium? triangulare (ten-tatively assigned here to Lusatia dendroidea) arepresent, whereas they make their entry, according toParsons and Anderson (2000) at higher levels ofMicroflora RA5. This could be explained by the scarceacritarch content in the lower part of RA5 from RandomIsland, by a different geographical distribution, or,possibly, because of a previously uninvestigated intervalin eastern Newfoundland.

One of the most characteristic and well-preservedtaxa of our association is the genus Lusatia, which isdoubtfully present in the Newfoundland microfloras.Uncertainties about taxonomic assignment derive from

Plate II. For each illustrated specimen the following information is given:coordinate. Scale bars: 10 μm, except where otherwise indicated.

1–4,7. Lusatia dendroidea Burmann, 1970.1. Tun-Filocar, slide II/sn, MGM-1061K, P49/2.2. Tun-Filocar, slide II/sn, MGM-1062K, U36/3.3. Tun-Filocar, slide II/sn, MGM-1063K, Q49/24. Tun-Filocar, stub 1, MGM-1064K, O44.7. Tun-Filocar, slide II/2, MGM-1065K, J39.5,9. Polygonium sp.5. Tun-Filocar, slide>10/1, MGM-1066K, F29.9. Tun-Filocar, stub 8, MGM-1067K, O45/4.6. Poikilofusa sp. A, Tun-Filocar, slide>10/1, MGM-1068K, F29.8. Virgatasporites rudii Combaz, 1967, Tun-Filocar, slide II/1, MG10. Saharidia sp., Tun-Filocar, slide>10/1, MGM-1070K, D41/4.

the fact that taxa herein tentatively assigned to Lusatia,i.e. Orthosphaeridium? extensum and Orthosphaeri-dium? triangulare of Parsons and Anderson (2000), arepoorly preserved and none of the figured specimens iscomplete.

Lusatia is well-represented in assemblage VK4 ofVolkova (1990), from the Moscow syneclise, Russia.Other shared species are Cristallinium cambriense(Slavíková, 1968) Vanguestaine, 1978, Vulcanisphaera(as Raphaesphaera) spinulifera, Impluviculus multi-angularis, Veryhachium? dumontii Vanguestaine, 1973,Timofevia phosphoritica Vanguestaine, 1978, Virgatas-porites rudii Combaz, 1967 (as Leiosphaeridia sp. 1).Nevertheless, according to Parsons and Anderson(2000), the stratigraphic position of assemblage VK4cannot be properly established, owing to possiblereworking from older beds.

The following species, namely Timofeevia phosphor-itica, Vulcanisphaera turbata, Impluviculus multiangu-laris, Veryhachium? dumontii, Cymatiogalea virgulta,Dasydiacrodium obsonum Martin in Martin and Dean,1988, Lusatia dendroidea (as Lusatia sp. 1) werereported also from the Upper Cambrian of Belgiumand northern France (Ribecai and Vanguestaine, 1993),from levels between Zones 5 and 6 of Vanguestaine(1986). We can exclude correlation of the studiedassemblage with the latter zones, owing to the absenceof Trunculumarium revinium (Zone 5) and Ladogellarommelaerei (Martin, 1981) Di Milia et al., 1989 (Zone6). The El Fabar microflora might correspond to the cf.Zone 5 that is said to correlate with the lower part ofmicroflora RA5 from Random Island by Parsons andAnderson (2000).

4. Conclusions

The rich and well-preserved acritarch assemblagefrom the El Fabar beds indicates the presence of a Late

sample label, slide number, repository number and England Finder

M-1069K, G28/4.

48 R. Albani et al. / Review of Palaeobotany and Palynology 139 (2006) 41–52

Cambrian palynoflora in the La Matosa Member of theBarrios Formation, allowing precise palynologicaldating of the El Fabar beds. The acritarch associationhas been correlated with the Protopeltura praecursor

trilobite Zone. This interval is here reported for the firsttime in Spain and it is characterized by the highvariability of representatives of the genus LusatiaBurmann, 1970.

49R. Albani et al. / Review of Palaeobotany and Palynology 139 (2006) 41–52

The studied acritarch assemblage and the presence ofarticulate carapaces of olenid trilobites and phylloaridsin the El Fabar beds support the interpretation of adeeper environmental setting for this level within LaMatosa Member (Gutiérrez-Marco et al., 2003).

5. Taxonomical notes

Identified taxa are all figured and listed in alphabet-ical order. Well known taxa are only listed and figuredand not discussed further.

Genus Acanthodiacrodium Timofeev, 1958, emend.Deflandre and Deflandre-Rigaud, 1962.

Type–species — Acanthodiacrodium dentiferum Timo-feev, 1958 (fixed by monotypy).

Acanthodiacrodium sp.(Plate I; 3, 4).

Dimensions (6 specimens): vesicle width 22.4 (24) 25.8μm, length 25.3 (27.8) 30.4 μm; equatorial zone length10 (12) 15 μm; process length 6.9 (12.3) 17.2 μm.Description: Vesicle outline sub-rectangular with straightto slightly convex sides. Processes distributed at theopposite poles, numerous, ca. 10–15 at each pole,homomorphic, hollow and freely communicating withvesicle interior, subconical,with pointed tips. Eilyma psilateto scabrate without diacrodian folds in the wide equatorialzone. Excystment structure in form of a longitudinal splitobserved only in one specimen (Plate I, 3).Remarks: Acanthodiacrodium achrasi differs fromAcanthodiacrodium sp. by having shorter processesand spiny ornamentation on vesicle and process eilyma.

Plate III. For each illustrated specimen the following information is givencoordinate. Scale bars: 10 μm, except where otherwise indicated.

1-2a. Stelliferidium? sp.1. Tun-Filocar, slide>10/1, MGM-1071K, P27/1.2. Tun-Filocar, stub 8, MGM-1072K, P46/2.2a. Enlargement of the same specimen, showing detail of processes3–4. Timofeevia phosphoritica Vanguestaine, 1978.3. Tun-Filocar, stub 2, MGM-1073K, R48.3a. Enlargement of the same specimen, showing detail of plate marg4. Tun-Filocar, slide>10/1, MGM-1074K, O45/1.5. Vulcanisphaera turbata Martin in Martin and Dean,1981. Tun-Fi6. Veryhachium? dumontii Vanguestaine, 1973. Tun-Filocar, slide II7. Stelliferidium cortinulum (Deunff, 1961) Deunff et al., 1974. Tun8–9a. Vulcanisphaera spinulifera (Volkova, 1990) Parsons and Anderso8. Tun-Filocar, slide>50/2, MGM-1078K, K48.9. Tun-Filocar, stub 2, MGM-1079K, Q45/3.9a. Detail of the same specimen showing the characteristic short pro

Genus Lusatia Burmann, 1970.

Type–species: Lusatia dendroidea Burmann, 1970.

Lusatia dendroidea Burmann, 1970.(Plate II; 1–4, 7)

1970 Lusatia dendroidea sp. n. Burmann, p. 296, Pl. VI,figs. 1–4.

? 1978 Lusatia aff. dendroidea Burmann—Dean andMartin, p. 8, Pl. 3, Fig. 21.

1990 Lusatia dendroidea Burmann—Volkova, p. 71, Pl.XXI, figs. 1–2.

?1990 Lusatia triangularis (N. Umnova, 1975) comb.nov. — Volkova, pp. 71–72, Pl. XXI, figs. 5–7.

?1990 Lusatia sp. 1 — Volkova, pp. 72–73, Pl. XXI,figs. 3–4.

?1993 Lusatia? sp. 1— Ribecai and Vanguestaine, Pl. I,fig. 11.

?2000 Orthosphaeridium? extensum sp. nov. Parsonsand Anderson, pp. 61–62 (partim), Pl. 9, figs. 1,3, 4, 10, 13 (non figs. 2, 11, 12).

?2000 Orthosphaeridium? triangulare Umnova, 1975,comb. nov.—Parsons and Anderson, p. 62, Pl. 9,fig. 5.

Dimensions (68 specimens): vesicle width 18.4 (26) 34.5μm, length 23.5 (33.2) 40.2 μm; apical process length43.7 (69.9) 90.8 μm; antapical process length 42.5(62.7) 88.5 μm; branching length 12.6 (31.1) 49.5 μm.Remarks: According to the original diagnosis, Lusatiadendroidea is characterized by a vesicle with threeprocesses, two of which are branched. Most of studiedspecimens conform with Burmann's (1970) diagnosis;however, some forms exhibit one, two or four processes.

: sample label, slide number, repository number and England Finder

arranged in small polygonal fields.

ins

locar, slide II/1, MGM-1075K, J49/2./1. MGM-1076K, G29.-Filocar, slide>10/1, MGM-1077K, T28/1.n, 2000.

cess tuft.

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Tentatively, the present authors include them in Lusatiadendroidea. Studies on more than one sample arenecessary to understand whether this wide morpholog-ical variability indicates one or more species.Previous records: Upper Cambrian: Moscow Sineclise,East European Platform (Volkova, 1990); N France(Ribecai andVanguestaine, 1993); easternNewfoundland,Canada (Parsons and Anderson, 2000)? Tremadocian:Saxo-Thuringia, Germany (Burmann, 1970); easternNewfoundland, Canada (Dean and Martin, 1978).

Genus Poikilofusa (Staplin et al., 1965) Loeblich andTappan, 1978.

Type–species: Poikilofusa spinata Staplin et al., 1965(by original designation).

Poikilofusa sp. A.(Plate II; 6).

2000 Poikilofusa sp. A—Parsons and Anderson, pp.62–63, Pl. 9, fig. 9 (cum syn.)

Dimensions (2 specimens): vesicle width 20.7–26.4 μm;vesicle length 136.2–149.7 μm.Remarks: The outline of the present specimens closelyconform with that of Poikilofusa sp. A described byParsons and Anderson (2000), the vesicle being slightlyconstricted towards either ends. The present forms haveslightly sculptured eilyma with longitudinally arrangedgrana, more visible on the distal ends.Previous records: Upper Cambrian: northwest Wales(Young et al., 1994); Estonia (Paalits, 1992); easternNewfoundland, Canada (Parsons and Anderson, 2000).

Genus Stelliferidium Deunff et al., 1974.

Type–species: Stelliferidium striatulum (Vavrdová,1966) Deunff et al., 1974 (by original designation).

Stelliferidium? sp.(Plate III; 1–2a).

2000 Stelliferidium sp. B—Parsons and Anderson, pp.67–68, Pl. 12, figs. 10–12.

Dimensions (6 specimens): vesicle diameter 25.8 (27.2)28.1 μm; process length 3.4 (4.9) 6.9 μm; pylomediameter 18.4 μm.Remarks: Stelliferidium? sp. conforms with the descrip-tion of Stelliferidium sp. B by Parsons and Anderson(2000), having 40–60 short cylindrical processes with

palmate terminations, and a pattern of radiating striaeextending from the process bases. A veil connecting theprocesses is frequently present (Plate III, 1,2). Theeilyma sculpture consists of irregularly arranged wrinklesgiving the appearance of a pitted surface visible alsounder light microscope. However, the present formsappear to have processes arranged in polygonal fields(Plate III, 2,2a). Thus a tentative generic attribution ofthe above specimens is herein preferred.Previous records: Upper Cambrian: eastern Newfound-land, Canada (Parsons and Anderson, 2000).

Acknowledgements

Stewart Molyneux and Michel Vanguestaine contrib-uted to improve the manuscript with useful commentsand suggestions. This work was supported by a grant toProf. G. Bagnoli (“Cofinanziamento di Ateneo”, PisaUniversity).

Appendix A. List of acritarch taxa

Acanthodiacrodium achrasi Martin, 1973.Acanthodiacrodium sp.Baltisphaeridium sp.Cristallinium cambriense (Slavíková, 1968) Vanguestaine,

1978.Cymatiogalea virgultaMartin in Martin and Dean, 1988.Dasydiacrodium obsonum Martin in Martin and Dean,

1988.Impluviculus multiangularis (Umnova in Umnova and

Vanderflit, 1971) Volkova, 1990.Lusatia dendroidea Burmann, 1970.Micrhystridium spp.Polygonium sp.Poikilofusa sp. ASaharidia sp.Stelliferidium cortinulum (Deunff, 1961) Deunff et al.,

1974.Stelliferidium? sp.Timofeevia phosphoritica Vanguestaine, 1978.Veryhachium? dumontii Vanguestaine, 1973.Virgatasporites rudii Combaz, 1967Vulcanisphaera spinulifera (Volkova, 1990) Parsons and

Anderson, 2000.Vulcanisphaera turbataMartin in Martin and Dean,

1981.

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